Equivalence testing may provide complementary information to more frequently used statistical procedures because it determines whether physical behavior outcomes are statistically equivalent to criterion measures. A caveat of this procedure is the predetermined selection of upper and lower bounds of acceptable error around a specified zone of equivalence. With no clear guidelines available to assist researchers, these equivalence zones are arbitrarily selected. A scoping review of articles implementing equivalence testing was performed to determine the validity of physical behavior outcomes; the aim was to characterize how this procedure has been implemented and to provide recommendations. A literature search from five databases initially identified potentially 1,153 articles which resulted in the acceptance of 19 studies (20 arms) conducted in children/youth and 40 in adults (49 arms). Most studies were conducted in free-living conditions (children/youth = 13 arms; adults = 22 arms) and employed a ±10% equivalence zone. However, equivalence zones ranged from ±3% to ±25% with only a subset using absolute thresholds (e.g., ±1,000 steps/day). If these equivalence zones were increased or decreased by ±5%, 75% (15/20, children/youth) and 71% (35/49, adults), they would have exhibited opposing equivalence test outcomes (i.e., equivalent to nonequivalent or vice versa). This scoping review identifies the heterogeneous usage of equivalence testing in studies examining the accuracy of (in)activity measures. In the absence of evidence-based standardized equivalence criteria, presenting the percentage required to achieve statistical equivalence or using absolute thresholds as a proportion of the SD may be a better practice than arbitrarily selecting zones a priori.
Search Results
You are looking at 1 - 9 of 9 items for
- Author: Myles W. O’Brien x
- Refine by Access: All Content x
Implications and Recommendations for Equivalence Testing in Measures of Movement Behaviors: A Scoping Review
Myles W. O’Brien
Applying Average Real Variability to Quantifying Day–Day Physical Activity and Sedentary Postures Variability: A Comparison With Standard Deviation
Madeline E. Shivgulam and Myles W. O’Brien
Intraindividual activity variability is often overlooked, with some existing work using SD as a variability metric. However, average real variability (ARV) may be a more suitable metric as it accounts for temporal variability. The purpose of this exploratory study was to (a) apply ARV analyses to habitual activity outcomes; (b) assess the agreement between ARV and SD for habitual step counts, standing time, and sedentary time; and (c) determine the relationship between activity variability (SD and ARV) with average activity values. One hundred and eighty-nine participants (37 ± 22 years, 109 females) wore the activPAL inclinometer on their thigh 24 hr/day for 6.4 ± 0.9 days. SD and ARV were calculated for each participant across their wear time. A Wilcoxon signed-rank test revealed that ARV was significantly higher than SD for step count, standing time, and sedentary time (all, p < .001). Equivalence testing demonstrated mixed equivalence for step counts (10%), standing time (12%), and sedentary time (14%). SD and ARV were highly correlated to each other for all activity metrics (all, ρ > .857, p < .001). SD was moderately (ρ = .601, p < .001) and weakly (ρ = .296, p < .001) correlated with average step count and standing time, respectively. ARV was weakly correlated with average step count and standing time (both: ρ < .499, p < .001). However, average sedentary time was not associated with SD or ARV (both, p > .177). While the two measurements of variability were strongly correlated, they cannot be used interchangeably. More monitoring research should consider intraindividual activity variability and use methods, such as ARV, that consider the temporal nature of day–day activity.
