Reliability of center of pressure measures in chronic stroke survivors: Effect of motor and cognitive loads

Reliability of center of pressure measures in chronic stroke survivors: Effect of motor and cognitive loads | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Reliability of center of pressure measures in chronic stroke survivors: Effect of motor and cognitive loads Mitra Parsa, Iraj Abdollahi, Hossein Negahban, Mohammad Ali Sanjari, and 5 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4066043/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Background: One of the major objectives of stroke rehabilitation is to enhance balance control. Therefore, it is crucial to have standardized and reliable balance measures to pinpoint areas for rehabilitation. This study examines the between-day and within-day reliabilities of the center of pressure (CoP) measures in chronic stroke survivors in different standing positions during the effect of motor and cognitive loads. Methods: Sixteen people (49.31±15.5 years, 5 females) with chronic stroke were assessed in two sessions, 48 hours apart in three conditions: single-task, motor dual-task, and cognitive dual-task. In each condition, three trials of open-eyes quiet standing and three trials of semi-tandem standing were completed, while in the single task condition, three trials of closed-eyes quiet standing were also done. Intraclass correlation coefficient (ICC 2,3 ), standard error of measurement (SEM), and minimal detectable change (MDC) were calculated for CoP mean velocity, mean velocity in the anterior-posterior (AP) and medial-lateral (ML) directions, the standard deviation of AP and ML velocity, and sway area. Results: Within-day ICC values were higher than between-day values (ICCs ranged from 0.78 to 0.96). Mean velocity and mean and SD of velocity in the AP direction showed the highest relative (ICC: 0.82 and 0.92, 0.83 and 0.90, and 0.84 and 0.90, respectively) and absolute reliabilities (SEM: 0.74 and 1.24, 0.67 and 0.84, and 0.87 and 1.08) in an open-eyes quiet standing position. Dual-task performance could also increase the reliability of the CoP measures, except for the sway area (ICC:0.53-0.93 changed to 0.84-0.96). The semi-tandem standing position was the least reliable position in a single-task condition (ICC:0.53-0.89). Conclusions: CoP measures during various positions and conditions have sufficient reliability in chronic stroke survivors. Assessing the postural control system during dual-task conditions provides more reliable CoP measures, especially in a semi-tandem standing position. reliability CoP measures dual task stroke Background Approximately, 50% of stroke survivors experience residual physical disabilities ( 1 , 2 ). These individuals experience deficits in the sensory, musculoskeletal, perceptual, and cognitive systems, which affect their balance control and increase the risk of falls ( 1 – 3 ). Therefore, the major objective of stroke rehabilitation is to enhance balance control. It is crucial to have standardized and reliable balance measures in clinical settings to pinpoint areas for rehabilitation and monitor progress over time ( 4 , 5 ). Clinicians often use observational performance-based scales to evaluate balance performance ( 6 ). However, the compensatory strategies used to complete tasks within the scales are unknown. This lack of knowledge fails to reveal underlying dyscontrol, which could potentially increase the risk of falling, and should be focused on rehabilitation programs ( 5 ). To evaluate the specific deficits of the balance control system, center of pressure (CoP) excursion is typically recorded using a force platform in a laboratory setting ( 2 , 4 , 7 ). CoP excursions can differentiate between fallers and non-fallers ( 8 – 10 ) and are associated with clinical outcome measures, such as the Berg Balance Scale and Timed Up and Go Test, in elderly and post-stroke individuals ( 2 ). Given the promising ability of CoP measures to detect impaired balance control mechanisms, limited information about their reliability for assessing balance among chronic stroke survivors is available. Similar to many biological measurements, the intrinsic variability of CoP measures influences their reliability as well as the validity and responsiveness of postural control assessments. Additionally, reliability is not a static characteristic and varies based on the population studied ( 11 , 12 ). To date, several studies have reported the reliability of CoP measures of standing position in different populations with disequilibrium problems ( 13 – 16 ) and healthy elders ( 12 , 17 – 20 ). Few studies have reported these findings collectively throughout various stages of post-stroke recovery ( 11 , 21 – 23 ). It is worth noting that only one study has specifically examined the reliability of CoP-based variables among chronic stroke survivors, in which a limited number of conventional variables were selected as a part of the main objective ( 3 ). During the chronic stage of stroke recovery, rehabilitative interventions have an approximately net effect on the patient improvement, when spontaneous recovery of the brain has almost plateaued ( 24 ). Accordingly, assessing the reliability of CoP measures in chronic stroke survivors could provide deeper insights into clinical decision-making and upcoming research. Moreover, to our knowledge, no study has investigated the reliability of the tandem standing position in individuals with chronic stroke; however, this position is commonly used to predict the risk of falling ( 10 , 25 ). It is believed that to define underlying deficiencies in the postural control system that may increase the potential risk of falling, clinicians should use an eye-closed narrow stance condition during balance assessment ( 9 ). Therefore, in the present study, an open-eyes semi-tandem standing position was selected to enable post-stroke individuals to successfully complete the assessment procedure. So far, only one study has examined the reliability of CoP measures during different postural stability tasks in post-stroke patients at different stages of recovery. This study aimed to evaluate the reliability of CoP measures across three different postural stability tasks regardless of the impact of motor dual-task on the reliability of CoP measures ( 22 ). Furthermore, it has been mentioned that performing a cognitive dual-task while walking is a more challenging activity for post-stroke individuals than for healthy individuals. Dual-tasking results in spatiotemporal locomotor adaptations, which may help post-stroke individuals maintain balance. At the same time, their attention is simultaneously directed to an external source of attention in dual-task conditions ( 26 ). Post-stroke survivors can exhibit enhanced balance control with either motor or cognitive dual-task training ( 27 ). Thus, the present study aimed to examine the within-day and between-day reliabilities of CoP measures in chronic stroke survivors in different standing positions with the effect of motor and cognitive loads. Methods 2.1. Participants This study was approved by the Ethics Committee of the University of Social Welfare and Rehabilitation Sciences (No: IR.USWR.REC.1398,136), and all subjects provided informed consent before participating in the study (Including the agreement for publication of anonymized data) in accordance with the declaration of Helsinki recommendations for investigations with human participants. Participants were sixteen people with chronic stroke (> 6 months post-stroke) participated in an unpublished clinical trial (No: IRCT20220703055350N1) that aimed to determine the effect of frontal plane-focused balance training on balance performance and falls in chronic stroke patients. Common inclusion criteria were as follows: 1) ability to stand and walk independently for at least one minute 2) ability to hold a semi-tandem position for at least 30 seconds without the support of another person, and 3) no recent limb surgery or uncorrected visual or auditory impairments. Participants with 1) a score higher than 2 on the Modified Ashworth Scale in Gastrocnemius muscle, 2) a score lower than 24 on the Mini-Mental State Examination-Persian version ( 28 ), 3) a standard deviation (SD) of ± 1 or greater on the Line Bisection Test (hemineglect history) ( 29 ), and 4) conditions other than stroke that may affect their balance control were excluded. Age, height, weight, sex, and type of stroke were obtained from participants. They were also assessed by clinical balance-related scales, including, the Berg Balance Scale (BBS), Mini-Balance Evaluation System Test (Mini-BEST), and Activities-Specific Balance Confidence (ABC) (Table 1 ). Table 1 Demographic and clinical characteristics of the participants (n:16) Variable Mean / count SD Minimum Maximum Age (years) 49.31 15.50 27 76 Height (cm) 166.33 11.93 147 187 Weight (kg) 69.27 13.06 52 86 Sex Male:11 Female:5 Stroke type Ischemic:8 Hemorragic:5 Unknown:3 Hemiparetic side Right:6 Left:10 BBS (score out of 56) 51.81 4.51 42 56 Mini-BEST (score out of 28) 20.43 5.42 12 27 ABC (score out of 100) 70.96 19.28 23.43 70.96 SD: standard deviation, BBS: Berg Balance Scale, Mini-BEST: Mini-Balance Evaluation System Test, ABC: Activities- Specific Balance Confidence. 2.2. Procedure CoP data were obtained using two adjacent strain gauge Kistler force platforms (model No: 9286BA, Switzerland) along the anterior-posterior and medial-lateral directions. Assessments were accomplished by the same raters, in the same place and at the same time in two sessions, 48 hours apart, with three trials per session. Postural sway was measured in three conditions: single-task, motor dual-task, and cognitive dual-task conditions. In the single-task condition, participants stood on the platforms while maintaining an open-eye quiet standing position (Open-Quiet), a semi-tandem standing position (Open-Tandem), and a closed-eye quiet standing position (Closed-Quiet). In the motor and cognitive dual-task conditions, the participants stood in the quiet standing position and the semi-tandem standing position (Motor-Quiet, Motor-Tandem, and Cognitive-Quiet, Cognitive-Tandem, respectively). For a quiet standing position, the participants were instructed to stand barefoot in a comfortable position on two adjacent force plates. Each foot was placed on a separate force plate about the center of its length with the feet shoulder-width apart. During the semi-tandem position, both feet were placed on the same plate, with a foot-width distance between them, and the affected leg in front ( 30 ). The rater, position of the feet, time, and environment of the assessment remained the same throughout all assessment sessions. In the motor dual-task condition, participants were asked to hold a tray containing a glass of water. In the cognitive dual-task, they performed the congruent Stroop test ( 31 ). For the Stroop task, a board with forty-five words was placed two meters away from the participants. The words were names of four different colors, were written in the same color ink, and were arranged in nine rows of five words. All positions were held for approximately 30 seconds. The assessment session consisted of three trials for each testing position with a 30-second break between trials. During the test, participants were instructed to stand still and quietly and if possible, with their arms at their sides, looking ahead, except in the eyes-closed condition. To ensure safety during the assessments, participants were supervised by a physiotherapist. 2.3. Data processing Force platform data were sampled at 100 Hz, and processed using a low-pass filter at 10 Hz. A MATLAB routine computed CoP measures for combining both plates (net-CoP). The mean and SD of the velocity of the net-CoP along the anterior-posterior (AP) (Vap and SD.Vap) and medial-lateral (ML) directions (Vml and SD.Vml), mean velocity (Vmean), and sway area (Area) were chosen as CoP measures because of their demonstrated relevance in hemiplegic stroke patients ( 11 ). Moreover, the selected measures followed previous recommendations ( 32 ). The velocity of the CoP reflects the efficiency of the postural control system to counteract postural sway via neuromuscular activity. The lower the velocity is, the better the balance control. SD is the variability index of CoP movements ( 33 ). The sway area quantifies the 95% ellipse formed by the CoP excursion, representing overall postural control system performance. A smaller sway area generally indicates better balance control system performance ( 33 ). 2.4. Statistical analysis Data analysis was conducted using SPSS version 21. A two-way random model of the intraclass correlation coefficient ( \({ICC}_{\text{2,3}}\) ) with a corresponding 95% confidence interval (CI) was chosen to estimate the relative reliability. ICC values were calculated for within-day reliability using three assessment trials in a single session. The average of three trials in two separate sessions was implemented for between-day reliability. Munro’s classification for reliability coefficients was used to represent the degree of reliability: 0.00–0.25 – little, if any correlation; 0.26–0.49 – low correlation; 0.50–0.69 – moderate correlation; 0.70–0.89 – high correlation and 0.90–1.00 – very high correlation ( 34 ). Absolute reliability was determined using the standard error of measurement (SEM). The SEM ( SD × \(\sqrt{1-ICC})\) indicates how much a change in measurement score is due to random error, where SD is the standard deviation of the measurements ( 35 ). SEM indicates how much a change in the measurement score is due to random error ( 35 ). The minimal detectable change (MDC = 1.96×√2× SEM ) was also calculated, representing a clinically significant change between two measurement scores not due to random error ( 35 ). The statistical significance level was considered to be α = 0.05. Results The demographic characteristics of the participants are presented in Table 1 . Please insert Table 1 near here. Table 2 represents the mean scores and standard deviations (SDs) for the COP measures under different test conditions. Table 2 Test-Retest means and SDs of the CoP measures in all conditions CoP measure Single-task Motor dual-task Cognitive dual-task Test position Test mean (SD) Retest mean (SD) Test position Test mean (SD) Retest mean (SD) Test position Test mean (SD) Retest mean (SD) Vml (mm/s) Open-Quiet Closed-Quiet Open-Tandem 9.78 (2.62) 10.69 (2.77) 15.05 (4.50) 9.42 (1.56) 10.81 (2.47) 15.14 (3.03) Motor-Quiet Motor-Tandem 9.95 (3.31) 14.87 (4.24) 9.51 (2.25) 14.00 (4.40) Cognitive-Quiet Cognitive-Tandem 10.47 (2.21) 16.12 (4.30) 10.23 (1.67) 16.36 (3.53) SD.Vml (mm/s) Open-Quiet Closed-Quiet Open-Tandem 12.41 (3.51) 13.60 (3.48) 19.61 (5.92) 11.92 (2.00) 13.80 (3.24) 19.20 (3.86) Motor-Quiet Motor-Tandem 12.65 (4.60) 18.82 (5.38) 12.10 (3.06) 18.43 (5.83) Cognitive-Quiet Cognitive-Tandem 13.33 (2.92) 21.23 (5.41) 12.94 (2.12) 21.29 (4.73) Vap (mm/s) Open-Quiet Closed-Quiet Open-Tandem 12.23 (2.33) 16.47 (4.16) 14.81 (3.77) 12.60 (2.11) 17.39 (4.54) 14.98 (3.23) Motor-Quiet Motor-Tandem 12.55 (3.36) 14.53 (4.37) 12.48 (3.22) 13.97 (4.49) Cognitive-Quiet Cognitive-Tandem 13.58 (2.25) 16.45 (4.88) 14.02 (2.09) 17.11 (5.80) SD.Vap (mm/s) Open-Quiet Closed-Quiet Open-Tandem 15.65 (3.09) 21.43 (5.52) 19.30 (5.00) 16.09 (2.75) 22.68 (6.01) 19.00 (4.68) Motor-Quiet Motor-Tandem 16.03 (4.65) 18.84 (5.93) 15.92 (4.26) 17.99 (5.80) Cognitive-Quiet Cognitive-Tandem 17.34 (3.08) 21.58 (5.71) 18.08 (2.69) 22.29 (7.88) Vmean (mm/s) Open-Quiet Closed-Quiet Open-Tandem 17.34 (3.66) 21.56 (5.20) 23.26 (6.12) 17.38 (2.61) 22.43 (5.28) 22.91 (4.71) Motor-Quiet Motor-Tandem 17.74 (5.12) 22.86 (6.54) 17.36 (4.15) 21.71 (6.58) Cognitive-Quiet Cognitive-Tandem 19.00 (3.26) 25.75 (6.33) 19.16 (2.44) 26.07 (6.82) Area ( \({\varvec{m}\varvec{m}}^{2})\) Open-Quiet Closed-Quiet Open-Tandem 550.63 (700.24) 640.82 (746.46) 897.88 (838.02) 415.83 (433.50) 757.01 (840.56) 807.28 (499.67) Motor-Quiet Motor-Tandem 623.04 (811.53) 879.94 (708.19) 512.60 (502.157) 765.38 (471.91) Cognitive-Quiet Cognitive-Tandem 526.71 (404.46) 769.63 (537.86) 436.19 (181.27) 805.33 (549.10) SD: standard deviation, CoP: center of pressure, V: velocity, ml: medial-lateral, ap: anterior-posterior, Open-Quiet: open-eyes quiet standing, Closed-Quiet: closed-eyes quiet standing, Open-Tandem: open-eyes semi-tandem standing, Motor-Quiet: Motor dual-task Quiet standing, Motor-Tandem: Motor dual-task semi-Tandem standing, Cognitive- Quiet: Cognitive dual-task quiet standing, Cognitive-Tandem: Cognitive dual-task semi-Tandem standing, Vmean: mean velocity, Area: sway area Please insert Table 2 near here. 3.1. The within-day reliability results are presented in Table 3 . Table 3 Within-day Intraclass correlation coefficients, SEM, and MDC of the CoP measures in