Sparks, S. A., Bridge, N. E., Cable, N. T., Doran, D. A., & McLaren, D. P. (2006). The effect of pre-exercise dietary manipulation on ATP utilization and metabolism during simulated duathlon performance. Medicine and Science in Sports and Exercise, 38(5), Supplement abstract 1982.

This study investigated the effect of high carbohydrate and high fat pre-exercise meals on the metabolic responses to simulated duathlon time trials. Males (N = 9) completed three laboratory simulated duathlon time trials (5-km run, 30-km cycle, and 5-km run). Ss fasted overnight before each duathlon and were randomly given isoenergetic meals 3.5 hours before exercise. The meals consisted of predominantly low carbohydrate (50 g), high carbohydrate (214.8 g), or a fasting condition in which Ss ate nothing.

Time to complete the duathlon was not significantly affected by the pre-exercise meals. Total ATP utilization also was unaffected by the pre-exercise meals although there were significant changes in the rate of ATP use because of a change in exercise modality. Carbohydrate oxidation rate was significantly increased following high carbohydrate and significantly reduced following low carbohydrate meals. Fat oxidation rate was suppressed because of the availability of carbohydrate following high carbohydrate and increased following low carbohydrate meals.

Implication. ATP utilization was unaffected by pre-exercise meals despite changes in substrate availability and differences in the oxidation rates of both carbohydrate and fat.

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