Effect of short-duration physical activity and ventilation threshold on subjective appetite and short-term energy intake in boys.

The purpose of this investigation was twofold: (1) to examine the role of low- to moderate-intensity, short-duration physical activity on subjective appetite and (2) to identify the role of and associations between ventilation threshold (VeT) and energy intake at a pizza lunch 30 min after glucose and whey protein drinks in normal weight boys. In 14 boys (age: 12.5+/-0.4 years) subjective appetite was measured before and after a 12 min walking protocol designed to determine physical fitness based on the VeT. On a separate occasion food intake (FI) and subjective appetite were measured in response to sweetened preloads of either a SPLENDA Sucralose control, glucose or whey protein made up to 250 ml with water, given in random order to each boy, 2h after a standardized breakfast. Subjective average appetite and prospective food consumption scores increased after physical activity. VeT was positively associated with FI at a pizza lunch consumed 30 min after glucose and whey protein drinks. Glucose and whey protein reduced FI similarly at lunch compared with control. In conclusion, appetite is increased by low- to moderate-intensity, short-duration physical activity and FI following glucose and protein preloads is positively associated with fitness levels in boys.