all conditions. CoP measure Single-task Motor dual-task Cognitive dual-task Test position ICC (95% CI) SEM MDC Test position ICC (95% CI) SEM MDC Test position ICC (95% CI) SEM MDC Vml (mm/s) Open-Quiet Closed-Quiet Open-Tandem 0.93 (0.85–0.98) 0.91 (0.79–0.97) 0.78 (0.50–0.92) 0.41 0.74 1.42 1.14 2.05 3.94 Motor-Quiet Motor-Tandem 0.89 (0.76–0.96) 0.93 (0.84–0.97) 0.75 1.16 2.07 3.22 Cognitive-Quiet Cognitive-Tandem 0.95 (0.88–0.98) 0.85 (0.66–0.94) 0.37 1.37 1.03 3.79 SD.Vml (mm/s) Open-Quiet Closed-Quiet Open-Tandem 0.93 (0.85–0.97) 0.91 (0.79–0.96) 0.79 (0.52–0.92) 0.53 0.97 1.77 1.47 2.69 4.90 Motor-Quiet Motor-Tandem 0.86 (0.68–0.95) 0.94 (0.84–0.98) 1.14 1.43 3.17 3.96 Cognitive-Quiet Cognitive-Tandem 0.94 (0.86–0.98) 0.84 (0.64–0.94) 0.52 1.89 1.44 5.24 Vap (mm/s) Open-Quiet Closed-Quiet Open-Tandem 0.90 (0.77–0.96) 0.90 (0.77–0.96) 0.83 (0.62–0.94) 0.67 1.43 1.33 1.84 3.98 3.69 Motor-Quiet Motor-Tandem 0.96 (0.90–0.98) 0.94 (0.86–0.98) 0.64 1.10 1.78 3.05 Cognitive-Quiet Cognitive-Tandem 0.90 (0.77–0.96) 0.98 (0.95–0.99) 0.66 0.82 1.83 2.27 SD.Vap (mm/s) Open-Quiet Closed-Quiet Open-Tandem 0.90 (0.76–0.96) 0.88 (0.72–0.95) 0.86 (0.68–0.95) 0.87 2.08 1.75 2.41 5.77 4.85 Motor-Quiet Motor-Tandem 0.95 (0.88–0.98) 0.95 (0.88–0.98) 0.95 1.30 2.64 3.59 Cognitive-Quiet Cognitive-Tandem 0.90 (0.75–0.96) 0.96 (0.91–0.99) 0.89 1.58 2.48 4.37 Vmean (mm/s) Open-Quiet Closed-Quiet Open-Tandem 0.92 (0.82–0.97) 0.90 (0.78–0.96) 0.85 (0.65-094) 0.74 1.67 1.82 2.04 4.63 5.05 Motor-Quiet Motor-Tandem 0.94 (0.86–0.98) 0.95 (0.88–0.98) 1.02 1.47 2.82 4.08 Cognitive-Quiet Cognitive-Tandem 0.93 (0.84–0.97) 0.95 (0.89–0.98) 0.64 1.52 1.79 4.22 Area ( \({\varvec{m}\varvec{m}}^{2})\) Open-Quiet Closed-Quiet Open-Tandem 0.95 (0.89–0.98) 0.93 (0.84–0.97) 0.84 (0.63–0.94) 96.93 222.39 199.88 268.60 616.25 553.87 Motor-Quiet Motor-Tandem 0.90 (0.77–0.96) 0.82 (0.59–0.93) 158.80 200.21 440.03 554.79 Cognitive-Quiet Cognitive-Tandem 0.60 (0.12–0.84) 0.86 (0.68–0.95) 114.64 205.45 317.68 569.31 SEM: standard error of measurement, MDC: minimal detectable change, CoP: center of pressure, ICC: Intraclass correlation coefficients, CI: confidence interval, V: velocity, ml: medial-lateral, ap: anterior-posterior, Open-Quiet: open-eyes quiet standing, Closed-Quiet: closed-eyes quiet standing, Open-Tandem: open-eyes semi-tandem standing, Motor-Quiet: Motor dual-task Quiet standing, Motor-Tandem: Motor dual-task semi-Tandem standing, Cognitive- Quiet: Cognitive dual-task quiet standing, Cognitive-Tandem: Cognitive dual-task semi-Tandem standing, Vmean: mean velocity, Area: sway area. Values with ICC greater than 0.70 were highlighted in bold. Generally, the within-day ICCs were greater than the between-day ICCs. 3.1.1 The ICCs for the single-task conditions ranged from 0.78 to 0.95, with high to very high reliability found for all the CoP measures. A semi-tandem standing position showed lower relative and absolute reliabilities than quiet standing positions in single-task conditions (Open-Quiet, Closed-Quiet). The reliabilities of the CoP measures were lower in the closed-eyes quiet standing position than in the open-eyes quiet standing position, especially in terms of the SEM values (0.74-222.39 versus 0.41–96.93, respectively). The sagittal plane measurements (Vap & SD. Vap) had greater reliabilities than did the frontal plane (Vml & SD.Vml) in an open-eyes semi-tandem standing position (Table 3 ). 3.1.2 The ICCs for the motor dual-task conditions ranged from 0.82 to 0.96. As in the single-task condition, all the CoP measures had high to very high reliability. In the motor dual-task condition, a semi-tandem standing position showed lower absolute reliability than quiet standing positions (SEM: 1.10-200.21 versus 0.64–158.80, respectively). Performing a secondary motor task improved the relative and absolute reliabilities in a semi-tandem standing position (ICC: 0.86–0.95 and SEM: 1.10–1.47) compared to the single-task condition (ICC: 0.78–0.86 and SEM: 1.33–1.82), except for the sway area (Table 3 ). 3.1.3 The ICCs for the cognitive dual-task conditions ranged from 0.60 to 0.96. All the CoP measures had high to very high reliability, except for the sway area in the quiet standing position. In the cognitive dual-task condition, a semi-tandem standing position had lower absolute reliability than the quiet standing positions (SEM: 0.82-205.45 versus 0.37-114.64, respectively) (Table 3 ). Performing a secondary cognitive task improved the relative and absolute reliabilities in a semi-tandem standing position (ICC: 0.84–0.98 and SEM: 0.82–1.89) compared to the single-task condition (ICC: 0.78–0.86 and SEM: 1.33–1.82) except for the sway area (Table 3 ). The MDCs ranged from 1.03 mm/s for the Vml (Cognitive-Quiet) to 5.77 mm/s for the SD. Vap (Closed-Quiet) and 268.60 \({mm}^{2}\) for the area of Open-Quiet condition to 616.25 \({mm}^{2}\) for the area of Closed-Quiet condition (Table 3 ). Please insert Table 3 near here. 3.2. The between-day reliability results are presented in Table 4 . Table 4 Between-day Intraclass correlation coefficients, SEM, and MDC of the CoP measures in all conditions. CoP measure Single-task Motor dual-task Cognitive dual-task Test position ICC (95% CI) SEM MDC Test position ICC (95% CI) SEM MDC Test position ICC (95% CI) SEM MDC Vml (mm/s) Open-Quiet Closed-Quiet Open-Tandem 0.78 (0.38–0.92) 0.82 (0.49–0.94) 0.65 (-0.51-0.88) 0.91 0.99 1.94 2.53 2.75 5.38 Motor-Quiet Motor-Tandem 0.93 (0.81–0.98) 0.89 (0.69–0.96) 0.72 1.36 2.01 3.78 Cognitive-Quiet Cognitive-Tandem 0.93 (0.78–0.98) 0.89 (0.69–0.96) 0.49 1.24 1.37 3.43 SD.Vml (mm/s) Open-Quiet Closed-Quiet Open-Tandem 0.77 (0.34–0.92) 0.83 (0.51–0.94) 0.53 (-0.42-0.84) 1.23 1.28 2.80 3.41 3.54 7.77 Motor-Quiet Motor-Tandem 0.93 (0.82–0.98) 0.92 (0.78–0.97) 1.00 1.53 2.78 4.23 Cognitive-Quiet Cognitive-Tandem 0.90 (0.72–0.96) 0.93 (0.79–0.97) 0.77 1.30 2.13 3.59 Vap (mm/s) Open-Quiet Closed-Quiet Open-Tandem 0.83 (0.53–0.94) 0.90 (0.77–0.96) 0.83 (0.62–0.94) 0.84 1.91 1.33 2.34 5.31 3.70 Motor-Quiet Motor-Tandem 0.93 (0.80–0.98) 0.87 (0.63–0.95) 0.84 1.50 2.33 4.16 Cognitive-Quiet Cognitive-Tandem 0.90 (0.72–0.97) 0.89 (0.68–0.96) 0.65 1.68 1.80 4.67 SD.Vap (mm/s) Open-Quiet Closed-Quiet Open-Tandem 0.84 (0.54–0.94) 0.78 (0.37–0.92) 0.81 (0.45–0.93) 1.08 2.45 1.93 3.00 6.78 5.35 Motor-Quiet Motor-Tandem 0.92 (0.78–0.97) 0.87 (0.63–0.95) 1.21 1.98 3.36 5.49 Cognitive-Quiet Cognitive-Tandem 0.86 (0.61–0.95) 0.96 (0.91–0.99) 1.02 2.25 2.82 6.23 Vmean (mm/s) Open-Quiet Closed-Quiet Open-Tandem 0.82 (0.48–0.94) 0.78 (0.38–0.92) 0.66 (0.00-0.88) 1.24 2.22 2.74 3.43 6.16 7.59 Motor-Quiet Motor-Tandem 0.94 (0.82–0.98) 0.88 (0.68–0.96) 1.11 2.15 3.07 5.97 Cognitive-Quiet Cognitive-Tandem 0.88 (0.67–0.96) 0.91 (0.75–0.97) 0.98 1.89 2.72 5.24 Area ( \({\varvec{m}\varvec{m}}^{2})\) Open-Quiet Closed-Quiet Open-Tandem 0.92 (0.76–0.97) 0.96 (0.88–0.98) 0.89 (0.69–0.96) 159.17 156.01 217.04 441.07 432.30 601.42 Motor-Quiet Motor-Tandem 0.90 (0.71–0.96) 0.83 (0.52–0.94) 203.22 229.18 563.11 635.06 Cognitive-Quiet Cognitive-Tandem 0.66 (0.05–0.88) 0.92 (0.77–0.97) 157.94 147.62 437.66 409.06 SEM: standard error of measurement, MDC: minimal detectable change, CoP: center of pressure, ICC: Intraclass correlation coefficients, CI: confidence interval, V: velocity, ml: medial-lateral, ap: anterior-posterior, Open-Quiet: open-eyes quiet standing, Closed-Quiet: closed-eyes quiet standing, Open-Tandem: open-eyes semi-tandem standing, Motor-Quiet: Motor dual-task Quiet standing, Motor-Tandem: Motor dual-task semi-Tandem standing, Cognitive- Quiet: Cognitive dual-task quiet standing, Cognitive-Tandem: Cognitive dual-task semi-Tandem standing, Vmean: mean velocity, Area: sway area. Values with ICC greater than 0.70 were highlighted in bold. 3.2.1 The ICCs for the single-task conditions ranged from 0.53 to 0.96, with moderate to very high reliability found for all the CoP measures. A semi-tandem standing position showed lower relative and absolute reliabilities than quiet standing positions in single-task conditions (Table 4 ). The absolute reliability of CoP measures in a closed-eyes quiet standing position was almost lower than that in an open-eyes quiet standing position (SEM: 0.99–2.22 versus 0.91–1.24, respectively), except for the sway area (Table 4 ). The sagittal plane variables had greater reliabilities than did the frontal plane variables in the open-eyes quiet standing and semi-tandem standing positions in the single-task condition (Table 4 ). 3.2.1 The ICCs for the motor dual-task conditions ranged from 0.83 to 0.94. All the CoP measures had high to very high reliability. The relative and absolute reliabilities were greater in the quiet standing position than in the semi-tandem standing position (ICC: 0.90–0.93 and SEM: 0.72-203.22 versus ICC: 0.87–0.92 and SEM: 1.36-229.18, respectively). Similar to within-day reliability, performing a secondary motor task improved the relative and absolute reliabilities of all CoP measures compared to the single-task condition except for the sway area (Table 4 ). 3.2.2 The ICCs for the cognitive dual-task conditions ranged from 0.66 to 0.96. All the CoP measures had high to very high reliability, except for the sway area in a quiet standing position. In the cognitive dual-task condition, a semi-tandem standing position showed almost lower absolute reliability than the quiet standing position (Table 4 ). Again, performing a secondary cognitive task improved the relative and absolute reliabilities of all CoP measures compared to the single-task condition except for the sway area (Table 4 ). The MDCs ranged from 1.37 mm/s for the Vml (Cognitive-Quiet) to 7.77 mm/s for SD. Vml (Open-Tandem) and 409.06 \({mm}^{2}\) for the Area of the Cognitive-Tandem condition to 635.06 \({mm}^{2}\) for the Area of the Motor-Tandem condition (Table 4 ). Please insert Table 4 near here. Discussion This study aimed to determine the within-day and between-day reliability of COP measures from two adjacent force plates in different standing positions, while a motor or cognitive dual-task was imposed on the postural control system. The findings of this study demonstrated nearly high to very high reliability across all three conditions for CoP measures. Overall, the mean velocity and mean and SD of velocity in the AP direction showed the highest relative and absolute reliabilities, followed by the sway area and mean and SD of velocity in the ML direction. Our results regarding the mean velocity, especially in an open-eyes quiet standing position, are in accordance with previous research on healthy elders ( 14 , 17 , 19 , 20 , 36 ), elderly fallers, and non-fallers ( 37 ), and post-stroke individuals ( 11 , 22 ). According to a review by Ruhe et al., mean velocity is the most reliable conventional parameter of CoP ( 14 ). This means that it is considered more reliable than other parameters such as displacement or sway area. The reason for this is that mean velocity is not solely dependent on the position of the CoP ( 22 ). The CoP mean velocity, which is a summary parameter of the CoP, is commonly preferred since it can minimize the extreme effects of peak values. Moreover, the high reliability of the mean velocity makes it a suitable parameter for evaluating balance control and tracking progress after therapeutic exercises ( 3 ). Our findings also confirmed its high reliability. Additionally, comparing the reliability of velocity in the AP and ML directions in a semi-tandem standing position during the single-task condition, the mean and SD of velocity in the AP direction were found to be more reliable. The lower reliability of frontal plane variables most likely stems from the varying ability to control balance in the ML direction between sessions in stroke survivors. It is possible that the asymmetry in weight bearing due to hemiparesis, along with difficulty in shifting the weight to the affected limb ( 22 ), resulted in inconsistent measures of the CoP in the ML direction across sessions. This inconsistency led to reduced reliability in the variables related to the frontal plane, which is noticeable in the semi-tandem standing position. However, there have been no studies on the reliability of tandem standing in post-stroke individuals. Swanenburg et al. reported that as the stance width increases, there is a disproportionate decrease in the angular motion of ankles and feet. For instance, the mobility of the ankle joint in the frontal plane is reduced when the feet are separated ( 37 ). Similarly, it is possible that standing in a semi-tandem position reduces the range of motion in the sagittal plane, especially at the ankle joint. On the other hand, the base of support increases in the anterior-posterior direction ( 30 ) while maintaining semi-tandem standing, which may result in decreased variability in controlling sagittal plane stability. This, in turn, may improve the reliability of the mentioned variables. Further research could reveal the exact rationale for this finding. Compared to quiet standing positions, the semi-tandem standing position had lower relative and absolute reliability during a single-task condition, however, implementing a dual-task assessment enhanced the reliability except for in the sway area (Tables 3 and 4 ). It is believed that performing a dual task can improve performance by directing attention toward an external source of attention. This may lead to automatic motor function, allowing for more effective performance by shifting motor control from higher cognitive centers to basic noncognitive centers ( 27 ). The automatization of postural control may decrease participants' performance variability and increase the reliability of the results. However, further investigations are needed to prove this opinion. Terra et al. evaluated patients with Parkinson's disease in the tandem standing position under single-task and cognitive dual-task conditions but, the reliability decreased in the dual-task condition compared to the single-task condition in their study, possibly due to significant differences in the foot position, study population, age of the participants, and selected cognitive task ( 16 ). The participants stood with their backfoot’s big toe 5 centimeters apart from the frontfoot’s heel. They conducted their study on patients diagnosed with Parkinson’s disease, with an average age of 71 ± 7.8 years. They instructed them to perform simple mathematical operations as a secondary task while standing in this position. Closing eyes had no significant effect on the CoP parameters in our study, which is the same as the findings of Gasq et al. obtained in their study on post-stroke patients ( 11 ) and other studies on elderlies ( 17 , 19 , 20 , 38 ). However, future studies may reveal the exact effect of closing one’s eyes on the reliability of CoP measures in assessing postural control in stroke survivors. Previous research has reported lower reliability for the CoP sway area in stroke patients ( 11 , 22 , 39 ), which contradicts our findings. As few studies have investigated the sway area of the CoP in post-stroke individuals, it is difficult to determine the reason for this discrepancy. It is possible that the wide range of participants' ages in our study (27 to 76 years) caused a large amount of variability between them and masked the test-retest inconsistency, as Ruhe et al. stated in their review ( 14 ). Additionally, differences in trial duration and foot position on the force plates may also contribute to the inconsistent results. Previous studies have shown that sway area is a reliable measure of the CoP in older adults ( 18 – 20 , 35 , 36 ) and older adults with Parkinson's disease ( 16 ). The high reliability of the sway area of the CoP in our study could be attributed to some similarities between the participants of previous studies and recent populations. 4.1. Within-day reliability Higher within-day ICCs were found than between-day ICCs, consistent with previous studies on both young and old participants ( 14 , 18 , 40 ). Gray and colleagues concluded that averaging out 10 internal perturbation trials in post-stroke individuals improved between-day reliability compared to within-day reliability ( 21 ). However, this population has achieved high within-day reliability in fewer trials ( 3 , 21 ). The decrease in reliability observed in pathologically affected individuals or elderly subjects during extra trials may be caused by fatigue ( 14 , 21 ) According to the results, the quiet standing position showed high absolute reliability in all three conditions. Jagroop et al. studied people with chronic stroke in a quiet standing position and found lower absolute reliability in the quiet standing position compared to our findings. However, they measured the root mean square (RMS) of the CoP velocity. SEM was 4.9 mm for the RMS of the ML velocity and 3.7 mm for the RMS of the AP velocity ( 3 ). In contrast to the participants in the present study, their participants were older (mean age: 64 ± 9.5 years) and they conducted two assessment trials despite identifying that three trials would result in an ICC > 0.9 ( 3 ). The MDC values were lower in an open-eyes standing position compared to previous study results ( 39 ). Aryan et al. investigated the within-session reliability of CoP measures in the subacute post-stroke individuals. They reported higher SEMs, and consequently higher MDCs, for the mean velocity in the AP and ML directions in a quiet standing position than we found (SEM: 2.83, MDC: 7.84 versus SEM:0.67, MDC:1.84 for Vap, and SEM: 1.59, MDC:4.41 versus SEM:0.41, MDC:1,14 for Vml) ( 39 ). It was suggested that balance measures may be less stable among people in the early stages of stroke recovery ( 3 ), resulting in higher MDC values in their study. 