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

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Title: Convergent Validity of Garmin Vivofit Jr. 3 and Fitbit Ace 3 for Monitoring Daily Physical Activity of Children
Language: English
Authors: Sunku Kwon, Yang Bai, Youngwon Kim, Ryan D. Burns, Timothy A. Brusseau, Wonwoo Byun
Source: Measurement in Physical Education and Exercise Science. 2025 29(2):133-144.
Availability: Routledge. Available from: Taylor & Francis, Ltd. 530 Walnut Street Suite 850, Philadelphia, PA 19106. Tel: 800-354-1420; Tel: 215-625-8900; Fax: 215-207-0050; Web site: http://www.tandf.co.uk/journals
Peer Reviewed: Y
Page Count: 12
Publication Date: 2025
Document Type: Journal Articles
Reports - Research
Descriptors: Physical Activity Level, Children, Validity, Handheld Devices, Health Behavior, Merchandise Information, Biofeedback
DOI: 10.1080/1091367X.2024.2417793
ISSN: 1091-367X
1532-7841
Abstract: 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: r = 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.
Abstractor: As Provided
Entry Date: 2025
Accession Number: EJ1468513
Database: ERIC
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  Value: <anid>AN0184594844;7mm01apr.25;2025Apr22.02:30;v2.2.500</anid> <title id="AN0184594844-1">Convergent Validity of Garmin Vivofit Jr. 3 and Fitbit Ace 3 for Monitoring Daily Physical Activity of Children </title> <p>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/m<sup>2</sup>) 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: r = 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.</p> <p>Keywords: daily steps; moderate-to-vigorous physical activity; Garmin Vivofit Jr. 3; Fitbit Ace 3; children</p> <hd id="AN0184594844-2">Introduction</hd> <p>Regular participation in moderate-to-vigorous physical activity (MVPA) leads to physical and mental health benefits in children and lowers the risk of childhood obesity, which is connected to metabolic disorders in adulthood (U.S. Department of Health and Human Services, [<reflink idref="bib56" id="ref1">56</reflink>]). Self-monitoring of daily physical activity levels has been emphasized to promote a physically active lifestyle in children (Lee & Shiroma, [<reflink idref="bib33" id="ref2">33</reflink>]; Rowlands & Eston, [<reflink idref="bib46" id="ref3">46</reflink>]). Accelerometry-based wearable devices allow the objective assessment of habitual physical activity in children. Such devices record accelerations from bodily movement to quantify the activity intensity and frequency in daily life (Yang & Hsu, [<reflink idref="bib64" id="ref4">64</reflink>]). Given children's limited ability to recall their habitual activities (Hussey et al., [<reflink idref="bib26" id="ref5">26</reflink>]; Lee et al., [<reflink idref="bib34" id="ref6">34</reflink>]; Welk et al., [<reflink idref="bib61" id="ref7">61</reflink>]), it is necessary to widely adopt accelerometry-based wearable devices as a device-based self-monitoring tool for children's PA in research and clinical settings (Bai et al., [<reflink idref="bib4" id="ref8">4</reflink>]; Kwon, Kim, et al., [<reflink idref="bib30" id="ref9">30</reflink>]).</p> <p>With advances in technology over the past decades, there has been a growing number of wearable activity monitors (WAM), offering appealing solutions for self-monitoring of daily PA. The currently available WAMs are comfortable to wear, simple to use, and equipped with various sensors (i.e., triaxial accelerometer, heart-rate monitor, gyroscope, etc.) (Evenson et al., [<reflink idref="bib15" id="ref10">15</reflink>]). The most WAMs compute various PA metrics (e.g., step counts, activity intensity and frequency, and energy expenditure) using their proprietary algorithms, allowing users to constantly monitor their PA levels without complex analysis. Also, the users get feedback against individualized set goals in real-time via a visual display or an accompanying mobile app (Hoy, [<reflink idref="bib25" id="ref11">25</reflink>]). Such features of WAMs provide the main components of behavioral change techniques, including self-monitoring, goal setting, and feedback (Duncan et al., [<reflink idref="bib13" id="ref12">13</reflink>]; Lyons et al., [<reflink idref="bib36" id="ref13">36</reflink>]).</p> <p>Given the potential uses and application for WAMs in measuring children's PA, leading manufacturers, such as Garmin and Fitbit, have recently developed WAMs for children, which are specifically designed to help children become more physically active in a more enjoyable manner. In general, the WAMs for children focus on the accumulated daily activity and do not provide the data that can affect children's self-esteem, such as calories burned (Evenson et al., [<reflink idref="bib15" id="ref14">15</reflink>]; Shin et al., [<reflink idref="bib49" id="ref15">49</reflink>]). Through the intuitive and kids-friendly graphics for steps taken, active minutes, and goal achievement, children can easily track their PA levels in real-time. Also, the WAMs for children can help motivate children to engage in more physical activity via kids-friendly animation and reward features. For example, Fitbit Ace 3 and Garmin Vivofit Jr. 3 display PA levels toward a daily goal via motivational animations, such as a rocket ship flying across the screen, and award virtual badges or coins when children accomplish the daily goal. These characteristics of WAMs for children are shown to be very age-appropriate and effective in encouraging MVPA participation in children (Bianchi-Hayes et al., [<reflink idref="bib6" id="ref16">6</reflink>]; Gaudet et al., [<reflink idref="bib19" id="ref17">19</reflink>]).