The Impact of different Standing positions on Pelvic Muscle Activation and Lumbar Lordosis in LBP-developers during prolonged standing 

The Impact of different Standing positions on Pelvic Muscle Activation and Lumbar Lordosis in LBP-developers during prolonged standing | 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 Article The Impact of different Standing positions on Pelvic Muscle Activation and Lumbar Lordosis in LBP-developers during prolonged standing Saeedeh Abbasi, Hooman Minoonejad, Seyed Hamed Mousavi, Hamed Abbasi This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4659238/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 Low back pain (LBP) development has been associated with increased hip muscle co-activation and lumbar lordosis during standing in previously asymptomatic individuals. It is commonly advised to use footrests to relieve LB. The impact of adjusting arm position on lumbar biomechanics can also be impressive. This study aimed to compare the effects of normalized footrest height and changing arm position on muscle activity, lumbar lordosis, and pain intensity. Twenty-four female pain developers (PDs) were recruited, identified by a > 10 mm increase on the visual analog scale (VAS) during prolonged standing. Electromyography (EMG) recorded hip muscle activity, and photogrammetry measured lumbar lordosis during one hour of standing. The first group used the footrest intermittently, while the second group additionally changed their arm positions. Both groups showed decreased gluteus medius co-activation during prolonged standing (p = 0.003), with the second group showing lower levels. A significant time effect on lumbar lordosis angle was observed in both groups (p < 0.01). Although lumbar discomfort increased over time and stepping interventions reduced this discomfort, with the second group reporting lower pain intensity (p < 0.05). Applying these interventions in the workplace could be beneficial to reduce discomfort for individuals who stand for long periods of time. Further research is needed to optimize these strategies and assess long-term benefits. Health sciences/Health care Health sciences/Medical research/Study design low back pain developer PD footrest arm lordosis gluteus medius Figures Figure 1 Figure 2 Figure 3 Figure 4 Introduction Low Back Pain (LBP) is a prevalent and debilitating condition worldwide, affecting individuals under 45 years old 1 , 2 . Its prevalence varies significantly, with risk factors including anthropometric characteristics, reduced spinal mobility, lumbar lordosis severity, and psychological factors 3 , 4 . A history of previous LBP episodes is a notable contributor. Prolonged standing, often leading to pain after 30 to 45 minutes 3 , 5 , is a risk factor for LBP Developers (PDs), despite having no clinical history of LBP 6 . Studies have reported a prevalence of 31–80% of LBP due to prolonged standing, primarily among individuals aged 18 to 35 years 7 – 15 . The Visual Analog Score (VAS) during prolonged standing protocol is used to identify PDs 7 , 13 – 18 , but results are not always conclusive 16 , 19 , so the Active Hip Abduction (AHAbd) test can help with this screening 16 , 17 , 19 . A meta-analysis study highlights the importance of considering various anthropometric, structural, psychological, postural, and muscular dimensions in identifying PD and designing preventive measures 6 , 11 , 14 , 18 , 20 – 24 . Changes in motor control, greater lumbar lordosis in individuals over 25 years old, and co-activation of Gluteus Medius (Gmed) muscles may be potential risk factors for LBP due to prolonged standing 17 .Also, task type affects trunk muscle co-contraction and Gmed muscles, with assembly and sorting tasks increasing indices, while tasks without upper limb movement reduce this co-contraction 25 . Several studies have provided varying insights into the relationship between lumbar lordosis and LBP development during prolonged standing. They have indicated significantly greater lumbar lordosis in PD, with a significant correlation observed between lumbar lordosis and LBP prevalence 26 , 27 . The severity of lumbar lordosis has also been associated with negative Sagittal Vertical Axis (SVA) displacement 26 , 28 , 29 . Arm positions can alter sagittal spinal balance, causing changes in lumbar lordosis 30 . The weight of the arms increases the moment of the spine, requiring increased back muscle forces 31 , 32 . Positions with flexed shoulders and the hands are placed on the clavicles can reduce negative displacement or decrease lumbar lordosis 33 – 35 . Correct upper extremity and arm positions during standing activate muscles crucial for pelvic and lumbar stability, leading to improved lumbar lordosis and sagittal vertical axis. This may reduce co-activation of trunk and pelvic or change positive in lumbopelvic alignment, alleviating pain and preventing back injuries from prolonged standing 33 , 36 – 38 . Another way to prevention LBP during prolonged standing are assistive devices, such as steps and slopes, have been studied for their biomechanical effects on trunk and pelvic factors 24 , 39 , 40 . Research has shown that standing protocol durations from 48 to 120 minutes induce fatigue from prolonged standing, with interventions carried out every 5 to 25 minutes of standing 12 , 39 , 40 . Footrests during standing influence the co-activation profiles of the Gmed 3 . Different heights of footrests have been mentioned 3 , 19 , 39 – 41 , with a footrest height equivalent to 10% of the body height showing better effects in reducing fatigue and pain intensity 40 . An adjustable height to achieve a 135-degree angle of the trunk and thigh on the step is recommended 41 . The suitable height condition caused the lowest muscle fatigue and placed the lowest load on the lumbar region, with the lowest pain development 40 . Previous studies show that PD women have a smaller anterior-posterior height ratio, indicating more flexion in the lumbar region, while PD men have a larger ratio, indicating more extension. Women also have longer endurance and less force analysis compared to men 42 , 43 . This suggests that gender plays a significant role in lumbar pain and mobility. The current study aims to examine changes in lumbar lordosis angle, pain severity, and Gmed muscle co-activation in PD women in various standing positions, incorporating suitable height footrests and upper limb positions. This may alleviate pain intensity and reduce future incidence of LBP at younger ages. Methods Participants 24 participants (female) volunteered for this study (Table.1). Participants were excluded if they had a history of back, shoulder, or arm pain (requiring medical intervention or more than three days off work in the past six months), previous back or hip surgery, inability to stand, and any dizziness or fainting during standing. The Baecke questionnaire for the evaluation of habitual physical activity was used to exclude actives or elites 44 who achieve scores above 13. Every participant had previously taken part in a prolonged standing test, which was used to identify individuals as either PD or NPD. A subject was classified as PD if their VAS pain score was greater than 10 mm during the standing procedure. 45 – 47 ; As Table 1 , shows they often experienced their first ache at minute twenty. The AHAbd test, which assesses a person's ability to keep their pelvis and trunk in alignment when moving their lower limb in an unstable position, was also conducted (supplementary Table 1.) 17 , 21 , 48 . All participants were determined to be right leg dominant. Leg dominance was determined by asking participants to simulate the performance of four different tasks: kicking a ball, stomping out a simulated fire, tracing a shape, and picking up a marble 49 . Data collection and analysis will not be performed blind to the conditions of the experiments. It was accepted ethically by Tehran University's Research Ethics Committee, and Informed consent from the participants was secured for their participation in the experiment and consent for publication was obtained from the individuals for the identification of their information or images in an open-access online journal. Additionally, the study is registered under registration reference IRCT20230628058610N1 in the Iranian Registry of Clinical Trials (IRCT). We confirm that all methods were performed in accordance with relevant guidelines and regulations. Table 1 Demographic Information. Means (x̅) and Standard Deviations (SD) of Age, Height, Weight, BMI, and Written Outcome Measure Scores. Outcome Measures Include: Beck Questionnaire, AHAbd tests, and Baseline Visual Analogue Scale (VAS). Index x̅ ±SD Age(year) 29.15 ± 3.68 Height(cm) 164.35 ± 4.76 Weight (kg) : 60.14 ± 8.50 BMI (kg/m²) 22.28 ± 3.26 Beck Q 9.36 ± 1.80 AHAbd test (Right) 2.2 ± 0.69 AHAbd test (Left) 1.85 ± 0.36 VAS first pain (min) 20.85 ± 10.21 Experimental Protocol: Participants were required to stand another day in a confined working area marked on the ground only (0.50 0.46 m) for one hour while they completed a series of four different tasks in 15-min blocks. These tasks were chosen to simulate basic occupational activities often performed during prolonged standing. These tasks included putting together puzzles, assembling small objects, writing forms, and typing. Assignments were randomized across subjects to counter any order effect. A 20-cm high platform was used. After ten minutes of level ground time, they placed their right leg on the footrest for one minute, standing again for three minutes, and then repeated the process with their left leg on the footrest for one minute. This 5 minutes-protocol repeated each 10 minutes during 60 minutes-standing (Fig. 1 ). They were divided into two groups randomly: the first group (use the footrest intermittently) (Fig. 2.A) and the second group (use footrest plus arm flexion, hands crossed on clavicles intermittently) (Fig. 2. B). Figure.2 Example of a participant using the elevated surface (20 cm) during the leg raise (A) and the leg raise with changing arm position(B) conditions Instruments Two pairs of wireless Myon 320 Surface EMG electrodes (Myon AG, Switzerland) 50 were placed over the right and left gluteus medius muscles. The electrode was a SKINTACT® CT-601 type (Ag/AgCl differential electrode) that was placed halfway between the most superior aspect of the iliac crest and the greater trochanter 51 , 52 . EMG signals were collected at a frequency of 2000 Hz using a 16-bit A/D conversion card. The signal was differentially amplified using a common mode rejection ratio of 80 dB at 60 Hz and band-pass filtered from 20 to 450 