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Int J Exerc Sci. 2016 Oct 1;9(3):460-470. eCollection 2016.

The Effect of a Moderately Low and High Carbohydrate Intake on Crossfit Performance.

Author information

1
Department of Health, Exercise & Sport Sciences, University of New Mexico, Albuquerque, New Mexico, USA.
2
Department of Kinesiology, California State University, Fresno, Fresno, California, USA.
3
Department of Exercise Science & Sports Management, Kennesaw State University, Kennesaw, Georgia, USA.

Abstract

CrossFit is a metabolically demanding strength and conditioning method which performance may benefit from a carbohydrate (CHO)-rich diet. This study investigated the effect of three consecutive days of high CHO intake on CrossFit performance and corresponding metabolically -related variables in strength trained individuals. Eighteen subjects with a CHO intake of <6 g/kg/day were randomly assigned into a CHO (n = 9) or control (C) group (n =9) and underwent a 9-day training protocol. During days 1, 5, and 9, performance was measured as repetitions completed during a 12 minute CrossFit workout. Oxygen consumption (VO2), respiratory exchange ratio (RER), and blood lactate (BL) were also measured. Days 6-8, the CHO group increased CHO intake from <6 g/kg/day to 6-8 g/kg/day; the C group maintained their current intake of <6 g/kg/day. On days 6 and 7 both groups performed CrossFit workouts followed by a day of rest prior to day 9. There was a significant increase in repetitions completed in both groups in day 9 (vs. means score of day 1 + 5) (p = 0.002), but no differences between C and CHO groups (p = 0.111). However, the CHO group displayed a 15.2 repetition increase (+10.9%) in day 9, compared to 5.7 (+4.2%) by the C group. VO2, RER, and BL were not influenced by the experimental intervention. Our results suggest that the CrossFit-embraced practice of moderately-low CHO diets may be adequate in CHO during short periods of training, however, given the noted trend, extended training periods may be effected.

KEYWORDS:

Nutrition; anaerobic exercise; glycogen; high-intensity exercise; power; resistance training; strength training

PMID:
27766133
PMCID:
PMC5065325

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