on Performance

Abstract Ultra-marathons (footraces greater than 42.2 km) are increasing in popularity, however little is known about the habitual dietary intake of these runners. The aim of this investigation was to empirically describe the habitual training diet of ultra-marathon runners and determine if macronutrient intake was associated with 161-km race performance. To assess habitual diet, runners recruited from five 161-km ultra-marathons across the U.S. (N = 47) completed a diet and training questionnaire, and a web-based 24-hour dietary recall on three separate days within 1-4 weeks prior to a 161-km race. Multiple linear regression was used to predict finish time with covariates carbohydrate, fat and protein, expressed relative to body weight (g·kg -1 ) and total intake (% of diet). To determine differences in macronutrient intake between finishers and non-finishers, two-sample t-tests were used. Dietary intake was varied among participants; mean carbohydrate intake (5.19±2.62 g·kg ) predicted finish time (R 2 = 0.232, P =0.036), however fat was the only significant covariate (t = -2.90, P =0.007). Relative macronutrient intake (% of diet) did not predict finish time (R 2 =0.145, P =0.155). No significant differences were found in macronutrient intake between finishers (n=36) and non-finishers (n=11). Habitual dietary fat intake in ultra-marathon runners was a significant predictor of 161-km finish time, regardless of carbohydrate or protein intake. Further investigation is warranted to determine the optimal nutrient intake in ultra-marathon runners to maximize performance