Device-Guided Diastolic Stepping During Walking among Older Adults: A Home-Based Feasibility Pilot Study

Device-Guided Diastolic Stepping During Walking among Older Adults: A Home-Based Feasibility Pilot Study | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Device-Guided Diastolic Stepping During Walking among Older Adults: A Home-Based Feasibility Pilot Study Aurora Rosato, Tien-Ying Lu, Jie Che, Eva Andersson, Sanna Kuoppamäki, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6172990/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Background Wearable cardiovascular technologies constitute a promising avenue for self-directed home-based prevention and rehabilitation interventions for older adults at risk. In patients with congestive heart failure, it was recently shown that synchronized stepping to the diastole of the heartbeat during walking (diastolic stepping) increases stroke volume and oxygen delivery. A home-based approach may maximize health benefits, however the level of synchronization achievable in an everyday context remains completely unexplored. This prospective study aims to explore the feasibility of home-based synchronization among physically active older adults using a data-driven approach. Methods The 19 participants were instructed to use a wearable biofeedback device for three weeks that prompts users with an auditory cue to achieve synchronization. We have collected data on the level of synchronization, adherence, quality of life, exercise habits, rhythmic abilities, and physiological baseline and we discuss these results based on interview-based user feedback. Mean and standard deviation were calculated for each parameter of interest. Group comparisons were conducted using t-tests, and paired t-tests were applied for within-group comparisons. Results Our data suggest high feasibility in 58% of participants, as data revealed high-level synchronizers (n = 11), and low-level synchronizers (n = 8), performing diastolic stepping for 83 ± 6% vs. 11 ± 9% (p < 0.01) of the total usage time. Both physiological and rhythmic factors may play a role in the levels of synchronization achieved. Moreover, a high-level of synchronization is achieved with calmness, focus, and warming up. Additional guidance during learning could help find a synchronization ‘flow’ and increase levels of synchronization. Conclusions In conclusion, diastolic stepping is feasible as a self-directed cardiovascular prevention and rehabilitation strategy. Our results inform future research on improving biofeedback devices for prevention in patients at risk of cardiovascular disease, with the goal of improving exercise tolerance, and, in turn, patients’ quality of life. cardiac prevention real-time feedback device diastolic stepping rhythmic exercise cardiac locomotor synchronization Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 BACKGROUND Cardiovascular disease (CVD) acutely affects over half a billion people ( 1 ), with many at risk of developing chronic heart failure (HF). HF emerges as a hidden global pandemic, affecting around 26 million people worldwide, with prevalence expected to rise due to the aging population ( 2 ). HF severely impacts patients’ quality of life, manifesting shortness of breath, limited walking speed, and endurance, which restrict everyday life to minimal physical activity ( 3 ). Exercise training offers substantial benefits in reducing morbidity and mortality among individuals with CVD ( 4 ), and cardiac rehabilitation programs are recommended as a form of secondary prevention ( 5 ). However, in conditions such as HF, reduced functional capacity can hinder both the effectiveness and the adherence to exercise programs. It was recently shown that diastolic stepping to the heartbeat improves functional capacity momentarily in patients with HF ( 6 ) which may improve exercise-based rehabilitation efforts in older adults with CVD. The study of gait synchronization (locomotor rhythm) with the heartbeat (cardiac rhythm) is known as cardiac-locomotor synchronization (CLS). CLS, defined as a 1:1 ratio between the gait cycle and heart cycle, specifically aims to align steps with the diastole of the cardiac cycle and has been commonly achieved by letting people step to an auditory cue synchronized with their heart rate (HR) ( 7 , 8 ). Diastolic stepping to the heartbeat improves heart function in HF momentarily by augmenting stroke volume and oxygen delivery, together with a reduction in mean arterial blood pressure ( 6 ). The synchronized activation of the leg muscle pump during walking is hypothesized to decrease afterload, increase preload, and increase coronary perfusion. In healthy subjects, physiological benefits of synchronization have been demonstrated in terms of increased blood flow to active muscles ( 7 ) and reduced HR at a consistent workload ( 8 , 9 ). Importantly, it was shown that even people with congestive HF profit from synchronization health benefits when stepping to the beat of their implanted pacemaker ( 6 ). In summary, diastolic stepping may augment the effectiveness of exercise tolerance (ie, time to fatigue), as well as exercise capacity, together increasing patient quality of life in patients with HF ( 6 ). While this limited data suggests synchronization to be achievable in everyday life, the impact of synchronization for people at risk of advanced forms of cardiovascular disease would be maximized if CLS technology was available as a wearable, enabling self-care in a home-based setting. However, sustaining user adherence and engagement remains a key challenge for achieving long-term benefits. Mobile technologies for virtual cardiac rehabilitation have shown promise in improving adherence and longer-term patient engagement ( 10 ). This potential could be further amplified through a biofeedback mechanism. Unlike wearable devices that solely track physical activity, biofeedback systems actively involve the user in real-time interactions with the device. Such systems, which position the user as part of a feedback loop, have shown promising results in sports ( 11 ) and rehabilitation applications ( 12 ). The feasibility of implementing synchronization biofeedback for home-based diastolic stepping in the older adult population with the highest immediate cardiovascular risk remains an unexplored area. This study aims to explore the feasibility of home-based diastolic stepping synchronization in physically active older adults using a wearable data-driven approach. The wearable biofeedback device used is equipped with a chest strap and produces an auditory cue to guide participants to synchronize their steps with their heartbeat. Based on the wearable data, we distinguish two groups according to their level of synchronization “high-level” and “low-level” synchronizers from a cohort of active older adults with a generally high quality of life. We contextualize our findings via interview-based user feedback. We hypothesize that home-based synchronization success will be influenced by several key factors: physiological factors such as resting HR, baseline step rate (SR), individuals' baseline rhythmic skills, usability, learning, and guidance factors. METHODS Study design This cross-sectional study includes a prospective home-based walking intervention over a 3-week period, during which participants utilized a real-time biofeedback device with minimal guidance. Baseline data, including physical activity, health status, quality of life, and socio-demographic information, were collected through interviews and questionnaires, followed by a device demonstration, auditory reaction time measurement, and a 6-meter walking test to assess preferred and device-guided SR. During the 3-week period, participants were asked to use the device at least three times per week for 30 minutes each while walking. Post-intervention, participants completed follow-up questionnaires and participated in a laboratory session involving treadmill tests and repeated walking assessments. Additionally, individual user feedback was collected after the completion of the intervention in a 30-minute semi-structured interview to gain insights into the user experience with device-guided synchronized walking. The interview has been audio recorded and transcribed to text materials. User feedback from the perspective of self-perceived challenges in synchronizing, will complement the discussion and contextualize the device-generated data. A comprehensive analysis of the interview material has been performed parallelly to investigate the age heterogeneity in the use of wearables with real-time feedback ( 13 ). Ethical approval for the study was obtained from the Swedish authorities (2023-00426-01), and all participants provided written informed consent in accordance with the Declaration of Helsinki. Participants Participants were recruited through The Swedish School of Sport and Health Sciences (GIH). Participants are physically active as they attend weekly physical exercise classes three times a week at GIH. The choice of healthy participants was motivated by the lack of data on feasibility of synchronization in literature. Inclusion criteria were the ability to exercise independently, the possession of a mobile phone to run the phone application, and the ability to adequately see and hear to interact with the phone application. Participants were excluded from the study if they had any health problems that contraindicated exercise or were diagnosed with a balance or neurological disorder that seriously affected motor function (e.g., stroke, traumatic brain injury, or Parkinsonism). Biofeedback wearable The wearable biofeedback device used was Counterpace (Pulson Inc., USA), a commercially available chest strap used for running and equipped with a sensor to monitor HR via electrocardiogram and foot strike via accelerometry. The mobile app provides users with real-time auditory cues to help them synchronize their steps with the diastolic phase of their heartbeat. Participants’ SR, HR, and synchronization percentages were recorded by the device to a phone application and stored in an anonymized format. We demonstrated the use of the device to the participants and downloaded the app on their phones. We provided detailed written instructions for using the device. These included step-by-step guidance on how to open the app, to initiate physical activity, to optimize synchronization, and to troubleshoot potential issues. Participants had a phone number and email to contact researchers in case of difficulties using the device and were encouraged to ask for technical support throughout the study. The study controlled for usability and all participants reported ease of use. Data collection and analysis All analyses were performed using custom code in MATLAB R2024a (The MathWorks, Natick, MA). Baseline variables Walking speed and preferred SR have been measured using the 6-meter walking test ( 14 ). Participants completed the test twice, one without the guidance of the device and the second time with the guidance of the device. Baseline exercise capacity was evaluated as distance walked during a 6-min walking test in a flat corridor ( 15 ). At the end of the test, the self-perceived exertion is rated using the Borg RPE scale ( 16 ). Auditory reaction time A simple reaction time test (Millisecond Software LLC, Seattle) played on an iPad (Apple Inc., Cupertino) has been used to measure auditory reaction time ( 17 ). The auditory reaction time is a measure of how quickly a human responds to a stimulus and is defined as the interval of time between the presentation of the stimulus and the appearance of an appropriate voluntary response in the participant. The test lasted 5 minutes, during which participants had to press a button on the screen as soon as they heard an auditory cue. Wearable data and synchronization data Through the biofeedback device, we recorded HR, SR, the ratio between the two rates (SR/HR), and the diastolic synchronization percentages throughout the training episodes with a sampling frequency of 1 Hz. Additionally, we recorded the phase, as the time in percentage of the heartbeat, between the heartbeat and the moment of stepping. A value of 45 ± 20% constitutes the desirable diastolic timing. The level of synchronization is calculated as the percentage of time at equal rates (HR = SR) and in diastolic phase. We recorded training start and end time. Training sessions lasting less than 5 minutes were excluded from the analysis, and the first 5 minutes of each training were removed to only consider steady-state HR. HR, SR, ratio and the phase were then computed and averaged over each minute. Non-physiological outlier values outside the range of 60 to 250 bpm for HR and 60 to 250 steps/minute for SR were removed from the dataset. The device usage time was calculated as the total sum of each minute of training and is also reported as a percentage of the recommended usage time for each participant. The synchronization values over each training session were used to calculate the average