Activity, body composition and bone health in children

Abstract

OBJECTIVE: To examine relationships among daily activity levels, body composition and bone outcomes in children aged 6.7 years who were born at term with birth weights <20th centile. METHODS: Activity data collected using accelerometers were correlated with body composition and bone outcome z-scores from dual-energy X-ray absorptiometry in 36 children. RESULTS: Activity levels were related to body composition outcomes; for example, lean mass index (lean mass/height(2)) was positively associated with time spent in moderate activity (r=0.40, p=0.02) and negatively with time spent in sedentary activity (r=-0.50, p=0.002). Per cent time spent in sedentary activity correlated negatively with whole body bone mineral density z-score (r=-0.44, p=0.01) and hip bone mineral content (r=-0.38, p=0.03). CONCLUSIONS: Moderate and vigorous activity levels were associated with increased lean and bone mass in this population but not with conventional measures of adiposity such as weight and body mass index z-scores. Standard measures of adiposity may mask potential benefits of regular activity.