</p> <p>To date, Garmin Vivofit Jr. 3 and Fitbit Ace 3 are the top-rated WAMs for children on the wearable market. As such, both devices have the opportunity to be adopted in research as a scalable method for monitoring children's PA levels and delivering behavior change techniques. However, there is little to support the idea that these devices provide valid estimates of MVPA and step counts in children under free-living conditions. To the best of our knowledge, only one empirical research investigated the convergent validity of the WAM for children in estimating steps in children for a short period under a controlled setting (Sun et al., [<reflink idref="bib52" id="ref18">52</reflink>]); thus, the validity of the WAMs, specific to children, in estimating daily steps and MVPA in free-living conditions remains unknown. Given that WAMs for children are convenient and affordable and can play a key role in youth PA promotion programs (Casado-Robles et al., [<reflink idref="bib9" id="ref19">9</reflink>]), there is a need to support if daily steps and MVPA estimates of WAMs for children are at least valid to identify meeting the PA recommendations. Therefore, the purpose of this study was to examine the agreement of the Garmin VivoFit Jr. 3 and Fitbit Ace 3 in estimating the daily steps and MVPA time of children in a free-living condition.</p> <hd id="AN0184594844-3">Materials and methods</hd> <p></p> <hd id="AN0184594844-4">Design</hd> <p>The current study was designed as a cross-sectional study to evaluate the convergent validity of two commercially available WAMs for children in a free-living condition. Participants wore the two WAMs for children, Garmin Vivofit Jr. 3 and Fribit Ace 3, and a research-grade accelerometer simultaneously during waking hours and conducted their daily activities for 7 consecutive days. Afterward, the estimated daily MVPA and step counts from the Garmin Vivofit Jr. 3 and Fribit Ace 3 were concurrently compared to the measures from a research-grade accelerometer, wGT3X-BT. All procedures were in accordance with the ethical standards of the institutional review board at the University of Utah.</p> <hd id="AN0184594844-5">Participants</hd> <p>A convenient sample of 25 children, aged 7–13 years, were recruited via word of mouth, e-mail, and posted flyers. Participants who were able to (<reflink idref="bib1" id="ref20">1</reflink>) participate in regular PA without any functional impairment, (<reflink idref="bib2" id="ref21">2</reflink>) use a smartphone, and (<reflink idref="bib3" id="ref22">3</reflink>) communicate in English (speak, read, and write) were eligible to participate in this study. The current study excluded children who are (<reflink idref="bib1" id="ref23">1</reflink>) physically disabled, (<reflink idref="bib2" id="ref24">2</reflink>) unable to engage in regular PA, (<reflink idref="bib3" id="ref25">3</reflink>) physically unable to wear activity monitors and use a smartphone, or (<reflink idref="bib4" id="ref26">4</reflink>) have any unstable medical or psychiatric problems. All participants of the study provided consent to participate in the study protocol.</p> <hd id="AN0184594844-6">Instruments</hd> <p>Two most recent models of WAMs designed for children, including Garmin Vivofit Jr. 3 (VFJ 3; Garmin, Olathe, KS) and Fitbit Ace 3 (Ace 3; Fitbit, Inc., San Francisco, CA) were tested for their convergent validity against an ActiGraph GT3X+ accelerometer, which is the criterion measure. Both VFJ 3 and Ace 3 are wrist-band type wearable devices with a large organic light-emitting diode display (VFJ 3: 14.11 × 14.11 mm; Ace 3: 1.74") and use their built-in 3-axis accelerometer to track steps and estimate MVPA time (i.e., active minutes) in real-time. These devices are swim-proof (up to 50 m) and have a long battery life (VFJ 3: up to 1 year and Ace 3: up to 8 days).</p> <p>Moreover, VFJ 3 and Ace 3 continually acquire and store the detailed activity tracking data for 7 days and 14 days, respectively. Both devices can be connected to a mobile phone via Bluetooth technology to sync the obtained data with the accompanying Android and iOS mobile apps. With the built-in display and mobile app, children track the estimated PA metrics (i.e., steps and active minutes) and their progress toward activity goals in real-time. Data output on the mobile apps reflects daily MVPA time and steps, which does not include minute-by-minute data.</p> <p>In relation to data scoring, the step counts are directly recorded in their accompanying mobile apps. However, the manufacturers do not disclose the precise details of the algorithms employed to compute the MVPA minutes. Thus, in accordance with the assumptions made by previous studies (Mayorga-Vega et al., [<reflink idref="bib37" id="ref27">37</reflink>]; Schmidt et al., [<reflink idref="bib48" id="ref28">48</reflink>]; Viciana et al., [<reflink idref="bib58" id="ref29">58</reflink>]), the current study estimated MVPA minutes as follows: In the case of Garmin Vivofit Jr. 3 and Fitbit Ace 3, the term "minutes of activity" was employed to represent MVPA minutes.</p> <hd id="AN0184594844-7">Accelerometer</hd> <p>The current study used the ActiGraph wGT3X-BT accelerometer (wGT3X-BT; ActiGraph Corp., Pensacola, FL) as a reference standard. The wGT3X-BT records raw accelerations in the 3-axis at a user-specified sampling rate (30–100 hz) and provides various PA metrics, including activity intensities, energy expenditure, and steps taken, at a user-selected epoch length (1–60 sec) and detects wear-time via previously validated algorithms (Arguello et al., [<reflink idref="bib3" id="ref30">3</reflink>]; Hibbing et al., [<reflink idref="bib23" id="ref31">23</reflink>]; Valkenet et al., [<reflink idref="bib57" id="ref32">57</reflink>]). ActiGraph accelerometers have provided valid estimates of PA intensities and steps taken compared to indirect calorimetry and direct observation, respectively (Bai et al., [<reflink idref="bib5" id="ref33">5</reflink>]; Imboden et al., [<reflink idref="bib27" id="ref34">27</reflink>]). Thus, wGT3X-BT has been widely accepted for assessing children's PA (Aadland et al., [<reflink idref="bib1" id="ref35">1</reflink>]; DeriRodriguez-Ayllon et al., [<reflink idref="bib11" id="ref36">11</reflink>]; Kwon, Letuchy, et al., [<reflink idref="bib31" id="ref37">31</reflink>]) and