Hz 53 . For the aim of normalization, maximum voluntary contractions (MVCs) were gathered from the left and right Gmed. Hip abduction in a side laying posture was resisted (by the experimenter) to obtain MVCs 51 , 52 . Two sets of MVCs were completed for each leg, with a minimum of 30 seconds of rest between each exertion. Ten second rest trials were also taken with the participant lying in the supine and prone positions 3 . The lumbar lordosis angle was photogrammetried using a Panasonic digital camera. Three infrared markers, or rigid bodies, were employed at the L1/L2 (upper lumbar spine), L3, and L5/S1 levels 10 , 26 . Data Analysis Electromyography (EMG) : The sampling rate of the SEMG signal recording was set at 2000 Hz using a 20–450 Hz band pass filter 53 .The power frequency spectrums of the raw data were first identified using the fast fourier transform (FFT) analysis pipeline in ProEMG 2.0 to observe the characteristics of the artifact noises. Butterworth low-pass (450 Hz) and high-pass (20 Hz) filters were used before setting a notch filter at 200 Hz. Double passes were filtered through a fourth-order Butterworth filter with a cutoff frequency of 6 Hz 13 . Resting activation was subtracted from EMG, and EMG signals were then normalized to MVC 42 .The root mean square (RMS) values of the filtered raw data were calculated to be used in subsequent analysis. Raw EMG were imported directly into custom MATLAB (V.4). Data from each ten-minute trial was clipped into three, one-minute windows at minutes 9–10, 10–11, and 14–15 to represent the “condition1: before stepping” “condition2: right stepping” and “condition3: left stepping” respectively, four times. This was done for all EMG data. All EMG linear envelopes were expressed as a percentage of MVC. Mean EMG amplitudes were calculated for each of the three, fifteen-second windows. The co-contraction index (CCI) was used to quantify the level of co-activation between all possible muscle pairs using the following Eq. 5 4 : CCI=∑ (EMG low/ EMG high) (EMG low + EMG high) In practice, this technique is often used to assess the degree of joint activity between two muscles. Positive CCI values ​​indicate that the muscles are being activated together, while negative CCI values ​​indicate that one muscle is being activated while the other is not, indicating muscle cross-firing 55 . So, 24 1-min blocks of bilateral Gmed EMG were entered into a custom MATLAB to calculate CCI and exported for statistical analysis. Kinematic Data: Using Kinovea, after static calibration, three points (markers) were selected in order to measure the relative angle of the lumbar lordosis for any instance. The main marker under consideration was L3. The other two markers include the two markers on L1 and S1. For each participation, before and after of standing protocol, the relative angles of lordosis were captured. Visual Analogue Scale: Participant low back discomfort was measured using a 100-mm VAS before and after the interventions during standing, producing 8 total scores. The minimum clinically significant difference for the VAS score was set at 10 mm to align with previous research approaches 21 , 56 . Statistical analysis All statistical tests were conducted using SPSS (Version 24.0) for Windows 10 (SPSS, Inc., Chicago, IL, USA). Dependent variables of interest include the percentage of maximum excitation (%MVC) for EMG, the normalized change in joint angles for kinematic measures, and discomfort, which was measured by VAS displacement. A one-sample Kolmogorov-Smirnov test was used to evaluate the normality of the distribution of variables. All variables showed a normal distribution. Independent variables included one between factors (groups) and two within factors (i.e., three levels of standing conditions and four levels of time). These variables were analyzed using repeated measures (between/within) ANOVA procedures and required additional comparisons. In situations where the data did not satisfy the assumption of sphericity, Greenhouse-Geisser corrected values were used that appropriately adjusted degrees of freedom for the statistical test. In the co-activation model; conditions (level standing, right foot on the footrest, left foot on the footrest), time (four repeated measurements over 1 hour; 4 separate average 1-minute intervals of level standing, 4 separate average 1-minute intervals of right foot stepping, and 4 average intervals 1-minute separate left foot stepping), and the interaction effect of conditions and time (conditions * time) were modeled as independent variables within and between subjects for two groups (use of footrest and use of footrest and change of arm position). In the VAS model, it was modeled in the same way, only the conditions were defined in two states before and after right foot stepping. A paired T-test was used to compare the value of the lumbar lordosis angle at the beginning and end of the test. The level of significance was set at α < 0.05 for all statistical tests. Results EMG (co-activation) There were main effects or interactions, including time, condition, and time*condition. There was a nonsignificant interaction between two groups (p = 0.156), but a significant within groups difference was identified for LGmed–RGmed co-activation in three conditions (p = 0.002) and time effect was significantly identified along standing (p = 0.006). As can be seen in Fig. 3 , two groups showing the same pattern decrease in the co-activation of the bilateral Gmed muscles during condition*time (p = 0.003) but the second group had a lower than the first group. (4.08 ± 2.11 standing level, 2.97 ± 1.49 right step, 2.44 ± 0.77 left step in the first group) and (3.27 ± 1.36 standing level, 1.91 ± 0.92 right step, 2.05 ± 0.96 left step in the second group). Kinematic There was a main effect on time for lumbar spine angle in two groups (p = 0.001). In the first group this was significantly different(p = 0.008) in lumbar lordosis between before and after test (before test: 24.34 ± 5.89 degrees and after that: 18.35 ± 5.91 degrees). Also, the same result appeared in the second group (before test: 23.44 ± 5.10 degrees and after that: 18.70 ± 2.79 degrees) (p = 0.01). So, footrest played an important role in these decreases. Discomfort (VAS) A main effect of time (p = 0.001) was observed for lumbar discomfort within two groups as was the effect of condition(p = 0.001) and time *condition(p = 0.009). On average, discomfort levels increased by a total of 25.85mm over time regardless of the standing condition, but after every minute that a person goes on the steps, the trend of VAS is decreasing, and in the second group, the intensity of the pain is less (in average VAS before step 17.2 ± 3.08 and after step 15.77 ± 3.87 in group 1, before step and change arm position 16.12 ± 4.84 and after it 14.45 ± 3.95 in group 2)(Fig. 4 ). There was no significant effect between the two groups (p = 0.31). Discussion Intermittent placement of one foot on a 20-cm footrest demonstrated evidence of reducing LBP during a prolonged standing protocol. Despite the nonsignificant interaction between the two groups (the first group (use footrest) and the second group (use footrest and change arm position) in the overall analysis, significant within-group differences were observed for LGmed-RGmed co-activation across the three conditions, suggesting that both interventions influence muscle activity differently over time. Changing arm position to shoulder flexion and crossing hands on the clavicle led to a significant increase in lumbar spine flexion compared to standing at level, thereby reducing lumbar lordosis and subsequently decreasing Gmed co-activation and the intensity of pain. Therefore, the results of this study indicate that cyclic elevation of one foot on a footrest and arm position changes in one-minute intervals may be effective in reducing the progression of LBP in susceptible individuals during prolonged standing. These interventions were successful in the limited sample size. In previous studies, Sorensen and colleagues (2015) 26 reported a difference of 4.37 degrees in lumbar lordosis between PD and NPD, with PD individuals demonstrating greater lordosis. This increase in lumbar lordosis was directly associated with higher reported pain levels. Additionally, the intensity of lordosis changes in healthy individuals with different arm positions during standing, such as 90-degree shoulder flexion, hand on the cheek, and hand on the clavicles, were almost similar and had less lordosis change compared to the positions such as passive 90-degree shoulder flexion (using a support) and hand on the chest 30 . Another study examined the effect of arm position during standing on sagittal vertical axis (SVA) changes, which measure the displacement of the vertical axis from the upper posterior corner of the sacrum or S1 vertebra to a plumb line passing through the center of C7. Positive SVA displacement indicates the plumb line passing inside or anterior to the sacrum, while negative displacement indicates it passing behind the sacrum, and in individuals with lumbar hyper lordosis, this index is more negative. In that study, arm positions during standing were examined, and placing hands on the clavicles with shoulder flexion helped reduce the negative displacement by 24% (vs just shoulder flexion) 33 . Avotta et al.(2019) to catch a functional standing position also concluded these findings and reported a significant reduction in negative SVA displacement in the hand-on-clavicles position compared to 45-degree shoulder flexion 35 . but by comparing two positions of hands on the clavicles)not crosswise) with shoulder flexion and hands on the clavicles with elbow touching the trunk, the first position was superior in increasing negative SVA changes 38 . Even in people who have spinal deformities, the fists on the clavicles position for lateral radiograph acquisition has less negative shift in SVA and will have better spine vision 57 .Therefore, the participants would potentially lean their trunks forward to maintain balance, which would lead to a flatter back shape, and therefore a smaller lordosis. Consequently, although an external support would improve the variability of sacral orientation during standing, the risk of altering the sagittal spinal balance must also be considered. 