The Fueling Learning Through Exercise (FLEX) Study

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PURPOSE: Throughout the elementary school years school-time moderate-to-vigorous physical activity (MVPA) tends to decrease while sedentary time (SED) increases, contributing independent effects on health outcomes. There is insufficient research on how physical activity (PA) programming may impact SED in children. Our objective was to determine whether two innovative school-based PA programs impact school SED in children and if program reach differed by sex, race/ethnicity, and weight status. METHODS: Eighteen schools from lower-income Massachusetts school districts were enrolled in the Fueling Learning through Exercise Study (FLEX) and randomized to 100 Mile Club (100MC; walking/running program), Just Move (JM; active classroom breaks), or a Control group. Third- and fourth-grade children (n=883) were recruited and measured at baseline (Fall 2015) and short-term follow-up (Spring 2016) for height/weight and 7-day accelerometry (ActigraphGT3x). Demographic information was obtained by parent questionnaire. PA program effects on SED were examined using mixed-effects models adjusting for child sex, race/ethnicity, free or reduced-price lunch (FRPL) eligibility, weight status, accelerometer wear time, average daily temperature, and controlling for school-level clustering. RESULTS: 793 children (8.7 ± 0.7 years, 44% male, 65% non-white, 53% FRPL, 41% overweight/obese) had valid accelerometer wear-time (33 days, 310hrs/day) at both study visits. At baseline, few children achieved the recommended 30 minutes of school-time MVPA (9%; 18.1 ± 7.9 min) and children were sedentary for 59.7% (233 ± 43 min) of their school day. There was a significant effect of program on SED (p=0.041) with Control and JM increasing in SED (6.2 [95%CI: 2.7, 9.5], p<0.001 and 4.3 [95%CI: 0.9, 7.7] mins/day, p=0.012 respectively) while 100MC did not change (p=0.88). There were no differences in program effects by sex (p=0.58), race/ethnicity (p=0.08), or weight status (p=0.19). CONCLUSIONS: Short-term follow-up of program implementation during a two-year PA intervention demonstrates a potential effect of 100MC on mitigating an increase in SED that may occur over the elementary school years. Longer-term findings will demonstrate whether the effects of PA programming on SED are sustained.