Strenuous is Better

At least in children this seems to be the case. The Times Online brought this study by British investigators to my attention. It involved 5500 12 year old boys and girls who were evaluated for body fat and physical activity (amount and intensity). Unique to this study was the use of small activity monitors called accelerometers which were attached around the children's waists during waking hours. The investigators reported their findings in the February edition of the journal PloS Medicine and concluded that less than 30 minutes of “moderately vigorous exercise” each day was protective against obesity. The intensity of exercise needed was that which causes the individual to become slightly out of breath such as brisk walking or a game of football (soccer for us Americans). Participation in activities at this level of exertion appears to be a more powerful predictor of whether or not a child becomes obese than caloric intake or total energy expenditure, especially in boys. Although this is an important study in that activity was rigorously documented, the study is limitated by its cross-sectional design such that the possibility remains that overweight children are less capable of vigorous acitivity. This will need to be sorted out. Nevertheless, it is encouraging that even relatively short periods of exertion which amount to vigorous play can be so beneficial.