Gene-physical activity interactions: overview of human studies.

Physical activity level is an important component of the total daily energy expenditure and as such contributes to body weight regulation. A body of data indicates that the level of physical activity plays a role in the risk of excessive weight gain, in weight loss programs, and particularly in the prevention of weight regain. Most studies dealing with potential gene-physical activity interaction effects use an exercise and fitness or performance paradigm as opposed to an obesity-driven model. From these studies, it is clear that there are considerable individual differences in the response to an exercise regimen and that there is a substantial familial aggregation component to the observed heterogeneity. Few studies have focused on the role of specific genes in accounting for the highly prevalent gene-exercise interaction effects. Results for specific genes have been inconsistent with few exceptions. Progress is likely to come when studies will be designed to truly address gene-exercise or physical activity interaction issues and with sample sizes that will provide adequate statistical power.