About

Wonwoo Byun is a faculty member within the Department of Health & Kinesiology at the University of Utah. His research focuses on understanding and optimizing physical activity patterns and physiological and psychological well-being across all populations. His work encompasses exploring correlations between physical activity and health-related variables, examining the feasibility and effectiveness of physical activity interventions, and investigating the psychological aspects of physical activity, exercise, and sedentary behavior in relation to mental well-being. He is involved in research utilizing state-of-the-art facilities such as the Physical Activity and Well-Being Research Laboratory and the Human Performance Research Laboratory, which are equipped with advanced devices for assessing physical activity, health-related fitness, and exercise physiology. His contributions support the development of evidence-based strategies to improve health outcomes through physical activity and behavioral interventions.

Research topics

• Medicine
• Sociology
• Environmental health
• Gerontology
• Clinical psychology
• Demography
• Social psychology
• Statistics
• Geography
• Internal medicine
• Psychology
• Psychiatry
• Mathematics
• Physical therapy
• Developmental psychology

Selected publications

• Effects of Telerehabilitation on Quality of Life, Physical Capacity, and Symptom Burden within the Post–COVID-19 Condition: A Systematic Review and Meta-Analysis of Randomized Controlled Trials (Preprint)

  2026-03-15

  articleOpen accessSenior author

  <sec> <title>BACKGROUND</title> Telerehabilitation (TR) is an important option for patients with post-COVID-19 condition (PCC). However, current evidence on its effectiveness remains inconsistent, and the impact of different delivery modes is not fully understood. </sec> <sec> <title>OBJECTIVE</title> This study evaluated the effects of telerehabilitation on health-related quality of life (HRQoL), physical capacity, and symptom burden in adults with PCC, and to determine whether delivery mode (synchronous vs. asynchronous) modified these effects. </sec> <sec> <title>METHODS</title> We searched PubMed/MEDLINE, Cochrane Library, Web of Science, Scopus, Embase, EBSCO, and PEDro for randomized controlled trials (RCTs) published from January 2020 to December 2025. The primary outcome was HRQoL; secondary outcomes included functional capacity (6MWT, STS), dyspnea, fatigue, and HADS scores. Risk of bias was assessed using the Cochrane RoB 2 tool. Data were pooled using random-effects models with the Hartung-Knapp-Sidik-Jonkman (HKSJ) adjustment. </sec> <sec> <title>RESULTS</title> Twenty-three RCTs involving 2,320 participants were included. TR resulted in significant improvements in HRQoL (standardized mean difference [SMD] 1.26, 95% CI 0.07 to 2.45; P=.04), dyspnea (SMD 1.95, 95% CI 0.60 to 3.31; P=.005), and functional aerobic capacity (6MWT: mean difference [MD] 77.79 m, 95% CI 30.44 to 125.14; P=.001). Fatigue was also significantly reduced (SMD 0.89 95% CI: 0.16 to 1.62; P=.02), but no significant effects were observed for lower limb strength (STS: SMD 0.55, 95% CI -0.15 to 1.25; P=.12) or mental health outcomes (HADS: SMD 0.12, 95% CI −0.13 to 0.38; P=.36). No significant differences were observed be-tween delivery modes for most outcomes (P&gt;.05), except for lower limb strength, where a significant subgroup difference was noted (P=.02). </sec> <sec> <title>CONCLUSIONS</title> Telerehabilitation is effective for improving quality of life, aerobic capacity, and alleviating persistent symptoms in PCC patients. Asynchronous delivery appears sufficient for general conditioning, while synchronous supervision may be necessary for strength training. </sec> <sec> <title>CLINICALTRIAL</title> PROSPERO CRD42023490863; https://www.crd.york.ac.uk/PROSPERO/view/CRD42023490863 </sec>

  PublisherDOI

• Effectiveness and feasibility of family and peer challenge intervention with wearable technology on physical activity among middle schoolers in Utah: A pilot trial