30 So, in the current study, comparing the lumbar lordosis angle at the beginning and end of the experiment when participants stood with one foot on a raised footrest, in the first group, their lumbar lordosis decreased by almost 6 degrees, and in the second group, who also additionally changed arm position, their lumbar lordosis decreased by approximately 7 degrees compared to standing on level ground. These results are consistent with Fewster et al. (2017) 39 , who reported that intermittent one-minute elevation of each foot during prolonged standing led to increased lumbar spine flexion compared to standing on the ground. In contradiction, Callaghan and colleagues investigated the effects of postural footrests on various angles of the lumbosacral and intervertebral bones in radiographic images and the effects of footrests were similar in both PD and NPD individuals 8 . Changes in the lower region of the spine without significant changes in overall lumbar lordosis may indicate a greater importance in pelvic rotation and pelvic kinematics 10 .Moreover, considering proper arm positions can lead to improvements in lumbar lordosis and sagittal vertical axis changes. Additionally, arm position, besides maintaining body alignment, plays a role in activating muscles, especially those contributing to lumbar and pelvic stability. This finding suggests that stepping, with or without arm positioning, plays a crucial role in reducing lumbar lordosis during prolonged standing. The similar patterns of reduction across both groups highlight the potential of stepping exercises to mitigate changes in lumbar spine posture associated with prolonged standing. On the other hand, since PD demonstrates co-activation of the Gmed muscles during standing, it is believed that this activation may act as a compensatory mechanism to control trunk stability, leading to LBP 14 , 39 , 58 . After implementing an exercise protocol aimed at improving trunk stability, an increase in rest time for the Gmed muscles during the initial stages of standing was accompanied by a decrease in their co-contraction. Additionally, trunk instability, reduced strength, and endurance of the Gmed muscles are significantly associated with increased simultaneous activation of this muscle during prolonged standing 47 . In the study by Nelson and Wang 41 , investigating the effect of task type on trunk muscle co-contraction as well as Gmed muscles, it was demonstrated that assembly and sequencing tasks similarly lead to increased co-contraction indices, while tasks involving upper limb immobility significantly induced lower co-contraction in both trunk and Gmed muscles compared to more active tasks. Changes in lower limb levels at different heights during standing can lead to biomechanical alterations in the trunk and pelvis, which are influential factors in LBP. The effect of short-term placement of one foot on steps of varying heights during standing has also been noted to reduce co-activation or relative muscle activation of the Gmed 3 , 40 , 46 . Conversely, in another study, this intervention failed to significantly reduce midsection muscle co-contraction in PD; however, in NPD individuals, patterns of Gmed muscle co-contraction increased, and no significant difference was observed between the two groups 39 . In the current study, the significant within-group differences in LGmed–RGmed co-activation (p = 0.002) and the time effect (p = 0.006) indicate that both groups exhibited a decrease in the co-activation of the bilateral gluteus medius muscles during prolonged standing. This decreases, as seen in Fig. 3 , suggests that both interventions might alleviate the muscle tension typically associated with prolonged standing. Interestingly, the second group showed a consistently lower level of co-activation compared to the first group, implying that the addition of arm positioning might provide an extra benefit in reducing muscle strain. From another point of view ,Lee et al. (2018) 56 found that the use of a footrest may not reduce the progression of LBP, and it is unlikely that prolonged standing-induced pain occurs due to muscular fatigue or biomechanical mechanisms. Since the use of a footrest and long-term elevation of each foot for five minutes may be excessively long and lead to increased pressure on the standing foot, it may not aid in reducing LBP. Additionally, they did not specify whether the location of pain changed during the intervention, nor did they report the height of the footrest used. Spinal flexion resulting from placing one foot on a step will increase with increasing step height 53 , but as the footrest height increases, the standing foot must bear more weight. Therefore, potential differences in the height of the footrest used and the duration of foot placement on the step may also affect the success of the intervention during standing, as demonstrated by Sen et al. (2017) 40 , who achieved a successful reduction in the intensity of LBP in PDs during prolonged standing with intermittent 15-minute intervals using an optimally sized footrest at ten percent of the body height. Similarly, Fuster et al. reported successful results in reducing pain every eight minutes during 80 minutes of standing. Placing each foot alternately on a 13-cm footrest for one minute and performing a three-minute rest between each stepping protocol was the intervention. However, no significant difference in LBP intensity was observed at different footrest heights from 10 to 30 cm during only 15 minutes of standing on the step in the study by Floy et al.(2021) 53 . In the present study, considering a step height (20-cm) close to ten percent of the bodies height average and forming a 135-degree angle between the hip axis and the spine 59 we reached the conclusion of a significant reduction in pain intensity before and after stepping in both groups, although discomfort levels increased over time, which is expected with prolonged standing. However, stepping interventions appeared to mitigate this discomfort. Notably, the trend of decreasing VAS scores over time after stepping suggests that incorporating steps can reduce perceived discomfort by decreasing external lumbar moment and muscle activity 40 , which activates more and helps to stabilize the spine during the standing 37 , 60 . The second group consistently reported lower pain intensity compared to the first group, emphasizing the added benefit of arm positioning in alleviating discomfort. One possible hypothesis is that during standing, increased muscular activity may act as a compensatory mechanism for poor body posture control, leading to pain in the lumbar regions 56 and changing arm position to shoulder flexion and hand rest on the clavicle with stepping causes decreasing lumbar extension and muscle activity in which they play a role 35 , 61 and it make opportunity for decreasing pain in the lumbar region. Extending the current results to a study to confirm whether the results are transferable to individuals who need to stand for long periods but have the ability to use a small footrest and have time during work to change arm position may be valuable. Additionally, this research used a relatively small sample size, which may limit the generalizability of these findings to the general population. Conclusion This study demonstrates that stepping, both alone and with added arm positioning, can significantly influence muscle co-activation, lumbar spine posture, and discomfort levels during prolonged standing. Although no significant interaction between the two groups was found, the within-group analyses reveal meaningful differences and benefits associated with these interventions. Specifically, the footrest plus change arm position intervention showed a trend toward greater reductions in muscle co-activation and discomfort, suggesting that it might be a more effective strategy for mitigating the negative effects of prolonged standing. These findings have practical implications for designing workplace interventions to reduce musculoskeletal strain and improve comfort for individuals required to stand for extended periods in various occupational settings. Future research should explore the long-term effects of these interventions and investigate other potential combinations of more movements and positions to further enhance their effectiveness. Abbreviations LBP Low Back Pain AHAbd Active hip abduction BMI Body mass index Gmed Gluteus Medius PD Pain developer NPD non-pain developer VAS Visual Analogue Scale CCI Co-Contraction Index RMS Root Mean Square Declarations Competing interests The authors declare no competing interests. Author Contribution S.A. handled the research process from sampling and testing to analysis and writing. H.M. acting as a supervisor, provided guidance on research methodologies, data evaluation, and article composition. S.H.M. contributed to the statistical analysis methodology and reviewed the article. H.A. contributed to the testing at the Iran Research Institute of Sports Sciences. All authors collaborated on editing and critically revising the article, ultimately endorsing the final version. 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P., Hwang, C.-T. & Van Dillen, L. R. Is lumbar lordosis related to low back pain development during prolonged standing? Man. Ther. 20, 553–557 (2015). Misir, A. et al. Lumbar spine posture and spinopelvic parameters change in various standing and sitting postures. Eur. Spine J. 28, 1072–1081 (2019). Sparrey, C. J. et al. Etiology of lumbar lordosis and its pathophysiology: a review of the evolution of lumbar lordosis, and the mechanics and biology of lumbar degeneration. Neurosurg. Focus 36, E1 (2014). Been, E. & Kalichman, L. Lumbar lordosis. Spine J. 14, 87–97 (2014). Pan, F., Zhu, R., Zander, T., Lu, S. & Schmidt, H. The sagittal sways of back lordosis and sacral orientation during still standing at different arm positions. J. Biomech. 114, 110149 (2021). Angelini, L. et al. Effect of arm swinging on lumbar spine and hip joint forces. J. Biomech. 70, 185–195 (2018). Zander, T., Dreischarf, M., Schmidt, H., Bergmann, G. & Rohlmann, A. Spinal loads as influenced by external loads: A combined in vivo and in silico investigation. J. Biomech. 48, 578–584 (2015). Aota, Y. et al. Optimal arm position for evaluation of spinal sagittal balance. Clin. Spine Surg. 24, 105–109 (2011). Florindo, A. A. & Latorre, M. do R. D. de O. Validation and reliability of the Baecke questionnaire for the evaluation of habitual physical activity in adult men. Rev. Bras. Med. do Esporte 9, 129–135 (2003). Aota, Y. et al. Does the fists-on-clavicles position represent a functional standing position? Spine (Phila. Pa. 1976). 34, 808–812 (2009). Siu, A., Schinkel-Ivy, A. & Drake, J. D. M. Arm position influences the activation patterns of trunk muscles during trunk range-of-motion movements. Hum. Mov. Sci. 49, 267–276 (2016). Christe, G., Jolles, B. M. & Favre, J. Between/within-session reliability of spinal kinematic and lumbar muscle activity measures in patients with chronic low back pain and asymptomatic individuals. Gait Posture 95, 100–108 (2022). Kaneko, K., Aota, Y., Sekiya, T., Yamada, K. & Saito, T. Validation study of arm positions for evaluation of global spinal balance in EOS imaging. Eur. J. Orthop. Surg. Traumatol. 