synchronization level of each participant. To ensure consistency across participants, only the most successful 9 training sessions, corresponding to the recommended usage time, were included in this analysis. Questionnaires The questionnaires included reporting self-perceived physical activity level, self-perceived health, and EQ-5D-5L quality of life ( 18 ). The self-perceived health was evaluated with a question “How do you perceive your physical/mental health”, with a 6-point scale ranging from “I’m very satisfied with my health” to “I’m very dissatisfied with my health”. The self-perceived physical activity level was evaluated with two questions “In a typical week, how much time do you spend on physical exercise that leaves you breathless, e.g. running, gym, ball sports?” and “In a typical week, how much time do you spend on everyday exercise, for example walking, cycling, gardening? Add up all the time (at least 10 minutes at a time)”, with a 6-point scale ranging from 0-120min or more for the first question and 0-300 min or more for the second question. The quality of life questionnaire (EQ-5D-5L) consists of five dimensions: mobility, self-care, usual activities, pain/discomfort, and anxiety/depression. Each dimension has five levels: no problems, slight, moderate, severe, and extreme problems, which generate a 5-digit code representing the overall health, with each digit corresponding to the selected level in each dimension. The system allows for 3,125 possible health states, ranging from 11111 (full health) to 55555 (worst health). Usability was investigated through ten questions based on the System Usability Scale (SUS) ( 19 ), with a 5-point Likert scale ranging from “ Do not agree at all” to “ Strongly agree”. Summing up all the questions, the usability outcome is a score ranging from 0 (minimum) to 100 (maximum). Statistical analysis Mean and standard deviation were calculated for each parameter of interest. Linear regression analysis was performed to evaluate the relationship between HR and synchronization, as well as between total usage time and synchronization success. Group comparisons were conducted using t-tests, and paired t-tests were applied for within-group comparisons (e.g. synchronization in the laboratory vs. synchronization at home). Unless otherwise specified, values are presented as mean ± standard deviation. User groups Based on the level of synchronization, we observed a clear distinction between two user groups. Participants were classified as “high-level synchronizers” if their average synchronization exceeded 50%. Those with an average synchronization below 50% were classified as “low-level synchronizers.”’ Most results are reported per group to elucidate the potential reasons for high or low levels of synchronization. RESULTS Participants characteristics Twenty-two older adults (73 ± 4 years old, 13 female and 9 male) were enrolled in the study between November 2023 and June 2024. Of the twenty-two participants, two resigned some days after the start of the three-week exercise, and one subject successfully completed the study, but the device data was missing. In our cohort, all of them but one considered themselves healthy, however, 20% of participants have been treated for cardiovascular disease and the majority regularly take medications. Participants’ characteristics, use of the device, and average synchronization are presented in Table 1 . Table 1 Demographic characteristics of the participants, quality of life (EQ-5D-5L), average heart rate (beats/min), total use (min), number of sessions performed, and average synchronization (%). – correspond to a missing value. Bold , high-level synchronizers. ID Age Gender Quality of life Average Heart Rate (bpm) Tot use (min) # of session performed Synchronization % P01 70 F 11121 116 571 18 73 P02 74 M 11121 101 137 6 3 P03 70 M 11121 106 357 9 90 P04 74 M - 75 183 5 28 P05 78 F 11121 88 684 11 3 P07 72 M 11121 78 278 8 1 P08 76 M 11111 96 909 17 79 P09 71 F 21122 90 1532 37 89 P11 82 M 31232 112 1905 30 80 P13 70 F 11231 104 580 16 11 P14 70 F 22231 115 262 11 13 P15 72 M 11111 81 678 14 11 P16 78 F 11121 97 735 14 79 P18 75 F 11121 92 302 9 92 P20 72 F 11111 89 351 9 86 P21 67 F 11121 92 598 20 74 P22 66 F 11122 102 939 36 85 P23 72 F 11111 89 680 15 19 P24 67 F 11121 70 420 10 84 In our cohort, the most frequent EQ-5D-5L quality of life profiles are 11111 (4/19) and 11121 (9/19), indicating a homogenous high quality of life across participants. Pain/discomfort emerges as the most affected dimension, with only five subjects reporting no issues. All dimensions, including mobility, self-care, usual activities, pain/discomfort, and anxiety/depression, show a maximum severity score of 3, corresponding to mild problems. Only one subject experience a mild mobility issue, and none report problems in personal care, usual activities, or depression, reflecting the overall good quality of life of the cohort. The overall perceived physical and mental health is perceived as satisfactory in both groups with no significant difference before and after the 3-weeks study. All subjects with less than 1 hour of breathless physical activity per week prior to the study are in the high-level synchronizer group. All other participants engage in more than 1 h of breathless physical activity. The high-level synchronizer group performed slightly better in the 6-min walking test (520 ± 52 m vs. 501 ± 48m, insignificant) at an identical level of perceived exertion of 12.1 on the Borg scale on average, which lies in between “Light” and “Somewhat hard”. Wearable device use The overall usage of the device was high, with 84% of participants (16/19) exceeding the recommended usage time of 270 minutes, while 16% (3/19) used it less than the recommended time. Participants completed up to 37 valid sessions (16 ± 9 sessions). Additionally, the duration per session was longer than recommended, averaging 40 ± 12 minutes per session. These results indicate higher-than-expected engagement with the device. Although there was no significant difference in the overall usage time between the two groups, all participants who used the device for less than the recommended time (3/19) were in the low-level synchronizers group. Rate and phase synchronization Eleven participants achieved an average synchronization rate greater than 50%, while eight participants had a rate below 50%. The synchronization level was significantly different between the two groups, with the high-level synchronizer demonstrating a synchronization rate of 83 ± 6%, compared to 11 ± 9% for low-level synchronizers (p < 0.01), Fig. 1 . The clear distinction in synchronization level, motivated our data-driven approach to group participants. The high-level synchronizers had a higher ratio of SR/HR (1.1 ± 0.4 vs. 0.94 ± 0.3, p 50%) when compared to the high-level synchronizer (56 ± 19% vs. 51 ± 14%, p < 0.01), Fig. 2 B. Physiological factors A key aspect of the ability to synchronize is the proximity of HR and SR. We found that the HR and the SR during the home training are significantly different for high-level vs. low-level synchronizers. High-level synchronizers have higher HRs (98 ± 19 vs. 92 ± 14 bpm, p < 0.001), Fig. 3 A and lower SRs (96 ± 17 vs. 101 ± 16 steps/min, p < 0.001), Fig. 3 B. On individual basis, we observed a correlation between HR and level of synchronization, Fig. 4 A. For four participants, level of synchronization per training session significantly improved with higher HRs (0.3 < R² < 0.6, p < 0.05, Fig. 4 C). Conversely, 3 participants demonstrated the opposite effect, with a higher level of synchronization for lower HRs (0.2 < R²<0.8, p < 0.01, Fig. 4 B). Rhythmic factors Rhythmic factors related to synch are presented in Table 2 . Table 2 Rhythmic factors, high-level vs. low-level synchronizers. Variable High-level synchronizers Low-level synchronizers P-value Mean auditory reaction time (ms), baseline 249 ± 51 378 ± 140 < 0.05 Fastest auditory reaction time (ms), baseline 183 ± 14 227 ± 55 < 0.05 SR Prompted (steps/min), baseline 83 ± 11 98 ± 9 < 0.05 SR Preferred (steps/min), baseline 117 ± 10 117 ± 4 ns Difference SR prompted vs. preferred (steps/min), baseline 28 ± 12 16 ± 6 < 0.05 SR Preferred (steps/min), lab study 119 ± 7 114 ± 2 < 0.05 The high-level synchronizers had a lower mean and fastest auditory reaction time. Variability in reaction time was increased in the low-level compared to the high-level synchronizer group. The HR, and subsequently the prompted SR, is lower in the high-level synchronizer group, which is associated with a greater difference compared to their preferred SR. This suggests that stepping naturally close to one's HR is not necessarily a predictor of better synchronization success. Instead, synchronization can be improved by adjusting the HR or SR, regardless of their initial rate difference. An additional observation is that the preferred SR after the study does not significantly change compared to the baseline, suggesting that training with the device does not significantly alter an individual's preferred SR. Learning factors None of the participants had prior experience using the device for synchronization. All participants had to learn how to use a biofeedback wearable for synchronization. The learning process included finding the most favorable settings for using the device in terms of environment, pre-training warming up, and duration of use. The level of synchronization over time varied among participants: some participants showed immediate success, while others had fluctuating synchronization effectiveness or gradually improved with each day of use. Linear regression analysis revealed that 4/19 participants significantly improved synchronization over time (0.1 < R² < 0.9, p < 0.05, Fig. 5 ). Three out of the four participants reached high levels of synchronization through learning. Self-directed home use vs. guided lab use We investigated the effect of guidance, by comparing the home-based level of synchronization to the post-intervention laboratory study results, Fig. 6 . The low-level synchronizer group performed substantially better in the controlled lab environment compared to at home (44 ± 13% vs. 11 ± 9%, p < 0.05), although still at lower overall synchronization levels when compared to the high-level synchronizers (44 ± 13% vs. 74 ± 19%, p < 0.01). For high-level synchronizers, variability in levels of synchronization increased in the lab. Usability Regarding usability assessed by questionnaires, on average the high-level synchronizers rated the device slightly higher than low-level synchronizers, with an average SUS score of 64 ± 21 vs. 54 ± 12, although this result was not significant. Only 4/19 participants, all high-level synchronizers, would strongly use it more (4 or 5), while the low-level synchronizers' highest opinion was neutral. Overall, high-level synchronizers reported higher ease of use and confidence and a lower need for technical support compared to low- level synchronizers. Both groups report minimal learning needed on how to use the device. DISCUSSION This is the first pilot study investigating the feasibility of utilizing device-guided diastolic stepping as a self-directed exercise approach at home. Slightly over half of the study participants achieved high levels of synchronization upon limited instruction, which is an unexpectedly encouraging result when considering the high incidence of cardiovascular disease. Using data-driven grouping, we further identified physiological, rhythmic, guidance, and learning factors that influence levels of synchronization during home-based synchronization. Despite the cardiovascular health benefits, humans do not spontaneously walk with synchronization. Spontaneous synchronization has been studied in laboratory settings where the use of a treadmill sets limits on participants’ gait ( 20 – 22 ), showing that not all individuals spontaneously achieve synchronization in such controlled environments and that synchronization is more likely to occur at faster walking speeds or during running. In everyday life context, instead, young adults spend 40% of their time within 10% of their HR ( 23 ). Previous studies have indicated that synchronization of 50% is sufficient for positive health outcomes ( 6 , 8 ). In our study, more than half the participants achieved high levels of synchronization above 80%. In the interviews, synchronization of the SR to the HR was perceived as being challenging by most low-level synchronizers (P4, P7, P13, P14, P15, P23) and two high-level synchronizers ( P18, P24 ). Notably, ratio synchronization was deemed more easily achieved than phase synchronization, for instance, P24 expressed that " I would easily get to the correct range, but it always took ten minutes or more to achieve phase synchronization. ” Based on our result, we can assume that approximately 50% of the population could profit from CLS health benefits using a commercially available wearable device. The observed range of HRs and SRs indicate that individual physiological factors and