Resting Energy Expenditure And Body Composition In Crossfit

Abstract

Crossfit is a training program created by Greg Glessman in 1995 and consists of performing high intensity functional movements. Some studies have already reported reduction of body fat and increase of metabolic rate. PURPOSE: To investigate differences in body composition and resting energy expenditure (REE) in CrossFit beginners and athletes using electrical bioimpedance (BIA) and indirect calorimetry (IC), respectively. METHODS: 28 individuals (14 male) aged 20-34 years were selected in CrossFit boxes and divided into two groups: CrossFit athletes (GA) and CrossFit beginners (GI). In baseline and after 4 weeks, participants were submitted to body composition and metabolic evaluation. Fat-free mass (FFM), fat mass (FM) and body fat percentage (BFP) were evaluated by BIA and REE and oxygen consumption (VO2) were investigated using IC. Participants continued to perform their CrossFit training, usually in accordance with the spreadsheet prescribed by their coaches. Statistical analyses used: Kolmogorov-Smirnov and T of Student. RESULTS: There were no differences between groups in baseline. After 4 weeks, female GA showed higher REE (1656.0 ± 78.7 vs 1455.7 ± 157.8, P=0.02) and higher VO2 (240.4 ± 11.6 vs 211.3 ± 22.9, P=0.02) when compared to female GI. Only female GA showed a significant increase in baseline energy expenditure (1415.0 ± 236.7 vs 1656.0 ± 78.7, P=0.03) and a significant decrease in baseline body fat percentage (26.4 ± 1.7 vs. 25.2 ± 2.2, P=0.05) between baseline and 4 weeks. In female GI, a reduction in fat mass (15.8 ± 5.7 vs 14.3 ± 5.7, P=0.05) was observed, with no differences in others parameters. Among male groups, male GA showed higher REE (2275.0 ± 286.5 vs 1843.3 ± 336.8, P=0.03) and greater VO2 (330.0 ± 41.2 vs 267.2 ± 48.6, P=0.03) when compared to male GI after 4 weeks. But there were no differences for body composition and metabolic characteristics in the same male group, comparing baseline and 4 weeks evaluation. CONCLUSIONS: This study showed that 4 weeks of CrossFit training positively influenced REE and BFP, especially in female athletes when compared to beginners. Body composition was improved in bothfemale groups. Among men, there were no differences and, probably, four weeks represent a short period to observe changes in body composition and resting energy metabolism in male groups.