The pattern of physical activity in relation to health outcomes in boys

Spontaneous and transitory movement patterns are characteristic of children. The aim of this study was to explore the relationship between short, frequent activity bouts and children's health.

Physical activity was recorded every 2 s by accelerometry (ActiGraph GT1M) for seven days in 47 boys (age 8-10 years). Summary activity measures and activity pattern characteristics (frequency, intensity and duration of > or = 4 s [short] and > or = 5 min [long] bouts of > or= light [> or = LIGHT], > or = moderate [> or = MOD], > or = vigorous [> or = VIG], and > or = hard [> or = HARD] intensity activity) were recorded. Microvascular function was assessed using laser Doppler perfusion imaging as the forearm skin blood flow response to the iontophoretic application of acetylcholine (endothelial dependent vasodilator) and sodium nitroprusside (endothelial independent vasodilator) at rest and following maximal exercise. Waist circumference, resting blood pressure and aerobic fitness (VO(2peak)) were measured.

The intensity of short and long > or = LIGHT bouts and the frequency of short and long > or =MOD bouts were correlated with waist circumference (r = - 0.42 to -0.52, p < 0.01) and VO(2peak) (r = 0.42 to 0.47, p < 0.01), but not when scaled for lean body mass. The frequency of short and long > or =LIGHT bouts were associated with change in endothelial function from rest to post-exercise (r = 0.34 to 0.55, p < 0.05). No relationships were evident between blood pressure and activity.

The relationship between the frequency of short bouts (> or =4 s) of activity and health was as strong as relationships identified between longer bouts (> or =5 min) and health. This is encouraging as sporadic intermittent activity is characteristic of children's activity pattern.