walking preferences may play a role in the level of initial synchronization success. Both very high and very low HRs can make it difficult to achieve high levels of synchronization. While a very low HR can force an unnatural slow walking, a very high HR might result in a negative feedback cycle, where the stress to achieve higher SR would keep increasing HR, then SR, and so on till exhaustion. The challenge with addressing the discrepancy between HR and SR was highlighted by participants (P7, P8 , P13, P15, P18 , P21 ). P4 expressed that “ When the pace kept getting faster, I just cannot run like that” while P13 pointed out that “If I need to keep catch up my heart race with my steps, that does not feel like a proper exercise to me anymore. ” Participants may benefit from maintaining a SR that feels natural yet is not so high as to cause fatigue, allowing them to sustain it comfortably throughout the training. In general, our group of highly physically active older adults has low HRs and high SRs. A low HR was common (P7, P8 , P13, P15, P18 , P21 ), and resulted in difficulties to synchronize. P15 stated that “ (When reading the heart rate data) I found very quickly that my normal heart rate is around 70. My normal step rate is more like 120. So, it was a very big difference. ” In this user group, the health benefits from synchronization may not be outweighed by reduced motivation to exercise, which arises from the need to change their preferred SR. A better target group may be older adults with a lower general aptitude for physical activity. We found that participants with faster reaction time achieved higher levels of synchronization. The faster reaction time might indicate better coordination between the sensory and motor systems ( 24 , 25 ), which could provide an advantage in achieving high levels of synchronization during home training. In fact, for low-level synchronizers, the step timing is delayed compared to the ideal step timing (higher phase). The device-based data only showed clear learning of CLS over the period of 3-weeks in four participants. In many high-level synchronizers, the learning experience was a widely discussed topic for the participants’ experiences ( P1 , P3 , P4, P11 , P18 , P20 ). Participants considered the synchronization as a way to track themselves and a challenge to get better at over time. P3 gave a clear example of her improvement “ During the first week, … I was in sync 69%. The next week … I was in sync 95%. I was aiming for 97% in sync for the last week. It just gets better and better .” Meanwhile, P18 also highlighted that the time to achieve synchronization decreased with the learning process “ When I learned how to do it (achieve synchronization) the first time, it took me 45 minutes or 1 hour to get it. But on the last walks, it was only around 30, 35 minutes maybe. ” In their learning processes, different strategies were used by the participants to achieve synchronization and those strategies varied due to their personal goals or preferences. The most common one was to “ Increase the HR ” either by “ climbing up the stairs ” (P4, P18 )”, “ warming up ” ( P1 ) or “ jogging ” ( P3 ). On the other hand, P11 and P20 , resulted to ways to “ Shorten/Extend the Step Length .” For the participants with a low-level of synchronization, the supervised lab session had a greater positive impact on learning synchronization than three weeks of home training. We conclude that learning the ‘flow’ of synchronized walking is possible upon simple instruction and that additional support may be necessary to achieve high levels of synchronization in everyone. While understanding how external factors influence the effectiveness of device-guided interventions requires further investigation, some subjects suggested focus and calmness as determinant factors. Having full focus was considered necessary for synchronizing effectively, as described by P7, who needed to “ concentrate on it completely ”. Being alone when using the device was helpful as stated by P22 : “I thought it was easier to exercise in focus. You have to go alone and look down and see (my steps) and listen (to the cueing) .” Challenges that influenced their focus were mostly environmental. Participants who used the device to walk in the city noted got distracted either due to some unexpected encounters such as “ the bus coming ” ( P21 ) and “ the dogs ” (P7) or because of their caution to the pavement conditions such as “ pauses caused by the icy weather ” ( P1 ) and “ crossing a puddle of water ”( P22 ). On the other hand, positive feelings such as being relaxed or carefree were reported to be beneficial for getting in sync with the device. In this sense, P3 found it easier to synchronize in her normal exercise routine outdoor as compared to training indoors, despite potentially more environmental distractions: “ In the beginning, I tested at home due to the bad weather. But I discovered that it was difficult when I turned around. Then the next day, I used it outdoor, and it went much, much better .” Furthermore, P9 pointed out that “ I didn't have to think about anything. I would just walk and not fast (in order to attend to other tasks). Because as soon as you start thinking about the laundry room or tomorrow or the day after tomorrow. Then you get out of sync .” A similar experience was stressed by P22 when she said “ I must be relaxed. Then it's very easy. But if I was stressed or something like, it was very difficult for me to come in the synch .” Stress might also explain the worse performance of high-level synchronizers in the laboratory as compared to home use. A recent study on the most effective healthcare interventions highlights key aspects for success and adherence, which are also recognizable in our study ( 10 ). The findings of this study support the finding that training on the correct use of the technology and the data upload and management is crucial for intervention success. Secondly, the real-time feedback of the proposed device-guided intervention engages with the user continuously, and in this way is tailored to individual participants’ interaction with the technology. Device-guided diastolic stepping intervention might thus hold promising potential for high adherence. A comprehensive approach combining supervised sessions and home-based training, together with real-time feedback, could lead to greater engagement and improved exercise performance as compared to passive monitoring technologies. Incorporating these study findings into optimized design of wearable device-based exercise interventions could facilitate the integration of diastolic-stepping therapy as a self-directed care strategy for people needing cardiovascular support to sustain exercise. LIMITATIONS The small participant cohort (N = 19) was recruited through a group exercise class; hence, the data represents older adults who are relatively healthy with high levels of physical activity and high quality of life. Part of the data collection was done during the Swedish winter, characterized by cold and icy roads. Therefore, some participants will have faced more challenging conditions regarding the ability to adjust walking speed, but also the motivation to go out and take a walk. Furthermore, the device-mounted capacitive electrodes to measure heart rate are negatively affected by very dry winter weather, which could result in intermittent measurement, and thus unphysiological biofeedback prompts. To mitigate these challenges, we told our participants they could also walk in their house or on the treadmill and gave instructions on properly moisturizing the electrodes before each training session. The device used for synchronization guidance is specifically designed for running applications, which does not align with the design of this study to use the device during walking. This mismatch led to an average dissatisfaction with the device among the whole cohort. Finally, participants’ motivation to use and engage with the device could be influenced by their motivation to participate in the study. While the objective of this study did not intend to analyze motivation or engagement, different motivational reasons could explain variability in efforts toward learning synchronization. Our findings should be considered preliminary and must be confirmed in a clinical trial with a longer follow-up period to study the long-term impact of the intervention. CONCLUSIONS In this prospective study, we found that 58% of our participants achieved high-level of synchronization in diastolic stepping at home. High-level of synchronization is achieved with calmness, focus, and warming up, and both physiological and rhythmic factors may play a role in the levels of synchronization achieved. Additional guidance during learning helped find a synchronization ‘flow’ and increase levels of synchronization. Our results inform future research on improving biofeedback devices for prevention in patients at risk of cardiovascular disease, with the goal of improving exercise tolerance, and, in turn, patients’ quality of life. Abbreviations CLS Cardiac-locomotor Synchronization CVD Cardiovascolar Disease ECG Electrocardiogram HF Heart Failure HR Heart Rate SR Step Rate SUS System Usability Scale Declarations Ethics approval and consent to participate Ethical approval for the study was obtained from the Swedish authorities (2023-00426-01), and all participants provided written informed consent in accordance with the Declaration of Helsinki. Availability of data and materials The data that support the findings of this study are available from the corresponding author upon request. Competing interests The authors declare that they have no competing interests. Funding This work was supported by Promobilia Stiftelsen (A23042), Åke Wiberg Stiftelsen (M23-0018) and Kamprad Family Foundation (20233117). Authors’ contributions A.R.: Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Project administration, Software, Validation, Visualization, Writing – original draft. T.Y.L. : Data curation, Writing – review & editing. JC: Data curation, Writing – review & editing. E.A.: Resources, Writing – review & editing. S.K.: Data curation, Funding acquisition, Project administration, Supervision, Writing – review & editing. S.A.D.: Conceptualization, Funding acquisition, Investigation, Methodology, Project administration, Resources, Supervision, Validation, Writing – original draft. 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Effects of Synchronizing Foot Strike and Cardiac Phase on Exercise Hemodynamics in Patients With Cardiac Resynchronization Therapy: A Within-Subjects Pilot Study to Fine-Tune Cardio-Locomotor Coupling for Heart Failure. Circulation. 2023;148(25):2008–16. Takeuchi S, Nishida Y, Mizushima T. Evidence of an Association between Cardiac-Locomotor Synchronization and Lower Leg Muscle Blood Perfusion during Walking. J Phys Ther Sci. 2015;27(6):1819–22. Constantini K, Stickford ASL, Bleich JL, Mannheimer PD, Levine BD, Chapman RF. Synchronizing Gait with Cardiac Cycle Phase Alters Heart Rate Response during Running. Med Sci Sports Exerc. 2018;50(5):1046–53. Nomura K, Takei Y, Yoshida M, Yanagida Y. Phase-dependent chronotropic response of the heart during running in humans. Eur J Appl Physiol. 2006;97(2):240–7. Lee KCS, Breznen B, Ukhova A, Koehler F, Martin SS. Virtual healthcare solutions for cardiac rehabilitation: a literature review. Eur Heart J - Digit Health. 2023;4(2):99–111. Van Hooren B, Goudsmit J, Restrepo J, Vos S. Real-time feedback by wearables in running: Current approaches, challenges and suggestions for improvements. J Sports Sci. 2020;38(2):214–30. Schwerz de Lucena D, Rowe JB, Okita S, Chan V, Cramer SC, Reinkensmeyer DJ. Providing Real-Time Wearable Feedback to Increase Hand Use after Stroke: A Randomized, Controlled Trial. Sens (Basel). 2022;22(18):6938. Lu TY, Che J, Rosato A, Dual S, Kuoppamäki S. The use of wearables with real-time feedback in rhythmic activity among older adults: A qualitative study (Preprint) [Internet]. 2025 [cited 2025 Feb 5]. Available from: http://preprints.jmir.org/preprint/71509 Tiedemann A, Sherrington C, Lord SR. Physiological and Psychological Predictors of Walking Speed in Older Community-Dwelling People. Gerontology. 2005;51(6):390–5. Matos Casano HA, Anjum F. Six-Minute Walk Test. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 [cited 2024 Nov 20]. Available from: http://www.ncbi.nlm.nih.gov/books/NBK576420/ Borg Rating of Perceived Exertion (RPE). scale | Occupational Medicine | Oxford Academic [Internet]. [cited 2024 Nov 20]. Available from: https://academic.oup.com/occmed/article/67/5/404/3975235 Inquisit Lab 6 [Internet]. 2022. Available from: https://www.millisecond.com Devlin N, Parkin D, Janssen B. Methods for Analysing and Reporting EQ-5D Data [Internet]. Cham: Springer International Publishing; 2020 [cited 2024 Oct 23]. Available from: https://link.springer.com/ 10.1007/978-3-030-47622-9 Brooke J. In. SUS -- a quick and dirty usability scale. 