Associations Between Serum and Skeletal Muscle Androgens and Androgen Receptor-associated Biomarkers, Lean Body Mass, and Muscular Strength

The relationships between lean body mass (LBM), muscular strength, androgens, and several androgen receptor (AR)-associated biomarkers are sparsely described. PURPOSE: To examine any potential correlations linking these aforementioned factors. METHODS: 10 resistance-trained males were recruited for this crossover study, each assessing their leg and bench press one-repetition maximums (1RM) and body composition before completing two volume- and intensity-equated resistance training sessions separated by 7-10 days. Serum and skeletal muscle tissue samples were acquired in each session at baseline, 3-hours, and 24-hours post-exercise to assess circulating and muscle androgens (testosterone [TST] and dihydrotestosterone [DHT]), AR protein content and gene expression, as well as AR-DNA binding levels. Pearson correlation coefficients were employed to evaluate the intersectional relationships between LBM, 1RM assessments, androgens ([serum free and total] TST and muscle DHT), AR-associated biomarkers (AR protein, AR mRNA relative fold changes, and AR-DNA binding), whereby all previously mentioned analyses were performed at p<.05. RESULTS: Analyses detected several statistically significant correlations, all of which were positively associated. Specifically, LBM was significantly associated with leg press (p=.015; R=.705) and bench press (p=.048; R=.607) 1RM. Leg press 1RM was also significantly correlated to serum total TST (p=.012; R=.909), whereby serum total TST was further associated with serum free TST (p=.030; R=.339). Serum free TST was also significantly correlated with AR mRNA relative fold changes (p=.001; R=.392) and AR-DNA binding (p=.021; R=.287). Finally, muscle DHT was significantly correlated to muscle TST (p.<001; R=.415) and AR protein (p<.001; R=.421). CONCLUSION: These data corroborate the well-established relationships between LBM and strength, additionally providing insight into how these factors are influenced by serum and skeletal muscle androgens, as well as other androgen-receptor-associated biomarkers. Future research should explore the intersectional viability connecting muscular hypertrophy and performance to statistically significant relationships such as AR-DNA binding-serum free TST, serum free TST-leg press, and leg press-LBM.