The Effect Of Carbohydrate Intake On Crossfit Performance And Associated Metabolic,physiological Demands And Responses

Abstract

PURPOSE:CrossFit (CF) is a physically and metabolically demanding strength and conditioning method. Given the metabolic profile of CF training, a carbohydrate (CHO)-rich diet may enhance its performance. This study investigated the effect of three consecutive days of high CHO intake on CF performance and corresponding metabolically/physiologically-related variables in strength trained individuals with a chronic CHO intake of <6 g/kg/d. METHODS: Eighteen subjects were randomly assigned into a CHO (n = 9) or control (C) group (n =9) and underwent a 9-day training protocol. In days 1, 5, and 9, CF performance was measured in repetitions completed during a 12 minute CF workout. Oxygen consumption (VO2), respiratory exchange ratio (RER), and blood lactate (BL) were measured as well. From days 6-8, the CHO group increased CHO intake from <6 g/kg/day to 6-8 g/kg/day whereas the C group maintained their current intake of <6 g/kg/day. On days 6 and 7 both groups performed prescribed CF workouts followed by a day of rest prior day 9. RESULTS: A repeated measures ANOVA revealed a time main effect (p < 0.002) for repetitions completed in day 9 (vs. mean score of day 1 + day 5). There was no group effect or (time x group) interaction. Despite the latter, it should be noted that the CHO group displayed a 15.22 repetition increase (+10.9%) in day 9, whereas the C group did so by only 5.67 (+4.2%). Hence, the practical implications of our results warrant consideration in a competition-type setting. Scores for VO2, RER, and BL were not influenced by the experimental intervention. CONCLUSIONS: Despite the commonly practiced moderately-low CHO intake within the CF community (40% CHO), our results suggest that CF performance may be enhanced by practicing a CHO-rich diet during periods of training due to the expected pronounced reliance on glyocolytic energy production.