METABOLIC RESPONSES TO PREEXERCISE MEALS CONTAINING VARIOUS CARBOHYDRATES AND FAT

After a 12-h fast six different meals (potatoes, rice, sucrose solutio n, potatoes + margarine, rice + margarine, and a confectionery bar), e ach containing 0.7 g carbohydrate/kg body wt, were consumed 30 min bef ore exercise (n = 9). During the 30 min immediately after ingestion, t he glycemic and insulinemic responses to the meals distinguished these foods into two groups: 1) high glycemic (ie, potatoes, sucrose, confe ctionery bar) and 2) moderate glycemic (ie, rice, potatoes + margarine , rice + margarine). After 20 min of moderate-intensity exercise, plas ma glucose declined in all carbohydrate trials to values of 3.4 +/- 0. 1 mmol/L, which were significantly (P < 0.05) lower than values after subjects fasted (4.2 +/- 0.2 mmol/L). Therefore, the glycemic and insu linemic responses to these meals were independent of their carbohydrat e classification of simple or complex and the addition of fat reduced the glycemic and insulinemic responses. However, despite these differe nt responses before exercise, all of the meals caused plasma glucose t o decline to equally low concentrations early in exercise.