used as a reference standard (step counts and MVPA time) to assess the validity of commercially available activity monitors in free-living conditions (Kim & Lochbaum, [<reflink idref="bib29" id="ref38">29</reflink>]; Mayorga-Vega et al., [<reflink idref="bib37" id="ref39">37</reflink>]; Redenius et al., [<reflink idref="bib43" id="ref40">43</reflink>]; Yang et al., [<reflink idref="bib65" id="ref41">65</reflink>]). In this study, we set the sampling rate of the accelerometers to 100 hz and downloaded the data from the device to assess MVPA time and steps using the ActiLife 6 software (version: v6.13.3). Also, the low-frequency extension (LFE) filter was disabled to prevent overestimating actual steps and time engaged in MVPA (Feito et al., [<reflink idref="bib16" id="ref42">16</reflink>]; Filanowski et al., [<reflink idref="bib18" id="ref43">18</reflink>]). All devices will be synchronized with the computer clock.</p> <hd id="AN0184594844-8">Procedures</hd> <p>The anthropometric characteristics of each participant were measured using a stadiometer (ShorrBoard®, Olney, MD) for height (cm), an electric body-scale (Seca 869, Hamburg, Germany) for weight (kg), and a tape measure (Baseline® Evaluation Instruments, White Plains, NY) for waist circumference. For the anthropometric measure, participants were asked to wear minimal clothing and take off their shoes. The body mass index (BMI) percentile was calculated based on the children's age and measured height and weight. The research staff measured all the anthropometric characteristics three times to avoid measurement errors.</p> <p>Following the anthropometric measures, participants were instructed on how to simultaneously wear three devices (i.e., Ace 3, VFJ 3, and wGT3X-BT) on their wrists and waist for seven consecutive days. The placement of the VFJ 3 and Ace 3 on the wrist was randomized in this study. For example, the Ace 3 was on the left wrist if the VFJ 3 was placed on the right. Also, children wore both on a finger's width above their wrist bone (i.e., styloid process of ulna) following the manufacturer's recommendations. Also, we set up family accounts of Ace 3 and VFJ for each participant. Then, Ace 3 and VFJ 3 were connected with their accompanying mobile apps. Participants wore Ace 3 and VFJ 3 on the dorsal aspect of the right or left wrist in compliance with the manufacturer's recommendation. The wGT3X-BT was fitted on the participant's dominant hip using a manufacturer-provided belt. The wGT3X-BT device was secured medial to the anterior supra-iliac crest (Rhudy et al., [<reflink idref="bib44" id="ref44">44</reflink>]). Participants were asked to wear all devices for the next 7 days during all waking hours except while charging the Ace 3 or performing aquatic activities (e.g., bathing or swimming). In order to ensure consistency in the total wear time between devices, participants were instructed to remove all three devices if they needed to take off any device. In addition, we asked participants and their parents to record non-wear time during waking hours (e.g., charging device or swimming) and sleep times on the daily activity/sleep log. At the end of the data collection period, data from activity/sleep logs, activity monitors for children, and the ActiGraph accelerometer were retrieved and downloaded, respectively.</p> <hd id="AN0184594844-9">Data reduction process</hd> <p>Data from VFJ 3 and Ace 3 were synced to the Fitbit and Garmin mobile apps. Then, we obtained the recorded estimates of daily MVPA time and step counts directly from the mobile apps. Further, data from the wGT3X-BT was downloaded as activity counts and steps taken per 15-sec epoch using the ActiLife 6 software for further analysis. We calculated MVPA minutes by applying the cut-points specifically developed for children. In accordance with the cut-points for children, MVPA was defined as ≥2296 counts per minute (Evenson et al., [<reflink idref="bib14" id="ref45">14</reflink>]). The non-wear of the wGT3X-BT was excluded using a wear-time validation algorithm developed by Choi et al., which defines the non-wear time as 90 consecutive minutes of zero counts (Choi et al., [<reflink idref="bib10" id="ref46">10</reflink>]). Additionally, Chio's algorithm regards up to 2-min non-zero counts within 30-min windows of zero counts as artifactual movements of the accelerometer under non-wear periods (Choi et al., [<reflink idref="bib10" id="ref47">10</reflink>]). Non-wear time due to sleep and aquatic activities was also removed according to the self-reported sleep/activity log. Finally, the processed wGT3X-BT data were aggregated to calculate the average for each day. These averages were then merged and aligned with the data from WAMs for children for statistical analyses.</p> <hd id="AN0184594844-10">Statistical analysis</hd> <p>Descriptive analyses were conducted to summarize the demographic and anthropometric characteristics of the participants. The normality of the demographic and anthropometric characteristics was confirmed using the Shapiro–Wilk test. Pearson product-moment correlation was used to evaluate the correlation for daily steps and MVPA estimates between the wGT3X-BT and the VFJ 3 or Ace 3. Also, the current study systematically evaluated the agreement of activity monitors for children with reference standards at the group and individual levels via Bland–Altman plot, Equivalence testing, Mean percent error, and Mean absolute percent errors (Hopkins et al., [<reflink idref="bib24" id="ref48">24</reflink>]; Staudenmayer et al., [<reflink idref="bib51" id="ref49">51</reflink>]; Zaki et al., [<reflink idref="bib66" id="ref50">66</reflink>]).