Resistance training-induced improvement in exercise tolerance is not dependent on muscle mass gain in post-menopausal women

Abstract

Menopause transition may impair muscle function, decreasing exercise tolerance. The torque–duration relationship (hyperbolic curve) forms a practical framework within which exercise tolerance may be explored. In this regard, resistance training (RT) increases the curvature constant of this relationship (W′). Muscle hypertrophy and strength gains have been suggested as possible mediators of RT-induced improvement in Wʹ, however, it is unclear what the main mediator is. Higher-volume RT (HV-RT), beyond that recommended by RT-guidelines (i.e. three sets per exercise), may promote greater hypertrophy, but not higher strength gains. Hence, this study aimed to investigate whether greater hypertrophy in HV-RT maximizes Wʹ gain when compared to LVRT in postmenopausal women (PW). Fifty-eight PW were randomized to the control group (CTRL), HV-RT (six sets per exercise) or LV-RT (three sets per exercise). They underwent a 12-week RT program and were assessed for Wʹ, thigh lean body mass (TLBM) and maximal isometric voluntary contraction (MIVC). The TLBM gain was higher (P < 0.001) in the HV-RT (9.4%) than LV-RT (3.7%). However, both HV-RT and LV-RT similarly increased MIVC (9.7% vs. 16.5%, P= 0.063) and Wʹ (26.4 % vs. 34.6 % P= 0.163). Additionally, the changes in Wʹ were associated with the changes in TLBM (31%, P= 0.003) and MIVC (52%, P= <0.001). However, when the changes in TLBM and MIVC were inserted into the predictive model, only the MIVC (33%, P= 0.002) was a predictor of Wʹ. Thus, although HV-RT promoted greater hypertrophy than LV-RT, HV-RT does not seem to maximize W′ in PW.