1996. pp. 189–94. Kirby RL, Nugent ST, Marlow RW, Macli $ od DA, Alan, Marble E et al. Coupling of Cardiac and Locomotor Rhythms. J Appl Physiol. 1989;323–9. Takeuchi S, Nishida Y. Influence of coronary artery disease on cardiolocomotor coupling during walking: a preliminary study. All Life [Internet]. 2023 Dec 31 [cited 2024 May 10]; Available from: https://www.tandfonline.com/doi/abs/ 10.1080/26895293.2023.2219410 Novak V, Hu K, Vyas M, Lipsitz LA. Cardiolocomotor Coupling in Young and Elderly People. Journals Gerontol Ser A: Biol Sci Med Sci. 2007;62(1):86–92. Rosato A, Larsson M, Rullman E, Dual SA. Evidence of spontaneous cardiac-locomotor coupling during daily activities in healthy adults. Front Physiol [Internet]. 2024 Aug 13 [cited 2024 Sep 17];15. Available from: https://www.frontiersin.org/journals/physiology/articles/ 10.3389/fphys.2024.1394591/full Jain A, Bansal R, Kumar A, Singh K. A comparative study of visual and auditory reaction times on the basis of gender and physical activity levels of medical first year students. Int J Appl Basic Med Res. 2015;5(2):124–7. Repp BH, Su YH. Sensorimotor synchronization: A review of recent research (2006–2012). Psychon Bull Rev. 2013;20(3):403–52. Additional Declarations No competing interests reported. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-6172990","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":425559830,"identity":"3a2d99fe-490b-4029-8284-dbf915e91833","order_by":0,"name":"Aurora Rosato","email":"","orcid":"","institution":"KTH Royal Institute of Technology","correspondingAuthor":false,"prefix":"","firstName":"Aurora","middleName":"","lastName":"Rosato","suffix":""},{"id":425559831,"identity":"56d9395b-0d97-4005-9a3f-3f3b00547b67","order_by":1,"name":"Tien-Ying Lu","email":"","orcid":"","institution":"KTH Royal Institute of Technology","correspondingAuthor":false,"prefix":"","firstName":"Tien-Ying","middleName":"","lastName":"Lu","suffix":""},{"id":425559832,"identity":"8777fb4d-b423-4b73-a9ea-169ea962e72c","order_by":2,"name":"Jie Che","email":"","orcid":"","institution":"KTH Royal Institute of Technology","correspondingAuthor":false,"prefix":"","firstName":"Jie","middleName":"","lastName":"Che","suffix":""},{"id":425559833,"identity":"9a2cd4fe-2eeb-4364-a352-38679cec37d2","order_by":3,"name":"Eva Andersson","email":"","orcid":"","institution":"Swedish School of Sport and Health Sciences","correspondingAuthor":false,"prefix":"","firstName":"Eva","middleName":"","lastName":"Andersson","suffix":""},{"id":425559834,"identity":"27f22369-9be9-4101-8161-d8b6aabd7ecd","order_by":4,"name":"Sanna Kuoppamäki","email":"","orcid":"","institution":"KTH Royal Institute of Technology","correspondingAuthor":false,"prefix":"","firstName":"Sanna","middleName":"","lastName":"Kuoppamäki","suffix":""},{"id":425559835,"identity":"9292794c-3a1e-4731-bf5b-c3f9e3fa652b","order_by":5,"name":"Seraina Anne Dual","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAsklEQVRIiWNgGAWjYLCCBAYGOQkGHhK1GEuwkaQFCBJnEK1Fvr334YeHO+zSZ87vPcD4o4IILQZnjhtLJJ5Jzp3NxpfAzHOGGC0SaQwSiW3MufPYeAyYGduIcdj8Z8w/Etvq0+WAWhh//iNCC8MNNjagLYcTpIFaGHgbiHHYmTQ2i8S244Yz23IMDvMcI8Zh7ceYb/5sq5aXOHzG8OGPGmIchgwOkKphFIyCUTAKRgEOAAAJfi/w+15T5wAAAABJRU5ErkJggg==","orcid":"","institution":"KTH Royal Institute of Technology","correspondingAuthor":true,"prefix":"","firstName":"Seraina","middleName":"Anne","lastName":"Dual","suffix":""}],"badges":[],"createdAt":"2025-03-06 18:53:15","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6172990/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6172990/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":78264573,"identity":"ef5dc02f-4039-45c7-8645-244c1b657d2d","added_by":"auto","created_at":"2025-03-11 12:08:52","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":2196,"visible":true,"origin":"","legend":"\u003cp\u003eSynchronization level for the low-level and high-level synchronizers, average during the 3-week, one point per subject. ** indicates p\u0026lt;0.001.\u003c/p\u003e","description":"","filename":"Onlinefloatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-6172990/v1/a2d380bcd0b30e29b793c204.png"},{"id":78263310,"identity":"5c30a0fa-31fc-489a-84da-d778d455efae","added_by":"auto","created_at":"2025-03-11 12:00:52","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":4247,"visible":true,"origin":"","legend":"\u003cp\u003eA) Histogram of the ratio = step rate/heat rate. B) Histogram of the phase between R-wave and step timing. Distributions include data from the entire 3-week period, separately reported for high-level vs. low-level synchronizers.\u003c/p\u003e","description":"","filename":"Onlinefloatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-6172990/v1/bd5e0346a8c224be801c23fb.png"},{"id":78263309,"identity":"d7787e3e-58a8-4a6e-a2f6-cd3a0d387dfe","added_by":"auto","created_at":"2025-03-11 12:00:52","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":3833,"visible":true,"origin":"","legend":"\u003cp\u003eA) Histogram of the distribution of heart rates (HRs). B) Histogram of the distributions of step rates (SRs). Data from the entire 3-week period, separating high-level vs. low-level synchronizers.\u003c/p\u003e","description":"","filename":"Onlinefloatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-6172990/v1/d848fe8e90ceb0c81cf0bb57.png"},{"id":78263313,"identity":"6498373e-487d-4878-9232-c90ddf2a72e8","added_by":"auto","created_at":"2025-03-11 12:00:52","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":13239,"visible":true,"origin":"","legend":"\u003cp\u003eA) Synchronization dependence from heart rate in all subjects. B) P22, high-level synchronizer. C) P13, low-level synchronizer.\u003c/p\u003e","description":"","filename":"Onlinefloatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-6172990/v1/074a1daddffc34b6378db834.png"},{"id":78263317,"identity":"2b913857-53cb-4ced-884b-b734503de619","added_by":"auto","created_at":"2025-03-11 12:00:52","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":7112,"visible":true,"origin":"","legend":"\u003cp\u003eThe level of synchronization over the period of use, example cases of two subjects. A) P16, high-level synchronizer. B) P05, low-level synchronizer.\u003c/p\u003e","description":"","filename":"Onlinefloatimage5.png","url":"https://assets-eu.researchsquare.com/files/rs-6172990/v1/c58b2a07776adb1b1ca6de8a.png"},{"id":78263311,"identity":"4e3b7300-3719-4a3a-bd33-208579127e2a","added_by":"auto","created_at":"2025-03-11 12:00:52","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":3154,"visible":true,"origin":"","legend":"\u003cp\u003eSynchronization at home vs. synchronization in the lab. * indicates p\u0026lt;0.05 and ** p\u0026lt;0.01.\u003c/p\u003e","description":"","filename":"Onlinefloatimage6.png","url":"https://assets-eu.researchsquare.com/files/rs-6172990/v1/90fd69ffd5218a08c0d60f27.png"},{"id":78351965,"identity":"f3afdb67-7d75-40e5-9da2-db04c4134c25","added_by":"auto","created_at":"2025-03-12 10:47:08","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1011510,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6172990/v1/780c1fb7-2f5f-4d07-8e99-a4a8df13a1b4.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Device-Guided Diastolic Stepping During Walking among Older Adults: A Home-Based Feasibility Pilot Study","fulltext":[{"header":"BACKGROUND","content":"\u003cp\u003eCardiovascular disease (CVD) acutely affects over half a billion people (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e), with many at risk of developing chronic heart failure (HF). HF emerges as a hidden global pandemic, affecting around 26\u0026nbsp;million people worldwide, with prevalence expected to rise due to the aging population (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e). HF severely impacts patients\u0026rsquo; quality of life, manifesting shortness of breath, limited walking speed, and endurance, which restrict everyday life to minimal physical activity (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e). Exercise training offers substantial benefits in reducing morbidity and mortality among individuals with CVD (\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e), and cardiac rehabilitation programs are recommended as a form of secondary prevention (\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e). However, in conditions such as HF, reduced functional capacity can hinder both the effectiveness and the adherence to exercise programs.\u003c/p\u003e \u003cp\u003eIt was recently shown that diastolic stepping to the heartbeat improves functional capacity momentarily in patients with HF (\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e) which may improve exercise-based rehabilitation efforts in older adults with CVD.\u003c/p\u003e \u003cp\u003eThe study of gait synchronization (locomotor rhythm) with the heartbeat (cardiac rhythm) is known as cardiac-locomotor synchronization (CLS). CLS, defined as a 1:1 ratio between the gait cycle and heart cycle, specifically aims to align steps with the diastole of the cardiac cycle and has been commonly achieved by letting people step to an auditory cue synchronized with their heart rate (HR) (\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e). Diastolic stepping to the heartbeat improves heart function in HF momentarily by augmenting stroke volume and oxygen delivery, together with a reduction in mean arterial blood pressure (\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e). The synchronized activation of the leg muscle pump during walking is hypothesized to decrease afterload, increase preload, and increase coronary perfusion. In healthy subjects, physiological benefits of synchronization have been demonstrated in terms of increased blood flow to active muscles (\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e) and reduced HR at a consistent workload (\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e). Importantly, it was shown that even people with congestive HF profit from synchronization health benefits when stepping to the beat of their implanted pacemaker (\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e). In summary, diastolic stepping may augment the effectiveness of exercise tolerance (ie, time to fatigue), as well as exercise capacity, together increasing patient quality of life in patients with HF (\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eWhile this limited data suggests synchronization to be achievable in everyday life, the impact of synchronization for people at risk of advanced forms of cardiovascular disease would be maximized if CLS technology was available as a wearable, enabling self-care in a home-based setting. However, sustaining user adherence and engagement remains a key challenge for achieving long-term benefits. Mobile technologies for virtual cardiac rehabilitation have shown promise in improving adherence and longer-term patient engagement (\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e). This potential could be further amplified through a biofeedback mechanism. Unlike wearable devices that solely track physical activity, biofeedback systems actively involve the user in real-time interactions with the device. Such systems, which position the user as part of a feedback loop, have shown promising results in sports (\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e) and rehabilitation applications (\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe feasibility of implementing synchronization biofeedback for home-based diastolic stepping in the older adult population with the highest immediate cardiovascular risk remains an unexplored area. This study aims to explore the feasibility of home-based diastolic stepping synchronization in physically active older adults using a wearable data-driven approach. The wearable biofeedback device used is equipped with a chest strap and produces an auditory cue to guide participants to synchronize their steps with their heartbeat. Based on the wearable data, we distinguish two groups according to their level of synchronization \u0026ldquo;high-level\u0026rdquo; and \u0026ldquo;low-level\u0026rdquo; synchronizers from a cohort of active older adults with a generally high quality of life. We contextualize our findings via interview-based user feedback. We hypothesize that home-based synchronization success will be influenced by several key factors: physiological factors such as resting HR, baseline step rate (SR), individuals' baseline rhythmic skills, usability, learning, and guidance factors.