</p> <p>Bland–Altman plot was used to describe the agreement between the activity monitors and research-grade accelerometers (Bland & Altman, [<reflink idref="bib7" id="ref51">7</reflink>]). The Bland-Altman plot evaluates a bias between the two quantitative measurements and estimates an agreement interval, within which 95% of the mean bias of the second measurement, compared to the first one, falls. The confidence interval (CI) evaluates how precise the estimates from activity monitors are (Giavarina, [<reflink idref="bib20" id="ref52">20</reflink>]). The 95% CI of the mean bias showed the magnitude of the systematic difference (Giavarina, [<reflink idref="bib20" id="ref53">20</reflink>]).</p> <p>Equivalence tests were performed to assess the agreement between the ActiGraph accelerometers and WAMs for children at the group level (Dixon et al., [<reflink idref="bib12" id="ref54">12</reflink>]; Lakens, [<reflink idref="bib32" id="ref55">32</reflink>]). Typically, the equivalency between the reference standard and PA monitors is determined if the 90% confidence intervals (CI) of the estimates from the PA monitors completely fall within a prespecified (e.g., ±10%) equivalence zone (EZ) from the reference standards (Lakens, [<reflink idref="bib32" id="ref56">32</reflink>]; Welk et al., [<reflink idref="bib60" id="ref57">60</reflink>]). Given the absence of universally accepted EZ for the WAMs designed for children, the current study calculated the actual bounds of the reference standard that include the 90% CI of the estimates from VFJ 3 and Ace 3.</p> <p>Evaluating measurement errors at the individual level is an essential consideration because consumer-based activity monitors are almost always aimed at individual applications (Welk et al., [<reflink idref="bib60" id="ref58">60</reflink>]). The equivalence test can be accurate for assessing group-level estimations but relies on arbitrary thresholds of statistical significance and lacks the precision to assess the accuracy of activity monitors at the individual level. In this regard, mean absolute percent error (MAPE) was used to calculate the measurement errors at the individual level of Ace 3 and VFJ 3 compared to reference standards. All data analyses were conducted using STATA 17 software (Stata Corp LLC, College Station, TX, USA). Statistical significance was set at <emph>p</emph> <.05.</p> <hd id="AN0184594844-11">Results</hd> <p></p> <hd id="AN0184594844-12">Demographic and anthropometric characteristics</hd> <p>A total of 25 children (age: 10.1 ± 2.5 years) participated in the current study (Table 1). Their body mass index (BMI; 17.1 ± 2.4 kg/m2) and the corresponding BMI-for-age percentile (52.3 ± 29.9%) showed that participants fell within a normal, healthy weight on average. Moreover, there were no significant differences between the boys and girls in all observed characteristics (<emph>p</emph> ≥.05). The results of the Shapiro–Wilk test showed that the demographic and anthropometric characteristics of participants were normally distributed (<emph>p</emph> >.05), except for the BMI-for-age percentile (<emph>p</emph> <.05). Based on the BMI-for-age percentile, however, 85% of the participants had healthy body weight, and there were no obese children among the participants.</p> <p>Table 1. Anthropometric characteristics of participants, mean ± standard deviation.</p> <p> <ephtml> <table><thead><tr><td>Characteristics</td><td>Total (<italic>N</italic> = 25)</td><td>Boys (<italic>N</italic> = 11)</td><td>Girls (<italic>N</italic> = 14)</td><td><italic>p</italic>-value*</td></tr></thead><tbody><tr><td>Age (years)</td><td>10.1 ± 2.5</td><td>10.9 ± 2.3</td><td>9.4 ± 2.7</td><td>.15</td></tr><tr><td>Height (cm)</td><td>142.1 ± 14.0</td><td>148.3 ± 14.3</td><td>137.2 ± 12.2</td><td>.05</td></tr><tr><td>Weight (kg)</td><td>35.6 ± 11.1</td><td>40.3 ± 9.8</td><td>31.9 ± 10.9</td><td>.07</td></tr><tr><td>Waist circumference (cm)</td><td>66.5 ± 9.2</td><td>70.1 ± 6.9</td><td>63.7 ± 10.0</td><td>.08</td></tr><tr><td>Body Mass Index (kg/m<sup>2</sup>)</td><td>17.1 ± 2.4</td><td>18.0 ± 1.8</td><td>16.4 ± 2.6</td><td>.10</td></tr><tr><td>BMI percentile (%)</td><td>52.3 ± 29.9</td><td>63.9 ± 28.0</td><td>43.1 ± 29.1</td><td>.08</td></tr><tr><td>Valid days</td><td>6.9 ± 1.3</td><td>7.0 ± 1.2</td><td>6.8 ± 1.4</td><td>.69</td></tr><tr><td>Daily wear time (min)</td><td>657.1 ± 109.9</td><td>694.1 ± 84.6</td><td>628.0 ± 121.3</td><td>.14</td></tr></tbody></table> </ephtml> </p> <p>1 <emph>Note:</emph> BMI: body mass index; *<emph>p</emph>-value for gender difference.</p> <hd id="AN0184594844-13">Step counts</hd> <p>Descriptive statistics (mean ± standard deviation), limits of agreement, MAPE, MPE, and correlation for each device are summarized in Table 2. Pearson-product correlation coefficients showed that both activity monitors for children had strong positive correlations with the reference standard (VFJ 3: <emph>r</emph> = 0.90, <emph>p</emph> <.01; Ace 3: <emph>r</emph> = 0.95, <emph>p</emph> <.01). MPE values showed that the VFJ 3 and Ace 3 overestimated step counts at the group level by 12.4% and 20.3%, respectively. The magnitudes of measurement error in both devices at individual-level were presented by MAPE values. The VFJ 3 had less than 20% MAPE (14.8%) compared to the reference standard in a free-living condition, whereas the MAPE of the Ace 3 was close to 20% (20.3%).</p> <p>Table 2. Mean difference, levels of agreement, and mean absolute percentage errors of the step counts estimated by activity monitors for children compared to the accelerometer in the free-living condition.</p> <p> <ephtml> <table><thead><tr><td>Device</td><td>N</td><td>Accelerometer</td><td>Activity monitors</td><td>Diff. ± SD</td><td>Lower LOA</td><td>Upper LOA</td><td>MAPE (%)</td><td>MPE (%)</td><td>Cor.</td></tr><tr><td>Mean ± SD</td><td>Mean ± SD</td></tr></thead><tbody><tr><td>Garmin FVJ 3</td><td>25</td><td>8326.2 ± 2469.8</td><td>9089.8 ± 2061.3</td><td>−763.6 ± 1090.3</td><td>−2900.0</td><td>1416.9</td><td>14.8</td><td>−12.4</td><td>0.90**</td></tr><tr><td>Fitbit Ace 3</td><td>21</td><td>8634.0 ± 2461.8</td><td>10318.6 ± 2952.0</td><td>−1684.6 ± 1015.3</td><td>−3700.0</td><td>346.0</td><td>20.3</td><td>−20.3</td><td>0.95**</td></tr></tbody></table> </ephtml> </p> <p>2 <emph>Note:</emph> SD: Standard Deviation; Diff.: Mean Difference; LOA: Limit of Agreement; MAPE: Mean Absolute Percent Error; MPE: Mean Percent Error; Cor.: Correlation; **: Correlation is significant at an α level of 0.01.