  Preventive Medicine Reports · 2025-05-02 · 1 citations

  articleOpen accessSenior authorCorresponding

  To examine the preliminary effectiveness and feasibility of physical activity (PA) intervention in middle schoolers. This 6-week, multi-component PA intervention was conducted in Salt Lake City, Utah, between November 2021 and January 2022. The intervention included tracking daily PA using a wearable activity monitor, education on PA and health, weekly motivational videos, and group challenges within family or peer groups. Three classes from one public middle school ( N = 75; 51 % girls, aged 12–13 years) were randomly allocated into the intervention (i.e., family or peer challenges) or control groups. Changes in daily activity time between pre- and post-intervention were assessed using ActiGraph accelerometers. The feasibility of the intervention was evaluated through measures of adherence, retention, and acceptability. After the intervention, 51 (girls: 51 %; age: 13.0 ± 0.7) of all participants completed the entire study protocol. Linear mixed models showed no statistically significant differences between interventions and control in daily sedentary behavior and PA times. Adherence to the intervention was moderately high (> 60 %), with a retention of 68 %. We also observed high satisfaction with wearable technology (≥ 78 %) in middle school students. However, only 39 % of participants frequently used the mobile app for their group challenge. Wearable technology in PA intervention may be of interest to young adolescents but not effectively change youth PA behavior during a 6-week intervention. Further research with larger samples, longer intervention durations, and refined engagement strategies is required to more accurately evaluate the impact and feasibility of this intervention. • A six-week wearable tech intervention targeted middle schoolers' physical activity. • The intervention used goal setting, self-monitoring, and social support. • No significant physical activity difference was found between study groups. • High satisfaction with wearables, but Fitbit app and group challenge use were low.

  PublisherDOI

• Evaluation of Optimal Epoch Lengths for Real-Time Physical Activity Measurement for mHealth Applications: Cross-Sectional Study (Preprint)

  2025-10-31

  articleOpen access1st authorCorresponding

  <sec> <title>BACKGROUND</title> Wearable accelerometers have become integral to mobile health (mHealth) research, particularly for delivering real-time physical activity (PA) monitoring and applications in interventions such as Just-in-Time Adaptive Interventions (JITAIs). One critical yet underexplored factor in real-time PA monitoring is epoch length, which is the time interval over which raw accelerometry data are aggregated to classify activity intensities and levels. Shorter epochs (e.g., 1 second) enhance precision but increase computational and battery demands, while longer epochs (e.g., 60 seconds) reduce data burden but may miss brief activity bouts. Although previous studies have examined epoch effects using post-processed data, limited evidence exists regarding their influence on real-time, wrist-based PA estimates, especially for moderate-to-vigorous PA (MVPA). Identifying an optimal epoch length for real-time PA measurement remains a critical gap in supporting scalable and efficient mHealth interventions. </sec> <sec> <title>OBJECTIVE</title> This study determined the impact of varying epoch lengths on real-time MVPA estimates derived from a wrist-worn accelerometer to identify an optimal epoch that balances measurement accuracy with practical feasibility for mHealth applications. </sec> <sec> <title>METHODS</title> Twenty adults (Age: 32.5 ± 15.1 years) completed a series of carefully selected simulated free-living activities in a controlled laboratory setting. Participants wore the MotionSense HRV wristband, which computed real-time Euclidean Norm Minus One (ENMO) values, and a COSMED K5 indirect calorimetry for metabolic reference. ENMO values were aggregated into 5-, 10-, 15-, 30-, and 60-second epochs. MVPA was classified using validated ENMO cut-points. Epoch-level MVPA estimates were compared against the 1-second reference using mean absolute percent error (MAPE), Pearson’s correlations, Bland-Altman (BA) plots, and equivalence testing with a ±10% equivalence zone. </sec> <sec> <title>RESULTS</title> MVPA estimates from all epoch lengths were statistically equivalent to the 1-second standard. The 15-second epoch demonstrated the best trade-off between accuracy and efficiency, with minimal bias (0.05 min), low MAPE (6.3%), and strong correlation (r = 0.97). However, indicators of individual-level error increased with longer epochs; MAPE increased to 9.5% at 60 seconds, and the limits of agreement widened (from ± 2.9 min at 15s to ± 4.9 min at 60s), suggesting greater potential misclassifications in estimating MVPA with longer epochs. </sec> <sec> <title>CONCLUSIONS</title> Although MVPA estimates using the MotionSense HRV wristband were robust across all epoch lengths, findings from this study suggest that a 15-second epoch provides an optimal balance between measurement precision and processing efficiency, making it well-suited for mHealth interventions, such as JITAIs that rely on timely activity detection. </sec>