26, 725–733 (2016). Fewster, K. M., Gallagher, K. M. & Callaghan, J. P. The effect of standing interventions on acute low-back postures and muscle activation patterns. Appl. Ergon. 58, 281–286 (2017). Son, J.-I. et al. Effects of footrest heights on muscle fatigue, kinematics, and kinetics during prolonged standing work. J. Back Musculoskelet. Rehabil. 31, 389–396 (2018). Nelson-Wong, E. & Callaghan, J. P. The impact of a sloped surface on low back pain during prolonged standing work: a biomechanical analysis. Appl. Ergon. 41, 787–795 (2010). Nelson-Wong, E., Howarth, S. J. & Callaghan, J. P. Acute biomechanical responses to a prolonged standing exposure in a simulated occupational setting. Ergonomics 53, 1117–1128 (2010). Weber, C. I. K. Structural and Tissue-level Adaptations of Lumbar Intervertebral Discs in Humans with Inducible Low Back Pain Symptoms . (Washington University in St. Louis, 2019). Baecke, J. A. H., Burema, J. & Frijters, J. E. R. A short questionnaire for the measurement of habitual physical activity in epidemiological studies. Am. J. Clin. Nutr. 36, 936–942 (1982). Gallagher, K. M., Campbell, T. & Callaghan, J. P. The influence of a seated break on prolonged standing induced low back pain development. Ergonomics 57, 555–562 (2014). Nelson-Wong, E. & Callaghan, J. P. Repeatability of clinical, biomechanical, and motor control profiles in people with and without standing-induced low back pain. Rehabil. Res. Pract. 2010, (2010). Marshall, P. W. M., Desai, I. & Robbins, D. W. Core stability exercises in individuals with and without chronic nonspecific low back pain. J. Strength Cond. Res. 25, 3404–3411 (2011). Davis, A. M., Bridge, P., Miller, J. & Nelson-Wong, E. Interrater and intrarater reliability of the active hip abduction test. J. Orthop. Sports Phys. Ther. 41, 953–960 (2011). Schneiders, A. G. et al. A valid and reliable clinical determination of footedness. Pm&r 2, 835–841 (2010). Rashid, H. et al. Usage of wireless Myon 320 surface electromyography (sEMG) system in recording motorcyclist muscle activities on real roads: a case study. Procedia Manuf. 3, 2566–2573 (2015). Vink, P., Daanen, H. A. M. & Verbout, A. J. Specificity of surface-EMG on the intrinsic lumbar back muscles. Hum. Mov. Sci. 8, 67–78 (1989). Stegeman, D. & Hermens, H. Standards for surface electromyography: The European project Surface EMG for non-invasive assessment of muscles (SENIAM). Enschede Roessingh Res. Dev. 10, 8–12 (2007). Cregg, A. C., Foley, R. C. A., Livingston, L. A. & La Delfa, N. J. A biomechanical evaluation of different footrest heights during standing computer work. Ergonomics 64, 342–353 (2021). Nelson-Wong, E. & Callaghan, J. P. Changes in muscle activation patterns and subjective low back pain ratings during prolonged standing in response to an exercise intervention. J. Electromyogr. Kinesiol. 20, 1125–1133 (2010). Nelson-Wong, E., Howarth, S., Winter, D. A. & Callaghan, J. P. Application of autocorrelation and cross-correlation analyses in human movement and rehabilitation research. J. Orthop. Sport. Phys. Ther. 39, 287–295 (2009). Lee, J. Y., Baker, R., Coenen, P. & Straker, L. Use of a footrest to reduce low back discomfort development due to prolonged standing. Appl. Ergon. 67, 218–224 (2018). Faro, F. D., Marks, M. C., Pawelek, J. & Newton, P. O. Evaluation of a functional position for lateral radiograph acquisition in adolescent idiopathic scoliosis. Spine (Phila. Pa. 1976). 29, 2284–2289 (2004). Nairn, B. C., Azar, N. R. & Drake, J. D. M. Transient pain developers show increased abdominal muscle activity during prolonged sitting. J. Electromyogr. Kinesiol. 23, 1421–1427 (2013). Keegan, J. J. Alterations of the lumbar curve related to posture and seating. JBJS 35, 589–603 (1953). Hwang, C.-T. et al. The use of intermittent trunk flexion to alleviate low back pain during prolonged standing. J. Electromyogr. Kinesiol. 28, 46–51 (2019). Mitani, Y., Hanafusa, M., Hashimoto, J., Inada, R. & Koda, H. Effects of arm and leg positions on lumbar multifidus muscle activity while on hands and knees or while standing. J. Physiol. Anthropol. 41, (2022). Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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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-4659238","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":330197297,"identity":"1d98bee0-d730-4cf8-acfe-1d16090666ce","order_by":0,"name":"Saeedeh Abbasi","email":"","orcid":"","institution":"University of Tehran","correspondingAuthor":false,"prefix":"","firstName":"Saeedeh","middleName":"","lastName":"Abbasi","suffix":""},{"id":330197299,"identity":"897aae4a-40e2-4155-99af-5937a394e44d","order_by":1,"name":"Hooman Minoonejad","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA3ElEQVRIie3OMQrCMBSA4VccjXRtKdQrVIRKsd7FLG6KIEjHTnVRXHuMigfwScAuwbng5A0UQRwcjIqiIDGjYH4IeQ/yQQB0uh/MEwfvI4K1g8eoSuz0tiuQZw553z/XgDJl/SjsmQbbblrJGcwRGiySkCCuZCzlnYEdr+rNbuKBxduw5LKPoSCVhNEM0XeuBAqAZaxCFpgfnUCQqjLJgPuOIYj3lTBBCO/QFPkgGK/rpMZpLCf5ZH4gUUinaT4rTkPXdXPG9jICpcdg4e0iAIYUvGSqPtTpdLq/6wJ40VO2HcaGLgAAAABJRU5ErkJggg==","orcid":"","institution":"University of Tehran","correspondingAuthor":true,"prefix":"","firstName":"Hooman","middleName":"","lastName":"Minoonejad","suffix":""},{"id":330197300,"identity":"b508c9ef-d19c-4df8-8d7c-68bb7292aaf8","order_by":2,"name":"Seyed Hamed Mousavi","email":"","orcid":"","institution":"University of Tehran","correspondingAuthor":false,"prefix":"","firstName":"Seyed","middleName":"Hamed","lastName":"Mousavi","suffix":""},{"id":330197301,"identity":"08083b04-444c-467c-aa96-b82b7e536fdd","order_by":3,"name":"Hamed Abbasi","email":"","orcid":"","institution":"Sport Sciences Research Institute","correspondingAuthor":false,"prefix":"","firstName":"Hamed","middleName":"","lastName":"Abbasi","suffix":""}],"badges":[],"createdAt":"2024-06-29 12:08:28","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4659238/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4659238/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":61194553,"identity":"8a579c29-f0bf-418b-bd83-a1c5e7b212f3","added_by":"auto","created_at":"2024-07-26 21:17:00","extension":"jpeg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":101317,"visible":true,"origin":"","legend":"\u003cp\u003eDiagram of experimental protocol in 5 minutes each 10 minutes during 60 minutes standing.\u003c/p\u003e","description":"","filename":"floatimage1.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-4659238/v1/37f62d204842b4a12ce97f78.jpeg"},{"id":61193586,"identity":"909f5e07-22a4-4cd7-967d-0ce607b63c91","added_by":"auto","created_at":"2024-07-26 21:01:00","extension":"jpeg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":82753,"visible":true,"origin":"","legend":"\u003cp\u003eExample of a participant using the elevated surface (20 cm) during the leg raise (A) and the leg raise with changing arm position(B) conditions\u003c/p\u003e","description":"","filename":"floatimage2.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-4659238/v1/5c3cfabc0a27bc9e14e28c6a.jpeg"},{"id":61193584,"identity":"a304738f-b5b5-4c47-ac3b-bfada25acb69","added_by":"auto","created_at":"2024-07-26 21:01:00","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":163589,"visible":true,"origin":"","legend":"\u003cp\u003eCo-activation of right and left gluteus medius during 60 minutes standing (time- condition). conditions: con1=level standing, con2= right leg on footrest, con3= left leg on footrest.\u003c/p\u003e","description":"","filename":"Picture1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4659238/v1/3843ebc05a87847757fd8650.jpg"},{"id":61194271,"identity":"60ac00e3-21a9-48c3-9902-f73b69f160db","added_by":"auto","created_at":"2024-07-26 21:09:00","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":142021,"visible":true,"origin":"","legend":"\u003cp\u003eVAS score in specific minutes between two groups. pre right step and post right step every 15 minutes during 60 minutes of standing.\u003c/p\u003e","description":"","filename":"Picture2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4659238/v1/d4abee5f67370d958e2ab146.jpg"},{"id":65734742,"identity":"d967410f-e1aa-40ee-b899-9876ee7c02e8","added_by":"auto","created_at":"2024-10-01 23:16:23","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":945594,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4659238/v1/eb23edc9-900c-44c6-a40a-5f901b7113a2.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"The Impact of different Standing positions on Pelvic Muscle Activation and Lumbar Lordosis in LBP-developers during prolonged standing ","fulltext":[{"header":"Introduction","content":"\u003cp\u003eLow Back Pain (LBP) is a prevalent and debilitating condition worldwide, affecting individuals under 45 years old \u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e,\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e. Its prevalence varies significantly, with risk factors including anthropometric characteristics, reduced spinal mobility, lumbar lordosis severity, and psychological factors \u003csup\u003e\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e,\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u003c/sup\u003e. A history of previous LBP episodes is a notable contributor. Prolonged standing, often leading to pain after 30 to 45 minutes \u003csup\u003e\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e,\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u003c/sup\u003e, is a risk factor for LBP Developers (PDs), despite having no clinical history of LBP \u003csup\u003e\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u003c/sup\u003e. Studies have reported a prevalence of 31\u0026ndash;80% of LBP due to prolonged standing, primarily among individuals aged 18 to 35 years\u003csup\u003e\u003cspan additionalcitationids=\"CR8 CR9 CR10 CR11 CR12 CR13 CR14\" citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u003c/sup\u003e. The Visual Analog Score (VAS) during prolonged standing protocol is used to identify PDs \u003csup\u003e\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e,\u003cspan additionalcitationids=\"CR14 CR15 CR16 CR17\" citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e\u003c/sup\u003e, but results are not always conclusive\u003csup\u003e\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e,\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e\u003c/sup\u003e, so