</p> <p>Bland–Altman (BA) plots comparing the wGT3X-BT to VFJ 3 and Ace 3 are illustrated in Figure 1. The mean bias of the VFJ 3 (–763.6 steps/day) was smaller than that of the Ace 3 (–1684.6 steps/day). Also, the 95% CI of the mean bias in VFJ 3 (–1213.7 to −313.6 steps/day) and Ace 3 (–2146.7 to −1222.4 steps/day) did not include the line of equality (i.e., Criterion – Device = 0). These results showed that both devices had a systematic bias, which significantly overestimated the daily step counts compared to the hip-worn accelerometer in a free-living condition. In addition, VFJ 3 had a slightly wider 95% limits of agreement (–2900.0 to 1416.9 steps/day) than the values for Ace 3 (–3700.0 to 346.0 steps/day).</p> <p>Graph: Figure 1. Bland–Altman plots for comparing step counts between the reference standard (i.e., wGt3X-BT) and WAMs for children (i.e., Garmin VivoFit Jr. 3 and Fitbit Ace 3). Red solid line shows the line of equality. Gray solid line and blue short-dashed lines indicate mean bias and 95% confidence interval of the mean bias, respectively. Gray dashed lines show 95% limits of agreement (±1.96 standard deviation).</p> <p>The results of equivalence tests for daily step counts are demonstrated in Table 3 and Figure 2. The 90% confidence intervals (CI) calculated from the VFJ 3 (8384.5 to 9795.2 steps/day) and Ace 3 (9207.6 to 11,429.6 steps/day) did not fall within the ±10% equivalence zone (EZ; 7493.6 to 9158.8 steps/day) of the hip worn accelerometer (Figure 3.2). The actual EZs of the wGT3X-BT, which included the 90% CI of the estimates from activity monitors for children, were established at ±17.7% (6852.5 to 9799.9 steps/day) for VFJ 3 and at ±37.3% (5220.5 to 11,431.9 steps/day) for Ace 3.</p> <p>Graph: Figure 2. Equivalence testing for step counts between the accelerometer and activity monitors for children. Gray vertical solid lines indicate the ±10% equivalence zone (EZ) from the wGt3X-BT. Dark horizontal solid lines show the 90% confidence interval of estimated step counts from activity monitors. Vertical dashed lines indicate the actual bounds within which the Garmin VFJ 3 and Fitbit Ace 3 are statistically equivalent to the wGt3X-BT for step counts (orange dashed lines: ±17.7% EZ; blue dashed lines: ±37.1% EZ).</p> <p>Table 3. 90% confidence intervals of step counts estimated from the wearable activity monitors for children and equivalence zones of the step counts from the hip worn GT3X+.</p> <p> <ephtml> <table><thead><tr><td>Device</td><td>SC estimates ± SE</td><td>90% CI of WAMs</td><td>EZ of GT3X+</td><td>EZ (%)</td></tr></thead><tbody><tr><td>Garmin VFJ 3</td><td>9089.8 ± 412.3</td><td>8384.5 to 9795.2</td><td>6852.5 to 9799.9</td><td>17.7%</td></tr><tr><td>Fitbit Ace 3</td><td>10318.6 ± 644.2</td><td>9207.6 to 11,459.6</td><td>5220.5 to 11,431.9</td><td>37.3%</td></tr></tbody></table> </ephtml> </p> <p>3 <emph>Note:</emph> SC: step counts; SE: standard error; CI: confidence interval; WAMs: wearable activity monitors; EZ: equivalence zone.</p> <hd id="AN0184594844-14">Moderate-to-vigorous physical activity (MVPA)</hd> <p>Table 4 shows the descriptive statistics of MVPA estimates from two WAMs, correlations, and measurement errors (i.e., MAPE and MPE). Pearson correlation showed a strong correlation for MVPA estimates (<emph>r</emph> = 0.71, <emph>p</emph> <.01) between the VFJ 3 and wGT3X-BT in a free-living condition. We also observed a strong positive correlation between the Ace 3 and reference standards in estimating the daily MVPA of children (<emph>r</emph> = 0.82, <emph>p</emph> <.01). The MPEs of daily MVPA estimates from the VFJ 3 and Ace 3 were −126.0% and −10.1%, respectively. The results indicate that both devices overestimated daily MVPA time in children, and the Ace 3 had less measurement error than VFJ 3 at the group level. Also, the observed MAPE values demonstrated that the measurement errors of VFJ 3 and Ace 3 in estimating daily MVPA time were 127.0% and 31.2%, respectively, at the individual-level.</p> <p>Table 4. Mean difference, levels of agreement, and mean absolute percentage errors of the MVPA estimated by activity monitors for children compared to the accelerometer in the free-living condition.</p> <p> <ephtml> <table><thead><tr><td>Device</td><td>N</td><td>Accelerometer (Evenson)</td><td>Activity monitors</td><td>Diff. ± SD</td><td>Lower LOA</td><td>Upper LOA</td><td>MAPE (%)</td><td>MPE (%)</td><td>Cor.</td></tr><tr><td>Mean ± SD</td><td>Mean ± SD</td></tr></thead><tbody><tr><td>Garmin FVJ 3</td><td>25</td><td>45.4 ± 25.6</td><td>82.7 ± 19.8</td><td>−37.3 ± 19.8</td><td>−73.6</td><td>−0.9</td><td>127.0</td><td>−126.0</td><td>0.71**</td></tr><tr><td>Fitbit Ace 3</td><td>21</td><td>48.9 ± 26.2</td><td>52.3 ± 30.7</td><td>−3.4 ± 17.8</td><td>−39.0</td><td>32.2</td><td>31.2</td><td>−10.1</td><td>0.82**</td></tr></tbody></table> </ephtml> </p> <p>4 <emph>Note:</emph> SD: Standard Deviation; MVPA: Moderate-to-Vigorous Physical Activity; Diff.: Mean Difference; LOA: Limit of Agreement; MAPE: Mean Absolute Percent Error; MPE: Mean Percent Error; Cor.: Correlation; **: Correlation is significant at an α level of 0.01.</p> <p>BA plots displaying the agreements between the WAMs for children and wGT3X-BT for MVPA estimates are shown in Figure 3. The upper limit of agreement between the wGT3X-BT and VFJ 3 was less than zero, and the 95% CI of the mean bias did not include the line of equality. Thus, we found that the VFJ 3 constantly overestimated MVPA of children compared to the reference standard in a free-living condition, indicating that there was a significant systematic bias for agreement in MVPA between the wGT3X-BT and VFJ 3. On the contrary, the 95% CI of the mean bias in Ace 3 included the line of equality, indicating no apparent systemic bias for agreement between Ace 3 and wGT3X-BT in estimating children's MVPA. Further, the VFJ 3 had slightly wider limits of agreement (–73.6 to −0.9 min/day) than Ace 3 (–39.0 to 32.2 min/day) in estimating MVPA in children.