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 prolon ged stimulatory effect on energy expenditure while at rest. Four weigh t maintaining male adults had their 24 h energy expenditure measured b y direct calorimetry on four separate occasions. During the 24 h in th e calorimeter each subject received a diet which in total supplied 35 kcal (146 kJ) per kg body weight. All studies in an individual were co mpleted within four to six weeks during which time body weight remaine d stable. On two of these 24 h periods, individuals rested throughout while on the other two, they also performed the prescribed exercise. T his consisted of cycling for two 1 h sessions; the first while they we re fasting while the second period was approximately 45 min after cons uming a 800 kcal(3.4 MJ) meal. Total 24 h energy expenditure was great er 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 cycli ng 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 i nfluence on non-exercising resting energy expenditure following physic al activity likely to be achieved by non-athletes. These data provide no evidence that such exercise is associated with a greater energy def icit than that due to the activity itself.