Effect of 4h Preexercise High Carbohydrate and High Fat Meal Ingestion on Endurance Performance and Metabolism

 

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The effect of a single high carbohydrate meal (HCM) and high fat meal (HFM) given 4h before cycling exercises was determined for performance 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) as a 4 h preexercise meal. The intensity of exercise required was 65 % of the maximal oxygen consumption (VO₂max) for the first 120 min of exercise, followed by an increased dose of 80 % VO₂max. Endurance capacity did not differ between the HCM (128 ± 3 min [SEM]) and HFM (122 ± 3 min) trials. There was no significant difference in blood glucose levels in the HCM and HFM trials. A significantly higher (p < 0.01) 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) during cycling remained below the anaerobic threshold. Respiratory exchange 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 β-HOB for the HCM trial. There was no significant difference between both diet regimens as to heart rate, oxygen consumption and perceived exertion during exercise. These results suggest 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.