</p> <p>Graph: Figure 3. Bland–Altman plots for comparing moderate-to-vigorous physical activity (MVPA) between the reference standard (i.e., wGt3X-BT) and WAMs for children (i.e., Garmin VivoFit Jr. 3 and Fitbit Ace 3). Red solid line shows the line of equality. Gray solid line and blue short-dashed lines indicate mean bias and 95% confidence interval of the mean bias, respectively. Gray dashed lines show 95% limits of agreement (±1.96 standard deviation).</p> <p>The results of the equivalence tests for daily MVPA time are illustrated in Table 5 and Figure 4. The 90% CI of the MVPA estimates from the Ace 3 (40.7 to 63.9 min) fell within ±40.7% EZ (26.9 to 63.9 min) of the wGT3X-BT. In addition, the 90% CI of the mean estimate in the VFJ 3 (75.9 to 89.5 min) reached equivalence when the EZ of the reference standard was set at ±97.1% (1.3 to 89.5 min) for daily MVPA time under a free-living condition.</p> <p>Graph: Figure 4. Equivalence testing for MVPA between the accelerometer and activity monitors for children. Gray vertical solid lines indicate the ±10% equivalence zone (EZ) from the hip worn GT3X+ (Evenson cut-point method). Dark horizontal solid lines show the 90% confidence interval of estimated step counts from activity monitors. Vertical dashed lines indicate the actual bounds within which the Garmin VFJ 3 and Fitbit Ace 3 are statistically equivalent to the wGt3X-BT for MVPA estimates (Orange dashed lines: ±40.7% EZ; blue dashed lines: ±97.1% EZ).</p> <p>Table 5. 90% confidence intervals of MVPA time estimated from the wearable activity monitors for children and equivalence zones of the MVPA time from the hip worn GT3X+.</p> <p> <ephtml> <table><thead><tr><td>Device</td><td>MVPA estimates ± SE</td><td>90% CI of WAMs</td><td>EZ of GT3X+</td><td>EZ (%)</td></tr></thead><tbody><tr><td>Garmin VFJ 3</td><td>82.7 ± 4.0 min</td><td>75.9 to 89.5 min</td><td>1.3 to 89.5 min</td><td>97.1%</td></tr><tr><td>Fitbit Ace 3</td><td>52.3 ± 6.7 min</td><td>40.7 to 63.9 min</td><td>26.9 to 63.9 min</td><td>40.7%</td></tr></tbody></table> </ephtml> </p> <p>5 <emph>Note:</emph> MVPA: moderate-to-vigorous physical activity; SE: standard error; CI: confidence interval; WAMs: wearable activity monitors; EZ: equivalence zone.</p> <hd id="AN0184594844-15">Discussion</hd> <p>The current study assessed the convergent validity of the WAMs designed for children in estimating daily steps and MVPA times compared to a research-grade accelerometer. The major finding of this study was that the VFJ 3 and Ace 3 provided comparable daily step estimates in children relative to the wGTX-BT under free-living conditions. Both WAMs showed strong positive correlations with the wGT3X-BT in estimating daily steps and MVPA time, indicating acceptable convergent validity. In addition, Ace 3 showed adequate validity for estimating group-level MVPA time, given the relatively less mean bias and measurement errors at the group level. However, notable measurement biases were also observed, warranting caution when interpreting these results. Specifically, the VFJ 3 consistently overestimated daily MVPA time, while the Ace 3 consistently overestimated daily step counts. Our findings highlight comparability and differences between WAMs for children and a research-grade accelerometer, which should help shape future applications of the VFJ 3 and Ace 3 for assessing daily steps and MVPA time in research and practice.</p> <p>The current study demonstrated that the VFJ 3 and Ace 3 had acceptable convergent validity in estimating daily steps in children when compared to a hip-worn research-grade accelerometer under free-living conditions. The observed strong correlations with the reference standard can be the preliminary evidence of validity for daily step counting in VFJ 3 or Ace 3 (Ferguson et al., [<reflink idref="bib17" id="ref59">17</reflink>]). The measurement errors at the individual level of both devices were approximately 20% or less, indicating the acceptable validity of the VFJ 3 and Ace 3 for assessing children's daily steps in free-living settings. Step counts are an intuitive metric by which to assess the physical activity levels of individuals. A previous investigation highlighted that ≥11,500 steps/day can be equivalent to ≥60 minutes of MVPA daily (Adams et al., [<reflink idref="bib2" id="ref60">2</reflink>]), which is the PA recommendation for children (World Health Organization, [<reflink idref="bib63" id="ref61">63</reflink>]). VFJ 3 and Ace 3 are designed to help children aged 4 to 12 (VFJ 3: 4 years and older; Ace 3: 6–12 years) develop healthy habits and physically active lifestyles. In this regard, our findings support that the use of VFJ and Ace 3 enables children to identify their adherence to daily step-based PA recommendations. Therefore, VFJ 3 and Ace 3 may be affordable and readily accessible options for self-monitoring daily PA in children.</p> <p>While both WAMs for children showed acceptable convergent validity, it is noteworthy that Ace 3 consistently overcounted daily steps compared to the hip-worn research-grade accelerometer under free-living conditions. This finding was consistent with previous studies, which also found that Fitbit devices overcounted daily steps in children. A recent study including 147 children reported that Fitbit Zip overcounted steps by approximately 18% when compared with the ActiGraph accelerometer during school hours (Mooses et al., [<reflink idref="bib42" id="ref62">42</reflink>]). Further, Voss et al. reported that daily steps measured using Fitbit Charger HR were, on average, 2242 steps/day (MAPE: 28%) higher when compared to the ActiGraph accelerometer (Voss et al., [<reflink idref="bib59" id="ref63">59</reflink>]). Although direct comparisons may not be possible between the studies due to the differences in methodologies, the mean bias in step counts estimates from our study (mean bias: 1684.6 steps/day; MAPE: 20.3%) seemed lower than the bias estimates from those studies. It can be speculated that Ace 3 may use different algorithms (manufacturer's updated version: 1.134.84), which could be more accurate and sensitive to the movement of children. We suggest subsequent research under a controlled laboratory setting to evaluate if any specific movements can mislead the step counting of Ace 3.