Validity and Interinstrument Reliability of a Medical Grade Physical Activity Monitor in Older Adults
Myles W. O’Brien, William R. Wojcik, and Jonathon R. Fowles
Wearable physical activity monitors are associated with an increase in user’s habitual physical activity levels. Most of the older adult population do not meet the national moderate- to vigorous-intensity physical activity (MVPA) recommendations and may benefit from being prescribed a physical activity monitor. The PiezoRx is a class one medical grade device that uses step rate thresholds to measure MVPA. The validity and reliability of the PiezoRx in measuring MVPA has yet to be determined in older persons. We assessed the validity and interinstrument reliability of the PiezoRx to measure steps and MVPA in older adults. Participants (n = 19; 68.8 ± 2.3 years) wore an Omron HJ-320 pedometer, ActiGraph GT3X accelerometer, and four PiezoRx monitors during a five-stage treadmill walking protocol. The PiezoRx devices were set at moderate physical activity and vigorous physical activity step rate thresholds (steps per minute) of 100/120, 110/130, adjusted for height and adjusted for height + fitness. The PiezoRx exhibited a stronger correlation (intraclass correlation coefficient = .82) with manually counted steps than the ActiGraph (intraclass correlation coefficient = .53) and Omron (intraclass correlation coefficient = .54) and had a low absolute percentage error (3 ± 6%). The PiezoRx with moderate physical activity/vigorous physical activity step thresholds adjusted to 110/130 was strongly correlated to indirect calorimetry (0.84, p < .001) and best distinguished each walking stage as MVPA or not (sensitivity: 88%; specificity: 95%). The PiezoRx monitor is a valid and reliable measure of step count and MVPA among older adults. The device’s ability to measure MVPA in absolute terms was improved when step rate thresholds for moderate physical activity/vigorous physical activity were increased to 110/130 steps per minute in this population.
Criterion Validity of Commonly Used Sedentary Behavior Questionnaires to Measure Total Sedentary Time in Adults
Madeline E. Shivgulam, Derek S. Kimmerly, and Myles W. O’Brien
Background: Self-report questionnaires are a fast and cost-efficient method to determine habitual sedentary time (sitting/lying time while awake), but their accuracy versus thigh-worn accelerometry (criterion), which can distinguish between sitting and standing postures, is unclear. While the validity of sedentary questionnaires has previously been evaluated, they have not been investigated simultaneously in the same sample population. We tested the hypothesis that common sedentary questionnaires underpredict habitual sedentary time compared with an objective, monitor-based assessment. Methods: Ninety-three participants (30 ± 18 years, 59 females) wore the activPAL inclinometer on the midthigh 24 hr per day for 6.9 ± 0.4 days and completed the SIT-Q, Sedentary Behavior Questionnaire (SBQ), International Physical Activity Questionnaire (IPAQ), and Physical Activity and Sedentary Behavior Questionnaire (PASB-Q). Results: In comparison to the activPAL (9.9 ± 1.9 hr/day), the SIT-Q measured more time (12.9 ± 5.4 hr/day), but the SBQ (7.5 ± 3.3 hr/day), IPAQ (7.4 ± 3.0 hr/day), and PASB-Q (6.6 ± 3.0 hr/day) measured less time (all p < .001). The SIT-Q was positively and weakly correlated (ρ = .230 [95% confidence interval: .020, .422], p = .028) with the activPAL, but the SBQ, IPAQ, and PASB-Q were not (all ps > .760). Equivalence testing demonstrated poor equivalence for the SIT-Q (±40%), SBQ (±31%), IPAQ (±36%), and PASB-Q (±29%). The SIT-Q (β = −1.36), SBQ (β = −0.97), and IPAQ (β = −0.78) exhibited a negative proportional bias (all ps < .002). Conclusions: In summary, the SIT-Q, SBQ, IPAQ, and PASB-Q demonstrated poor validity. Researchers and health promoters should be cautious when implementing these self-report sedentary time questionnaires, as they may not reflect the true sedentary activity and negatively impact study results.
Standing Still or Standing Out: Distinguishing Passive and Active Standing Is a Step in the Right Direction
Madeline E. Shivgulam, Emily E. MacDonald, Jocelyn Waghorn, and Myles W. O’Brien
Standing is a solution to reduce or break-up sedentary time (sitting/reclining/lying while awake); however, the measurable health benefits of standing are conflicting. A recent article in the Journal for the Measurement of Physical Behaviour has demonstrated that the thigh-worn activPAL inclinometer can distinguish between passive (no movement) and active (structured micromovements) standing using a machine learning model in lab-based and free-living environments. The predictive model extends beyond previous research by considering three-dimensional aspects of movement into the decision tree model. The ability to characterize these distinct postures is increasingly important to understand the physiological difference between passive and active standing. Notably, active standing, when stepping is not feasible, may be superior to passive standing for improving metabolic activity, reducing fatigue, and enhancing blood flow. Applied to free-living settings, active standing could help mitigate or attenuate some adverse cardiometabolic effects of stationary activity, thereby yielding positive cardiovascular outcomes. As standing gains recognition as a potentially important health behavior, distinguishing between passive and active standing offers a unique opportunity to clarify the health impacts of standing time, contributing to the evidence base. This evidence may contribute to more detailed activity guidelines and support public health initiatives to promote active standing. These advancements have the potential to enhance our understanding of standing behaviors’ health impacts and the possible divergent physiological effects of active versus passive standing.