\u003c/p\u003e"},{"header":"METHODS","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eStudy design\u003c/h2\u003e \u003cp\u003eThis cross-sectional study includes a prospective home-based walking intervention over a 3-week period, during which participants utilized a real-time biofeedback device with minimal guidance. Baseline data, including physical activity, health status, quality of life, and socio-demographic information, were collected through interviews and questionnaires, followed by a device demonstration, auditory reaction time measurement, and a 6-meter walking test to assess preferred and device-guided SR. During the 3-week period, participants were asked to use the device at least three times per week for 30 minutes each while walking. Post-intervention, participants completed follow-up questionnaires and participated in a laboratory session involving treadmill tests and repeated walking assessments. Additionally, individual user feedback was collected after the completion of the intervention in a 30-minute semi-structured interview to gain insights into the user experience with device-guided synchronized walking. The interview has been audio recorded and transcribed to text materials. User feedback from the perspective of self-perceived challenges in synchronizing, will complement the discussion and contextualize the device-generated data. A comprehensive analysis of the interview material has been performed parallelly to investigate the age heterogeneity in the use of wearables with real-time feedback (\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e). Ethical approval for the study was obtained from the Swedish authorities (2023-00426-01), and all participants provided written informed consent in accordance with the Declaration of Helsinki.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eParticipants\u003c/h3\u003e\n\u003cp\u003eParticipants were recruited through The Swedish School of Sport and Health Sciences (GIH). Participants are physically active as they attend weekly physical exercise classes three times a week at GIH. The choice of healthy participants was motivated by the lack of data on feasibility of synchronization in literature. Inclusion criteria were the ability to exercise independently, the possession of a mobile phone to run the phone application, and the ability to adequately see and hear to interact with the phone application. Participants were excluded from the study if they had any health problems that contraindicated exercise or were diagnosed with a balance or neurological disorder that seriously affected motor function (e.g., stroke, traumatic brain injury, or Parkinsonism).\u003c/p\u003e\n\u003ch3\u003eBiofeedback wearable\u003c/h3\u003e\n\u003cp\u003eThe wearable biofeedback device used was Counterpace (Pulson Inc., USA), a commercially available chest strap used for running and equipped with a sensor to monitor HR via electrocardiogram and foot strike via accelerometry. The mobile app provides users with real-time auditory cues to help them synchronize their steps with the diastolic phase of their heartbeat. Participants\u0026rsquo; SR, HR, and synchronization percentages were recorded by the device to a phone application and stored in an anonymized format. We demonstrated the use of the device to the participants and downloaded the app on their phones. We provided detailed written instructions for using the device. These included step-by-step guidance on how to open the app, to initiate physical activity, to optimize synchronization, and to troubleshoot potential issues. Participants had a phone number and email to contact researchers in case of difficulties using the device and were encouraged to ask for technical support throughout the study. The study controlled for usability and all participants reported ease of use.\u003c/p\u003e\n\u003ch3\u003eData collection and analysis\u003c/h3\u003e\n\u003cp\u003eAll analyses were performed using custom code in MATLAB R2024a (The MathWorks, Natick, MA).\u003c/p\u003e\n\u003ch3\u003eBaseline variables\u003c/h3\u003e\n\u003cp\u003eWalking speed and preferred SR have been measured using the 6-meter walking test (\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e). Participants completed the test twice, one without the guidance of the device and the second time with the guidance of the device. Baseline exercise capacity was evaluated as distance walked during a 6-min walking test in a flat corridor (\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e). At the end of the test, the self-perceived exertion is rated using the Borg RPE scale (\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e).\u003c/p\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eAuditory reaction time\u003c/h2\u003e \u003cp\u003eA simple reaction time test (Millisecond Software LLC, Seattle) played on an iPad (Apple Inc., Cupertino) has been used to measure auditory reaction time (\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e). The auditory reaction time is a measure of how quickly a human responds to a stimulus and is defined as the interval of time between the presentation of the stimulus and the appearance of an appropriate voluntary response in the participant. The test lasted 5 minutes, during which participants had to press a button on the screen as soon as they heard an auditory cue.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eWearable data and synchronization data\u003c/h3\u003e\n\u003cp\u003eThrough the biofeedback device, we recorded HR, SR, the ratio between the two rates (SR/HR), and the diastolic synchronization percentages throughout the training episodes with a sampling frequency of 1 Hz. Additionally, we recorded the phase, as the time in percentage of the heartbeat, between the heartbeat and the moment of stepping. A value of 45\u0026thinsp;\u0026plusmn;\u0026thinsp;20% constitutes the desirable diastolic timing. The level of synchronization is calculated as the percentage of time at equal rates (HR\u0026thinsp;=\u0026thinsp;SR) and in diastolic phase.\u003c/p\u003e \u003cp\u003eWe recorded training start and end time. Training sessions lasting less than 5 minutes were excluded from the analysis, and the first 5 minutes of each training were removed to only consider steady-state HR. HR, SR, ratio and the phase were then computed and averaged over each minute. Non-physiological outlier values outside the range of 60 to 250 bpm for HR and 60 to 250 steps/minute for SR were removed from the dataset.\u003c/p\u003e \u003cp\u003eThe device usage time was calculated as the total sum of each minute of training and is also reported as a percentage of the recommended usage time for each participant. The synchronization values over each training session were used to calculate the average synchronization level of each participant. To ensure consistency across participants, only the most successful 9 training sessions, corresponding to the recommended usage time, were included in this analysis.\u003c/p\u003e\n\u003ch3\u003eQuestionnaires\u003c/h3\u003e\n\u003cp\u003eThe questionnaires included reporting self-perceived physical activity level, self-perceived health, and EQ-5D-5L quality of life (\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e). The self-perceived health was evaluated with a question \u0026ldquo;How do you perceive your physical/mental health\u0026rdquo;, with a 6-point scale ranging from \u0026ldquo;I\u0026rsquo;m very satisfied with my health\u0026rdquo; to \u0026ldquo;I\u0026rsquo;m very dissatisfied with my health\u0026rdquo;. The self-perceived physical activity level was evaluated with two questions \u0026ldquo;In a typical week, how much time do you spend on physical exercise that leaves you breathless, e.g. running, gym, ball sports?\u0026rdquo; and \u0026ldquo;In a typical week, how much time do you spend on everyday exercise, for example walking, cycling, gardening? Add up all the time (at least 10 minutes at a time)\u0026rdquo;, with a 6-point scale ranging from 0-120min or more for the first question and 0-300 min or more for the second question.\u003c/p\u003e \u003cp\u003eThe quality of life questionnaire (EQ-5D-5L) consists of five dimensions: mobility, self-care, usual activities, pain/discomfort, and anxiety/depression. Each dimension has five levels: no problems, slight, moderate, severe, and extreme problems, which generate a 5-digit code representing the overall health, with each digit corresponding to the selected level in each dimension. The system allows for 3,125 possible health states, ranging from 11111 (full health) to 55555 (worst health).\u003c/p\u003e \u003cp\u003eUsability was investigated through ten questions based on the System Usability Scale (SUS) (\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e), with a 5-point Likert scale ranging from \u0026ldquo; Do not agree at all\u0026rdquo; to \u0026ldquo; Strongly agree\u0026rdquo;. Summing up all the questions, the usability outcome is a score ranging from 0 (minimum) to 100 (maximum).\u003c/p\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003eStatistical analysis\u003c/h2\u003e \u003cp\u003eMean and standard deviation were calculated for each parameter of interest. Linear regression analysis was performed to evaluate the relationship between HR and synchronization, as well as between total usage time and synchronization success. Group comparisons were conducted using t-tests, and paired t-tests were applied for within-group comparisons (e.g. synchronization in the laboratory vs. synchronization at home). Unless otherwise specified, values are presented as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003eUser groups\u003c/h2\u003e \u003cp\u003eBased on the level of synchronization, we observed a clear distinction between two user groups. Participants were classified as \u0026ldquo;high-level synchronizers\u0026rdquo; if their average synchronization exceeded 50%. Those with an average synchronization below 50% were classified as \u0026ldquo;low-level synchronizers.\u0026rdquo;\u0026rsquo; Most results are reported per group to elucidate the potential reasons for high or low levels of synchronization.\u003c/p\u003e \u003c/div\u003e"},{"header":"RESULTS","content":"\u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003eParticipants characteristics\u003c/h2\u003e \u003cp\u003eTwenty-two older adults (73\u0026thinsp;\u0026plusmn;\u0026thinsp;4 years old, 13 female and 9 male) were enrolled in the study between November 2023 and June 2024. Of the twenty-two participants, two resigned some days after the start of the three-week exercise, and one subject successfully completed the study, but the device data was missing. In our cohort, all of them but one considered themselves healthy, however, 20% of participants have been treated for cardiovascular disease and the majority regularly take medications. Participants\u0026rsquo; characteristics, use of the device, and average synchronization are presented in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\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 characteristics of the participants, quality of life (EQ-5D-5L), average heart rate (beats/min), total use (min), number of sessions performed, and average synchronization (%). \u0026ndash; correspond to a missing value. \u003cb\u003eBold\u003c/b\u003e, high-level synchronizers.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"8\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eID\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAge\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eGender\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eQuality of life\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eAverage Heart Rate (bpm)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eTot use (min)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003e# of session performed\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003eSynchronization %\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\u003eP01\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003e70\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cb\u003eF\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003e11121\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003e116\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e\u003cb\u003e571\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e\u003cb\u003e18\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e\u003cb\u003e73\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eP02\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e74\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eM\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e11121\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e101\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e137\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eP03\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003e70\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cb\u003eM\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003e11121\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003e106\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e\u003cb\u003e357\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e\u003cb\u003e9\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e\u003cb\u003e90\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eP04\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e74\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eM\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e75\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e183\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e28\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eP05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e78\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eF\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e11121\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e88\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e684\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eP07\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e72\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eM\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e11121\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e78\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e278\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eP08\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003e76\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cb\u003eM\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003e11111\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003e96\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e\u003cb\u003e909\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e\u003cb\u003e17\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e\u003cb\u003e79\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eP09\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003e71\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cb\u003eF\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003e21122\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003e90\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e\u003cb\u003e1532\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e\u003cb\u003e37\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e\u003cb\u003e89\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eP11\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003e82\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cb\u003eM\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003e31232\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003e112\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e\u003cb\u003e1905\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e\u003cb\u003e30\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e\u003cb\u003e80\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eP13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e70\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eF\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e11231\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e104\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e580\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e16\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e11\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eP14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e70\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eF\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e22231\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e115\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e262\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e13\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eP15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e72\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eM\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e11111\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e81\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e678\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e11\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eP16\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003e78\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cb\u003eF\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003e11121\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003e97\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e\u003cb\u003e735\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e\u003cb\u003e14\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e\u003cb\u003e79\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eP18\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003e75\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cb\u003eF\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003e11121\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003e92\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e\u003cb\u003e302\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e\u003cb\u003e9\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e\u003cb\u003e92\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eP20\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003e72\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cb\u003eF\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003e11111\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003e89\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e\u003cb\u003e351\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e\u003cb\u003e9\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e\u003cb\u003e86\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eP21\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003e67\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cb\u003eF\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003e11121\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003e92\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e\u003cb\u003e598\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e\u003cb\u003e20\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e\u003cb\u003e74\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eP22\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003e66\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cb\u003eF\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003e11122\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003e102\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e\u003cb\u003e939\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e\u003cb\u003e36\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e\u003cb\u003e85\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eP23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e72\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eF\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e11111\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e89\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e680\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e19\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eP24\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003e67\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cb\u003eF\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003e11121\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003e70\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e\u003cb\u003e420\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e\u003cb\u003e10\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e\u003cb\u003e84\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eIn our cohort, the most frequent EQ-5D-5L quality of life profiles are 11111 (4/19) and 11121 (9/19), indicating a homogenous high quality of life across participants. Pain/discomfort emerges as the most affected dimension, with only five subjects reporting no issues. All dimensions, including mobility, self-care, usual activities, pain/discomfort, and anxiety/depression, show a maximum severity score of 3, corresponding to mild problems. Only one subject experience a mild mobility issue, and none report problems in personal care, usual activities, or depression, reflecting the overall good quality of life of the cohort. The overall perceived physical and mental health is perceived as satisfactory in both groups with no significant difference before and after the 3-weeks study. All subjects with less than 1 hour of breathless physical activity per week prior to the study are in the high-level synchronizer group. All other participants engage in more than 1 h of breathless physical activity. The high-level synchronizer group performed slightly better in the 6-min walking test (520\u0026thinsp;\u0026plusmn;\u0026thinsp;52 m vs. 501\u0026thinsp;\u0026plusmn;\u0026thinsp;48m, insignificant) at an identical level of perceived exertion of 12.1 on the Borg scale on average, which lies in between \u0026ldquo;Light\u0026rdquo; and \u0026ldquo;Somewhat hard\u0026rdquo;.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec15\" class=\"Section2\"\u003e \u003ch2\u003eWearable device use\u003c/h2\u003e \u003cp\u003eThe overall usage of the device was high, with 84% of participants (16/19) exceeding the recommended usage time of 270 minutes, while 16% (3/19) used it less than the recommended time. Participants completed up to 37 valid sessions (16\u0026thinsp;\u0026plusmn;\u0026thinsp;9 sessions). Additionally, the duration per session was longer than recommended, averaging 40\u0026thinsp;\u0026plusmn;\u0026thinsp;12 minutes per session. These results indicate higher-than-expected engagement with the device. Although there was no significant difference in the overall usage time between the two groups, all participants who used the device for less than the recommended time (3/19) were in the low-level synchronizers group.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec16\" class=\"Section2\"\u003e \u003ch2\u003eRate and phase synchronization\u003c/h2\u003e \u003cp\u003eEleven participants achieved an average synchronization rate greater than 50%, while eight participants had a rate below 50%. The synchronization level was significantly different between the two groups, with the high-level synchronizer demonstrating a synchronization rate of 83\u0026thinsp;\u0026plusmn;\u0026thinsp;6%, compared to 11\u0026thinsp;\u0026plusmn;\u0026thinsp;9% for low-level synchronizers (p\u0026thinsp;\u0026lt;\u0026thinsp;0.01), Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. The clear distinction in synchronization level, motivated our data-driven approach to group participants.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe high-level synchronizers had a higher ratio of SR/HR (1.1\u0026thinsp;\u0026plusmn;\u0026thinsp;0.4 vs. 0.94\u0026thinsp;\u0026plusmn;\u0026thinsp;0.3, p\u0026thinsp;\u0026lt;\u0026thinsp;0.01), Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eA. Low-level synchronizers stepped with a larger delay (corresponding to a phase\u0026thinsp;\u0026gt;\u0026thinsp;50%) when compared to the high-level synchronizer (56\u0026thinsp;\u0026plusmn;\u0026thinsp;19% vs. 51\u0026thinsp;\u0026plusmn;\u0026thinsp;14%, p\u0026thinsp;\u0026lt;\u0026thinsp;0.01), Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eB.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec17\" class=\"Section2\"\u003e \u003ch2\u003ePhysiological factors\u003c/h2\u003e \u003cp\u003eA key aspect of the ability to synchronize is the proximity of HR and SR. We found that the HR and the SR during the home training are significantly different for high-level vs. low-level synchronizers. High-level synchronizers have higher HRs (98\u0026thinsp;\u0026plusmn;\u0026thinsp;19 vs. 92\u0026thinsp;\u0026plusmn;\u0026thinsp;14 bpm, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001), Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eA and lower SRs (96\u0026thinsp;\u0026plusmn;\u0026thinsp;17 vs. 101\u0026thinsp;\u0026plusmn;\u0026thinsp;16 steps/min, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001), Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eB.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eOn individual basis, we observed a correlation between HR and level of synchronization, Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eA. For four participants, level of synchronization per training session significantly improved with higher HRs (0.3\u0026thinsp;\u0026lt;\u0026thinsp;R\u0026sup2; \u0026lt; 0.6, p\u0026thinsp;\u0026lt;\u0026thinsp;0.05, Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eC). Conversely, 3 participants demonstrated the opposite effect, with a higher level of synchronization for lower HRs (0.2\u0026thinsp;\u0026lt;\u0026thinsp;R\u0026sup2;\u0026lt;0.8, p\u0026thinsp;\u0026lt;\u0026thinsp;0.01, Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eB).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec18\" class=\"Section2\"\u003e \u003ch2\u003eRhythmic factors\u003c/h2\u003e \u003cp\u003eRhythmic factors related to synch are presented in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eRhythmic factors, high-level vs. low-level synchronizers.