  PublisherDOI

• Exploring The Preliminary Effect Of Physical Activity Intervention Through Family And Peer Challenge In Young Adolescents: A Pilot Cluster Randomized Trial

  Medicine & Science in Sports & Exercise · 2024-09-16

  articleSenior author

  PURPOSE: Social support is a key component influencing physical activity (PA) in young adolescents. Given that parents and peers are major supporters of PA during adolescence, social support from parents or peers can be an effective mediator for increasing adolescents' PA levels. This study examined the preliminary effect of a family and peer challenge intervention using wearable technology on sedentary behavior (SED) and moderate-to-vigorous PA (MVPA) in young adolescents. METHODS: The study design was a three-arm cluster randomized controlled trial to assess a 6-week PA intervention targeted young adolescents. Three classes (51 students; 51% girls, 13.0 ± 0.7 years) within a middle school were randomly selected and then randomly allocated into one of the three groups: (a) Control, (b) Family challenge (FC), or (c) Peer challenge (PC). All participants received a Fitbit activity monitor (Inspire 2) and educational resources about the benefits of PA and self-monitoring skills. Participants in the intervention groups (FC and PC) were additionally given access to a group challenge feature within the Fitbit app that is designed to enable them to share their PA progress and provide encouragement to one another within their group. Primary outcomes were daily SED and MVPA time measured by hip-worn accelerometers. Linear mixed models were used to evaluate the intervention effects on daily SED and MVPA over time, adjusting for covariates. RESULTS: No significant intervention effect on daily SED was observed post-intervention (FC: b = - 20.7 min, 95% CI = - 54.5-14.0; PC: b = - 7.1 min, 95% CI = - 39.4-24.6). Participants in the FC and PC groups engaged in more MVPA by 11.4 min/day (95% CI = - 2.5-25.5) and 1.1 min/day (95% CI = - 12.0-14.2) than those in the control group, respectively; however, these differences were not statistically significant. CONCLUSIONS: Family and peer challenge strategies via the wearable device and its accompanying mobile app did not effectively improve young adolescents' PA. However, the intervention effects are still inconclusive due to the small sample size. Further investigations with appropriate statistical power are needed to determine if these changes lead to the statistical significance that can support intervention effectiveness.

  PublisherDOI

• Convergent Validity of Garmin Vivofit Jr. 3 and Fitbit Ace 3 for Monitoring Daily Physical Activity of Children

