Author(s): LIBARDI, C., BERGAMASCO, J.1, SCARPELLI, M.1, GODWIN, J.2, MESQUITA, P.2, CHAVES, T.1, SILVA, D.1, BITTENCOURT, D.1, DIAS, N.1, UGRINOWITSCH, C.3,4, ROBERTS, M.2, Institution: FEDERAL UNIVERSITY OF SÃO CARLOS, Country: BRAZIL, Abstract-ID: 2400

INTRODUCTION:
The expression of androgen receptors (AR) has emerged as a potential mechanism for muscle hypertrophy. While studies establish a connection between AR and skeletal muscle hypertrophy, how AR under physiological circumstances affects this process in humans remains unclear (1). The purpose of this study was to investigate the acute and chronic effects of resistance training (RT) on total AR contents in women and men. Additionally, we investigated whether these acute and chronic changes are associated with the hypertrophy of type I and II fibers in women and men.
METHODS:
Thirty-eight young women (n = 19) and men (n = 19) underwent 10 weeks of RT. Muscle biopsies were performed at baseline, 24 h after the first RT session (acute effect), and 96-120 h after the last session (chronic effect). AR were analyzed using Western blotting and muscle fiber cross-sectional area (fCSA) were analyzed through immunohistochemistry.
RESULTS:
Acutely, only a main time effect was demonstrated for AR (F = 57.52; p < 0.0001), in which the 24 h values were smaller than the Pre values. Acute AR responses did not significantly correlate with hypertrophy of type I and II fibers in women (r = -0.154, p = 0.553 and r = -0.082, p = 0.754, respectively) or men (r = -0.089, p = 0.717 and r = 0.159, p = 0.516, respectively). Chronically, no main or interaction effect was shown for AR (P > 0.05). Additionally, chronic AR responses did not significantly correlate with hypertrophy of type I and II fibers in women (r = -0.071; p = 0.787 and r = -0.077; p = 0.769, respectively) or men (r = 0.066; p = 0.787 and r = 0.190; p = 0.436, respectively).
CONCLUSION:
While animal studies suggest a link between AR content and muscle hypertrophy, the results in humans are controversial. Therefore, the precise role of AR in human muscle hypertrophy under physiological conditions remains unclear and warrants further investigation. In summary, acute and chronic changes in androgen receptors are not associated with muscle hypertrophy in women and men.
REFERENCE:
1. Roberts et al. Physiol Rev. 103(4):2679-757, 2023.