EFFECT OF 4-H PREEXERCISE HIGH-CARBOHYDRATE AND HIGH-FAT MEAL INGESTION ON ENDURANCE PERFORMANCE AND METABOLISM

The effect of a single high carbohydrate meal (HCM) and high fat meal (HFM) given 4 h before cycling exercises was determined for performanc e and metabolism. On the morning of the day of the trial, 10 endurance -trained collegiate males consumed either a single HCM (4669 kJ; 79 % CHO, 10 % F and 11 % P) or HFM (4711 kJ; 30 % CHO, 61 % F and 9 % P) a s a 4 h preexercise meal. The intensity of exercise required was 65 % of the maximal oxygen consumption (VO(2)max) for the first 120 min of exercise, followed by an increased dose of 80 % VO(2)max. Endurance ca pacity did not differ between the HCM (128 +/- 3 min [SEM]) and HFM (1 22 +/- 3 min) trials. There was no significant difference in blood glu cose levels in the HCM and HFM trials. A significantly higher (p < 0.0 1) serum insulin level in the HCM trials over the HFM trials was only observed at the start of exercise. Blood lactate levels (< 2.6 mM) dur ing cycling remained below the anaerobic threshold. Respiratory exchan ge ratio in the HCM trials was significantly higher (p < 0.05 or p < 0 .01) than that in HFM trials during the first 40 min of exercise. This was accompanied by significantly lower(p( 0.05 or p < 0.01) levels in serum free fatty acid and beta-HOB for the HCM trial, There was no si gnificant difference between both diet regimens as to heart rate, oxyg en consumption and perceived exertion during exercise. These results s uggest that a single HCM and HFM given 4 h before exercise influences fuel utilization in the initial stages of prolonged cycling, but these meals may have little effect on endurance capacity.