Influence of bouts of physical activity on overweight in youth.
BACKGROUND
It is unknown whether bouts of physical activity confer benefits beyond the total volume of physical activity. It was hypothesize that bouts of physical activity would independently predict overweight in youth.


METHODS
The sample included 2498 youth (aged 8-17 years) from the 2003-2004 and 2005-2006 cycles of the National Health and Nutrition Examination Survey. Analyses were conducted in 2008. Sporadic sessions (1-4 minutes) of moderate-to-vigorous physical activity (MVPA); short bouts (5-9 minutes) of MVPA; and medium-to-long bouts (>or=10 minutes) of MVPA were measured over 7 days using Actigraph accelerometers. BMI was used to classify participants as normal weight or overweight. Logistic regression was used to predict the relative odds of overweight according to total MVPA and bouts of MVPA.


RESULTS
After controlling for the volume of MVPA, individuals in the highest quartile for total bouts of MVPA (short + medium-to-long bouts) were only 0.38 (95% CI=0.18, 0.80) times as likely to be overweight compared to the lowest quartile. After controlling for the volume of MVPA and the amount accumulated in short bouts, individuals in the highest quartile for medium-to-long bouts of MVPA were only 0.55 (95% CI=0.32, 0.95) times as likely to be overweight compared to the lowest quartile.


CONCLUSIONS
Moderate-to-vigorous physical activity that took place in bouts conferred benefits on adiposity status that were independent of the total volume of MVPA in this large sample of youth.
School of Kinesiology and Health Studies, Queen's University, Kingston, Ontario, Canada.
Amy E
AE
Mark
Ian
I
Janssen
D050154:Adiposity; D000293:Adolescent; D015992:Body Mass Index; D002648:Child; D005260:Female; D006801:Humans; D008297:Male; D008991:Monitoring, Physiologic; D009043:Motor Activity; D009749:Nutrition Surveys; D050177:Overweight; D014481:United States