The purpose of this study was to examine the effects of long-term habitual exercise on daily total energy expenditure (TEE) and its components, body composition and maximal oxygen uptake (VO2max) in middle-aged Japanese women. Twenty-eight subjects aged 39 to 58 years were assigned either to a nonhabitual exercise group (Control ; n=12) or a habitual exercise group (Exercise ; n=16). TEE, physical activity level (PAL) and the daily physical activity energy expenditure (PAEE) were assessed by doubly labeled water (DLW) method. The exercise-induced energy expenditure (ExEE) and nonexercise-induced energy expenditure (NExEE) were evaluated based on the activity record investigation conducted simultaneously during the DLW measurement period. The result follows that TEE was significantly (p<0.01) higher in the Exercise group (2520 kcal · day-1) than in the Control group (1921 kcal · day-1). There was no significant difference in basal metabolic rate between the groups. PAEE and ExEE were significantly higher in the Exercise group than in the Control group (p<0.01). Habitual exercise induced an increase in TEE without resulting in a compensatory reduction of NExEE. The percentage body fat (fat%) was significantly lower in the Exercise group (25.5%) than in the Control group (30.9%). VO2max was higher in the Exercise group (1788 ml · min-1) than in the Control group (1417 ml. min-1). After correction for body weight, fat% was negatively associated with TEE (p<0.01), PAEE (p<0.01) and ExEE (p=0.05), while VO2max was positively associated with TEE (p<0.05), PAL (p<0.05), PAEE (p<0.05) and ExEE (p<0.01). These results suggest that habitual exercise is associated with the increase of TEE, the improvement of body composition and VO2max. The improvement of VO2max was mainly caused by the increase in ExEE, indicating that the exercise intensity is important to the improvement of cardiorespiratory endurance fitness.