4.2. Between-day reliability Similar to within-day reliability, most measures of the CoP had high to very high between-day reliability (Table 4 ). Correspondingly, dual-task performance could also increase the reliability of the open-eyes quiet standing position except for the CoP sway area. Gray et al. conducted a study on the reliability of CoP measures in individuals post-stroke performing arm raises and load drops while standing upright ( 22 ). Calculating the between-day reliability, they found that the load drop task during a quiet standing position achieved higher between-day reliability (ICC: 0.78–0.89) than did the arm rise task (ICC: 0.12–0.80) and to some extent the primary quiet standing task (0.52–0.98) ( 22 ). However, their methodology, particularly the trial repetition and their participants’ stage of recovery, was completely different from that of the present study. They used additional trials and argued that reduced reliability could result from fatigue ( 22 ). Swanenburg et al. examined the reliability of CoP measures in fallers and non-fallers under single and cognitive dual-task conditions. They reported no significant differences in reliability between the test conditions ( 37 ). However, the ICC for the mean velocity increased from 0.70 to 0.94 in the fallers when they performed a secondary cognitive task. Interestingly, their study also revealed a decrease in the reliability of the sway area in fallers due to cognitive dual-tasking (ICC 0.69 changed to 0.57), which is consistent with the findings of a previous study on healthy elderlies ( 19 ), as well as, our study. Further investigation is necessary to determine the cause of reduced sway area reliability during dual-task assessment. Limitations It is important to note that the results of this study may not apply to people other than those with hemiplegic stroke or at different stages of recovery. Additionally, our sample size was limited, which could influence the generalizability of the results as it may not encompass the heterogeneous postural control mechanisms among chronic stroke survivors. Conclusion In summary, measures of the CoP in different positions and under different conditions are reliable enough to assess chronic stroke survivors. When assessing the postural control system, measuring the CoP during dual-task conditions is a more reliable method. The semi-tandem standing position is only a reliable measurement if it is assessed during dual-task conditions in this population. Improving the accuracy of balance assessments using more reliable measures during dual-tasking can help us better understand the degree of balance impairments and lead to more effective rehabilitation interventions. Abbreviations CoP: Center of Pressure ICC: Intraclass Correlation Coefficient SEM: Standard Error of Measurement MDC: Minimal Detectable Change AP: Anterior-Posterior ML: Medial-Lateral BBS: Berg Balance Scale Mini-BEST: Mini-Balance Evaluation System Test ABC: Activities-Specific Balance Confidence SD: Standard Deviation Open-Quiet: Open-eye Quiet standing position Open-Tandem: semi-Tandem standing position Closed-Quiet: Closed-eye Quiet standing position Motor-Quiet: Motor dual-task Quiet standing position Motor-Tandem: Motor dual-task semi-Tandem standing position Cognitive-Quiet: Cognitive dual-task Quiet standing position Cognitive-Tandem: Cognitive dual-task semi-Tandem standing position V: Velocity Vmean: mean Velocity Area: sway area CI: Confidence Interval RMS: Root Mean Square Declarations Ethics approval and consent to participate This study was approved by the Ethics Committee of the University of Social Welfare and Rehabilitation Sciences (No: IR.USWR.REC.1398,136). The objectives of the study were explained to the research participants and they were provided informed consent before participating in the study (Including the agreement for publication of anonymized data) in accordance with the declaration of Helsinki recommendations for investigations with human participants. Consent for publication Not applicable. Availability of data and materials The datasets used and/or analyzed during the current study are available from the corresponding author upon reasonable request. Competing interest None of the authors have any financial or other interests related to the manuscript to declare. Funding This study did not receive funding from any public, commercial, or non-profit organization. Authors’ contributions MP, MAS, HN, IA, and BA contributed to the conception and design of the study, interpretation of data, and drafting or substantial revision of the work. MP, HFH, MR, and MSTM contributed to the acquisition of data. MP and EB contributed to the statistical analysis of data. MAS performed software programming and data processing. MP, MAS, and HN have drafted and revised the final manuscript. All authors have approved the submitted version. Acknowledgment The authors would like to thank Mr. Mohammad Parsa and Dr. Payam Sasan Nezhad for contributing to patient selection and the staff of the Rehabilitation section of the Ghaem Hospital. The experiment was conducted in the Biomechanics Laboratory, Rehabilitation Research Center, Ghaem Hospital, Mashhad University of Medical Sciences. References Corriveau H, Hébert R, Raı̂che M, Prince F. Evaluation of postural stability in the elderly with stroke. Archives of physical medicine and rehabilitation. 2004;85(7):1095-101. Sawacha Z, Carraro E, Contessa P, Guiotto A, Masiero S, Cobelli C. Relationship between clinical and instrumental balance assessments in chronic post-stroke hemiparesis subjects. 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Center of pressure-based balance evaluation in individuals with Parkinson’s disease: a reliability study. Physiotherapy theory and practice. 2020;36(7):826-33. Li Z, Liang Y-Y, Wang L, Sheng J, Ma S-J. Reliability and validity of center of pressure measures for balance assessment in older adults. Journal of Physical Therapy Science. 2016;28(4):1364-7. Lin D, Seol H, Nussbaum MA, Madigan ML. Reliability of COP-based postural sway measures and age-related differences. Gait & posture. 2008;28(2):337-42. Moghadam M, Ashayeri H, Salavati M, Sarafzadeh J, Taghipoor KD, Saeedi A, et al. Reliability of center of pressure measures of postural stability in healthy older adults: effects of postural task difficulty and cognitive load. Gait & posture. 2011;33(4):651-5. Salehi R, Ebrahimi TI, Esteki A, Maroufi N, Parnianpour M. Test-retest reliability and minimal detectable change for center of pressure measures of postural stability in elderly subjects. 2010. Bower KJ, McGinley JL, Miller KJ, Clark RA. Instrumented static and dynamic balance assessment after stroke using Wii Balance Boards: Reliability and association with clinical tests. PloS one. 2014;9(12):e115282. Gray VL, Ivanova TD, Garland SJ. Reliability of center of pressure measures within and between sessions in individuals post-stroke and healthy controls. Gait & posture. 2014;40(1):198-203. Martello SK, Boumer TC, Almeida JCd, Correa KP, Devetak GF, Faucz R, et al. Reliability and minimal detectable change of between-limb synchronization, weight-bearing symmetry, and amplitude of postural sway in individuals with stroke. Research on Biomedical Engineering. 2017;33:113-20. Bernhardt J, Hayward KS, Kwakkel G, Ward NS, Wolf SL, Borschmann K, et al. Agreed definitions and a shared vision for new standards in stroke recovery research: the stroke recovery and rehabilitation roundtable taskforce. International Journal of Stroke. 2017;12(5):444-50. Stel VS, Smit JH, Pluijm SM, Lips P. Balance and mobility performance as treatable risk factors for recurrent falling in older persons. Journal of clinical epidemiology. 2003;56(7):659-68. Tisserand R, Armand S, Allali G, Schnider A, Baillieul S. Cognitive-motor dual-task interference modulates mediolateral dynamic stability during gait in post-stroke individuals. Hum Mov Sci. 2018;58:175-84. Ghai S, Ghai I, Effenberg AO. Effects of dual tasks and dual-task training on postural stability: a systematic review and meta-analysis. Clinical interventions in aging. 2017:557-77. Ansari NN, Naghdi S, Hasson S, Valizadeh L, Jalaie S. Validation of a Mini-Mental State Examination (MMSE) for the Persian population: a pilot study. Appl Neuropsychol. 2010;17(3):190-5. Plummer P, Morris ME, Dunai J. Assessment of Unilateral Neglect. Physical Therapy. 2003;83(8):732-40. Jonsson E, Seiger A, Hirschfeld H. Postural steadiness and weight distribution during tandem stance in healthy young and elderly adults. Clin Biomech (Bristol, Avon). 2005;20(2):202-8. MacLeod CM. Half a century of research on the Stroop effect: an integrative review. Psychological bulletin. 1991;109(2):163. Palmieri RM, Ingersoll CD, Stone MB, Krause BA. Center-of-pressure parameters used in the assessment of postural control. Journal of sport rehabilitation. 2002;11(1):51-66. Paillard T, Noé F. Techniques and methods for testing the postural function in healthy and pathological subjects. BioMed research international. 2015;2015. Domholdt E. Rehabilitation research: principles and applications. (No Title). 2005. Atkinson G, Nevill AM. Statistical methods for assessing measurement error (reliability) in variables relevant to sports medicine. Sports Med. 1998;26(4):217-38. Kwon Y-R, Eom G-M, Kim J-W. TEST–RETEST reliability of postural sway measures during static standing balance performance in healthy elderly adults. Journal of Mechanics in Medicine and Biology. 2022;22(08):2240034. Swanenburg J, de Bruin ED, Favero K, Uebelhart D, Mulder T. The reliability of postural balance measures in single and dual tasking in elderly fallers and non-fallers. BMC musculoskeletal disorders. 2008;9:1-10. Lo P-Y, Su B-L, You Y-L, Yen C-W, Wang S-T, Guo L-Y. Measuring the Reliability of Postural Sway Measurements for a Static Standing Task: The Effect of Age. Frontiers in Physiology. 2022;13:850707. Aryan R, Inness E, Patterson KK, Mochizuki G, Mansfield A. Reliability of force plate-based measures of standing balance in the sub-acute stage of post-stroke recovery. medRxiv. 2023:2023.05. 18.23290052. Benvenuti F, Mecacci R, Gineprari I, Bandinelli S, Benvenuti E, Ferrucci L, et al. Kinematic characteristics of standing disequilibrium: reliability and validity of a posturographic protocol. Arch Phys Med Rehabil. 1999;80(3):278-87. Additional Declarations No competing interests reported. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4066043","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":285968370,"identity":"54bd42cc-1e7d-479a-9cb7-c06a655886f6","order_by":0,"name":"Mitra Parsa","email":"","orcid":"","institution":"University of Social Welfare and Rehabilitation Sciences","correspondingAuthor":false,"prefix":"","firstName":"Mitra","middleName":"","lastName":"Parsa","suffix":""},{"id":285968371,"identity":"9d01debf-b49e-4130-8053-f8522fd22c2f","order_by":1,"name":"Iraj Abdollahi","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA6ElEQVRIiWNgGAWjYBACNiBmBpIyfAw8DAc+wMUNCGvhASKGgzOI0cKArIWZhxiH8UkfYPxcUGbDw8Z+9uBh27a6xO0NzA8/MBTcw+0wvgRm6Rnn0njYePISDue2HU6cc4DNWILBoBi3FqBbpHnbDgMdlmMA1HIgF+gfM6BfEvBpYf4N1sL/xuCwZVsdUAv7N0Ja2CC2SABtYWxjBmrhIWQLY5s12C8SbwwO9pw7XD+DmadYIgGPFvke5sO3gSEmx8+fY/zhR1mdsQR7+8YPH/7g1sLAwNiAJsAMxPg0jIJRMApGwSggDABEuUI4JredXgAAAABJRU5ErkJggg==","orcid":"","institution":"University of Social Welfare and Rehabilitation Sciences","correspondingAuthor":true,"prefix":"","firstName":"Iraj","middleName":"","lastName":"Abdollahi","suffix":""},{"id":285968372,"identity":"a5b4a5ba-21f5-4732-abca-d567e76099bd","order_by":2,"name":"Hossein Negahban","email":"","orcid":"","institution":"Mashhad University of Medical Sciences","correspondingAuthor":false,"prefix":"","firstName":"Hossein","middleName":"","lastName":"Negahban","suffix":""},{"id":285968376,"identity":"7287f739-7a03-44bb-b64f-0b5eddad0672","order_by":3,"name":"Mohammad Ali Sanjari","email":"","orcid":"","institution":"Iran University of Medical Sciences","correspondingAuthor":false,"prefix":"","firstName":"Mohammad","middleName":"Ali","lastName":"Sanjari","suffix":""},{"id":285968378,"identity":"deb0b680-e285-40b8-a0e4-1c22a5c98cf9","order_by":4,"name":"Behnam Akhbari","email":"","orcid":"","institution":"University of Social Welfare and Rehabilitation Sciences","correspondingAuthor":false,"prefix":"","firstName":"Behnam","middleName":"","lastName":"Akhbari","suffix":""},{"id":285968381,"identity":"9fe0df9e-1fc0-4258-a999-6d0f15bfd448","order_by":5,"name":"Enayatollah Bakhshi","email":"","orcid":"","institution":"University of Social Welfare and Rehabilitation Sciences","correspondingAuthor":false,"prefix":"","firstName":"Enayatollah","middleName":"","lastName":"Bakhshi","suffix":""},{"id":285968384,"identity":"39e7d768-26b3-4026-96b7-4e7d230f2db7","order_by":6,"name":"Haniyeh Fakur Haddadiyan","email":"","orcid":"","institution":"Mashhad University of Medical Sciences","correspondingAuthor":false,"prefix":"","firstName":"Haniyeh","middleName":"Fakur","lastName":"Haddadiyan","suffix":""},{"id":285968386,"identity":"36ae9012-9d1d-4819-8748-d827854aca4b","order_by":7,"name":"Mina Rouhani","email":"","orcid":"","institution":"Mashhad University of Medical Sciences","correspondingAuthor":false,"prefix":"","firstName":"Mina","middleName":"","lastName":"Rouhani","suffix":""},{"id":285968389,"identity":"4109d450-adf2-418d-8cf9-3cfe53bac49b","order_by":8,"name":"Mohammad Sadegh Torabi Moghaddam","email":"","orcid":"","institution":"Kerman University of Medical Sciences","correspondingAuthor":false,"prefix":"","firstName":"Mohammad","middleName":"Sadegh Torabi","lastName":"Moghaddam","suffix":""}],"badges":[],"createdAt":"2024-03-10 15:44:50","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4066043/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4066043/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":62038535,"identity":"1408cf20-3c30-4f1b-81af-5cb48a21b793","added_by":"auto","created_at":"2024-08-08 14:07:24","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1008491,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4066043/v1/d9ce679e-c8d1-457e-89de-6744717993a2.