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\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 \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVariable\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eHigh-level synchronizers\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eLow-level synchronizers\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eP-value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMean auditory reaction time (ms), baseline\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e249\u0026thinsp;\u0026plusmn;\u0026thinsp;51\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e378\u0026thinsp;\u0026plusmn;\u0026thinsp;140\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.05\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFastest auditory reaction time (ms), baseline\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e183\u0026thinsp;\u0026plusmn;\u0026thinsp;14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e227\u0026thinsp;\u0026plusmn;\u0026thinsp;55\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.05\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSR Prompted (steps/min), baseline\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e83\u0026thinsp;\u0026plusmn;\u0026thinsp;11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e98\u0026thinsp;\u0026plusmn;\u0026thinsp;9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.05\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSR Preferred (steps/min), baseline\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e117\u0026thinsp;\u0026plusmn;\u0026thinsp;10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e117\u0026thinsp;\u0026plusmn;\u0026thinsp;4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003ens\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDifference SR prompted vs. preferred (steps/min), baseline\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e28\u0026thinsp;\u0026plusmn;\u0026thinsp;12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e16\u0026thinsp;\u0026plusmn;\u0026thinsp;6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.05\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSR Preferred (steps/min), lab study\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e119\u0026thinsp;\u0026plusmn;\u0026thinsp;7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e114\u0026thinsp;\u0026plusmn;\u0026thinsp;2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.05\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eThe high-level synchronizers had a lower mean and fastest auditory reaction time. Variability in reaction time was increased in the low-level compared to the high-level synchronizer group.\u003c/p\u003e \u003cp\u003eThe HR, and subsequently the prompted SR, is lower in the high-level synchronizer group, which is associated with a greater difference compared to their preferred SR. This suggests that stepping naturally close to one's HR is not necessarily a predictor of better synchronization success. Instead, synchronization can be improved by adjusting the HR or SR, regardless of their initial rate difference. An additional observation is that the preferred SR after the study does not significantly change compared to the baseline, suggesting that training with the device does not significantly alter an individual's preferred SR.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec19\" class=\"Section2\"\u003e \u003ch2\u003eLearning factors\u003c/h2\u003e \u003cp\u003eNone of the participants had prior experience using the device for synchronization. All participants had to learn how to use a biofeedback wearable for synchronization. The learning process included finding the most favorable settings for using the device in terms of environment, pre-training warming up, and duration of use. The level of synchronization over time varied among participants: some participants showed immediate success, while others had fluctuating synchronization effectiveness or gradually improved with each day of use. Linear regression analysis revealed that 4/19 participants significantly improved synchronization over time (0.1\u0026thinsp;\u0026lt;\u0026thinsp;R\u0026sup2; \u0026lt; 0.9, p\u0026thinsp;\u0026lt;\u0026thinsp;0.05, Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e). Three out of the four participants reached high levels of synchronization through learning.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec20\" class=\"Section2\"\u003e \u003ch2\u003eSelf-directed home use vs. guided lab use\u003c/h2\u003e \u003cp\u003eWe investigated the effect of guidance, by comparing the home-based level of synchronization to the post-intervention laboratory study results, Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe low-level synchronizer group performed substantially better in the controlled lab environment compared to at home (44\u0026thinsp;\u0026plusmn;\u0026thinsp;13% vs. 11\u0026thinsp;\u0026plusmn;\u0026thinsp;9%, p\u0026thinsp;\u0026lt;\u0026thinsp;0.05), although still at lower overall synchronization levels when compared to the high-level synchronizers (44\u0026thinsp;\u0026plusmn;\u0026thinsp;13% vs. 74\u0026thinsp;\u0026plusmn;\u0026thinsp;19%, p\u0026thinsp;\u0026lt;\u0026thinsp;0.01). For high-level synchronizers, variability in levels of synchronization increased in the lab.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec21\" class=\"Section2\"\u003e \u003ch2\u003eUsability\u003c/h2\u003e \u003cp\u003eRegarding usability assessed by questionnaires, on average the high-level synchronizers rated the device slightly higher than low-level synchronizers, with an average SUS score of 64\u0026thinsp;\u0026plusmn;\u0026thinsp;21 vs. 54\u0026thinsp;\u0026plusmn;\u0026thinsp;12, although this result was not significant. Only 4/19 participants, all high-level synchronizers, would strongly use it more (4 or 5), while the low-level synchronizers' highest opinion was neutral. Overall, high-level synchronizers reported higher ease of use and confidence and a lower need for technical support compared to low- level synchronizers. Both groups report minimal learning needed on how to use the device.\u003c/p\u003e \u003c/div\u003e"},{"header":"DISCUSSION","content":"\u003cp\u003eThis is the first pilot study investigating the feasibility of utilizing device-guided diastolic stepping as a self-directed exercise approach at home. Slightly over half of the study participants achieved high levels of synchronization upon limited instruction, which is an unexpectedly encouraging result when considering the high incidence of cardiovascular disease. Using data-driven grouping, we further identified physiological, rhythmic, guidance, and learning factors that influence levels of synchronization during home-based synchronization.\u003c/p\u003e \u003cp\u003eDespite the cardiovascular health benefits, humans do not spontaneously walk with synchronization. Spontaneous synchronization has been studied in laboratory settings where the use of a treadmill sets limits on participants\u0026rsquo; gait (\u003cspan additionalcitationids=\"CR21\" citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e), showing that not all individuals spontaneously achieve synchronization in such controlled environments and that synchronization is more likely to occur at faster walking speeds or during running. In everyday life context, instead, young adults spend 40% of their time within 10% of their HR (\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e). Previous studies have indicated that synchronization of 50% is sufficient for positive health outcomes (\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e). In our study, more than half the participants achieved high levels of synchronization above 80%. In the interviews, synchronization of the SR to the HR was perceived as being challenging by most low-level synchronizers (P4, P7, P13, P14, P15, P23) and two high-level synchronizers (\u003cb\u003eP18, P24\u003c/b\u003e). Notably, ratio synchronization was deemed more easily achieved than phase synchronization, for instance, \u003cb\u003eP24\u003c/b\u003e expressed that \"\u003cem\u003eI would easily get to the correct range, but it always took ten minutes or more to achieve phase synchronization.\u003c/em\u003e\u0026rdquo; Based on our result, we can assume that approximately 50% of the population could profit from CLS health benefits using a commercially available wearable device.\u003c/p\u003e \u003cp\u003eThe observed range of HRs and SRs indicate that individual physiological factors and walking preferences may play a role in the level of initial synchronization success. Both very high and very low HRs can make it difficult to achieve high levels of synchronization. While a very low HR can force an unnatural slow walking, a very high HR might result in a negative feedback cycle, where the stress to achieve higher SR would keep increasing HR, then SR, and so on till exhaustion. The challenge with addressing the discrepancy between HR and SR was highlighted by participants (P7, \u003cb\u003eP8\u003c/b\u003e, P13, P15, \u003cb\u003eP18\u003c/b\u003e, \u003cb\u003eP21\u003c/b\u003e). P4 expressed that \u0026ldquo;\u003cem\u003eWhen the pace kept getting faster, I just cannot run like that\u0026rdquo;\u003c/em\u003e while P13 pointed out that \u003cem\u003e\u0026ldquo;If I need to keep catch up my heart race with my steps, that does not feel like a proper exercise to me anymore.\u003c/em\u003e\u0026rdquo; Participants may benefit from maintaining a SR that feels natural yet is not so high as to cause fatigue, allowing them to sustain it comfortably throughout the training. In general, our group of highly physically active older adults has low HRs and high SRs. A low HR was common (P7, \u003cb\u003eP8\u003c/b\u003e, P13, P15, \u003cb\u003eP18\u003c/b\u003e, \u003cb\u003eP21\u003c/b\u003e), and resulted in difficulties to synchronize. P15 stated that \u0026ldquo;\u003cem\u003e(When reading the heart rate data) I found very quickly that my normal heart rate is around 70. My normal step rate is more like 120. So, it was a very big difference.\u003c/em\u003e\u0026rdquo; In this user group, the health benefits from synchronization may not be outweighed by reduced motivation to exercise, which arises from the need to change their preferred SR. A better target group may be older adults with a lower general aptitude for physical activity.\u003c/p\u003e \u003cp\u003eWe found that participants with faster reaction time achieved higher levels of synchronization. The faster reaction time might indicate better coordination between the sensory and motor systems (\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e), which could provide an advantage in achieving high levels of synchronization during home training. In fact, for low-level synchronizers, the step timing is delayed compared to the ideal step timing (higher phase).\u003c/p\u003e \u003cp\u003eThe device-based data only showed clear learning of CLS over the period of 3-weeks in four participants. In many high-level synchronizers, the learning experience was a widely discussed topic for the participants\u0026rsquo; experiences (\u003cb\u003eP1\u003c/b\u003e, \u003cb\u003eP3\u003c/b\u003e, P4, \u003cb\u003eP11\u003c/b\u003e, \u003cb\u003eP18\u003c/b\u003e, \u003cb\u003eP20\u003c/b\u003e). Participants considered the synchronization as a way to track themselves and a challenge to get better at over time. \u003cb\u003eP3\u003c/b\u003e gave a clear example of her improvement \u0026ldquo;\u003cem\u003eDuring the first week, \u0026hellip; I was in sync 69%. The next week \u0026hellip; I was in sync 95%. I was aiming for 97% in sync for the last week. It just gets better and better\u003c/em\u003e.\u0026rdquo; Meanwhile, \u003cb\u003eP18\u003c/b\u003e also highlighted that the time to achieve synchronization decreased with the learning process \u0026ldquo;\u003cem\u003eWhen I learned how to do it (achieve synchronization) the first time, it took me 45 minutes or 1 hour to get it. But on the last walks, it was only around 30, 35 minutes maybe.\u003c/em\u003e\u0026rdquo; In their learning processes, different strategies were used by the participants to achieve synchronization and those strategies varied due to their personal goals or preferences. The most common one was to \u0026ldquo;\u003cem\u003eIncrease the HR\u003c/em\u003e\u0026rdquo; either by \u0026ldquo;\u003cem\u003eclimbing up the stairs\u003c/em\u003e\u0026rdquo; (P4, \u003cb\u003eP18\u003c/b\u003e)\u0026rdquo;, \u0026ldquo;\u003cem\u003ewarming up\u003c/em\u003e\u0026rdquo; (\u003cb\u003eP1\u003c/b\u003e) or \u0026ldquo;\u003cem\u003ejogging\u003c/em\u003e\u0026rdquo; (\u003cb\u003eP3\u003c/b\u003e). On the other hand, \u003cb\u003eP11\u003c/b\u003e and \u003cb\u003eP20\u003c/b\u003e, resulted to ways to \u0026ldquo;\u003cem\u003eShorten/Extend the Step Length\u003c/em\u003e.\u0026rdquo; For the participants with a low-level of synchronization, the supervised lab session had a greater positive impact on learning synchronization than three weeks of home training. We conclude that learning the \u0026lsquo;flow\u0026rsquo; of synchronized walking is possible upon simple instruction and that additional support may be necessary to achieve high levels of synchronization in everyone.