Calibrating the Physical Activity Vital Sign to Estimate Habitual Moderate to Vigorous Physical Activity More Accurately in Active Young Adults: A Cautionary Tale
Liam P. Pellerine, Derek S. Kimmerly, Jonathon R. Fowles, and Myles W. O’Brien
The Physical Activity Vital Sign (PAVS) is a two-question assessment used to estimate habitual moderate to vigorous aerobic physical activity (MVPA). Previous studies have shown active adults cannot estimate the physical activity intensity properly. The initial purpose was to investigate the criterion validity of the PAVS for quantifying habitual MVPA in young adults meeting weekly MVPA guidelines (n = 140; 21 ± 3 years). A previously validated PiezoRx waist-worn accelerometer served as the criterion measure (wear time, 6.7 ± 0.6 days). All participants completed the PAVS once before wearing the PiezoRx. Standardized activity monitor validation procedures were followed. The PAVS (201 ± 142 min/week) underestimated (p < .001) MVPA compared to the PiezoRx (381 ± 155 min/week). To correct for this large error, the sample was divided into calibration model development (n = 70; 21 ± 3 years) and criterion validation (n = 70; 21 ± 3 years) groups. The PAVS score, age, gender, and body mass index outcomes from the development group were used to construct a multiple linear regression model-based calibrated PAVS (cPAVS) equation. In the validation group, the cPAVS was similar (p = .113; 352 ± 23 min/week) compared to accelerometry. Equivalence testing demonstrated the cPAVS, but not the PAVS, was equivalent to the PiezoRx. Despite achieving most statistical criteria, the PAVS and cPAVS still had high degrees of variability, preventing their use on an individual level. Alternative strategies are needed for the PAVS in an active young adult population. These results caution using the PAVS in active young adults and identify a case where obvious variabilities in accuracy conflict with statistically congruent results.
Criterion Validity of Accelerometers in Determining Knee-Flexion Angles During Sitting in a Laboratory Setting
Yanlin Wu, Myles W. O’Brien, Alexander Peddle, W. Seth Daley, Beverly D. Schwartz, Derek S. Kimmerly, and Ryan J. Frayne
Introduction: Device-based monitors often classify all sedentary positions as the sitting posture, but sitting with bent or straight legs may exhibit unique physiological and biomechanical effects. The classifications of the specific nuances of sitting have not been understood. The purpose of this study was to validate a dual-monitor approach from a trimonitor configuration measuring knee-flexion angles compared to motion capture (criterion) during sitting in laboratory setting. Methods: Nineteen adults (12♀, 24 ± 4 years) wore three activPALs (torso, thigh, tibia) while 14 motion capture cameras simultaneously tracked 15 markers located on bony landmarks. Each participant completed a 45-s supine resting period and eight, 45-s seated trials at different knee flexion angles (15° increment between 0° and 105°, determined via goniometry), followed by 15 s of standing. Validity was assessed via Friedman’s test (adjusted p value = .006), mean absolute error, Bland–Altman analyses, equivalence testing, and intraclass correlation. Results: Compared to motion capture, the calculated angles from activPALs were not different during 15°–90° (all, p ≥ .009), underestimated at 105° (p = .002) and overestimated at 0°, as well as the supine position (both, p < .001). Knee angles between 15° and 105° exhibited a mean absolute error of ∼5°, but knee angles <15° exhibited larger degrees of error (∼10°). A proportional (β = −0.12, p < .001) bias was observed, but a fixed (0.5° ± 1.7°, p = .405) bias did not exist. In equivalence testing, the activPALs were statistically equivalent to motion capture across 30°–105°. Strong agreement between the activPALs and motion capture was observed (intraclass correlation = .97, p < .001). Conclusions: The usage of a three-activPAL configuration detecting seated knee-flexion angles in free-living conditions is promising.