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Reliability of center of pressure measures in chronic stroke survivors: Effect of motor and cognitive loads","fulltext":[{"header":"Background","content":"\u003cp\u003eApproximately, 50% of stroke survivors experience residual physical\u003c/p\u003e \u003cp\u003edisabilities (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e). These individuals experience deficits in the sensory, musculoskeletal, perceptual, and cognitive systems, which affect their balance control and increase the risk of falls (\u003cspan additionalcitationids=\"CR2\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e–\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e). Therefore, the major objective of stroke rehabilitation is to enhance balance control. It is crucial to have standardized and reliable balance measures in clinical settings to pinpoint areas for rehabilitation and monitor progress over time (\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e). Clinicians often use observational performance-based scales to evaluate balance performance (\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e). However, the compensatory strategies used to complete tasks within the scales are unknown. This lack of knowledge fails to reveal underlying dyscontrol, which could potentially increase the risk of falling, and should be focused on rehabilitation programs (\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eTo evaluate the specific deficits of the balance control system, center of pressure (CoP) excursion is typically recorded using a force platform in a laboratory setting (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e). CoP excursions can differentiate between fallers and non-fallers (\u003cspan additionalcitationids=\"CR9\" citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e–\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e) and are associated with clinical outcome measures, such as the Berg Balance Scale and Timed Up and Go Test, in elderly and post-stroke individuals (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e). Given the promising ability of CoP measures to detect impaired balance control mechanisms, limited information about their reliability for assessing balance among chronic stroke survivors is available. Similar to many biological measurements, the intrinsic variability of CoP measures influences their reliability as well as the validity and responsiveness of postural control assessments. Additionally, reliability is not a static characteristic and varies based on the population studied (\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eTo date, several studies have reported the reliability of CoP measures of standing position in different populations with disequilibrium problems (\u003cspan additionalcitationids=\"CR14 CR15\" citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e–\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e) and healthy elders (\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan additionalcitationids=\"CR18 CR19\" citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e–\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e). Few studies have reported these findings collectively throughout various stages of post-stroke recovery (\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan additionalcitationids=\"CR22\" citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e–\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e). It is worth noting that only one study has specifically examined the reliability of CoP-based variables among chronic stroke survivors, in which a limited number of conventional variables were selected as a part of the main objective (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e). During the chronic stage of stroke recovery, rehabilitative interventions have an approximately net effect on the patient improvement, when spontaneous recovery of the brain has almost plateaued (\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e). Accordingly, assessing the reliability of CoP measures in chronic stroke survivors could provide deeper insights into clinical decision-making and upcoming research.\u003c/p\u003e \u003cp\u003eMoreover, to our knowledge, no study has investigated the reliability of the tandem standing position in individuals with chronic stroke; however, this position is commonly used to predict the risk of falling (\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e). It is believed that to define underlying deficiencies in the postural control system that may increase the potential risk of falling, clinicians should use an eye-closed narrow stance condition during balance assessment (\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e). Therefore, in the present study, an open-eyes semi-tandem standing position was selected to enable post-stroke individuals to successfully complete the assessment procedure.\u003c/p\u003e \u003cp\u003eSo far, only one study has examined the reliability of CoP measures during different postural stability tasks in post-stroke patients at different stages of recovery. This study aimed to evaluate the reliability of CoP measures across three different postural stability tasks regardless of the impact of motor dual-task on the reliability of CoP measures (\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e). Furthermore, it has been mentioned that performing a cognitive dual-task while walking is a more challenging activity for post-stroke individuals than for healthy individuals. Dual-tasking results in spatiotemporal locomotor adaptations, which may help post-stroke individuals maintain balance. At the same time, their attention is simultaneously directed to an external source of attention in dual-task conditions (\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e). Post-stroke survivors can exhibit enhanced balance control with either motor or cognitive dual-task training (\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThus, the present study aimed to examine the within-day and between-day reliabilities of CoP measures in chronic stroke survivors in different standing positions with the effect of motor and cognitive loads.\u003c/p\u003e \u003cdiv id=\"Sec2\" class=\"Section2\"\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e\u003c/p\u003e \u003c/div\u003e "},{"header":"Methods","content":"\u003ch2\u003e2.1. Participants\u003c/h2\u003e\u003cp\u003e This study was approved by the Ethics Committee of the University of Social Welfare and Rehabilitation Sciences (No: IR.USWR.REC.1398,136), and all subjects provided informed consent before participating in the study (Including the agreement for publication of anonymized data) in accordance with the declaration of Helsinki recommendations for investigations with human participants. Participants were sixteen people with chronic stroke (\u0026gt; 6 months post-stroke) participated in an unpublished clinical trial (No: IRCT20220703055350N1) that aimed to determine the effect of frontal plane-focused balance training on balance performance and falls in chronic stroke patients. Common inclusion criteria were as follows: 1) ability to stand and walk independently for at least one minute 2) ability to hold a semi-tandem position for at least 30 seconds without the support of another person, and 3) no recent limb surgery or uncorrected visual or auditory impairments. Participants with 1) a score higher than 2 on the Modified Ashworth Scale in Gastrocnemius muscle, 2) a score lower than 24 on the Mini-Mental State Examination-Persian version (\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e), 3) a standard deviation (SD) of ± 1 or greater on the Line Bisection Test (hemineglect history) (\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e), and 4) conditions other than stroke that may affect their balance control were excluded. Age, height, weight, sex, and type of stroke were obtained from participants. They were also assessed by clinical balance-related scales, including, the Berg Balance Scale (BBS), Mini-Balance Evaluation System Test (Mini-BEST), and Activities-Specific Balance Confidence (ABC) (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e\u003cdiv class=\"gridtable\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eDemographic and clinical characteristics of the participants (n:16)\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e\u003ccolgroup cols=\"5\"\u003e\u003c/colgroup\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eVariable\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eMean / count\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003eSD\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003eMinimum\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cem\u003eMaximum\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eAge (years)\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e49.31\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e15.50\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e27\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e76\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eHeight (cm)\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e166.33\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e11.93\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e147\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e187\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eWeight (kg)\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e69.27\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e13.06\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e52\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e86\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eSex\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMale:11\u003c/p\u003e \u003cp\u003eFemale:5\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eStroke type\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eIschemic:8\u003c/p\u003e \u003cp\u003eHemorragic:5\u003c/p\u003e \u003cp\u003eUnknown:3\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eHemiparetic side\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eRight:6\u003c/p\u003e \u003cp\u003eLeft:10\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eBBS (score out of 56)\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e51.81\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4.51\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e42\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e56\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eMini-BEST (score out of 28)\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e20.43\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e5.42\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e12\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e27\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eABC (score out of 100)\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e70.96\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e19.28\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e23.43\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e70.96\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"5\"\u003e\u003cem\u003eSD: standard deviation, BBS: Berg Balance Scale, Mini-BEST: Mini-Balance\u003c/em\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd colspan=\"5\"\u003e\u003cem\u003eEvaluation System Test, ABC: Activities- Specific Balance Confidence.\u003c/em\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003ch2\u003e2.2. Procedure\u003c/h2\u003e\u003cp\u003eCoP data were obtained using two adjacent strain gauge Kistler force platforms (model No: 9286BA, Switzerland) along the anterior-posterior and medial-lateral directions. Assessments were accomplished by the same raters, in the same place and at the same time in two sessions, 48 hours apart, with three trials per session. Postural sway was measured in three conditions: single-task, motor dual-task, and cognitive dual-task conditions. In the single-task condition, participants stood on the platforms while maintaining an open-eye quiet standing position (Open-Quiet), a semi-tandem standing position (Open-Tandem), and a closed-eye quiet standing position (Closed-Quiet). In the motor and cognitive dual-task conditions, the participants stood in the quiet standing position and the semi-tandem standing position (Motor-Quiet, Motor-Tandem, and Cognitive-Quiet, Cognitive-Tandem, respectively). For a quiet standing position, the participants were instructed to stand barefoot in a comfortable position on two adjacent force plates. Each foot was placed on a separate force plate about the center of its length with the feet shoulder-width apart. During the semi-tandem position, both feet were placed on the same plate, with a foot-width distance between them, and the affected leg in front (\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e). The rater, position of the feet, time, and environment of the assessment remained the same throughout all assessment sessions. In the motor dual-task condition, participants were asked to hold a tray containing a glass of water. In the cognitive dual-task, they performed the congruent Stroop test (\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e). For the Stroop task, a board with forty-five words was placed two meters away from the participants. The words were names of four different colors, were written in the same color ink, and were arranged in nine rows of five words. All positions were held for approximately 30 seconds. The assessment session consisted of three trials for each testing position with a 30-second break between trials. During the test, participants were instructed to stand still and quietly and if possible, with their arms at their sides, looking ahead, except in the eyes-closed condition. To ensure safety during the assessments, participants were supervised by a physiotherapist.\u003c/p\u003e\u003ch2\u003e2.3. Data processing\u003c/h2\u003e\u003cp\u003eForce platform data were sampled at 100 Hz, and processed using a low-pass filter at 10 Hz. A MATLAB routine computed CoP measures for combining both plates (net-CoP). The mean and SD of the velocity of the net-CoP along the anterior-posterior (AP) (Vap and SD.Vap) and medial-lateral (ML) directions (Vml and SD.Vml), mean velocity (Vmean), and sway area (Area) were chosen as CoP measures because of their demonstrated relevance in hemiplegic stroke patients (\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e). Moreover, the selected measures followed previous recommendations (\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e). The velocity of the CoP reflects the efficiency of the postural control system to counteract postural sway via neuromuscular activity. The lower the velocity is, the better the balance control. SD is the variability index of CoP movements (\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e). The sway area quantifies the 95% ellipse formed by the CoP excursion, representing overall postural control system performance. A smaller sway area generally indicates better balance control system performance (\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e).\u003c/p\u003e\u003ch2\u003e2.4. Statistical analysis\u003c/h2\u003e\u003cp\u003eData analysis was conducted using SPSS version 21. A two-way random model of the intraclass correlation coefficient (\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({ICC}_{\\text{2,3}}\\)\u003c/span\u003e\u003c/span\u003e) with a corresponding 95% confidence interval (CI) was chosen to estimate the relative reliability. ICC values were calculated for within-day reliability using three assessment trials in a single session. The average of three trials in two separate sessions was implemented for between-day reliability. Munro’s classification for reliability coefficients was used to represent the degree of reliability: 0.00–0.25 – little, if any correlation; 0.26–0.49 – low correlation; 0.50–0.69 – moderate correlation; 0.70–0.89 – high correlation and 0.90–1.00 – very high correlation (\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e). Absolute reliability was determined using the standard error of measurement (SEM). The SEM (\u003cem\u003eSD\u003c/em\u003e ×\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\sqrt{1-ICC})\\)\u003c/span\u003e\u003c/span\u003e indicates how much a change in measurement score is due to random error, where \u003cem\u003eSD\u003c/em\u003e is the standard deviation of the measurements (\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e). SEM indicates how much a change in the measurement score is due to random error (\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e). The minimal detectable change (MDC = 1.96×√2×\u003cem\u003eSEM\u003c/em\u003e) was also calculated, representing a clinically significant change between two measurement scores not due to random error (\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e). The statistical significance level was considered to be α = 0.05.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eThe demographic characteristics of the participants are presented in Table \u003cspan\u003e1\u003c/span\u003e.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003ePlease insert\u003c/em\u003e Table \u003cspan\u003e1\u003c/span\u003e \u003cem\u003enear here.\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eTable \u003cspan\u003e2\u003c/span\u003e represents the mean scores and standard deviations (SDs) for the COP measures under different test conditions.