Does The Number Of Bouts Used To Accumulate Mvpa Matter For Fitness And Fatness?

Abstract

Previous research has demonstrated that accumulating moderate to vigorous physical activity (MVPA) in at least 10 minute bouts is important for health outcomes such as body fat percent (BF%) and cardiorespiratory fitness (CRF). However, less is understood as to whether the way in which we accumulate our activity, such as in one large bout vs. a few moderate bouts vs. many shorter bouts, has a differential impact on BF% and CRF. PURPOSE: To determine whether the number of bouts of MVPA per day is associated with BF% and CRF independent of the total amount of MVPA. METHODS: Participants were 375 adults (175 women, ages 20 to 35 years, BMI 24.7±3.4) enrolled in the Energy Balance Study, who averaged at least one 10+ minute bout of MVPA per day. BF% was measured using dual energy X-ray absorptiometery and CRF was measured using a treadmill maximal graded exercise test (VO2max, mL/kg/min). MVPA in at least 10 minute bouts was measured using the SenseWear Mini Armband for an average of 9.8±1.0 days, 23.1±1.2 hrs/day. Individuals were grouped into four bout categories, <3, 3-<5, 5-<7, and ≥7 bouts/day . Generalized linear models evaluated the association of BF% and VO2max with the bouts/day categories, adjusting for age, race, gender, BMI, energy intake, and MVPA duration. RESULTS: A significant inverse association existed across bout groups for CRF (VO2max (mL/kg/min) least squares mean±SE: 38.3±0.9, 38.4±0.8, 36.6±1.1, 30.6±1.8 for bout categories <3, 3-<5, 5-<7, ≥7 bouts/day, respectively, p-value for linear trend=0.0006). Additionally, a signficant direct association existed across bout groups for BF% (BF% least squares mean±SE 27.6±0.7, 27.4±0.6, 28.6±0.9, 31.9±1.5 for bout categories <3, 3-<5, 5-<7, ≥7 bouts/day, respectively, p-value for linear trend=0.02). CONCLUSIONS: There was an independent association of number of bouts of MVPA with CRF and BF%. The results demonstrate that for this sample of young adults, accumulating MVPA in fewer bouts/day, and in turn having bouts longer in duration, are associated with higher CRF and lower BF%.