the Active Hip Abduction (AHAbd) test can help with this screening\u003csup\u003e\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e,\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e,\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e\u003c/sup\u003e. A meta-analysis study highlights the importance of considering various anthropometric, structural, psychological, postural, and muscular dimensions in identifying PD and designing preventive measures\u003csup\u003e\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e,\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e,\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e,\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e,\u003cspan additionalcitationids=\"CR21 CR22 CR23\" citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e\u003c/sup\u003e. Changes in motor control, greater lumbar lordosis in individuals over 25 years old, and co-activation of Gluteus Medius (Gmed) muscles may be potential risk factors for LBP due to prolonged standing\u003csup\u003e\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u003c/sup\u003e.Also, task type affects trunk muscle co-contraction and Gmed muscles, with assembly and sorting tasks increasing indices, while tasks without upper limb movement reduce this co-contraction\u003csup\u003e\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eSeveral studies have provided varying insights into the relationship between lumbar lordosis and LBP development during prolonged standing. They have indicated significantly greater lumbar lordosis in PD, with a significant correlation observed between lumbar lordosis and LBP prevalence \u003csup\u003e\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e,\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e\u003c/sup\u003e. The severity of lumbar lordosis has also been associated with negative Sagittal Vertical Axis (SVA) displacement\u003csup\u003e\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e,\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e,\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e\u003c/sup\u003e. Arm positions can alter sagittal spinal balance, causing changes in lumbar lordosis\u003csup\u003e\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e\u003c/sup\u003e. The weight of the arms increases the moment of the spine, requiring increased back muscle forces\u003csup\u003e\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e,\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e\u003c/sup\u003e. Positions with flexed shoulders and the hands are placed on the clavicles can reduce negative displacement or decrease lumbar lordosis\u003csup\u003e\u003cspan additionalcitationids=\"CR34\" citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e\u003c/sup\u003e. Correct upper extremity and arm positions during standing activate muscles crucial for pelvic and lumbar stability, leading to improved lumbar lordosis and sagittal vertical axis. This may reduce co-activation of trunk and pelvic or change positive in lumbopelvic alignment, alleviating pain and preventing back injuries from prolonged standing\u003csup\u003e\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e,\u003cspan additionalcitationids=\"CR37\" citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eAnother way to prevention LBP during prolonged standing are assistive devices, such as steps and slopes, have been studied for their biomechanical effects on trunk and pelvic factors\u003csup\u003e\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e,\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e,\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e\u003c/sup\u003e. Research has shown that standing protocol durations from 48 to 120 minutes induce fatigue from prolonged standing, with interventions carried out every 5 to 25 minutes of standing\u003csup\u003e\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e,\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e,\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e\u003c/sup\u003e. Footrests during standing influence the co-activation profiles of the Gmed\u003csup\u003e\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u003c/sup\u003e. Different heights of footrests have been mentioned\u003csup\u003e\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e,\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e,\u003cspan additionalcitationids=\"CR40\" citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e\u003c/sup\u003e, with a footrest height equivalent to 10% of the body height showing better effects in reducing fatigue and pain intensity\u003csup\u003e\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e\u003c/sup\u003e. An adjustable height to achieve a 135-degree angle of the trunk and thigh on the step is recommended\u003csup\u003e\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e\u003c/sup\u003e. The suitable height condition caused the lowest muscle fatigue and placed the lowest load on the lumbar region, with the lowest pain development\u003csup\u003e\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003ePrevious studies show that PD women have a smaller anterior-posterior height ratio, indicating more flexion in the lumbar region, while PD men have a larger ratio, indicating more extension. Women also have longer endurance and less force analysis compared to men\u003csup\u003e\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e,\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e\u003c/sup\u003e. This suggests that gender plays a significant role in lumbar pain and mobility. The current study aims to examine changes in lumbar lordosis angle, pain severity, and Gmed muscle co-activation in PD women in various standing positions, incorporating suitable height footrests and upper limb positions. This may alleviate pain intensity and reduce future incidence of LBP at younger ages.\u003c/p\u003e"},{"header":"Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eParticipants\u003c/h2\u003e \u003cp\u003e24 participants (female) volunteered for this study (Table.1). Participants were excluded if they had a history of back, shoulder, or arm pain (requiring medical intervention or more than three days off work in the past six months), previous back or hip surgery, inability to stand, and any dizziness or fainting during standing. The Baecke questionnaire for the evaluation of habitual physical activity was used to exclude actives or elites \u003csup\u003e\u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e\u003c/sup\u003e who achieve scores above 13. Every participant had previously taken part in a prolonged standing test, which was used to identify individuals as either PD or NPD. A subject was classified as PD if their VAS pain score was greater than 10 mm during the standing procedure.\u003csup\u003e\u003cspan additionalcitationids=\"CR46\" citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e47\u003c/span\u003e\u003c/sup\u003e ; As Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, shows they often experienced their first ache at minute twenty. The AHAbd test, which assesses a person's ability to keep their pelvis and trunk in alignment when moving their lower limb in an unstable position, was also conducted (supplementary Table\u0026nbsp;1.)\u003csup\u003e\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e,\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e,\u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e48\u003c/span\u003e\u003c/sup\u003e. All participants were determined to be right leg dominant. Leg dominance was determined by asking participants to simulate the performance of four different tasks: kicking a ball, stomping out a simulated fire, tracing a shape, and picking up a marble\u003csup\u003e\u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e49\u003c/span\u003e\u003c/sup\u003e. Data collection and analysis will not be performed blind to the conditions of the experiments. It was accepted ethically by Tehran University's Research Ethics Committee, and Informed consent from the participants was secured for their participation in the experiment and consent for publication was obtained from the individuals for the identification of their information or images in an open-access online journal. Additionally, the study is registered under registration reference IRCT20230628058610N1 in the Iranian Registry of Clinical Trials (IRCT). We confirm that all methods were performed in accordance with relevant guidelines and regulations.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\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 Information. Means (x̅) and Standard Deviations (SD) of Age, Height, Weight, BMI, and Written Outcome Measure Scores. Outcome Measures Include: Beck Questionnaire, AHAbd tests, and Baseline Visual Analogue Scale (VAS).\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"2\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eIndex\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003ex̅ \u0026plusmn;SD\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eAge(year)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e29.15\u0026thinsp;\u0026plusmn;\u0026thinsp;3.68\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eHeight(cm)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e164.35\u0026thinsp;\u0026plusmn;\u0026thinsp;4.76\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eWeight (kg)\u003c/b\u003e:\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e60.14\u0026thinsp;\u0026plusmn;\u0026thinsp;8.50\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eBMI (kg/m\u0026sup2;)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e22.28\u0026thinsp;\u0026plusmn;\u0026thinsp;3.26\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eBeck Q\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e9.36\u0026thinsp;\u0026plusmn;\u0026thinsp;1.80\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eAHAbd test (Right)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e2.2\u0026thinsp;\u0026plusmn;\u0026thinsp;0.69\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eAHAbd test (Left)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e1.85\u0026thinsp;\u0026plusmn;\u0026thinsp;0.36\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eVAS first pain (min)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e20.85\u0026thinsp;\u0026plusmn;\u0026thinsp;10.21\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003eExperimental Protocol:\u003c/h2\u003e \u003cp\u003eParticipants were required to stand another day in a confined working area marked on the ground only (0.50 0.46 m) for one hour while they completed a series of four different tasks in 15-min blocks. These tasks were chosen to simulate basic occupational activities often performed during prolonged standing. These tasks included putting together puzzles, assembling small objects, writing forms, and typing. Assignments were randomized across subjects to counter any order effect. A 20-cm high platform was used. After ten minutes of level ground time, they placed their right leg on the footrest for one minute, standing again for three minutes, and then repeated the process with their left leg on the footrest for one minute. This 5 minutes-protocol repeated each 10 minutes during 60 minutes-standing (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). They were divided into two groups randomly: the first group (use the footrest intermittently) (Fig.