Does moderate aerobic activity have a stimulatory effect on 24 h resting energy expenditure: a direct calorimeter study.

This study was designed to establish whether moderate aerobic exercise (2 h at 30-35% VO2 max) in lean non-athletic male adults had a prolonged stimulatory effect on energy expenditure while at rest. Four weight maintaining male adults had their 24 h energy expenditure measured by direct calorimetry on four separate occasions. During the 24 h in the calorimeter each subject received a diet which in total supplied 35 kcal (146 kJ) per kg body weight. All studies in an individual were completed within four to six weeks during which time body weight remained stable. On two of these 24 h periods, individuals rested throughout while on the other two, they also performed the prescribed exercise. This consisted of cycling for two 1 h sessions; the first while they were fasting while the second period was approximately 45 min after consuming a 800 kcal (3.4 MJ) meal. Total 24 h energy expenditure was greater on exercise (8.3 +/- 1.8 MJ/day) than non-exercising days (6.3 +/- 1.4 MJ/day, P < 0.001) In contrast when the acute effects of the cycling where removed 24 h resting energy expenditure on the exercise day (6.8 +/- 1.7 MJ/day) was not significantly different from that of rest days (95% confidence intervals of the difference ranged from -0.36 to 1.27 MJ/day). This study did not demonstrate a prolonged stimulatory influence on non-exercising resting energy expenditure following physical activity likely to be achieved by non-athletes. These data provide no evidence that such exercise is associated with a greater energy deficit than that due to the activity itself.