Skeletal Muscle Androgen-Regulated Gene Expression Following High- and Low-Load Resistance Exercise

Resistance exercise (RE) is a well-known modality to increase skeletal muscle strength and hypertrophy. While both high-load (HL) and low-load (LL) RE stimulate skeletal muscle growth, the effects of RE load on androgen-regulated genes remain unclear. Further, the relationship between circulating and intramuscular androgen-associated targets and muscular strength and mass has not been well defined. Purpose: This investigation therein aimed to examine acute gene and hormone responses to volume- and intensity-equated RE at different loads, examining their relationships with lean body mass (LBM), strength, and circulating and intramuscular androgen-related biomarkers. Methods: Ten resistance-trained males completed one-repetition maximum (1RM) testing, as well as body composition testing, before two volume- and intensity-equated RE sessions, separated by a 7–10 day crossover period. Serum and skeletal muscle samples were collected at baseline, 3 h, and 24 h post-exercise to assess testosterone (TST), dihydrotestosterone (DHT), AR protein, AR mRNA, and AR–DNA binding. Pearson correlations evaluated any potential associations between LBM, strength, and androgen/AR biomarkers. Results: Training load did not significantly impact gene expression, but time effects were observed, whereby MyoD peaked 3 h post-exercise (2.03 ± 1.64 fold; p = 0.005), while AR mRNA decreased at 24 h (0.54 ± 0.42 fold; p = 0.021) versus baseline. LBM also correlated with bench press (r = 0.607, p = 0.048) and leg press (r = 0.705, p = 0.015) 1RM. Serum total TST correlated with leg press 1RM (r = 0.909, p = 0.012), while serum-free TST correlated with AR mRNA fold-change (r = 0.392, p = 0.001) and AR–DNA binding (r = 0.287, p = 0.021). Intramuscular DHT correlated with intramuscular TST (r = 0.415, p < 0.001) and AR protein (r = 0.421, p < 0.001). Lastly, fold changes in AR mRNA were correlated with MyoD mRNA fold changes (r = 0.785, p = 0.007) along with IGF1-Ea mRNA fold changes being significantly correlated with both myogenin mRNA fold changes (r = 0.865, p = 0.001) and AR-DNA binding (r = −0.727, p = 0.017). Conclusions: Despite no observable load-specific effects, RE elicited time-dependent increases in MyoD and AR mRNA expression. This reinforces prior LBM and maximal muscular strength relationship evidence whilst also lending new insights into circulating and intramuscular androgen interactions with AR.