BODY-COMPOSITION AND SLEEPING METABOLIC-RATE IN RESPONSE TO A 5-MONTH ENDURANCE-TRAINING PROGRAM IN ADULTS

This study examined the effect of exercise training on body composition and sleeping metabolic rate (SMR) in 15 men and 13 women who participated in a 20-week training programme aimed at running a half marathon. Body mass (BM) was measured after waking up, fasted and with an empty bladder. Body composition was assessed using densitometry. The SMR was measured from 0300-0600 hours during an overnight sleep in a respiration chamber. Assessment of SMR was at least 36 h after the last period of exercise training. After 20 weeks of endurance training no change in BM was observed. However, body composition changed significantly. On average men lost 2.4 kg body fat (P < 0.01) and gained 1.7 kg fat free mass (FFM) (P < 0.01). In women fat loss average 0.9 kg after 20 weeks (P < 0.01), while FFM increased by 1.0 kg (P < 0.05). Loss of fat mass was significantly larger in males (P < 0.05). No changes in SMR were found, either in absolute terms, or when normalised for BM of FFM. Therefore, we have concluded that exercise training has no chronic, long-tem effect of SMR. A possible explanation for this outcome in view of the different findings in similar studies is discussed.