</p> <p>The findings of this study indicate that Ace 3 can be an affordable and viable measurement tool to assess children's daily MVPA at the group level. On average, VFJ 3 and Ace 3 overestimated children's daily MVPA in comparison with the reference standard. VFJ 3 showed a consistent pattern of overestimation (MPE: −126.0%; MAPE: 127.0%), accompanied by a large amount of mean bias (–37.4 min/day). On the contrary, Ace 3 had no apparent systematic bias, and its mean bias was relatively small (–3.4 min/day). Also, the MPE for Ace 3 in estimating MVPA was quite low (–10.1%). This suggests that Ace 3 had a low level of measurement error for group-level MVPA estimations among school-aged children. Collectively, Ace 3 can provide reasonable estimates for children's daily MVPA at the group level. Despite this, Ace 3's MAPE value exceeded 30%, indicating a deficiency in the agreement with a research-grade accelerometer required for individual-level PA estimations. Hence, researchers and consumers need to be aware of the potential measurement error that may arise when estimating MVPA with the Ace 3.</p> <p>It is worth noting that there is no universally accepted range of measurement error for the children's WAMs in estimating daily steps and MVPA time. Opportunely, equivalence testing can document the range of measurement error for the WAMs by calculating the actual equivalence zones (EZ) within which the WAMs are statistically equivalent to the reference standard (Welk et al., [<reflink idref="bib60" id="ref64">60</reflink>]). Accordingly, the current study attempted to calculate the actual EZ that satisfies the equivalence of the VFJ 3 and Ace 3 against the reference standard. This approach was used not to determine the equivalence of VFJ 3 and Ace 3 in a dichotomous manner (equivalent vs. non-equivalent) but to compare the equivalence of the two WAMs for children against the reference standard. We found that the daily MVPA estimates of VFJ 3 and Ace 3 were statistically equivalent to the reference standards when the EZ of the reference standard was set as ± 97.1% and ± 40.7%, respectively; however, for step counts, VFJ 3 yielded more equivalent estimates than Ace 3 when compared with the wGT3X-BT (±17.7% vs. ±37.3%). Accordingly, the observed actual EZs enabled clear documentation regarding the range of measurement errors of the VFJ 3 and Ace 3, supporting the results from other statistical analyses that the difference in performance between the VFJ 3 and Ace 3 depends on the types of PA estimates. Although the property algorithms of the VFJ 3 and Ace 3 are unknown, it is speculated that there is a discrepancy in the algorithms and sensitivity of WAMs for children in terms of estimating different intensities of PA. Previous studies with children and adolescents also highlighted that the range of measurement errors for PA estimates in Garmin and Fitbit devices may vary with activity intensities (Byun et al., [<reflink idref="bib8" id="ref65">8</reflink>]; Hamari et al., [<reflink idref="bib22" id="ref66">22</reflink>]; Kang et al., [<reflink idref="bib28" id="ref67">28</reflink>]; Šimůnek et al., [<reflink idref="bib50" id="ref68">50</reflink>]). Thus, endorsing a single WAM for children to accurately estimate varying intensities of PA currently remains a challenge.</p> <p>Despite the previously noted limitations, commercially available WAMs for children offer several advantages over research-based accelerometers. First, WAMs for children are wrist-worn and waterproof and focus on providing easily understandable PA metrics (i.e., daily steps and MVPA time) via fun and intuitive graphics in real-time. Also, the adjustable wrist straps on WAMs for children are designed with the smaller-sized wrist of children in mind. Such beneficial features may increase wear times and facilitate periodic self-monitoring for daily PA in children (Troiano et al., [<reflink idref="bib53" id="ref69">53</reflink>]). Second, WAMs for children, such as VFJ 3 and Ace 3, enable incorporating self-monitoring, goal setting, and feedback, which are fundamental components of behavior change to increase PA levels in children (Michie et al., [<reflink idref="bib39" id="ref70">39</reflink>]; Williams & French, [<reflink idref="bib62" id="ref71">62</reflink>]). By default, for example, the VFJ 3 and Ace 3 are set daily PA goals with a 60-min MVPA and 10,000 steps determined by WHO's PA recommendations for children. Lastly, wearers can easily modify their daily PA goals and invite friends and parents for group challenges or social support using the mobile application. As such, the use of WAMs for children may create an opportunity for children to change their habitual behavior into physically active lifestyles (Evenson et al., [<reflink idref="bib15" id="ref72">15</reflink>]; Mercer et al., [<reflink idref="bib38" id="ref73">38</reflink>]; Miyamoto et al., [<reflink idref="bib41" id="ref74">41</reflink>]).