Female Collegiate Athletes and CrossFit Exercisers Exhibit Muscular Differences During Body Composition Testing

CrossFit facilities and Division 1 athletics programs are settings of intense and often competitive physical training. However, the participants' nutritional behaviors and characteristics of exercise programming may differ, which can influence accretion of lean mass. PURPOSE: To compare muscular parameters of body composition testing in female Division 1 collegiate athletes (DCA) and CrossFit exercisers (CFE). METHODS: We scanned 244 female exercisers (32 DCA and 212 CFE) on the InBody 770 body composition analyzer. From this pool of subjects, we used coarsened exact matching (CEM) to create new subsamples matched for age and bodyweight. The comparison groups generated by CEM consisted of 22 DCA and 22 CFE. There were 7 different court, field, and aquatic sports represented in the DCA group. We used two-tailed independent-samples t-tests to compare the matched samples in InBody calculations of lean body mass, dry lean mass, skeletal muscle mass, lean leg mass (single leg average), lean arm mass (single arm average), lean trunk mass, and skeletal muscle index; 95% confidence intervals of the between-group differences are reported. RESULTS: Lean body mass was 119.7 ± 16.4 lb for DCA and 108.1 ± 13.5 lb for CFE (p = 0.013; 95% CI: 2.5, 20.8). Dry lean mass was 32.4 ± 4.5 lb for DCA and 29.0 ± 3.7 lb for CFE (p = 0.009; 95% CI: 0.9, 5.9). Skeletal muscle mass was 67.1 ± 9.5 lb for DCA and 60.3 ± 8.0 lb for CFE (p = 0.014; 95% CI: 1.5, 12.1). Lean leg mass was 18.1 ± 3.1 lb for DCA and 15.7 ± 2.3 lb for CFE (p = 0.006; 95% CI: 0.7, 4.1). Lean arm mass was 6.4 ± 1.1 lb for DCA and 5.9 ± 0.9 lb for CFE (p = 0.104; 95% CI: -0.1, 1.1). Lean trunk mass was 52.7 ± 6.9 lb for DCA and 49.2 ± 5.5 lb for CFE (p = 0.069; 95% CI: -0.3, 7.3). Skeletal muscle index was 7.4 ± 0.5 for DCA and 7.3 ± 0.6 for CFE (p = 0.409; 95% CI: -0.2, 0.5). All comparisons met Levene's test for equality of variance (p > 0.400). CONCLUSIONS: Despite subject matching, female DCA showed greater muscle mass overall than CFE. The most significant difference was observed in the legs, which may contribute to variance in athletic performance. Future studies should examine variables such as nutrition and training volume to determine which factors may contribute to these differences.