\u003c/p\u003e \u003cp\u003eWhile understanding how external factors influence the effectiveness of device-guided interventions requires further investigation, some subjects suggested focus and calmness as determinant factors. Having full focus was considered necessary for synchronizing effectively, as described by P7, who needed to \u0026ldquo;\u003cem\u003econcentrate on it completely\u003c/em\u003e\u0026rdquo;. Being alone when using the device was helpful as stated by \u003cb\u003eP22\u003c/b\u003e: \u003cem\u003e\u0026ldquo;I thought it was easier to exercise in focus. You have to go alone and look down and see (my steps) and listen (to the cueing)\u003c/em\u003e.\u0026rdquo; Challenges that influenced their focus were mostly environmental. Participants who used the device to walk in the city noted got distracted either due to some unexpected encounters such as \u0026ldquo;\u003cem\u003ethe bus coming\u003c/em\u003e\u0026rdquo; (\u003cb\u003eP21\u003c/b\u003e) and \u0026ldquo;\u003cem\u003ethe dogs\u003c/em\u003e\u0026rdquo; (P7) or because of their caution to the pavement conditions such as \u0026ldquo;\u003cem\u003epauses caused by the icy weather\u003c/em\u003e\u0026rdquo; (\u003cb\u003eP1\u003c/b\u003e) and \u0026ldquo;\u003cem\u003ecrossing a puddle of water\u003c/em\u003e\u0026rdquo;(\u003cb\u003eP22\u003c/b\u003e). On the other hand, positive feelings such as being relaxed or carefree were reported to be beneficial for getting in sync with the device. In this sense, \u003cb\u003eP3\u003c/b\u003e found it easier to synchronize in her normal exercise routine outdoor as compared to training indoors, despite potentially more environmental distractions: \u0026ldquo;\u003cem\u003eIn the beginning, I tested at home due to the bad weather. But I discovered that it was difficult when I turned around. Then the next day, I used it outdoor, and it went much, much better\u003c/em\u003e.\u0026rdquo; Furthermore, \u003cb\u003eP9\u003c/b\u003e pointed out that \u0026ldquo;\u003cem\u003eI didn't have to think about anything. I would just walk and not fast (in order to attend to other tasks). Because as soon as you start thinking about the laundry room or tomorrow or the day after tomorrow. Then you get out of sync\u003c/em\u003e.\u0026rdquo; A similar experience was stressed by \u003cb\u003eP22\u003c/b\u003e when she said \u0026ldquo;\u003cem\u003eI must be relaxed. Then it's very easy. But if I was stressed or something like, it was very difficult for me to come in the synch\u003c/em\u003e.\u0026rdquo; Stress might also explain the worse performance of high-level synchronizers in the laboratory as compared to home use.\u003c/p\u003e \u003cp\u003eA recent study on the most effective healthcare interventions highlights key aspects for success and adherence, which are also recognizable in our study (\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e). The findings of this study support the finding that training on the correct use of the technology and the data upload and management is crucial for intervention success. Secondly, the real-time feedback of the proposed device-guided intervention engages with the user continuously, and in this way is tailored to individual participants\u0026rsquo; interaction with the technology. Device-guided diastolic stepping intervention might thus hold promising potential for high adherence. A comprehensive approach combining supervised sessions and home-based training, together with real-time feedback, could lead to greater engagement and improved exercise performance as compared to passive monitoring technologies. Incorporating these study findings into optimized design of wearable device-based exercise interventions could facilitate the integration of diastolic-stepping therapy as a self-directed care strategy for people needing cardiovascular support to sustain exercise.\u003c/p\u003e \u003cdiv id=\"Sec23\" class=\"Section2\"\u003e \u003ch2\u003eLIMITATIONS\u003c/h2\u003e \u003cp\u003eThe small participant cohort (N\u0026thinsp;=\u0026thinsp;19) was recruited through a group exercise class; hence, the data represents older adults who are relatively healthy with high levels of physical activity and high quality of life. Part of the data collection was done during the Swedish winter, characterized by cold and icy roads. Therefore, some participants will have faced more challenging conditions regarding the ability to adjust walking speed, but also the motivation to go out and take a walk. Furthermore, the device-mounted capacitive electrodes to measure heart rate are negatively affected by very dry winter weather, which could result in intermittent measurement, and thus unphysiological biofeedback prompts. To mitigate these challenges, we told our participants they could also walk in their house or on the treadmill and gave instructions on properly moisturizing the electrodes before each training session. The device used for synchronization guidance is specifically designed for running applications, which does not align with the design of this study to use the device during walking. This mismatch led to an average dissatisfaction with the device among the whole cohort. Finally, participants\u0026rsquo; motivation to use and engage with the device could be influenced by their motivation to participate in the study. While the objective of this study did not intend to analyze motivation or engagement, different motivational reasons could explain variability in efforts toward learning synchronization. Our findings should be considered preliminary and must be confirmed in a clinical trial with a longer follow-up period to study the long-term impact of the intervention.\u003c/p\u003e \u003c/div\u003e"},{"header":"CONCLUSIONS","content":"\u003cp\u003eIn this prospective study, we found that 58% of our participants achieved high-level of synchronization in diastolic stepping at home. High-level of synchronization is achieved with calmness, focus, and warming up, and both physiological and rhythmic factors may play a role in the levels of synchronization achieved. Additional guidance during learning helped find a synchronization \u0026lsquo;flow\u0026rsquo; and increase levels of synchronization. Our results inform future research on improving biofeedback devices for prevention in patients at risk of cardiovascular disease, with the goal of improving exercise tolerance, and, in turn, patients\u0026rsquo; quality of life.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cdiv class=\"DefinitionList\"\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u003cb\u003eCLS\u003c/b\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eCardiac-locomotor Synchronization\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u003cb\u003eCVD\u003c/b\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eCardiovascolar Disease\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u003cb\u003eECG\u003c/b\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eElectrocardiogram\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u003cb\u003eHF\u003c/b\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eHeart Failure\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u003cb\u003eHR\u003c/b\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eHeart Rate\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u003cb\u003eSR\u003c/b\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eStep Rate\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u003cb\u003eSUS\u003c/b\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eSystem Usability Scale\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eEthical approval for the study was obtained from the Swedish authorities (2023-00426-01), and all participants provided written informed consent in accordance with the Declaration of Helsinki.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe data that support the findings of this study are available from the corresponding author upon request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis work was supported by Promobilia Stiftelsen (A23042), \u0026Aring;ke Wiberg Stiftelsen (M23-0018) and Kamprad Family Foundation (20233117).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026rsquo; contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eA.R.: Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Project administration, Software, Validation, Visualization, Writing \u0026ndash; original draft. T.Y.L. : Data curation, Writing \u0026ndash; review \u0026amp; editing. JC: Data curation, \u0026nbsp;Writing \u0026ndash; review \u0026amp; editing. \u0026nbsp;E.A.: \u0026nbsp; Resources, Writing \u0026ndash; review \u0026amp; editing. S.K.: \u0026nbsp;Data curation, \u0026nbsp;Funding acquisition, Project administration, Supervision, Writing \u0026ndash; review \u0026amp; editing. \u0026nbsp; S.A.D.: Conceptualization, Funding acquisition, Investigation, Methodology, Project administration, Resources, Supervision, Validation, Writing \u0026ndash; original draft.\u0026nbsp;\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eWorld Heart Report. 2023: Confronting the World\u0026rsquo;s Number One Killer. [Internet]. Geneva, Switzerland: World Heart Federation; 2023. 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Journals Gerontol Ser A: Biol Sci Med Sci. 2007;62(1):86\u0026ndash;92.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRosato A, Larsson M, Rullman E, Dual SA. Evidence of spontaneous cardiac-locomotor coupling during daily activities in healthy adults. Front Physiol [Internet]. 2024 Aug 13 [cited 2024 Sep 17];15. 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Sensorimotor synchronization: A review of recent research (2006\u0026ndash;2012). Psychon Bull Rev. 2013;20(3):403\u0026ndash;52.\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":"cardiac prevention, real-time feedback device, diastolic stepping, rhythmic exercise, cardiac locomotor synchronization","lastPublishedDoi":"10.21203/rs.3.rs-6172990/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6172990/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e \u003cp\u003eWearable cardiovascular technologies constitute a promising avenue for self-directed home-based prevention and rehabilitation interventions for older adults at risk. In patients with congestive heart failure, it was recently shown that synchronized stepping to the diastole of the heartbeat during walking (diastolic stepping) increases stroke volume and oxygen delivery. A home-based approach may maximize health benefits, however the level of synchronization achievable in an everyday context remains completely unexplored. This prospective study aims to explore the feasibility of home-based synchronization among physically active older adults using a data-driven approach.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003e The 19 participants were instructed to use a wearable biofeedback device for three weeks that prompts users with an auditory cue to achieve synchronization. We have collected data on the level of synchronization, adherence, quality of life, exercise habits, rhythmic abilities, and physiological baseline and we discuss these results based on interview-based user feedback. Mean and standard deviation were calculated for each parameter of interest. Group comparisons were conducted using t-tests, and paired t-tests were applied for within-group comparisons.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eOur data suggest high feasibility in 58% of participants, as data revealed high-level synchronizers (n\u0026thinsp;=\u0026thinsp;11), and low-level synchronizers (n\u0026thinsp;=\u0026thinsp;8), performing diastolic stepping for 83\u0026thinsp;\u0026plusmn;\u0026thinsp;6% vs. 11\u0026thinsp;\u0026plusmn;\u0026thinsp;9% (p\u0026thinsp;\u0026lt;\u0026thinsp;0.01) of the total usage time. Both physiological and rhythmic factors may play a role in the levels of synchronization achieved. Moreover, a high-level of synchronization is achieved with calmness, focus, and warming up. Additional guidance during learning could help find a synchronization \u0026lsquo;flow\u0026rsquo; and increase levels of synchronization.\u003c/p\u003e\u003ch2\u003eConclusions\u003c/h2\u003e \u003cp\u003eIn conclusion, diastolic stepping is feasible as a self-directed cardiovascular prevention and rehabilitation strategy. Our results inform future research on improving biofeedback devices for prevention in patients at risk of cardiovascular disease, with the goal of improving exercise tolerance, and, in turn, patients\u0026rsquo; quality of life.\u003c/p\u003e","manuscriptTitle":"Device-Guided Diastolic Stepping During Walking among Older Adults: A Home-Based Feasibility Pilot Study","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-03-11 12:00:47","doi":"10.21203/rs.3.rs-6172990/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":"e06f35e2-2e7c-4608-853d-c7b12f2bfe83","owner":[],"postedDate":"March 11th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-03-12T10:39:00+00:00","versionOfRecord":[],"versionCreatedAt":"2025-03-11 12:00:47","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6172990","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6172990","identity":"rs-6172990","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}