</p> <p>There were some noteworthy strengths in the current investigation. The measurement period in the current study was 7 days, including at least one weekend day, which is longer than previous studies that tested the validity of the WAMs in children with shorter study periods (1–5 days) (Godino et al., [<reflink idref="bib21" id="ref75">21</reflink>]; Kang et al., [<reflink idref="bib28" id="ref76">28</reflink>]; Kwon & Kim et al., [<reflink idref="bib30" id="ref77">30</reflink>]; Kim & Lochbaum, [<reflink idref="bib29" id="ref78">29</reflink>]; Mooses et al., [<reflink idref="bib42" id="ref79">42</reflink>]); thus, our data should reflect a more representative measure of habitual PA under free-living conditions. Moreover, the high level of compliance with the study protocol should be highlighted as another strength of the current study. On average, our participants wore all three devices for more than 10 hr a day for 6.9 days, and 92% of them completed at least 5 days of PA measurement, which is the recommended duration for PA monitoring to reliably estimate PA in children (Rowlands et al., [<reflink idref="bib45" id="ref80">45</reflink>]; Schaefer et al., [<reflink idref="bib47" id="ref81">47</reflink>]; Trost et al., [<reflink idref="bib54" id="ref82">54</reflink>]). Lastly, this study investigated the accuracy of both daily steps and MVPA estimates in the WAMs for children. The number of steps and MVPA time are widely used indices for assessing children's daily PA levels.</p> <p>Despite several strengths, there are limitations in this study that should be noted. The sample size of the current investigation was not much larger than previous studies (Godino et al., [<reflink idref="bib21" id="ref83">21</reflink>]; Kang et al., [<reflink idref="bib28" id="ref84">28</reflink>]; Mooses et al., [<reflink idref="bib42" id="ref85">42</reflink>]); however, the rigorous statistical analyses used in this study should minimize any potential threats to internal validity. Another limitation of this study was the lack of inclusion of a wrist-worn accelerometer as a reference standard. Considering the output of the accelerometer, comparisons between devices need to be made at the same placement is sensible (Migueles et al., [<reflink idref="bib40" id="ref86">40</reflink>]). However, the use of a hip-worn accelerometer was a reasonable method as a criterion measure in this study due to the higher accuracy for measuring step counts and physical activity in children compared with the wrist-worn accelerometer (Lynch et al., [<reflink idref="bib35" id="ref87">35</reflink>]; Tudor-Locke et al., [<reflink idref="bib55" id="ref88">55</reflink>]).</p> <hd id="AN0184594844-16">Conclusion</hd> <p>In conclusion, the current study provided adequate evidence for the convergent validity of newly developed WAMs for children compared to a hip-worn research-grade accelerometer. VFJ 3 and Ace 3 can provide acceptable estimates of daily steps in children under free-living conditions. Relative to the hip-worn accelerometer, VFJ 3 consistently overestimated daily MVPA with a large mean bias. On the other hand, Ace 3 showed a relatively low mean bias and good agreement with the reference standard in estimating daily MVPA at the group level. These findings suggest Ace 3 can be an affordable and viable measurement tool to assess children's MVPA in school-aged children. Despite this, it is still uncertain the precision of the Ace 3 needed for individual-level MVPA estimations in children. Considering the validity of daily step counting, VFJ 3 and Ace 3 can be feasible devices to monitor the total amount of daily PA in children. Further investigation with a large sample size is warranted to confirm the accuracy and reliability of WAMs designed for children in estimating children's MVPA.</p> <hd id="AN0184594844-17">Acknowledgments</hd> <p>The authors acknowledge appreciation to all volunteers for their dedication during the study.</p> <hd id="AN0184594844-18">Disclosure statement</hd> <p>No potential conflict of interest was reported by the author(s).</p> <ref id="AN0184594844-19"> <title> References </title> <blist> <bibl id="bib1" idref="ref20" type="bt">1</bibl> <bibtext> Aadland, E., Kvalheim, O. M., Anderssen, S. 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– Name: Abstract
  Label: Abstract
  Group: Ab
  Data: 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: r = 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.
– Name: AbstractInfo
  Label: Abstractor
  Group: Ab
  Data: As Provided
– Name: DateEntry
  Label: Entry Date
  Group: Date
  Data: 2025
– Name: AN
  Label: Accession Number
  Group: ID
  Data: EJ1468513
PLink https://search.ebscohost.com/login.aspx?direct=true&site=eds-live&db=eric&AN=EJ1468513
RecordInfo BibRecord:
  BibEntity:
    Identifiers:
      – Type: doi
        Value: 10.1080/1091367X.2024.2417793
    Languages:
      – Text: English
    PhysicalDescription:
      Pagination:
        PageCount: 12
        StartPage: 133
    Subjects:
      – SubjectFull: Physical Activity Level
        Type: general
      – SubjectFull: Children
        Type: general
      – SubjectFull: Validity
        Type: general
      – SubjectFull: Handheld Devices
        Type: general
      – SubjectFull: Health Behavior
        Type: general
      – SubjectFull: Merchandise Information
        Type: general
      – SubjectFull: Biofeedback
        Type: general
    Titles:
      – TitleFull: Convergent Validity of Garmin Vivofit Jr. 3 and Fitbit Ace 3 for Monitoring Daily Physical Activity of Children
        Type: main
  BibRelationships:
    HasContributorRelationships:
      – PersonEntity:
          Name:
            NameFull: Sunku Kwon
      – PersonEntity:
          Name:
            NameFull: Yang Bai
      – PersonEntity:
          Name:
            NameFull: Youngwon Kim
      – PersonEntity:
          Name:
            NameFull: Ryan D. Burns
      – PersonEntity:
          Name:
            NameFull: Timothy A. Brusseau
      – PersonEntity:
          Name:
            NameFull: Wonwoo Byun
    IsPartOfRelationships:
      – BibEntity:
          Dates:
            – D: 01
              M: 01
              Type: published
              Y: 2025
          Identifiers:
            – Type: issn-print
              Value: 1091-367X
            – Type: issn-electronic
              Value: 1532-7841
          Numbering:
            – Type: volume
              Value: 29
            – Type: issue
              Value: 2
          Titles:
            – TitleFull: Measurement in Physical Education and Exercise Science
              Type: main
ResultId 1