\u0026nbsp;2.A) and the second group (use footrest plus arm flexion, hands crossed on clavicles intermittently) (Fig.\u0026nbsp;2. B).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003cp\u003e \u003cb\u003eFigure.2\u003c/b\u003e Example of a participant using the elevated surface (20 cm) during the leg raise (A) and the leg raise with changing arm position(B) conditions\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003eInstruments\u003c/h2\u003e \u003cp\u003eTwo pairs of wireless Myon 320 Surface EMG electrodes (Myon AG, Switzerland) \u003csup\u003e\u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e50\u003c/span\u003e\u003c/sup\u003e were placed over the right and left gluteus medius muscles. The electrode was a SKINTACT\u0026reg; CT-601 type (Ag/AgCl differential electrode) that was placed halfway between the most superior aspect of the iliac crest and the greater trochanter\u003csup\u003e\u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e51\u003c/span\u003e,\u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e52\u003c/span\u003e\u003c/sup\u003e. EMG signals were collected at a frequency of 2000 Hz using a 16-bit A/D conversion card. The signal was differentially amplified using a common mode rejection ratio of 80 dB at 60 Hz and band-pass filtered from 20 to 450 Hz \u003csup\u003e\u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e53\u003c/span\u003e\u003c/sup\u003e. For the aim of normalization, maximum voluntary contractions (MVCs) were gathered from the left and right Gmed. Hip abduction in a side laying posture was resisted (by the experimenter) to obtain MVCs \u003csup\u003e\u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e51\u003c/span\u003e,\u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e52\u003c/span\u003e\u003c/sup\u003e. Two sets of MVCs were completed for each leg, with a minimum of 30 seconds of rest between each exertion. Ten second rest trials were also taken with the participant lying in the supine and prone positions\u003csup\u003e\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eThe lumbar lordosis angle was photogrammetried using a Panasonic digital camera. Three infrared markers, or rigid bodies, were employed at the L1/L2 (upper lumbar spine), L3, and L5/S1 levels\u003csup\u003e\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e,\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003eData Analysis\u003c/h2\u003e \u003cdiv id=\"Sec8\" class=\"Section3\"\u003e \u003ch2\u003e\u003cb\u003eElectromyography (EMG)\u003c/b\u003e:\u003c/h2\u003e \u003cp\u003eThe sampling rate of the SEMG signal recording was set at 2000 Hz using a 20\u0026ndash;450 Hz band pass filter\u003csup\u003e\u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e53\u003c/span\u003e\u003c/sup\u003e.The power frequency spectrums of the raw data were first identified using the fast fourier transform (FFT) analysis pipeline in ProEMG 2.0 to observe the characteristics of the artifact noises. Butterworth low-pass (450 Hz) and high-pass (20 Hz) filters were used before setting a notch filter at 200 Hz. Double passes were filtered through a fourth-order Butterworth filter with a cutoff frequency of 6 Hz \u003csup\u003e\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u003c/sup\u003e. Resting activation was subtracted from EMG, and EMG signals were then normalized to MVC\u003csup\u003e\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e\u003c/sup\u003e.The root mean square (RMS) values of the filtered raw data were calculated to be used in subsequent analysis. Raw EMG were imported directly into custom MATLAB (V.4). Data from each ten-minute trial was clipped into three, one-minute windows at minutes 9\u0026ndash;10, 10\u0026ndash;11, and 14\u0026ndash;15 to represent the \u0026ldquo;condition1: before stepping\u0026rdquo; \u0026ldquo;condition2: right stepping\u0026rdquo; and \u0026ldquo;condition3: left stepping\u0026rdquo; respectively, four times. This was done for all EMG data. All EMG linear envelopes were expressed as a percentage of MVC. Mean EMG amplitudes were calculated for each of the three, fifteen-second windows. The co-contraction index (CCI) was used to quantify the level of co-activation between all possible muscle pairs using the following Eq.\u0026nbsp;5\u003csup\u003e4\u003c/sup\u003e:\u003c/p\u003e \u003cp\u003eCCI=\u0026sum; (EMG low/ EMG high) (EMG low\u0026thinsp;+\u0026thinsp;EMG high)\u003c/p\u003e \u003cp\u003eIn practice, this technique is often used to assess the degree of joint activity between two muscles. Positive CCI values ​​indicate that the muscles are being activated together, while negative CCI values ​​indicate that one muscle is being activated while the other is not, indicating muscle cross-firing\u003csup\u003e\u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e55\u003c/span\u003e\u003c/sup\u003e. So, 24 1-min blocks of bilateral Gmed EMG were entered into a custom MATLAB to calculate CCI and exported for statistical analysis.\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003eKinematic Data:\u003c/h2\u003e \u003cp\u003eUsing Kinovea, after static calibration, three points (markers) were selected in order to measure the relative angle of the lumbar lordosis for any instance. The main marker under consideration was L3. The other two markers include the two markers on L1 and S1. For each participation, before and after of standing protocol, the relative angles of lordosis were captured.\u003c/p\u003e \u003cdiv id=\"Sec10\" class=\"Section3\"\u003e \u003ch2\u003eVisual Analogue Scale:\u003c/h2\u003e \u003cp\u003eParticipant low back discomfort was measured using a 100-mm VAS before and after the interventions during standing, producing 8 total scores. The minimum clinically significant difference for the VAS score was set at 10 mm to align with previous research approaches\u003csup\u003e\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e,\u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e56\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003eStatistical analysis\u003c/h2\u003e \u003cp\u003eAll statistical tests were conducted using SPSS (Version 24.0) for Windows 10 (SPSS, Inc., Chicago, IL, USA). Dependent variables of interest include the percentage of maximum excitation (%MVC) for EMG, the normalized change in joint angles for kinematic measures, and discomfort, which was measured by VAS displacement. A one-sample Kolmogorov-Smirnov test was used to evaluate the normality of the distribution of variables. All variables showed a normal distribution. Independent variables included one between factors (groups) and two within factors (i.e., three levels of standing conditions and four levels of time). These variables were analyzed using repeated measures (between/within) ANOVA procedures and required additional comparisons. In situations where the data did not satisfy the assumption of sphericity, Greenhouse-Geisser corrected values were used that appropriately adjusted degrees of freedom for the statistical test.\u003c/p\u003e \u003cp\u003eIn the co-activation model; conditions (level standing, right foot on the footrest, left foot on the footrest), time (four repeated measurements over 1 hour; 4 separate average 1-minute intervals of level standing, 4 separate average 1-minute intervals of right foot stepping, and 4 average intervals 1-minute separate left foot stepping), and the interaction effect of conditions and time (conditions * time) were modeled as independent variables within and between subjects for two groups (use of footrest and use of footrest and change of arm position). In the VAS model, it was modeled in the same way, only the conditions were defined in two states before and after right foot stepping. A paired T-test was used to compare the value of the lumbar lordosis angle at the beginning and end of the test. The level of significance was set at α\u0026thinsp;\u0026lt;\u0026thinsp;0.05 for all statistical tests.\u003c/p\u003e \u003c/div\u003e "},{"header":"Results","content":"\u003cdiv id=\"Sec12\" type=\"Results\" class=\"Section2\"\u003e \u003cdiv id=\"Sec13\" class=\"Section3\"\u003e \u003ch2\u003eEMG (co-activation)\u003c/h2\u003e \u003cp\u003eThere were main effects or interactions, including time, condition, and time*condition. There was a nonsignificant interaction between two groups (p\u0026thinsp;=\u0026thinsp;0.156), but a significant within groups difference was identified for LGmed\u0026ndash;RGmed co-activation in three conditions (p\u0026thinsp;=\u0026thinsp;0.002) and time effect was significantly identified along standing (p\u0026thinsp;=\u0026thinsp;0.006). As can be seen in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e3\u003c/span\u003e, two groups showing the same pattern decrease in the co-activation of the bilateral Gmed muscles during condition*time (p\u0026thinsp;=\u0026thinsp;0.003) but the second group had a lower than the first group. (4.08\u0026thinsp;\u0026plusmn;\u0026thinsp;2.11 standing level, 2.97\u0026thinsp;\u0026plusmn;\u0026thinsp;1.49 right step, 2.44\u0026thinsp;\u0026plusmn;\u0026thinsp;0.77 left step in the first group) and (3.27\u0026thinsp;\u0026plusmn;\u0026thinsp;1.36 standing level, 1.91\u0026thinsp;\u0026plusmn;\u0026thinsp;0.92 right step, 2.05\u0026thinsp;\u0026plusmn;\u0026thinsp;0.96 left step in the second group).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003eKinematic\u003c/h2\u003e \u003cp\u003eThere was a main effect on time for lumbar spine angle in two groups (p\u0026thinsp;=\u0026thinsp;0.001). In the first group this was significantly different(p\u0026thinsp;=\u0026thinsp;0.008) in lumbar lordosis between before and after test (before test: 24.34\u0026thinsp;\u0026plusmn;\u0026thinsp;5.89 degrees and after that: 18.35\u0026thinsp;\u0026plusmn;\u0026thinsp;5.91 degrees). Also, the same result appeared in the second group (before test: 23.44\u0026thinsp;\u0026plusmn;\u0026thinsp;5.10 degrees and after that: 18.70\u0026thinsp;\u0026plusmn;\u0026thinsp;2.79 degrees) (p\u0026thinsp;=\u0026thinsp;0.01). So, footrest played an important role in these decreases.