Measurement Reactivity to Hip-Worn Accelerometry Among Adolescent Females: A Concurrent Wear Approach

Device-based measurement of physical activity (PA) is crucial for valid research, but reactivity to these devices can undermine validity. Inconsistent findings in prior reactivity research warrant unique approaches among diverse populations, including those habituated to wearing another device. We aimed to estimate reactivity to ActiGraph GT3X+ via concurrent Fitbit Inspire HR wear among Latina adolescents using a person-day matched cross-sectional design. Fitbit data estimated steps, moderate-vigorous PA, light PA, and sedentary time for all days in the 2 weeks preceding and following matched ActiGraph wear days. Linear models estimated the association of ActiGraph wear day with activity after adjustment for covariates. There were 2987 total days across 107 participants, ~35% classified as ActiGraph wear days. Steps statistically significantly differed (p = .0499) with ActiGraph wear days corresponding to 248 greater average steps. Measurement reactivity to ActiGraph may impact steps among adolescent females. Future research could benefit from concurrent wear strategies if feasible.