\u003c/p\u003e\n\u003cdiv\u003e\n \u003ctable id=\"Tab2\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv\u003eTable 2\u003c/div\u003e\n \u003cdiv\u003e\n \u003cp\u003eTest-Retest means and SDs of the CoP measures in all conditions\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003ccolgroup cols=\"10\"\u003e\u003c/colgroup\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eCoP measure\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"3\"\u003e\n \u003cp\u003e\u003cspan type=\"Underline\" name=\"Emphasis\"\u003eSingle-task\u003c/span\u003e\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e\u003cspan type=\"Underline\" name=\"Emphasis\"\u003eMotor dual-task\u003c/span\u003e\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e\u003cspan type=\"Underline\" name=\"Emphasis\"\u003eCognitive dual-task\u003c/span\u003e\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cspan type=\"Underline\" name=\"Emphasis\"\u003eTest position\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cspan type=\"Underline\" name=\"Emphasis\"\u003eTest mean (SD)\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cspan type=\"Underline\" name=\"Emphasis\"\u003eRetest mean (SD)\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cspan type=\"Underline\" name=\"Emphasis\"\u003eTest position\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cspan type=\"Underline\" name=\"Emphasis\"\u003eTest mean (SD)\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cspan type=\"Underline\" name=\"Emphasis\"\u003eRetest mean (SD)\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cspan type=\"Underline\" name=\"Emphasis\"\u003eTest position\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cspan type=\"Underline\" name=\"Emphasis\"\u003eTest mean (SD)\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cspan type=\"Underline\" name=\"Emphasis\"\u003eRetest mean (SD)\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eVml\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(mm/s)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eOpen-Quiet\u003c/p\u003e\n \u003cp\u003eClosed-Quiet\u003c/p\u003e\n \u003cp\u003eOpen-Tandem\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e9.78 (2.62)\u003c/p\u003e\n \u003cp\u003e10.69 (2.77)\u003c/p\u003e\n \u003cp\u003e15.05 (4.50)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e9.42 (1.56)\u003c/p\u003e\n \u003cp\u003e10.81 (2.47)\u003c/p\u003e\n \u003cp\u003e15.14 (3.03)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMotor-Quiet\u003c/p\u003e\n \u003cp\u003eMotor-Tandem\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e9.95 (3.31)\u003c/p\u003e\n \u003cp\u003e14.87 (4.24)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e9.51 (2.25)\u003c/p\u003e\n \u003cp\u003e14.00 (4.40)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCognitive-Quiet\u003c/p\u003e\n \u003cp\u003eCognitive-Tandem\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e10.47 (2.21)\u003c/p\u003e\n \u003cp\u003e16.12 (4.30)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e10.23 (1.67)\u003c/p\u003e\n \u003cp\u003e16.36 (3.53)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eSD.Vml\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(mm/s)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eOpen-Quiet\u003c/p\u003e\n \u003cp\u003eClosed-Quiet\u003c/p\u003e\n \u003cp\u003eOpen-Tandem\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e12.41 (3.51)\u003c/p\u003e\n \u003cp\u003e13.60 (3.48)\u003c/p\u003e\n \u003cp\u003e19.61 (5.92)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e11.92 (2.00)\u003c/p\u003e\n \u003cp\u003e13.80 (3.24)\u003c/p\u003e\n \u003cp\u003e19.20 (3.86)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMotor-Quiet\u003c/p\u003e\n \u003cp\u003eMotor-Tandem\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e12.65 (4.60)\u003c/p\u003e\n \u003cp\u003e18.82 (5.38)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e12.10 (3.06)\u003c/p\u003e\n \u003cp\u003e18.43 (5.83)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCognitive-Quiet\u003c/p\u003e\n \u003cp\u003eCognitive-Tandem\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e13.33 (2.92)\u003c/p\u003e\n \u003cp\u003e21.23 (5.41)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e12.94 (2.12)\u003c/p\u003e\n \u003cp\u003e21.29 (4.73)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eVap\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(mm/s)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eOpen-Quiet\u003c/p\u003e\n \u003cp\u003eClosed-Quiet\u003c/p\u003e\n \u003cp\u003eOpen-Tandem\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e12.23 (2.33)\u003c/p\u003e\n \u003cp\u003e16.47 (4.16)\u003c/p\u003e\n \u003cp\u003e14.81 (3.77)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e12.60 (2.11)\u003c/p\u003e\n \u003cp\u003e17.39 (4.54)\u003c/p\u003e\n \u003cp\u003e14.98 (3.23)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMotor-Quiet\u003c/p\u003e\n \u003cp\u003eMotor-Tandem\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e12.55 (3.36)\u003c/p\u003e\n \u003cp\u003e14.53 (4.37)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e12.48 (3.22)\u003c/p\u003e\n \u003cp\u003e13.97 (4.49)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCognitive-Quiet\u003c/p\u003e\n \u003cp\u003eCognitive-Tandem\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e13.58 (2.25)\u003c/p\u003e\n \u003cp\u003e16.45 (4.88)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e14.02 (2.09)\u003c/p\u003e\n \u003cp\u003e17.11 (5.80)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eSD.Vap\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(mm/s)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eOpen-Quiet\u003c/p\u003e\n \u003cp\u003eClosed-Quiet\u003c/p\u003e\n \u003cp\u003eOpen-Tandem\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e15.65 (3.09)\u003c/p\u003e\n \u003cp\u003e21.43 (5.52)\u003c/p\u003e\n \u003cp\u003e19.30 (5.00)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e16.09 (2.75)\u003c/p\u003e\n \u003cp\u003e22.68 (6.01)\u003c/p\u003e\n \u003cp\u003e19.00 (4.68)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMotor-Quiet\u003c/p\u003e\n \u003cp\u003eMotor-Tandem\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e16.03 (4.65)\u003c/p\u003e\n \u003cp\u003e18.84 (5.93)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e15.92 (4.26)\u003c/p\u003e\n \u003cp\u003e17.99 (5.80)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCognitive-Quiet\u003c/p\u003e\n \u003cp\u003eCognitive-Tandem\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e17.34 (3.08)\u003c/p\u003e\n \u003cp\u003e21.58 (5.71)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e18.08 (2.69)\u003c/p\u003e\n \u003cp\u003e22.29 (7.88)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eVmean\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(mm/s)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eOpen-Quiet\u003c/p\u003e\n \u003cp\u003eClosed-Quiet\u003c/p\u003e\n \u003cp\u003eOpen-Tandem\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e17.34 (3.66)\u003c/p\u003e\n \u003cp\u003e21.56 (5.20)\u003c/p\u003e\n \u003cp\u003e23.26 (6.12)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e17.38 (2.61)\u003c/p\u003e\n \u003cp\u003e22.43 (5.28)\u003c/p\u003e\n \u003cp\u003e22.91 (4.71)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMotor-Quiet\u003c/p\u003e\n \u003cp\u003eMotor-Tandem\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e17.74 (5.12)\u003c/p\u003e\n \u003cp\u003e22.86 (6.54)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e17.36 (4.15)\u003c/p\u003e\n \u003cp\u003e21.71 (6.58)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCognitive-Quiet\u003c/p\u003e\n \u003cp\u003eCognitive-Tandem\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e19.00 (3.26)\u003c/p\u003e\n \u003cp\u003e25.75 (6.33)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e19.16 (2.44)\u003c/p\u003e\n \u003cp\u003e26.07 (6.82)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eArea\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(\u003c/strong\u003e\u003cspan\u003e\u003cspan\u003e\\({\\varvec{m}\\varvec{m}}^{2})\\)\u003c/span\u003e\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eOpen-Quiet\u003c/p\u003e\n \u003cp\u003eClosed-Quiet\u003c/p\u003e\n \u003cp\u003eOpen-Tandem\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e550.63 (700.24)\u003c/p\u003e\n \u003cp\u003e640.82 (746.46)\u003c/p\u003e\n \u003cp\u003e897.88 (838.02)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e415.83 (433.50)\u003c/p\u003e\n \u003cp\u003e757.01 (840.56)\u003c/p\u003e\n \u003cp\u003e807.28 (499.67)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMotor-Quiet\u003c/p\u003e\n \u003cp\u003eMotor-Tandem\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e623.04 (811.53)\u003c/p\u003e\n \u003cp\u003e879.94 (708.19)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e512.60 (502.157)\u003c/p\u003e\n \u003cp\u003e765.38 (471.91)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCognitive-Quiet\u003c/p\u003e\n \u003cp\u003eCognitive-Tandem\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e526.71 (404.46)\u003c/p\u003e\n \u003cp\u003e769.63 (537.86)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e436.19 (181.27)\u003c/p\u003e\n \u003cp\u003e805.33 (549.10)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003ctfoot\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"10\"\u003e\u003cem\u003eSD: standard deviation, CoP: center of pressure, V: velocity, ml: medial-lateral, ap: anterior-posterior, Open-Quiet: open-eyes quiet standing, Closed-Quiet: closed-eyes quiet standing, Open-Tandem: open-eyes semi-tandem standing, Motor-Quiet: Motor dual-task Quiet standing, Motor-Tandem: Motor dual-task semi-Tandem standing, Cognitive- Quiet: Cognitive dual-task quiet standing, Cognitive-Tandem: Cognitive dual-task semi-Tandem standing, Vmean: mean velocity, Area: sway area\u003c/em\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tfoot\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003e\u003cem\u003ePlease insert\u003c/em\u003e Table \u003cspan\u003e2\u003c/span\u003e \u003cem\u003enear here.\u003c/em\u003e\u003c/p\u003e\n\u003cdiv id=\"Sec7\"\u003e\n \u003ch2\u003e3.1. The within-day reliability results are presented in Table \u003cspan\u003e3\u003c/span\u003e.\u003c/h2\u003e\n \u003cdiv\u003e\n \u003ctable id=\"Tab3\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv\u003eTable 3\u003c/div\u003e\n \u003cdiv\u003e\n \u003cp\u003eWithin-day Intraclass correlation coefficients, SEM, and MDC of the CoP measures in all conditions.\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003ccolgroup cols=\"13\"\u003e\u003c/colgroup\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eCoP measure\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"4\"\u003e\n \u003cp\u003e\u003cspan type=\"Underline\" name=\"Emphasis\"\u003eSingle-task\u003c/span\u003e\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"4\"\u003e\n \u003cp\u003e\u003cspan type=\"Underline\" name=\"Emphasis\"\u003eMotor dual-task\u003c/span\u003e\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"4\"\u003e\n \u003cp\u003e\u003cspan type=\"Underline\" name=\"Emphasis\"\u003eCognitive dual-task\u003c/span\u003e\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cspan type=\"Underline\" name=\"Emphasis\"\u003eTest position\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cspan type=\"Underline\" name=\"Emphasis\"\u003eICC (95% CI)\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cspan type=\"Underline\" name=\"Emphasis\"\u003eSEM\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cspan type=\"Underline\" name=\"Emphasis\"\u003eMDC\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cspan type=\"Underline\" name=\"Emphasis\"\u003eTest position\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cspan type=\"Underline\" name=\"Emphasis\"\u003eICC (95% CI)\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cspan type=\"Underline\" name=\"Emphasis\"\u003eSEM\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cspan type=\"Underline\" name=\"Emphasis\"\u003eMDC\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cspan type=\"Underline\" name=\"Emphasis\"\u003eTest position\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cspan type=\"Underline\" name=\"Emphasis\"\u003eICC (95% CI)\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cspan type=\"Underline\" name=\"Emphasis\"\u003eSEM\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cspan type=\"Underline\" name=\"Emphasis\"\u003eMDC\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eVml\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(mm/s)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eOpen-Quiet\u003c/p\u003e\n \u003cp\u003eClosed-Quiet\u003c/p\u003e\n \u003cp\u003eOpen-Tandem\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.93\u003c/strong\u003e (0.85\u0026ndash;0.98)\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e0.91\u003c/strong\u003e (0.79\u0026ndash;0.97)\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e0.78\u003c/strong\u003e (0.50\u0026ndash;0.92)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.41\u003c/p\u003e\n \u003cp\u003e0.74\u003c/p\u003e\n \u003cp\u003e1.42\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.14\u003c/p\u003e\n \u003cp\u003e2.05\u003c/p\u003e\n \u003cp\u003e3.94\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMotor-Quiet\u003c/p\u003e\n \u003cp\u003eMotor-Tandem\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.89\u003c/strong\u003e (0.76\u0026ndash;0.96)\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e0.93\u003c/strong\u003e (0.84\u0026ndash;0.97)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.75\u003c/p\u003e\n \u003cp\u003e1.16\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.07\u003c/p\u003e\n \u003cp\u003e3.22\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCognitive-Quiet\u003c/p\u003e\n \u003cp\u003eCognitive-Tandem\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.95\u003c/strong\u003e (0.88\u0026ndash;0.98)\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e0.85\u003c/strong\u003e (0.66\u0026ndash;0.94)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.37\u003c/p\u003e\n \u003cp\u003e1.37\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.03\u003c/p\u003e\n \u003cp\u003e3.79\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eSD.Vml\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(mm/s)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eOpen-Quiet\u003c/p\u003e\n \u003cp\u003eClosed-Quiet\u003c/p\u003e\n \u003cp\u003eOpen-Tandem\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.93\u003c/strong\u003e (0.85\u0026ndash;0.97)\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e0.91\u003c/strong\u003e (0.79\u0026ndash;0.96)\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e0.79\u003c/strong\u003e (0.52\u0026ndash;0.92)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.53\u003c/p\u003e\n \u003cp\u003e0.97\u003c/p\u003e\n \u003cp\u003e1.77\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.47\u003c/p\u003e\n \u003cp\u003e2.69\u003c/p\u003e\n \u003cp\u003e4.90\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMotor-Quiet\u003c/p\u003e\n \u003cp\u003eMotor-Tandem\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.86\u003c/strong\u003e (0.68\u0026ndash;0.95)\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e0.94\u003c/strong\u003e (0.84\u0026ndash;0.98)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.14\u003c/p\u003e\n \u003cp\u003e1.43\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.17\u003c/p\u003e\n \u003cp\u003e3.96\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCognitive-Quiet\u003c/p\u003e\n \u003cp\u003eCognitive-Tandem\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.94\u003c/strong\u003e (0.86\u0026ndash;0.98)\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e0.84\u003c/strong\u003e (0.64\u0026ndash;0.94)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.52\u003c/p\u003e\n \u003cp\u003e1.89\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.44\u003c/p\u003e\n \u003cp\u003e5.24\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eVap\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(mm/s)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eOpen-Quiet\u003c/p\u003e\n \u003cp\u003eClosed-Quiet\u003c/p\u003e\n \u003cp\u003eOpen-Tandem\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.90\u003c/strong\u003e (0.77\u0026ndash;0.96)\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e0.90\u003c/strong\u003e (0.77\u0026ndash;0.96)\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e0.83\u003c/strong\u003e (0.62\u0026ndash;0.94)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.67\u003c/p\u003e\n \u003cp\u003e1.43\u003c/p\u003e\n \u003cp\u003e1.33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.84\u003c/p\u003e\n \u003cp\u003e3.98\u003c/p\u003e\n \u003cp\u003e3.69\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMotor-Quiet\u003c/p\u003e\n \u003cp\u003eMotor-Tandem\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.96\u003c/strong\u003e (0.90\u0026ndash;0.98)\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e0.94\u003c/strong\u003e (0.86\u0026ndash;0.98)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.64\u003c/p\u003e\n \u003cp\u003e1.10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.78\u003c/p\u003e\n \u003cp\u003e3.05\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCognitive-Quiet\u003c/p\u003e\n \u003cp\u003eCognitive-Tandem\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.90\u003c/strong\u003e (0.77\u0026ndash;0.96)\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e0.98\u003c/strong\u003e (0.95\u0026ndash;0.99)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.66\u003c/p\u003e\n \u003cp\u003e0.82\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.83\u003c/p\u003e\n \u003cp\u003e2.27\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eSD.Vap\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(mm/s)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eOpen-Quiet\u003c/p\u003e\n \u003cp\u003eClosed-Quiet\u003c/p\u003e\n \u003cp\u003eOpen-Tandem\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.90\u003c/strong\u003e (0.76\u0026ndash;0.96)\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e0.88\u003c/strong\u003e (0.72\u0026ndash;0.95)\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e0.86\u003c/strong\u003e (0.68\u0026ndash;0.95)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.87\u003c/p\u003e\n \u003cp\u003e2.08\u003c/p\u003e\n \u003cp\u003e1.75\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.41\u003c/p\u003e\n \u003cp\u003e5.77\u003c/p\u003e\n \u003cp\u003e4.85\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMotor-Quiet\u003c/p\u003e\n \u003cp\u003eMotor-Tandem\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.95\u003c/strong\u003e (0.88\u0026ndash;0.98)\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e0.95\u003c/strong\u003e (0.88\u0026ndash;0.98)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.95\u003c/p\u003e\n \u003cp\u003e1.30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.64\u003c/p\u003e\n \u003cp\u003e3.59\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCognitive-Quiet\u003c/p\u003e\n \u003cp\u003eCognitive-Tandem\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.90\u003c/strong\u003e (0.75\u0026ndash;0.96)\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e0.96\u003c/strong\u003e (0.91\u0026ndash;0.99)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.89\u003c/p\u003e\n \u003cp\u003e1.58\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.48\u003c/p\u003e\n \u003cp\u003e4.37\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eVmean\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(mm/s)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eOpen-Quiet\u003c/p\u003e\n \u003cp\u003eClosed-Quiet\u003c/p\u003e\n \u003cp\u003eOpen-Tandem\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.92\u003c/strong\u003e (0.82\u0026ndash;0.97)\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e0.90\u003c/strong\u003e (0.78\u0026ndash;0.96)\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e0.85\u003c/strong\u003e (0.65-094)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.74\u003c/p\u003e\n \u003cp\u003e1.67\u003c/p\u003e\n \u003cp\u003e1.82\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.04\u003c/p\u003e\n \u003cp\u003e4.63\u003c/p\u003e\n \u003cp\u003e5.05\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMotor-Quiet\u003c/p\u003e\n \u003cp\u003eMotor-Tandem\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.94\u003c/strong\u003e (0.86\u0026ndash;0.98)\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e0.95\u003c/strong\u003e (0.88\u0026ndash;0.98)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.02\u003c/p\u003e\n \u003cp\u003e1.47\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.82\u003c/p\u003e\n \u003cp\u003e4.08\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCognitive-Quiet\u003c/p\u003e\n \u003cp\u003eCognitive-Tandem\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.93\u003c/strong\u003e (0.84\u0026ndash;0.97)\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e0.95\u003c/strong\u003e (0.89\u0026ndash;0.98)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.64\u003c/p\u003e\n \u003cp\u003e1.52\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.79\u003c/p\u003e\n \u003cp\u003e4.22\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eArea\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(\u003c/strong\u003e\u003cspan\u003e\u003cspan\u003e\\({\\varvec{m}\\varvec{m}}^{2})\\)\u003c/span\u003e\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eOpen-Quiet\u003c/p\u003e\n \u003cp\u003eClosed-Quiet\u003c/p\u003e\n \u003cp\u003eOpen-Tandem\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.95\u003c/strong\u003e (0.89\u0026ndash;0.98)\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e0.93\u003c/strong\u003e (0.84\u0026ndash;0.97)\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e0.84\u003c/strong\u003e (0.63\u0026ndash;0.94)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e96.93\u003c/p\u003e\n \u003cp\u003e222.39\u003c/p\u003e\n \u003cp\u003e199.88\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e268.60\u003c/p\u003e\n \u003cp\u003e616.25\u003c/p\u003e\n \u003cp\u003e553.87\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMotor-Quiet\u003c/p\u003e\n \u003cp\u003eMotor-Tandem\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.90\u003c/strong\u003e (0.77\u0026ndash;0.96)\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e0.82\u003c/strong\u003e (0.59\u0026ndash;0.93)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e158.80\u003c/p\u003e\n \u003cp\u003e200.21\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e440.03\u003c/p\u003e\n \u003cp\u003e554.79\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCognitive-Quiet\u003c/p\u003e\n \u003cp\u003eCognitive-Tandem\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.60 (0.12\u0026ndash;0.84)\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e0.86\u003c/strong\u003e (0.68\u0026ndash;0.95)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e114.64\u003c/p\u003e\n \u003cp\u003e205.45\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e317.68\u003c/p\u003e\n \u003cp\u003e569.31\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003ctfoot\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"13\"\u003e\u003cem\u003eSEM: standard error of measurement, MDC: minimal detectable change, CoP: center of pressure, ICC: Intraclass correlation coefficients, CI: confidence interval, V: velocity, ml: medial-lateral, ap: anterior-posterior, Open-Quiet: open-eyes quiet standing, Closed-Quiet: closed-eyes quiet standing, Open-Tandem: open-eyes semi-tandem standing, Motor-Quiet: Motor dual-task Quiet standing, Motor-Tandem: Motor dual-task semi-Tandem standing, Cognitive- Quiet: Cognitive dual-task quiet standing, Cognitive-Tandem: Cognitive dual-task semi-Tandem standing, Vmean: mean velocity, Area: sway area. Values with ICC greater than 0.70 were highlighted in bold.\u003c/em\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tfoot\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n \u003cp\u003eGenerally, the within-day ICCs were greater than the between-day ICCs.\u003c/p\u003e\n \u003cspan\u003e3.1.1 The ICCs for the single-task conditions ranged from 0.78 to 0.95, with high to very high reliability found for all the CoP measures. A semi-tandem standing position showed lower relative and absolute reliabilities than quiet standing positions in single-task conditions (Open-Quiet, Closed-Quiet). The reliabilities of the CoP measures were lower in the closed-eyes quiet standing position than in the open-eyes quiet standing position, especially in terms of the SEM values (0.74-222.39 versus 0.41\u0026ndash;96.93, respectively). The sagittal plane measurements (Vap \u0026amp; SD. Vap) had greater reliabilities than did the frontal plane (Vml \u0026amp; SD.Vml) in an open-eyes semi-tandem standing position (Table\u0026nbsp;\u003cspan\u003e3\u003c/span\u003e).\u003cbr\u003e\u003cspan\u003e\n \u003cp\u003e3.1.2 The ICCs for the motor dual-task conditions ranged from 0.82 to 0.96. As in the single-task condition, all the CoP measures had high to very high reliability. In the motor dual-task condition, a semi-tandem standing position showed lower absolute reliability than quiet standing positions (SEM: 1.10-200.21 versus 0.64\u0026ndash;158.80, respectively). Performing a secondary motor task improved the relative and absolute reliabilities in a semi-tandem standing position (ICC: 0.86\u0026ndash;0.95 and SEM: 1.10\u0026ndash;1.47) compared to the single-task condition (ICC: 0.78\u0026ndash;0.86 and SEM: 1.33\u0026ndash;1.82), except for the sway area (Table \u003cspan\u003e3\u003c/span\u003e).\u003c/p\u003e\u0026nbsp;\u003cspan\u003e\n \u003cp\u003e3.1.3 The ICCs for the cognitive dual-task conditions ranged from 0.60 to 0.96. All the CoP measures had high to very high reliability, except for the sway area in the quiet standing position. In the cognitive dual-task condition, a semi-tandem standing position had lower absolute reliability than the quiet standing positions (SEM: 0.82-205.45 versus 0.37-114.64, respectively) (Table \u003cspan\u003e3\u003c/span\u003e). Performing a secondary cognitive task improved the relative and absolute reliabilities in a semi-tandem standing position (ICC: 0.84\u0026ndash;0.98 and SEM: 0.82\u0026ndash;1.89) compared to the single-task condition (ICC: 0.78\u0026ndash;0.86 and SEM: 1.33\u0026ndash;1.82) except for the sway area (Table \u003cspan\u003e3\u003c/span\u003e).\u003c/p\u003e\n \u003c/span\u003e\n \u003c/span\u003e\n \u003c/span\u003e\n \u003cdiv\u003e\n \u003cp\u003eThe MDCs ranged from 1.03 mm/s for the Vml (Cognitive-Quiet) to 5.77 mm/s for the SD. Vap (Closed-Quiet) and 268.60 \u003cspan\u003e\u003cspan\u003e\\({mm}^{2}\\)\u003c/span\u003e\u003c/span\u003e for the area of Open-Quiet condition to 616.25 \u003cspan\u003e\u003cspan\u003e\\({mm}^{2}\\)\u003c/span\u003e\u003c/span\u003e for the area of Closed-Quiet condition (Table \u003cspan\u003e3\u003c/span\u003e).\u003c/p\u003e\n \u003c/div\u003e\n \u003cp\u003e\u003cem\u003ePlease insert\u003c/em\u003e Table \u003cspan\u003e3\u003c/span\u003e \u003cem\u003enear here.\u003c/em\u003e\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec8\"\u003e\n \u003ch2\u003e3.2. The between-day reliability results are presented in Table \u003cspan\u003e4\u003c/span\u003e.\u003c/h2\u003e\n \u003cdiv\u003e\n \u003ctable id=\"Tab4\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv\u003eTable 4\u003c/div\u003e\n \u003cdiv\u003e\n \u003cp\u003eBetween-day Intraclass correlation coefficients, SEM, and MDC of the CoP measures in all conditions.\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003ccolgroup cols=\"13\"\u003e\u003c/colgroup\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eCoP measure\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"4\"\u003e\n \u003cp\u003e\u003cspan type=\"Underline\" name=\"Emphasis\"\u003eSingle-task\u003c/span\u003e\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"4\"\u003e\n \u003cp\u003e\u003cspan type=\"Underline\" name=\"Emphasis\"\u003eMotor dual-task\u003c/span\u003e\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"4\"\u003e\n \u003cp\u003e\u003cspan type=\"Underline\" name=\"Emphasis\"\u003eCognitive dual-task\u003c/span\u003e\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cspan type=\"Underline\" name=\"Emphasis\"\u003eTest position\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cspan type=\"Underline\" name=\"Emphasis\"\u003eICC (95% CI)\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cspan type=\"Underline\" name=\"Emphasis\"\u003eSEM\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cspan type=\"Underline\" name=\"Emphasis\"\u003eMDC\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cspan type=\"Underline\" name=\"Emphasis\"\u003eTest position\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cspan type=\"Underline\" name=\"Emphasis\"\u003eICC (95% CI)\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cspan type=\"Underline\" name=\"Emphasis\"\u003eSEM\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cspan type=\"Underline\" name=\"Emphasis\"\u003eMDC\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cspan type=\"Underline\" name=\"Emphasis\"\u003eTest position\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cspan type=\"Underline\" name=\"Emphasis\"\u003eICC (95% CI)\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cspan type=\"Underline\" name=\"Emphasis\"\u003eSEM\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cspan type=\"Underline\" name=\"Emphasis\"\u003eMDC\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eVml\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(mm/s)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eOpen-Quiet\u003c/p\u003e\n \u003cp\u003eClosed-Quiet\u003c/p\u003e\n \u003cp\u003eOpen-Tandem\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.78\u003c/strong\u003e (0.38\u0026ndash;0.92)\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e0.82\u003c/strong\u003e (0.49\u0026ndash;0.94)\u003c/p\u003e\n \u003cp\u003e0.65 (-0.51-0.88)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.91\u003c/p\u003e\n \u003cp\u003e0.99\u003c/p\u003e\n \u003cp\u003e1.94\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.53\u003c/p\u003e\n \u003cp\u003e2.75\u003c/p\u003e\n \u003cp\u003e5.38\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMotor-Quiet\u003c/p\u003e\n \u003cp\u003eMotor-Tandem\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.93\u003c/strong\u003e (0.81\u0026ndash;0.98)\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e0.89\u003c/strong\u003e (0.69\u0026ndash;0.96)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.72\u003c/p\u003e\n \u003cp\u003e1.36\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.01\u003c/p\u003e\n \u003cp\u003e3.78\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCognitive-Quiet\u003c/p\u003e\n \u003cp\u003eCognitive-Tandem\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.93\u003c/strong\u003e (0.78\u0026ndash;0.98)\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e0.89\u003c/strong\u003e (0.69\u0026ndash;0.96)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.49\u003c/p\u003e\n \u003cp\u003e1.24\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.37\u003c/p\u003e\n \u003cp\u003e3.43\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eSD.Vml\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(mm/s)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eOpen-Quiet\u003c/p\u003e\n \u003cp\u003eClosed-Quiet\u003c/p\u003e\n \u003cp\u003eOpen-Tandem\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.77\u003c/strong\u003e (0.34\u0026ndash;0.92)\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e0.83\u003c/strong\u003e (0.51\u0026ndash;0.94)\u003c/p\u003e\n \u003cp\u003e0.53 (-0.42-0.84)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.23\u003c/p\u003e\n \u003cp\u003e1.28\u003c/p\u003e\n \u003cp\u003e2.80\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.41\u003c/p\u003e\n \u003cp\u003e3.54\u003c/p\u003e\n \u003cp\u003e7.77\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMotor-Quiet\u003c/p\u003e\n \u003cp\u003eMotor-Tandem\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.93\u003c/strong\u003e (0.82\u0026ndash;0.98)\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e0.92\u003c/strong\u003e (0.78\u0026ndash;0.97)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.00\u003c/p\u003e\n \u003cp\u003e1.53\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.78\u003c/p\u003e\n \u003cp\u003e4.23\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCognitive-Quiet\u003c/p\u003e\n \u003cp\u003eCognitive-Tandem\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.90\u003c/strong\u003e (0.72\u0026ndash;0.96)\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e0.93\u003c/strong\u003e (0.79\u0026ndash;0.97)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.77\u003c/p\u003e\n \u003cp\u003e1.30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.13\u003c/p\u003e\n \u003cp\u003e3.59\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eVap\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(mm/s)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eOpen-Quiet\u003c/p\u003e\n \u003cp\u003eClosed-Quiet\u003c/p\u003e\n \u003cp\u003eOpen-Tandem\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.83\u003c/strong\u003e (0.53\u0026ndash;0.94)\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e0.90\u003c/strong\u003e (0.77\u0026ndash;0.96)\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e0.83\u003c/strong\u003e (0.62\u0026ndash;0.94)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.84\u003c/p\u003e\n \u003cp\u003e1.91\u003c/p\u003e\n \u003cp\u003e1.33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.34\u003c/p\u003e\n \u003cp\u003e5.31\u003c/p\u003e\n \u003cp\u003e3.70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMotor-Quiet\u003c/p\u003e\n \u003cp\u003eMotor-Tandem\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.93\u003c/strong\u003e (0.80\u0026ndash;0.98)\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e0.87\u003c/strong\u003e (0.63\u0026ndash;0.95)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.84\u003c/p\u003e\n \u003cp\u003e1.50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.33\u003c/p\u003e\n \u003cp\u003e4.16\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCognitive-Quiet\u003c/p\u003e\n \u003cp\u003eCognitive-Tandem\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.90\u003c/strong\u003e (0.72\u0026ndash;0.97)\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e0.89\u003c/strong\u003e (0.68\u0026ndash;0.96)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.65\u003c/p\u003e\n \u003cp\u003e1.68\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.80\u003c/p\u003e\n \u003cp\u003e4.67\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eSD.Vap\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(mm/s)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eOpen-Quiet\u003c/p\u003e\n \u003cp\u003eClosed-Quiet\u003c/p\u003e\n \u003cp\u003eOpen-Tandem\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.84\u003c/strong\u003e (0.54\u0026ndash;0.94)\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e0.78\u003c/strong\u003e (0.37\u0026ndash;0.92)\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e0.81\u003c/strong\u003e (0.45\u0026ndash;0.93)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.08\u003c/p\u003e\n \u003cp\u003e2.45\u003c/p\u003e\n \u003cp\u003e1.93\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.00\u003c/p\u003e\n \u003cp\u003e6.78\u003c/p\u003e\n \u003cp\u003e5.35\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMotor-Quiet\u003c/p\u003e\n \u003cp\u003eMotor-Tandem\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.92\u003c/strong\u003e (0.78\u0026ndash;0.97)\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e0.87\u003c/strong\u003e (0.63\u0026ndash;0.95)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.21\u003c/p\u003e\n \u003cp\u003e1.98\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.36\u003c/p\u003e\n \u003cp\u003e5.49\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCognitive-Quiet\u003c/p\u003e\n \u003cp\u003eCognitive-Tandem\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.86\u003c/strong\u003e (0.61\u0026ndash;0.95)\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e0.96\u003c/strong\u003e (0.91\u0026ndash;0.99)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.02\u003c/p\u003e\n \u003cp\u003e2.25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.82\u003c/p\u003e\n \u003cp\u003e6.23\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eVmean\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(mm/s)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eOpen-Quiet\u003c/p\u003e\n \u003cp\u003eClosed-Quiet\u003c/p\u003e\n \u003cp\u003eOpen-Tandem\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.82\u003c/strong\u003e (0.48\u0026ndash;0.94)\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e0.78\u003c/strong\u003e (0.38\u0026ndash;0.92)\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e0.66\u003c/strong\u003e (0.00-0.88)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.24\u003c/p\u003e\n \u003cp\u003e2.22\u003c/p\u003e\n \u003cp\u003e2.74\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.43\u003c/p\u003e\n \u003cp\u003e6.16\u003c/p\u003e\n \u003cp\u003e7.59\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMotor-Quiet\u003c/p\u003e\n \u003cp\u003eMotor-Tandem\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.94\u003c/strong\u003e (0.82\u0026ndash;0.98)\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e0.88\u003c/strong\u003e (0.68\u0026ndash;0.96)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.11\u003c/p\u003e\n \u003cp\u003e2.15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.07\u003c/p\u003e\n \u003cp\u003e5.97\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCognitive-Quiet\u003c/p\u003e\n \u003cp\u003eCognitive-Tandem\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.88\u003c/strong\u003e (0.67\u0026ndash;0.96)\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e0.91\u003c/strong\u003e (0.75\u0026ndash;0.97)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.98\u003c/p\u003e\n \u003cp\u003e1.89\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.72\u003c/p\u003e\n \u003cp\u003e5.24\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eArea\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(\u003c/strong\u003e\u003cspan\u003e\u003cspan\u003e\\({\\varvec{m}\\varvec{m}}^{2})\\)\u003c/span\u003e\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eOpen-Quiet\u003c/p\u003e\n \u003cp\u003eClosed-Quiet\u003c/p\u003e\n \u003cp\u003eOpen-Tandem\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.92\u003c/strong\u003e (0.76\u0026ndash;0.97)\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e0.96\u003c/strong\u003e (0.88\u0026ndash;0.98)\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e0.89\u003c/strong\u003e (0.69\u0026ndash;0.96)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e159.17\u003c/p\u003e\n \u003cp\u003e156.01\u003c/p\u003e\n \u003cp\u003e217.04\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e441.07\u003c/p\u003e\n \u003cp\u003e432.30\u003c/p\u003e\n \u003cp\u003e601.42\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMotor-Quiet\u003c/p\u003e\n \u003cp\u003eMotor-Tandem\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.90\u003c/strong\u003e (0.71\u0026ndash;0.96)\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e0.83\u003c/strong\u003e (0.52\u0026ndash;0.94)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e203.22\u003c/p\u003e\n \u003cp\u003e229.18\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e563.11\u003c/p\u003e\n \u003cp\u003e635.06\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCognitive-Quiet\u003c/p\u003e\n \u003cp\u003eCognitive-Tandem\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.66 (0.05\u0026ndash;0.88)\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e0.92\u003c/strong\u003e (0.77\u0026ndash;0.97)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e157.94\u003c/p\u003e\n \u003cp\u003e147.62\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e437.66\u003c/p\u003e\n \u003cp\u003e409.06\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003ctfoot\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"13\"\u003e\u003cem\u003eSEM: standard error of measurement, MDC: minimal detectable change, CoP: center of pressure, ICC: Intraclass correlation coefficients, CI: confidence interval, V: velocity, ml: medial-lateral, ap: anterior-posterior, Open-Quiet: open-eyes quiet standing, Closed-Quiet: closed-eyes quiet standing, Open-Tandem: open-eyes semi-tandem standing, Motor-Quiet: Motor dual-task Quiet standing, Motor-Tandem: Motor dual-task semi-Tandem standing, Cognitive- Quiet: Cognitive dual-task quiet standing, Cognitive-Tandem: Cognitive dual-task semi-Tandem standing, Vmean: mean velocity, Area: sway area. Values with ICC greater than 0.70 were highlighted in bold.\u003c/em\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tfoot\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n \u003cspan\u003e\n \u003cp\u003e3.2.1 The ICCs for the single-task conditions ranged from 0.53 to 0.96, with moderate to very high reliability found for all the CoP measures. A semi-tandem standing position showed lower relative and absolute reliabilities than quiet standing positions in single-task conditions (Table \u003cspan\u003e4\u003c/span\u003e). The absolute reliability of CoP measures in a closed-eyes quiet standing position was almost lower than that in an open-eyes quiet standing position (SEM: 0.99\u0026ndash;2.22 versus 0.91\u0026ndash;1.24, respectively), except for the sway area (Table \u003cspan\u003e4\u003c/span\u003e). The sagittal plane variables had greater reliabilities than did the frontal plane variables in the open-eyes quiet standing and semi-tandem standing positions in the single-task condition (Table \u003cspan\u003e4\u003c/span\u003e).\u003c/p\u003e\n \u003c/span\u003e\u003cspan\u003e3.2.1 The ICCs for the motor dual-task conditions ranged from 0.83 to 0.94. All the CoP measures had high to very high reliability. The relative and absolute reliabilities were greater in the quiet standing position than in the semi-tandem standing position (ICC: 0.90\u0026ndash;0.93 and SEM: 0.72-203.22 versus ICC: 0.87\u0026ndash;0.92 and SEM: 1.36-229.18, respectively). Similar to within-day reliability, performing a secondary motor task improved the relative and absolute reliabilities of all CoP measures compared to the single-task condition except for the sway area (Table\u0026nbsp;\u003cspan\u003e4\u003c/span\u003e).\u003cbr\u003e\u003c/span\u003e\u003cspan\u003e3.2.2 The ICCs for the cognitive dual-task conditions ranged from 0.66 to 0.96. All the CoP measures had high to very high reliability, except for the sway area in a quiet standing position. In the cognitive dual-task condition, a semi-tandem standing position showed almost lower absolute reliability than the quiet standing position (Table \u003cspan\u003e4\u003c/span\u003e). Again, performing a secondary cognitive task improved the relative and absolute reliabilities of all CoP measures compared to the single-task condition except for the sway area (Table \u003cspan\u003e4\u003c/span\u003e).\u003cbr\u003e\u003c/span\u003e\n \u003cp\u003eThe MDCs ranged from 1.37 mm/s for the Vml (Cognitive-Quiet) to 7.77 mm/s for SD. Vml (Open-Tandem) and 409.06 \u003cspan\u003e\u003cspan\u003e\\({mm}^{2}\\)\u003c/span\u003e\u003c/span\u003e for the Area of the Cognitive-Tandem condition to 635.06 \u003cspan\u003e\u003cspan\u003e\\({mm}^{2}\\)\u003c/span\u003e\u003c/span\u003e for the Area of the Motor-Tandem condition (Table \u003cspan\u003e4\u003c/span\u003e).\u003c/p\u003e\n \u003cp\u003e\u003cem\u003ePlease insert\u003c/em\u003e Table \u003cspan\u003e4\u003c/span\u003e \u003cem\u003enear here.\u003c/em\u003e\u003c/p\u003e\n\u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eThis study aimed to determine the within-day and between-day reliability of COP measures from two adjacent force plates in different standing positions, while a motor or cognitive dual-task was imposed on the postural control system. The findings of this study demonstrated nearly high to very high reliability across all three conditions for CoP measures. Overall, the mean velocity and mean and SD of velocity in the AP direction showed the highest relative and absolute reliabilities, followed by the sway area and mean and SD of velocity in the ML direction.\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e \u003cp\u003eOur results regarding the mean velocity, especially in an open-eyes quiet standing position, are in accordance with previous research on healthy elders (\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e, \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e), elderly fallers, and non-fallers (\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e), and post-stroke individuals (\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e). According to a review by Ruhe et al., mean velocity is the most reliable conventional parameter of CoP (\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e). This means that it is considered more reliable than other parameters such as displacement or sway area. The reason for this is that mean velocity is not solely dependent on the position of the CoP (\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e). The CoP mean velocity, which is a summary parameter of the CoP, is commonly preferred since it can minimize the extreme effects of peak values. Moreover, the high reliability of the mean velocity makes it a suitable parameter for evaluating balance control and tracking progress after therapeutic exercises (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e). Our findings also confirmed its high reliability.\u003c/p\u003e \u003cp\u003eAdditionally, comparing the reliability of velocity in the AP and ML directions in a semi-tandem standing position during the single-task condition, the mean and SD of velocity in the AP direction were found to be more reliable. The lower reliability of frontal plane variables most likely stems from the varying ability to control balance in the ML direction between sessions in stroke survivors. It is possible that the asymmetry in weight bearing due to hemiparesis, along with difficulty in shifting the weight to the affected limb (\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e), resulted in inconsistent measures of the CoP in the ML direction across sessions. This inconsistency led to reduced reliability in the variables related to the frontal plane, which is noticeable in the semi-tandem standing position. However, there have been no studies on the reliability of tandem standing in post-stroke individuals. Swanenburg et al. reported that as the stance width increases, there is a disproportionate decrease in the angular motion of ankles and feet. For instance, the mobility of the ankle joint in the frontal plane is reduced when the feet are separated (\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e). Similarly, it is possible that standing in a semi-tandem position reduces the range of motion in the sagittal plane, especially at the ankle joint. On the other hand, the base of support increases in the anterior-posterior direction (\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e) while maintaining semi-tandem standing, which may result in decreased variability in controlling sagittal plane stability. This, in turn, may improve the reliability of the mentioned variables. Further research could reveal the exact rationale for this finding.\u003c/p\u003e \u003cp\u003eCompared to quiet standing positions, the semi-tandem standing position had lower relative and absolute reliability during a single-task condition, however, implementing a dual-task assessment enhanced the reliability except for in the sway area (Tables\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e and \u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). It is believed that performing a dual task can improve performance by directing attention toward an external source of attention. This may lead to automatic motor function, allowing for more effective performance by shifting motor control from higher cognitive centers to basic noncognitive centers (\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e). The automatization of postural control may decrease participants' performance variability and increase the reliability of the results. However, further investigations are needed to prove this opinion. Terra et al. evaluated patients with Parkinson's disease in the tandem standing position under single-task and cognitive dual-task conditions but, the reliability decreased in the dual-task condition compared to the single-task condition in their study, possibly due to significant differences in the foot position, study population, age of the participants, and selected cognitive task (\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e). The participants stood with their backfoot\u0026rsquo;s big toe 5 centimeters apart from the frontfoot\u0026rsquo;s heel. They conducted their study on patients diagnosed with Parkinson\u0026rsquo;s disease, with an average age of 71\u0026thinsp;\u0026plusmn;\u0026thinsp;7.8 years. They instructed them to perform simple mathematical operations as a secondary task while standing in this position.\u003c/p\u003e \u003cp\u003eClosing eyes had no significant effect on the CoP parameters in our study, which is the same as the findings of Gasq et al. obtained in their study on post-stroke patients (\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e) and other studies on elderlies (\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e, \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e). However, future studies may reveal the exact effect of closing one\u0026rsquo;s eyes on the reliability of CoP measures in assessing postural control in stroke survivors.\u003c/p\u003e \u003cp\u003ePrevious research has reported lower reliability for the CoP sway area in stroke patients (\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e, \u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e), which contradicts our findings. As few studies have investigated the sway area of the CoP in post-stroke individuals, it is difficult to determine the reason for this discrepancy. It is possible that the wide range of participants' ages in our study (27 to 76 years) caused a large amount of variability between them and masked the test-retest inconsistency, as Ruhe et al. stated in their review (\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e). Additionally, differences in trial duration and foot position on the force plates may also contribute to the inconsistent results. Previous studies have shown that sway area is a reliable measure of the CoP in older adults (\u003cspan additionalcitationids=\"CR19\" citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e, \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e, \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e) and older adults with Parkinson's disease (\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e). The high reliability of the sway area of the CoP in our study could be attributed to some similarities between the participants of previous studies and recent populations.