  Measurement in Physical Education and Exercise Science · 2024-10-23

  articleOpen accessSenior authorCorresponding

  This study aimed to assess the agreement in physical activity (PA) estimates from Garmin Vivofit Jr. 3 (VFJ 3) and Fitbit Ace 3 (Ace 3) with a research-grade accelerometer (wGT3X-BT) in children under free-living conditions. Twenty-five children (Girls: 56%, Age: 10.1 ± 2.5 years, BMI: 17.1 ± 2.4 kg/m²) performed daily activities for 7 consecutive days while wearing VFJ 3, Ace 3, and wGT3X-BT. Pearson correlations, Bland–Altman plots, mean percent error (MPE), mean absolute percent error (MAPE), and equivalence tests were conducted to evaluate the agreement of VFJ 3 and Ace 3 with wGT3X-BT. VFJ 3 and Ace 3 had strong positive correlations (range: <em>r</em> = 0.71 to 0.95) with wGT3X-BT in estimating steps and moderate-to-vigorous PA (MVPA) and provided relatively valid estimates for daily steps. Although Ace 3 had no systematic bias and a low group measurement error (MPE: −10.1%) in estimating MVPA, VFJ 3 consistently overestimated daily MVPA. Collectively, VFJ 3 and Ace 3 can be valid devices to monitor children’s PA levels with daily step counts.<br>

  PublisherOA PDFDOI

• Independent and joint associations of aerobic and muscle-strengthening exercise with mental health in adolescents: A cross-sectional analysis before and during COVID-19 using the 2015–2021 National Youth Risk Behavior Survey

  Preventive Medicine · 2023-11-02 · 6 citations

  article
  PublisherDOI

• The Association of Virtual Exercise Classes and Well-Being During COVID-19 Among University Employees

  International Journal of Physical Activity and Health · 2023-11-06

  articleOpen access

  NEED ABSTRACT

  PublisherOA PDFDOI

• Impact Of Mandatory School Masking On Adolescent Physical Activity During Structured And Unstructured Days

  Medicine & Science in Sports & Exercise · 2023-09-01

  article

  PURPOSE: Structured settings, specifically during school, have been crucial to promote physical activity (PA) in adolescents. During the COVID-19 pandemic in 2021 and early 2022, students in a US school district in the mountain west were required to wear a mask during school hours. Little is known how mandatory masking and other COVID-19 constraints impacted adolescents’ PA levels during and after school hours. The primary purpose of this study was to compare the PA of adolescents during weekdays, weekends, and winter break during COVID-19 during a period of mandatory school masking. The secondary aim was to examine the sex differences among the study variables. METHODS: Participants were 56 middle school students (M age = 13.1; 51% female) recruited from one US middle school. Students completed a baseline survey prior to being provided Fitbit Inspire 2 using Fitabase (Small Steps Labs LLC., San Diego, CA) to monitor PA. Students were asked to wear the Fitbit Inspire 2 for six weeks from the end of 2021 to the beginning of 2022. Weeks 3-4 were winter break and Weeks 1-2 and 5-6 were school weeks. Daily moderate-to-vigorous PA (MVPA) and daily step counts were collected from the Fitbits. Descriptive statistics including means and standard deviations for MVPA and steps were calculated. Multiple regression models were used to compare PA levels between the structured and unstructured days including winter break vs school weeks and weekday vs weekend, respectively. RESULTS: Despite the mandatory school masking protocols, students accumulated 765.7 more steps (p < 0.01) and 6.3 more MVPA minutes (p = 0.0725) per day during regular school days compared to winter break. Students also accumulated 779.5 more steps (p < 0.01) and accumulated 12.3 more MVPA minutes (p < 0.01) per day during weekdays compared to weekend days. Sex differences were also significant in that boys are more active than girls for both steps (β = 1439.3, p < 0.01) and MVPA (β = 34.1, p < 0.01) over 6 weeks. CONCLUSIONS: Despite mandatory school masking, students had higher levels of MVPA and steps during structured days (weekdays and school weeks) compared to unstructured days (weekends and winter break), supporting the importance of structured days for maintaining the recommended levels of PA. Boys were more active than girls throughout the duration of the study.