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec15\" class=\"Section2\"\u003e \u003ch2\u003eDiscomfort (VAS)\u003c/h2\u003e \u003cp\u003eA main effect of time (p\u0026thinsp;=\u0026thinsp;0.001) was observed for lumbar discomfort within two groups as was the effect of condition(p\u0026thinsp;=\u0026thinsp;0.001) and time *condition(p\u0026thinsp;=\u0026thinsp;0.009). On average, discomfort levels increased by a total of 25.85mm over time regardless of the standing condition, but after every minute that a person goes on the steps, the trend of VAS is decreasing, and in the second group, the intensity of the pain is less (in average VAS before step 17.2\u0026thinsp;\u0026plusmn;\u0026thinsp;3.08 and after step 15.77\u0026thinsp;\u0026plusmn;\u0026thinsp;3.87 in group 1, before step and change arm position 16.12\u0026thinsp;\u0026plusmn;\u0026thinsp;4.84 and after it 14.45\u0026thinsp;\u0026plusmn;\u0026thinsp;3.95 in group 2)(Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e4\u003c/span\u003e). There was no significant effect between the two groups (p\u0026thinsp;=\u0026thinsp;0.31).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eIntermittent placement of one foot on a 20-cm footrest demonstrated evidence of reducing LBP during a prolonged standing protocol. Despite the nonsignificant interaction between the two groups (the first group (use footrest) and the second group (use footrest and change arm position) in the overall analysis, significant within-group differences were observed for LGmed-RGmed co-activation across the three conditions, suggesting that both interventions influence muscle activity differently over time. Changing arm position to shoulder flexion and crossing hands on the clavicle led to a significant increase in lumbar spine flexion compared to standing at level, thereby reducing lumbar lordosis and subsequently decreasing Gmed co-activation and the intensity of pain. Therefore, the results of this study indicate that cyclic elevation of one foot on a footrest and arm position changes in one-minute intervals may be effective in reducing the progression of LBP in susceptible individuals during prolonged standing. These interventions were successful in the limited sample size.\u003c/p\u003e \u003cp\u003eIn previous studies, Sorensen and colleagues (2015)\u003csup\u003e\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e\u003c/sup\u003e reported a difference of 4.37 degrees in lumbar lordosis between PD and NPD, with PD individuals demonstrating greater lordosis. This increase in lumbar lordosis was directly associated with higher reported pain levels. Additionally, the intensity of lordosis changes in healthy individuals with different arm positions during standing, such as 90-degree shoulder flexion, hand on the cheek, and hand on the clavicles, were almost similar and had less lordosis change compared to the positions such as passive 90-degree shoulder flexion (using a support) and hand on the chest \u003csup\u003e\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e\u003c/sup\u003e. Another study examined the effect of arm position during standing on sagittal vertical axis (SVA) changes, which measure the displacement of the vertical axis from the upper posterior corner of the sacrum or S1 vertebra to a plumb line passing through the center of C7. Positive SVA displacement indicates the plumb line passing inside or anterior to the sacrum, while negative displacement indicates it passing behind the sacrum, and in individuals with lumbar hyper lordosis, this index is more negative. In that study, arm positions during standing were examined, and placing hands on the clavicles with shoulder flexion helped reduce the negative displacement by 24% (vs just shoulder flexion) \u003csup\u003e\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e\u003c/sup\u003e. Avotta et al.(2019) to catch a functional standing position also concluded these findings and reported a significant reduction in negative SVA displacement in the hand-on-clavicles position compared to 45-degree shoulder flexion\u003csup\u003e\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e\u003c/sup\u003e. but by comparing two positions of hands on the clavicles)not crosswise) with shoulder flexion and hands on the clavicles with elbow touching the trunk, the first position was superior in increasing negative SVA changes \u003csup\u003e\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e\u003c/sup\u003e. Even in people who have spinal deformities, the fists on the clavicles position for lateral radiograph acquisition has less negative shift in SVA and will have better spine vision\u003csup\u003e\u003cspan citationid=\"CR57\" class=\"CitationRef\"\u003e57\u003c/span\u003e\u003c/sup\u003e.Therefore, the participants would potentially lean their trunks forward to maintain balance, which would lead to a flatter back shape, and therefore a smaller lordosis. Consequently, although an external support would improve the variability of sacral orientation during standing, the risk of altering the sagittal spinal balance must also be considered.\u003csup\u003e\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e\u003c/sup\u003eSo, in the current study, comparing the lumbar lordosis angle at the beginning and end of the experiment when participants stood with one foot on a raised footrest, in the first group, their lumbar lordosis decreased by almost 6 degrees, and in the second group, who also additionally changed arm position, their lumbar lordosis decreased by approximately 7 degrees compared to standing on level ground. These results are consistent with Fewster et al. (2017)\u003csup\u003e\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e\u003c/sup\u003e, who reported that intermittent one-minute elevation of each foot during prolonged standing led to increased lumbar spine flexion compared to standing on the ground. In contradiction, Callaghan and colleagues investigated the effects of postural footrests on various angles of the lumbosacral and intervertebral bones in radiographic images and the effects of footrests were similar in both PD and NPD individuals\u003csup\u003e\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u003c/sup\u003e. Changes in the lower region of the spine without significant changes in overall lumbar lordosis may indicate a greater importance in pelvic rotation and pelvic kinematics\u003csup\u003e\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u003c/sup\u003e.Moreover, considering proper arm positions can lead to improvements in lumbar lordosis and sagittal vertical axis changes. Additionally, arm position, besides maintaining body alignment, plays a role in activating muscles, especially those contributing to lumbar and pelvic stability. This finding suggests that stepping, with or without arm positioning, plays a crucial role in reducing lumbar lordosis during prolonged standing. The similar patterns of reduction across both groups highlight the potential of stepping exercises to mitigate changes in lumbar spine posture associated with prolonged standing.\u003c/p\u003e \u003cp\u003eOn the other hand, since PD demonstrates co-activation of the Gmed muscles during standing, it is believed that this activation may act as a compensatory mechanism to control trunk stability, leading to LBP\u003csup\u003e\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e,\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e,\u003cspan citationid=\"CR58\" class=\"CitationRef\"\u003e58\u003c/span\u003e\u003c/sup\u003e. After implementing an exercise protocol aimed at improving trunk stability, an increase in rest time for the Gmed muscles during the initial stages of standing was accompanied by a decrease in their co-contraction. Additionally, trunk instability, reduced strength, and endurance of the Gmed muscles are significantly associated with increased simultaneous activation of this muscle during prolonged standing\u003csup\u003e\u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e47\u003c/span\u003e\u003c/sup\u003e. In the study by Nelson and Wang\u003csup\u003e\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e\u003c/sup\u003e, investigating the effect of task type on trunk muscle co-contraction as well as Gmed muscles, it was demonstrated that assembly and sequencing tasks similarly lead to increased co-contraction indices, while tasks involving upper limb immobility significantly induced lower co-contraction in both trunk and Gmed muscles compared to more active tasks. Changes in lower limb levels at different heights during standing can lead to biomechanical alterations in the trunk and pelvis, which are influential factors in LBP. The effect of short-term placement of one foot on steps of varying heights during standing has also been noted to reduce co-activation or relative muscle activation of the Gmed\u003csup\u003e\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e,\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e,\u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e\u003c/sup\u003e. Conversely, in another study, this intervention failed to significantly reduce midsection muscle co-contraction in PD; however, in NPD individuals, patterns of Gmed muscle co-contraction increased, and no significant difference was observed between the two groups\u003csup\u003e\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e\u003c/sup\u003e. In the current study, the significant within-group differences in LGmed\u0026ndash;RGmed co-activation (p\u0026thinsp;=\u0026thinsp;0.002) and the time effect (p\u0026thinsp;=\u0026thinsp;0.006) indicate that both groups exhibited a decrease in the co-activation of the bilateral gluteus medius muscles during prolonged standing. This decreases, as seen in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e3\u003c/span\u003e, suggests that both interventions might alleviate the muscle tension typically associated with prolonged standing. Interestingly, the second group showed a consistently lower level of co-activation compared to the first group, implying that the addition of arm positioning might provide an extra benefit in reducing muscle strain.