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Objectively Measured Physical Activity and Fat Mass in a Large Cohort of Children

2007; Public Library of Science; Volume: 4; Issue: 3 Linguagem: Inglês

10.1371/journal.pmed.0040097

1549-1676

Andy Ness, Sam Leary, Calum Mattocks, Steven N. Blair, John J. Reilly, Jonathan C. K. Wells, Sue Ingle, Kate Tilling, George Davey Smith, Chris Riddoch,

Health, Environment, Cognitive Aging

Background Previous studies have been unable to characterise the association between physical activity and obesity, possibly because most relied on inaccurate measures of physical activity and obesity. Methods and Findings We carried out a cross sectional analysis on 5,500 12-year-old children enrolled in the Avon Longitudinal Study of Parents and Children. Total physical activity and minutes of moderate and vigorous physical activity (MVPA) were measured using the Actigraph accelerometer. Fat mass and obesity (defined as the top decile of fat mass) were measured using the Lunar Prodigy dual x-ray emission absorptiometry scanner. We found strong negative associations between MVPA and fat mass that were unaltered after adjustment for total physical activity. We found a strong negative dose-response association between MVPA and obesity. The odds ratio for obesity in adjusted models between top and the bottom quintiles of minutes of MVPA was 0.03 (95% confidence interval [CI] 0.01–0.13, p-value for trend <0.0001) in boys and 0.36 (95% CI 0.17–0.74, p-value for trend = 0.006) in girls. Conclusions We demonstrated a strong graded inverse association between physical activity and obesity that was stronger in boys. Our data suggest that higher intensity physical activity may be more important than total activity.