ABSTRACT
Cross-sectional studies have shown that objectively measured physical activity is associated with childhood adiposity [1]–[6], and a strong inverse dose-response association with body mass index (BMI) has been found [1]. However, confounding or reverse causation (where adiposity influences inactivity, rather than vice versa) may explain part of the association [7],[8]. Indeed, there may be a bidirectional relationship between adiposity and physical activity, and this would imply that only a small change in
adiposity or physical activity may be required to initiate a cycle of weight gain and increased inactivity [9].
