Muscle Size and Strengths and their Associations with Sports Participation among Young Adults

Abstract

PURPOSE: A decision to participate in physical activity is heavily influenced by one’s self-efficacy related to exercise capacity, but it is not clear if muscle size and strength influence one’s decision to engage in sports and recreation. We examined this relationship and hypothesized that those with stronger and larger muscle would engage in more sports and recreation. METHODS: Subjects were young (23.4 ± 5.6yr), normal weight (24.4 ± 4.6 kg/m2) European-American women (n=227) and men (n=192). The Paffenbarger Physical Activity Questionnaire assessed self-reported weekly Kcal expended in sport and recreational physical activity. We obtained muscle size and strength on the dominant and non-dominant arms. Muscle strength was measured with the maximum voluntary contraction (MVC) and one repetition maximum (1RM), and muscle size by cross sectional area (CSA) using magnetic resonance imaging. Weekly sport and recreation participation was categorized by the median for purposes of statistical analysis. Logistic regression tested the associations among muscle size and strength and sport and recreation participation by gender adjusting for age and body mass index (BMI). Akaike Information Criterion was used to identify the most parsimonious model. RESULTS: On average, men spent about 1568.7±2397.5 kcal/wk and women spent 1732.2±2184.8kcal/wk in sports and recreation. Among men, a one-unit increase in dominant arm 1RM and MVC was associated with 16.9% (95%CI: 5.0-31.1%) and 2.3% (95%CI: 0.6-4.2%) higher odds of engaging in sports and recreation, respectively. Among women, a one-unit increase in non-dominant arm MVC was associated with 5.3% (95%CI = 2.2-8.7%) higher odds of engaging in sports and recreation, while a one- unit increase in non-dominant arm CSA was associated with 19.8 % (95%CI = 8.9-30.0%) lower odds of engaging in sports and recreation. CONCLUSIONS: As hypothesized, greater MVC predicted engaging in more sport and recreation for both men and women, but greater 1RM predicted engaging in more sport and recreation among men only. Contrary to our hypothesis, greater CSA (i.e., muscle size) predicted engaging in less sports and recreation among women only. The interactions among putative psychosocial mediators, muscle capacity, and sport and recreation participation warrants future investigation.