Physical Activity Patterns of Adolescents by Wrist-worn Geneactiv Accelerometer

Abstract

PURPOSE: Measurement of physical activity (PA) using GENEActiv monitors placed on the wrist is becoming more widely accepted due to increased compliance over waist monitors. Little data is available about adolescent PA measured at the wrist. The objective of this study is to describe the PA characteristics of a sample of high school students, overall and by sex, race/ethnicity, weight status, and day of the week. METHODS: In Spring of 2014, 207 students in grades 9 and 10 at 4 predominantly Hispanic high schools wore an accelerometer for 7 days. Valid data from 186 accelerometer records were evaluated to determine average minutes (min) of daily activity. Because adolescent cut-points for the GENEActiv have not been developed, adult cut-points were used to determine PA intensities: Sedentary/Light (S/L), Moderate (M), Moderate to Vigorous (MV), and Vigorous (V). T-tests were used to compare average min of PA by sex, Hispanic vs. non-Hispanic ethnicity, underweight/normal weight vs. overweight/obese weight status and day of the week. RESULTS: On average, adolescents accumulated 906 (95% CI: 894-920), 138 (95% CI: 131-145), 164 (95% CI: 153-174), and 25 (95% CI: 20-31) daily min of S/L, M, MV, and V activity, respectively. 98% of adolescents met the guidelines to do 60 min or more of MV PA per day. Compared to girls, boys did 9 min more of V (p = 0.006) activity. There were no significant differences in levels of S/L, M, and MV activity by gender, and in any level of activity by ethnicity or weight status. Average weekday MV min (164, 95% CI: 158 - 169) and V min (25, 95% CI: 23-27) were significantly higher than weekend MV min (127, 95% CI: 119 - 135, p<0.001) and V min (20, 95% CI: 17-22, p<0.001). Students were most active on Friday and least active on Sunday. CONCLUSIONS: Based on PA measured at the wrist, most students met the 2008 PA guidelines. This may be attributable to wrist vs. waist measurements and to the initial novelty of wearing the activity monitor. Based on our examination of PA levels by sex and weight status, we suggest that interventions for increasing PA and managing weight in adolescents may benefit from focusing on increasing weekend PA, increasing vigorous PA among girls, and by not automatically assuming that overweight/obese students have lower PA levels compared to other students. Supported by NIH Grant R0I HL118734