\u003c/p\u003e \u003cp\u003eFrom another point of view ,Lee et al. (2018) \u003csup\u003e\u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e56\u003c/span\u003e\u003c/sup\u003e found that the use of a footrest may not reduce the progression of LBP, and it is unlikely that prolonged standing-induced pain occurs due to muscular fatigue or biomechanical mechanisms. Since the use of a footrest and long-term elevation of each foot for five minutes may be excessively long and lead to increased pressure on the standing foot, it may not aid in reducing LBP. Additionally, they did not specify whether the location of pain changed during the intervention, nor did they report the height of the footrest used. Spinal flexion resulting from placing one foot on a step will increase with increasing step height \u003csup\u003e\u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e53\u003c/span\u003e\u003c/sup\u003e, but as the footrest height increases, the standing foot must bear more weight. Therefore, potential differences in the height of the footrest used and the duration of foot placement on the step may also affect the success of the intervention during standing, as demonstrated by Sen et al. (2017)\u003csup\u003e\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e\u003c/sup\u003e, who achieved a successful reduction in the intensity of LBP in PDs during prolonged standing with intermittent 15-minute intervals using an optimally sized footrest at ten percent of the body height. Similarly, Fuster et al. reported successful results in reducing pain every eight minutes during 80 minutes of standing. Placing each foot alternately on a 13-cm footrest for one minute and performing a three-minute rest between each stepping protocol was the intervention. However, no significant difference in LBP intensity was observed at different footrest heights from 10 to 30 cm during only 15 minutes of standing on the step in the study by Floy et al.(2021) \u003csup\u003e\u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e53\u003c/span\u003e\u003c/sup\u003e. In the present study, considering a step height (20-cm) close to ten percent of the bodies height average and forming a 135-degree angle between the hip axis and the spine \u003csup\u003e\u003cspan citationid=\"CR59\" class=\"CitationRef\"\u003e59\u003c/span\u003e\u003c/sup\u003e we reached the conclusion of a significant reduction in pain intensity before and after stepping in both groups, although discomfort levels increased over time, which is expected with prolonged standing. However, stepping interventions appeared to mitigate this discomfort. Notably, the trend of decreasing VAS scores over time after stepping suggests that incorporating steps can reduce perceived discomfort by decreasing external lumbar moment and muscle activity\u003csup\u003e\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e\u003c/sup\u003e, which activates more and helps to stabilize the spine during the standing\u003csup\u003e\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e,\u003cspan citationid=\"CR60\" class=\"CitationRef\"\u003e60\u003c/span\u003e\u003c/sup\u003e. The second group consistently reported lower pain intensity compared to the first group, emphasizing the added benefit of arm positioning in alleviating discomfort. One possible hypothesis is that during standing, increased muscular activity may act as a compensatory mechanism for poor body posture control, leading to pain in the lumbar regions \u003csup\u003e\u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e56\u003c/span\u003e\u003c/sup\u003e and changing arm position to shoulder flexion and hand rest on the clavicle with stepping causes decreasing lumbar extension and muscle activity in which they play a role\u003csup\u003e\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e,\u003cspan citationid=\"CR61\" class=\"CitationRef\"\u003e61\u003c/span\u003e\u003c/sup\u003e and it make opportunity for decreasing pain in the lumbar region.\u003c/p\u003e \u003cp\u003eExtending the current results to a study to confirm whether the results are transferable to individuals who need to stand for long periods but have the ability to use a small footrest and have time during work to change arm position may be valuable. Additionally, this research used a relatively small sample size, which may limit the generalizability of these findings to the general population.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThis study demonstrates that stepping, both alone and with added arm positioning, can significantly influence muscle co-activation, lumbar spine posture, and discomfort levels during prolonged standing. Although no significant interaction between the two groups was found, the within-group analyses reveal meaningful differences and benefits associated with these interventions. Specifically, the footrest plus change arm position intervention showed a trend toward greater reductions in muscle co-activation and discomfort, suggesting that it might be a more effective strategy for mitigating the negative effects of prolonged standing. These findings have practical implications for designing workplace interventions to reduce musculoskeletal strain and improve comfort for individuals required to stand for extended periods in various occupational settings. Future research should explore the long-term effects of these interventions and investigate other potential combinations of more movements and positions to further enhance their effectiveness.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eLBP \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;\u003cspan dir=\"RTL\"\u003e\u0026nbsp;\u0026nbsp;\u003c/span\u003e Low Back Pain\u003c/p\u003e\n\u003cp\u003eAHAbd \u0026nbsp; \u0026nbsp; \u0026nbsp;Active hip abduction\u003c/p\u003e\n\u003cp\u003eBMI \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;\u003cspan dir=\"RTL\"\u003e\u0026nbsp; \u0026nbsp;\u0026nbsp;\u003c/span\u003eBody mass index\u003c/p\u003e\n\u003cp\u003eGmed \u0026nbsp;\u003cspan dir=\"RTL\"\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp;\u003c/span\u003eGluteus Medius\u003c/p\u003e\n\u003cp\u003e\u003cspan dir=\"RTL\"\u003e\u0026nbsp;\u003c/span\u003ePD\u0026nbsp;\u003cspan dir=\"RTL\"\u003e\u0026nbsp;\u0026nbsp;\u003c/span\u003e \u003cspan dir=\"RTL\"\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u003c/span\u003ePain developer\u003c/p\u003e\n\u003cp\u003eNPD \u0026nbsp;\u003cspan dir=\"RTL\"\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u003c/span\u003enon-pain developer\u003c/p\u003e\n\u003cp\u003eVAS\u0026nbsp;\u003cspan dir=\"RTL\"\u003e\u0026nbsp;\u0026nbsp;\u003c/span\u003e \u0026nbsp;\u003cspan dir=\"RTL\"\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp;\u003c/span\u003eVisual Analogue Scale\u003c/p\u003e\n\u003cp\u003eCCI \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; Co-Contraction Index\u003c/p\u003e\n\u003cp\u003eRMS \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;Root Mean Square\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eCompeting interests\u003c/h2\u003e\n\u003cp\u003eThe authors declare no competing interests.\u003c/p\u003e\n\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\n\u003cp\u003eS.A. handled the research process from sampling and testing to analysis and writing. H.M. acting as a supervisor, provided guidance on research methodologies, data evaluation, and article composition. S.H.M. contributed to the statistical analysis methodology and reviewed the article. H.A. contributed to the testing at the Iran Research Institute of Sports Sciences. All authors collaborated on editing and critically revising the article, ultimately endorsing the final version.\u003c/p\u003e\n\u003ch2\u003eAcknowledgements\u003c/h2\u003e\n\u003cp\u003eThe authors received no specific funding for this work.\u003c/p\u003e\n\u003ch2\u003eData Availability\u003c/h2\u003e\n\u003cp\u003eThe data generated and analyzed during this study are available from the corresponding author upon reasonable request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eAndersson, G. B. J. Epidemiological features of chronic low-back pain. 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Anthropol. 41, (2022).\u003c/span\u003e\u003c/li\u003e\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":"low back pain developer, PD, footrest, arm, lordosis, gluteus medius","lastPublishedDoi":"10.21203/rs.3.rs-4659238/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4659238/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eLow back pain (LBP) development has been associated with increased hip muscle co-activation and lumbar lordosis during standing in previously asymptomatic individuals. It is commonly advised to use footrests to relieve LB. The impact of adjusting arm position on lumbar biomechanics can also be impressive. This study aimed to compare the effects of normalized footrest height and changing arm position on muscle activity, lumbar lordosis, and pain intensity. Twenty-four female pain developers (PDs) were recruited, identified by a\u0026thinsp;\u0026gt;\u0026thinsp;10 mm increase on the visual analog scale (VAS) during prolonged standing. Electromyography (EMG) recorded hip muscle activity, and photogrammetry measured lumbar lordosis during one hour of standing. The first group used the footrest intermittently, while the second group additionally changed their arm positions. Both groups showed decreased gluteus medius co-activation during prolonged standing (p\u0026thinsp;=\u0026thinsp;0.003), with the second group showing lower levels. A significant time effect on lumbar lordosis angle was observed in both groups (p\u0026thinsp;\u0026lt;\u0026thinsp;0.01). Although lumbar discomfort increased over time and stepping interventions reduced this discomfort, with the second group reporting lower pain intensity (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). Applying these interventions in the workplace could be beneficial to reduce discomfort for individuals who stand for long periods of time. Further research is needed to optimize these strategies and assess long-term benefits.\u003c/p\u003e","manuscriptTitle":"The Impact of different Standing positions on Pelvic Muscle Activation and Lumbar Lordosis in LBP-developers during prolonged standing ","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-07-26 21:00:56","doi":"10.21203/rs.3.rs-4659238/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":"e1c002d1-4359-406f-ad0c-245c4674a634","owner":[],"postedDate":"July 26th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":34951243,"name":"Health sciences/Health care"},{"id":34951244,"name":"Health sciences/Medical research/Study design"}],"tags":[],"updatedAt":"2024-10-01T23:08:16+00:00","versionOfRecord":[],"versionCreatedAt":"2024-07-26 21:00:56","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-4659238","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4659238","identity":"rs-4659238","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}