Abstract
Effects of dietary composition (high fat, FAT; or high carbohydrate, CHO) and exercise timing (preprandial exercise, Ex-; or postprandial exercise, -Ex) on postprandial energy expenditure and substrate utilization were studied in seven women aged 19-20 years. The experimental protocol included four different sessions (Ex-FAT, Ex-CHO, FAT-Ex, and CHO-Ex). The FAT and CHO diets provided 48 and 5% as fat, respectively. On the experimental days, subjects were fed a meal containing the same caloric energy at lunch time and they exercised for 30min on a bicycle ergometer at an intensity of 60% VO2max at pre- or post-meal followed by rest for 3h. The values of oxygen consumption were 1, 559, 1, 628, 1, 526, and 1, 557ml·kg-1·4h-1 in Ex-FAT, Ex-CHO, FAT-Ex, and CHO-Ex groups, respectively. Total levels of serum insulin were 7.6, 13.7, 4.5, and 7.8μU·ml-1·min·10-3, respectively. These results suggest that preprandial exercise, especially before CHO diet intake, has an advantage for increasing oxygen consumption. This advantage might be related to rates of substrate (“futile”) cycling and insulinemic responses at rest and during exercise.