The Stryd Foot Pod Is a Valid Measure of Stepping Cadence During Treadmill Walking and Running
Madeline E. Shivgulam, Jennifer L. Petterson, Liam P. Pellerine, Derek S. Kimmerly, and Myles W. O’Brien
Stepping cadence is an important determinant of activity intensity, with faster stepping associated with the most health benefits. The Stryd monitor provides real-time feedback on stepping cadence. The limited existing literature has neither validated the Stryd across slow walking to fast running speeds nor strictly followed statistical guidelines for monitor validation studies. We assessed the criterion validity of the Stryd monitor to detect stepping cadence across multiple walking and jogging/running speeds. It was hypothesized that the Stryd monitor would be an accurate measure of stepping cadence across all measured speeds. Forty-six participants (23 ± 5 years, 26 females) wore the Stryd monitor on their shoelaces during a 10-stage progressive treadmill walking (Speeds 1–5) and jogging/running (Speeds 6–10) protocol (criterion: manually counted video-recorded cadence; total stages: 438). Standardized guidelines for physical activity monitor statistical analyses were followed. A two-way repeated-measure analysis of variance revealed the Stryd monitor recorded a slightly higher cadence (<1 steps/min difference, all p < .001) at 2 miles/hr (92.1 ± 6.2 steps/min vs. 91.5 ± 6.4 steps/min, p < .001), 2.5 miles/hr (101.3 ± 6.1 steps/min vs. 100.7 ± 6.4 steps/min), and 3.5 miles/hr (117.4 ± 5.9 steps/min vs. 117.0 ± 6.0 steps/min). However, equivalence testing demonstrated high equivalence of the Stryd and manually counted cadence (equivalence zone required: ≤± 2.6%) across all speeds. The Stryd activity monitor is a valid measure of stepping cadence across walking, jogging, and running speeds. By providing real-time cadence feedback, the Stryd monitor has strong potential to help guide the general public monitor their stepping intensity to promote more habitual activity at faster cadences.
Moving Beyond the Characterization of Activity Intensity Bouts as Square Waves Signals
Myles W. O’Brien, Jennifer L. Petterson, Liam P. Pellerine, Madeline E. Shivgulam, Derek S. Kimmerly, Ryan J. Frayne, Pasan Hettiarachchi, and Peter J. Johansson
Wearable activity monitors provide objective estimates of time in different physical activity intensities. Each continuous stepping period is described by its length and a corresponding single intensity (in metabolic equivalents of task [METs]), creating square wave–shaped signals. We argue that physiological responses do not resemble square waves, with the purpose of this technical report to challenge this idea and use experimental data as a proof of concept and direct potential solutions to better characterize activity intensity. Healthy adults (n = 43, 19♀; 23 ± 5 years) completed 6-min treadmill stages (five walking and five jogging/running) where oxygen consumption (3.5 ml O2·kg−1·min−1 = 1 MET) was recorded throughout and following the cessation of stepping. The time to steady state was ∼1–1.5 min, and time back to baseline following exercise was ∼1–2 min, with faster stepping stages generally exhibiting longer durations. Instead of square waves, the duration intensity signal reflected a trapezoid shape for each stage. The METs per minute during the rise to steady state (upstroke slopes; average: 1.7–6.3 METs/min for slow walking to running) may be used to better characterize activity intensity for shorter activity bouts where steady state is not achieved (within ∼90 s). While treating each activity bout as a single intensity is a much simpler analytical procedure, characterizing each bout in a continuous manner may better reflect the true physiological responses to movement. The information provided herein may be used to improve the characterization of activity intensity, definition of bout breaks, and act as a starting point for researchers and software developers interested in using wearables to measure activity intensity.
