Objectives: A randomized crossover trial was designed to analyze the impact of a short-term, isoenergetic fat- or carbohydrate (CHO)-rich diet on substrate oxidation rates during submaximal exercise and on performance in a 10,000-m running time trial in trained, mid- to late-pubertal boys.
Methods: An incremental test was performed to determine the peak oxygen uptake (VO2peak). After two days on a fat-rich (24.2 +/- 0.8% CHO, 60.4 +/- 0.3% fat, and 15.5 +/- 1.0% protein), CHO-rich (69.3 +/- 1.2% CHO, 15.9 +/- 2.1% fat, and 15.1 +/- 1.1% protein), or habitual (56.1 +/- 7.0% CHO, 27.5 +/- 4.9% fat, and 16.5 +/- 4.0% protein) diet, nineteen trained adolescent boys (15.2 +/- 1.5 yr) performed a 10-minute constant run at 65% VO2peak to determine the respiratory exchange ratio (RER) during exercise and a 10,000-m running on an outdoor track.
Results: During the constant run, the RER and CHO contribution to energy expenditure were lower, and fat contribution higher, in the fat-rich diet than in the CHO-rich diet (P < 0.05), but the results were not different from those of the habitual diet. Performance in the 10,000-m run after consuming CHO- and fat-rich diets was similar to performance after a habitual diet (50.0 +/- 7.0, 51.9 +/- 8.3, and 50.9 +/- 7.4 min, respectively), but consuming a CHO-rich diet enhanced performance compared to that after the fat-rich diet (P = 0.03).
Conclusions: These findings indicate that CHO-rich diet provides additional benefits to 10,000-m running performance in trained adolescent boys compared to fat-rich diet.
(C) 2014 by European Society for Pediatric Gastroenterology, Hepatology, and Nutrition and North American Society for Pediatric Gastroenterology,