  PublisherDOI

• Associations of Monitor-Independent Movement Summary and Health-Related Fitness With Gross Motor Skills in Young Children

  Journal of Motor Learning and Development · 2023-07-13 · 2 citations

  articleOpen accessSenior author

  The purpose of this study was to determine the associations of device-based assessments of physical activity (PA) and health-related fitness (HRF) with gross motor skills (GMS) in preschool-aged children. Participants were 3- to 5-year-old children ( N = 316; 49.6% female) who participated in the 2012 National Youth Fitness Survey. GMS was assessed using the gross motor quotient calculated from the Test for Gross Motor Development—Second Edition. PA was assessed using wrist-worn ActiGraph GT3X accelerometers with raw triaxial acceleration data summarized using monitor-independent movement summary units (MIMS). Analyzed metrics included average MIMS per day and peak 30-min MIMS. HRF assessment consisted of a plank score and a sum of skinfold assessment. Weighted hierarchical regressions tested the associations between PA, HRF, and GMS variables with a secondary weighted mediation analysis that examined whether HRF mediated the association between PA and GMS. Peak 30-min MIMS significantly correlated with GMS ( b = 0.17, p = .005). Plank scores had the strongest correlation with GMS ( b = 0.23, p = .004), and weighted mediation analyses revealed that plank scores partially mediated the association between peak 30-min MIMS and GMS (indirect effect = 0.03, p = .01, 23.1% mediation). Peak 30-min MIMS significantly associated with GMS in preschool children, an association partially mediated by core muscular endurance.

  PublisherOA PDFDOI

• <scp>Dose–response</scp> associations of M<scp>onitor‐Independent</scp> Movement Summary with <scp>health‐related</scp> fitness in youth

  Scandinavian Journal of Medicine and Science in Sports · 2023-07-05 · 4 citations

  article

  Abstract The purpose of this study was to determine the dose–response associations between Monitor‐Independent Movement Summary (MIMS) units and health‐related fitness in youth. The sample comprised US children and adolescents who participated in the 2012 National Youth Fitness Survey (NNYFS; N = 1158, 48.9% female). Health‐related fitness domains were assessed using tests of cardiorespiratory endurance (timed maximal and graded treadmill tests), muscular strength (modified pull‐up and grip tests), and muscular endurance (plank test). Movement data were collected using wrist‐worn ActiGraph accelerometers with raw data processed using MIMS and the calculated metrics of average MIMS/day, Peak 60‐min MIMS, and Peak 30‐min MIMS. Weighted regression models examined linear associations between MIMS metrics and fitness test scores. Nonlinear associations were examined using weighted spline models with knots placed at the 10th, 50th, and 90th percentiles. Models were adjusted for covariates and fit was examined using the coefficient of determination ( R 2 ). The strongest adjusted linear relationships included a positive association between MIMS/day (per every 1000 units) and maximal endurance times ( b = 5.5 s, p &lt; 0.001) and between Peak 60‐min MIMS (per every 10 units) and estimated aerobic capacity ( b = 1.7 mL/kg/min, p &lt; 0.001), modified pull‐ups ( b = 0.7 reps, p &lt; 0.001), and plank test scores ( b = 5.0 s, p &lt; 0.001). Linear spline models had slightly higher R 2 values ( R 2 range = 16.9%–74.8%) compared to linear models ( R 2 range = 15.0%–74.5%). The relationship between MIMS metrics and fitness test scores was best modeled as piecewise linear functions. Although all MIMS metrics associated with cardiorespiratory endurance, Peak 60‐min MIMS showed stronger associations with tests of muscular strength and endurance.

  PublisherDOI

Frequent coauthors

• Leonard A. Kaminsky

  Ball State University

  31 shared

• Cemal Ozemek

  University of Illinois Urbana-Champaign

  31 shared

• Katrina Riggin

  A.P. Karpinsky Russian Geological Research Institute

  30 shared

• Scott J. Strath

  University of Wisconsin–Milwaukee

  29 shared

• Ryan D. Burns

  University of Utah

  28 shared

• Youngwon Kim

  University of Cambridge

  25 shared

• Timothy A. Brusseau

  University of Utah

  22 shared

• Yang Bai

  21 shared

Labs

• Physical Activity and Well-Being Research ThemePI