\u003c/p\u003e \u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003e4.1. Within-day reliability\u003c/h2\u003e \u003cp\u003eHigher within-day ICCs were found than between-day ICCs, consistent with\u003c/p\u003e \u003cp\u003eprevious studies on both young and old participants (\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e). Gray and colleagues concluded that averaging out 10 internal perturbation trials in post-stroke individuals improved between-day reliability compared to within-day reliability (\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e). However, this population has achieved high within-day reliability in fewer trials (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e). The decrease in reliability observed in pathologically affected individuals or elderly subjects during extra trials may be caused by fatigue (\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e)\u003c/p\u003e \u003cp\u003eAccording to the results, the quiet standing position showed high absolute reliability in all three conditions. Jagroop et al. studied people with chronic stroke in a quiet standing position and found lower absolute reliability in the quiet standing position compared to our findings. However, they measured the root mean square (RMS) of the CoP velocity. SEM was 4.9 mm for the RMS of the ML velocity and 3.7 mm for the RMS of the AP velocity (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e). In contrast to the participants in the present study, their participants were older (mean age: 64\u0026thinsp;\u0026plusmn;\u0026thinsp;9.5 years) and they conducted two assessment trials despite identifying that three trials would result in an ICC\u0026thinsp;\u0026gt;\u0026thinsp;0.9 (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe MDC values were lower in an open-eyes standing position compared to previous study results (\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e). Aryan et al. investigated the within-session reliability of CoP measures in the subacute post-stroke individuals. They reported higher SEMs, and consequently higher MDCs, for the mean velocity in the AP and ML directions in a quiet standing position than we found (SEM: 2.83, MDC: 7.84 versus SEM:0.67, MDC:1.84 for Vap, and SEM: 1.59, MDC:4.41 versus SEM:0.41, MDC:1,14 for Vml) (\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e). It was suggested that balance measures may be less stable among people in the early stages of stroke recovery (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e), resulting in higher MDC values in their study.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003e4.2. Between-day reliability\u003c/h2\u003e \u003cp\u003eSimilar to within-day reliability, most measures of the CoP had high to very high between-day reliability (Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eCorrespondingly, dual-task performance could also increase the reliability of the open-eyes quiet standing position except for the CoP sway area. Gray et al. conducted a study on the reliability of CoP measures in individuals post-stroke performing arm raises and load drops while standing upright (\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e). Calculating the between-day reliability, they found that the load drop task during a quiet standing position achieved higher between-day reliability (ICC: 0.78\u0026ndash;0.89) than did the arm rise task (ICC: 0.12\u0026ndash;0.80) and to some extent the primary quiet standing task (0.52\u0026ndash;0.98) (\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e). However, their methodology, particularly the trial repetition and their participants\u0026rsquo; stage of recovery, was completely different from that of the present study. They used additional trials and argued that reduced reliability could result from fatigue (\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e). Swanenburg et al. examined the reliability of CoP measures in fallers and non-fallers under single and cognitive dual-task conditions. They reported no significant differences in reliability between the test conditions (\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e). However, the ICC for the mean velocity increased from 0.70 to 0.94 in the fallers when they performed a secondary cognitive task. Interestingly, their study also revealed a decrease in the reliability of the sway area in fallers due to cognitive dual-tasking (ICC 0.69 changed to 0.57), which is consistent with the findings of a previous study on healthy elderlies (\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e), as well as, our study. Further investigation is necessary to determine the cause of reduced sway area reliability during dual-task assessment.\u003c/p\u003e \u003cp\u003e \u003cb\u003eLimitations\u003c/b\u003e \u003c/p\u003e \u003cp\u003eIt is important to note that the results of this study may not apply to people other than those with hemiplegic stroke or at different stages of recovery. Additionally, our sample size was limited, which could influence the generalizability of the results as it may not encompass the heterogeneous postural control mechanisms among chronic stroke survivors.\u003c/p\u003e \u003c/div\u003e"},{"header":"Conclusion","content":"\u003cp\u003eIn summary, measures of the CoP in different positions and under different conditions are reliable enough to assess chronic stroke survivors. When assessing the postural control system, measuring the CoP during dual-task conditions is a more reliable method. The semi-tandem standing position is only a reliable measurement if it is assessed during dual-task conditions in this population. Improving the accuracy of balance assessments using more reliable measures during dual-tasking can help us better understand the degree of balance impairments and lead to more effective rehabilitation interventions.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eCoP: Center of Pressure\u003c/p\u003e\n\u003cp\u003eICC: Intraclass Correlation Coefficient\u003c/p\u003e\n\u003cp\u003eSEM: Standard Error of Measurement\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eMDC: Minimal Detectable Change\u003c/p\u003e\n\u003cp\u003eAP: Anterior-Posterior\u003c/p\u003e\n\u003cp\u003eML: Medial-Lateral\u003c/p\u003e\n\u003cp\u003eBBS: Berg Balance Scale\u003c/p\u003e\n\u003cp\u003eMini-BEST: Mini-Balance Evaluation System Test\u003c/p\u003e\n\u003cp\u003eABC: Activities-Specific Balance Confidence\u003c/p\u003e\n\u003cp\u003eSD: Standard Deviation\u003c/p\u003e\n\u003cp\u003eOpen-Quiet: Open-eye Quiet standing position\u003c/p\u003e\n\u003cp\u003eOpen-Tandem: semi-Tandem standing position\u003c/p\u003e\n\u003cp\u003eClosed-Quiet: Closed-eye Quiet standing position\u003c/p\u003e\n\u003cp\u003eMotor-Quiet: Motor dual-task Quiet standing\u0026nbsp;position\u003c/p\u003e\n\u003cp\u003eMotor-Tandem: Motor dual-task semi-Tandem standing\u0026nbsp;position\u003c/p\u003e\n\u003cp\u003eCognitive-Quiet: Cognitive dual-task Quiet standing\u0026nbsp;position\u003c/p\u003e\n\u003cp\u003eCognitive-Tandem: Cognitive dual-task semi-Tandem standing\u0026nbsp;position\u003c/p\u003e\n\u003cp\u003eV: Velocity\u003c/p\u003e\n\u003cp\u003eVmean: mean Velocity\u003c/p\u003e\n\u003cp\u003eArea: sway area\u003c/p\u003e\n\u003cp\u003eCI: Confidence Interval\u003c/p\u003e\n\u003cp\u003eRMS: Root Mean Square\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003e\u003cem\u003eEthics approval and consent to participate\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was approved by the Ethics Committee of the\u0026nbsp;University of Social\u003c/p\u003e\n\u003cp\u003eWelfare and Rehabilitation Sciences (No: IR.USWR.REC.1398,136).\u0026nbsp;The objectives of the study were explained to the research participants\u0026nbsp;and they were provided informed consent before participating in the study\u0026nbsp;(Including the agreement for publication of anonymized data) in accordance with the declaration of Helsinki recommendations for investigations with human participants.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eConsent for publication\u0026nbsp;\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eAvailability of data and materials\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets used and/or analyzed during the current study are available from the corresponding author upon reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eCompeting interest\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNone of the authors have any financial or other interests related to the manuscript to declare.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eFunding\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study did not receive funding from any public, commercial, or non-profit organization.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eAuthors\u0026rsquo; contributions\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eMP, MAS, HN, IA, and BA contributed to the conception and design of the study, interpretation of data, and drafting or substantial revision of the work. MP, HFH, MR, and MSTM contributed to the acquisition of data. MP and EB contributed to the statistical analysis of data. MAS performed software programming and data processing. MP, MAS, and HN have drafted and revised the final manuscript. All authors have approved the submitted version.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eAcknowledgment\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors would like to thank Mr. Mohammad Parsa and Dr. Payam Sasan Nezhad for contributing to patient selection and the staff of the Rehabilitation section of the Ghaem Hospital. The experiment was conducted in the Biomechanics Laboratory, Rehabilitation Research Center, Ghaem Hospital, Mashhad University of Medical Sciences.\u0026nbsp;\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eCorriveau H, H\u0026eacute;bert R, Raı̂che M, Prince F. Evaluation of postural stability in the elderly with stroke. 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Test-retest reliability and minimal detectable change for center of pressure measures of postural stability in elderly subjects. 2010.\u003c/li\u003e\n\u003cli\u003eBower KJ, McGinley JL, Miller KJ, Clark RA. Instrumented static and dynamic balance assessment after stroke using Wii Balance Boards: Reliability and association with clinical tests. PloS one. 2014;9(12):e115282.\u003c/li\u003e\n\u003cli\u003eGray VL, Ivanova TD, Garland SJ. Reliability of center of pressure measures within and between sessions in individuals post-stroke and healthy controls. Gait \u0026amp; posture. 2014;40(1):198-203.\u003c/li\u003e\n\u003cli\u003eMartello SK, Boumer TC, Almeida JCd, Correa KP, Devetak GF, Faucz R, et al. Reliability and minimal detectable change of between-limb synchronization, weight-bearing symmetry, and amplitude of postural sway in individuals with stroke. Research on Biomedical Engineering. 2017;33:113-20.\u003c/li\u003e\n\u003cli\u003eBernhardt J, Hayward KS, Kwakkel G, Ward NS, Wolf SL, Borschmann K, et al. Agreed definitions and a shared vision for new standards in stroke recovery research: the stroke recovery and rehabilitation roundtable taskforce. International Journal of Stroke. 2017;12(5):444-50.\u003c/li\u003e\n\u003cli\u003eStel VS, Smit JH, Pluijm SM, Lips P. Balance and mobility performance as treatable risk factors for recurrent falling in older persons. Journal of clinical epidemiology. 2003;56(7):659-68.\u003c/li\u003e\n\u003cli\u003eTisserand R, Armand S, Allali G, Schnider A, Baillieul S. Cognitive-motor dual-task interference modulates mediolateral dynamic stability during gait in post-stroke individuals. Hum Mov Sci. 2018;58:175-84.\u003c/li\u003e\n\u003cli\u003eGhai S, Ghai I, Effenberg AO. Effects of dual tasks and dual-task training on postural stability: a systematic review and meta-analysis. Clinical interventions in aging. 2017:557-77.\u003c/li\u003e\n\u003cli\u003eAnsari NN, Naghdi S, Hasson S, Valizadeh L, Jalaie S. Validation of a Mini-Mental State Examination (MMSE) for the Persian population: a pilot study. Appl Neuropsychol. 2010;17(3):190-5.\u003c/li\u003e\n\u003cli\u003ePlummer P, Morris ME, Dunai J. Assessment of Unilateral Neglect. Physical Therapy. 2003;83(8):732-40.\u003c/li\u003e\n\u003cli\u003eJonsson E, Seiger A, Hirschfeld H. Postural steadiness and weight distribution during tandem stance in healthy young and elderly adults. Clin Biomech (Bristol, Avon). 2005;20(2):202-8.\u003c/li\u003e\n\u003cli\u003eMacLeod CM. Half a century of research on the Stroop effect: an integrative review. Psychological bulletin. 1991;109(2):163.\u003c/li\u003e\n\u003cli\u003ePalmieri RM, Ingersoll CD, Stone MB, Krause BA. Center-of-pressure parameters used in the assessment of postural control. 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The reliability of postural balance measures in single and dual tasking in elderly fallers and non-fallers. BMC musculoskeletal disorders. 2008;9:1-10.\u003c/li\u003e\n\u003cli\u003eLo P-Y, Su B-L, You Y-L, Yen C-W, Wang S-T, Guo L-Y. Measuring the Reliability of Postural Sway Measurements for a Static Standing Task: The Effect of Age. Frontiers in Physiology. 2022;13:850707.\u003c/li\u003e\n\u003cli\u003eAryan R, Inness E, Patterson KK, Mochizuki G, Mansfield A. Reliability of force plate-based measures of standing balance in the sub-acute stage of post-stroke recovery. medRxiv. 2023:2023.05. 18.23290052.\u003c/li\u003e\n\u003cli\u003eBenvenuti F, Mecacci R, Gineprari I, Bandinelli S, Benvenuti E, Ferrucci L, et al. Kinematic characteristics of standing disequilibrium: reliability and validity of a posturographic protocol. Arch Phys Med Rehabil. 1999;80(3):278-87.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"reliability, CoP measures, dual task, stroke","lastPublishedDoi":"10.21203/rs.3.rs-4066043/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4066043/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground:\u003c/strong\u003e One of the major objectives of stroke rehabilitation is to\u003c/p\u003e\n\u003cp\u003eenhance balance control. Therefore, it is crucial to have standardized and reliable balance measures to pinpoint areas for rehabilitation. This study examines the between-day and within-day reliabilities of the center of pressure (CoP) measures in chronic stroke survivors in different standing positions during the effect of motor and cognitive loads.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods:\u003c/strong\u003e Sixteen people (49.31±15.5 years, 5 females) with chronic stroke were assessed in two sessions, 48 hours apart in three conditions: single-task, motor dual-task, and cognitive dual-task. In each condition, three trials of open-eyes quiet standing and three trials of semi-tandem standing were completed, while in the single task condition, three trials of closed-eyes quiet standing were also done. Intraclass correlation coefficient (ICC\u003csub\u003e2,3\u003c/sub\u003e), standard error of measurement (SEM), and minimal detectable change (MDC) were calculated for CoP mean velocity, mean velocity in the anterior-posterior (AP) and medial-lateral (ML) directions, the standard deviation of AP and ML velocity, and sway area.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults:\u003c/strong\u003e Within-day ICC values were higher than between-day values (ICCs ranged from 0.78 to 0.96). Mean velocity and mean and SD of velocity in the AP direction showed the highest relative (ICC: 0.82 and 0.92, 0.83 and 0.90, and 0.84 and 0.90, respectively) and absolute reliabilities (SEM: 0.74 and 1.24, 0.67 and 0.84, and 0.87 and 1.08) in an open-eyes quiet standing position. Dual-task performance could also increase the reliability of the CoP measures, except for the sway area (ICC:0.53-0.93 changed to 0.84-0.96). The semi-tandem standing position was the least reliable position in a single-task condition (ICC:0.53-0.89).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusions:\u003c/strong\u003e CoP measures during various positions and conditions have sufficient reliability in chronic stroke survivors. Assessing the postural control system during dual-task conditions provides more reliable CoP measures, especially in a semi-tandem standing position.\u003c/p\u003e","manuscriptTitle":"Reliability of center of pressure measures in chronic stroke survivors: Effect of motor and cognitive loads","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-04-04 07:59:22","doi":"10.21203/rs.3.rs-4066043/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"e918e1e3-fe61-4124-9382-eccee62bb166","owner":[],"postedDate":"April 4th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2024-08-08T13:59:16+00:00","versionOfRecord":[],"versionCreatedAt":"2024-04-04 07:59:22","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-4066043","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4066043","identity":"rs-4066043","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}