Purpose: The purpose of this study was to assess the relationship between intensity of physical activity and body composition in 239 young adult women.

Methods: This study was cross-sectional. Participants were recruited from October 2009 to December 2011 and included women from 36 different states and 6 different countries. Physical activity was objectively measured using accelerometers worn for seven days. Body composition was measured using the BOD POD. Height, weight, and circumferences were assessed.

Results: Participant's mean age was 20.6±1.6 years. Their mean BMI was 22.6±3.0 kg/m2 and mean body fat percentage was 26.4±6.3 %. Average total activity counts per day were 387,560 ± 172,000, with 61.6±22.5 min per day spent in MVPA, 169.4±43 min per day in light activity, 55.6±19 min per day in moderate activity, and 6±9.2 min per day in vigorous activity. Total activity counts per day were inversely correlated with body fat (r = -0.17, p = 0.007). Light activity was positively correlated with both BMI (r = 0.17, p = 0.007) and waist circumference (r = 0.15, p = 0.0164). Moderate activity was inversely associated with body fat (r = -0.18, p = 0.0051) and hip circumference (r = -0.12, p = 0.0459). MVPA was inversely associated with body fat (r = -0.19, p = 0.0026) and hip circumference (r = -0.14, p = 0.0291). Vigorous physical activity was inversely related to body fat (r = -0.20, p = 0.0023). Using stepwise regression, the best predictor of body fat was time spent in vigorous PA (F = 9.45, p = 0.0024). The best predictor of BMI was light activity per day, which was positively correlated with BMI (F = 7.5, p = 0.0066) followed by moderate activity per day which was negatively correlated (F = 4.25, p = 0.0403). Young adult women who spent no time performing vigorous PA had significantly higher body fat percentages than women who performed some vigorous PA. Young adult women who spent less than 30 minutes per day in MVPA had significantly higher body fat percentages and BMIs than those who obtained more than 30 minutes per day. For every 10 minutes spent in MVPA per day, the odds of being obese by body fat decreased by 33%.

Conclusion: Vigorous PA and MVPA appear to be the most important aspects of PA associated with lower body fat and BMI levels. Young adult women should be encouraged to obtain at least 30 minutes of MVPA per day.



College and Department

Life Sciences; Exercise Sciences



Date Submitted


Document Type





body composition, physical activity, body fat, accelerometer