Minimal dose resistance training enhances strength without affecting cardiac autonomic modulation in menopausal women: a randomized clinical trial

The proposition of a minimal dose of resistance training (RT) to elicit health benefits, encompassing physiological and psychological aspects, has garnered attention. While empirical investigations have demonstrated the efficacy of low-volume RT protocols in inducing adaptations such as enhanced strength and functional capacity, further exploration of the effects of this paradigm across a broader spectrum of variables is warranted. Thus, this study aimed to investigate the effects of minimal dose RT on strength and functional capacity, cardiac autonomic modulation, and hemodynamic parameters in menopausal women. Twenty-six women were randomly assigned to the training (TG: 63.2 ± 9.3 years) or control group (CG: 59.3 ± 7.6 years). Anthropometric measurements, strength and functional performance tests, cardiac autonomic assessment, and hemodynamic parameters were performed before and after four weeks of intervention. The TG performed the minimum dose RT twice weekly for four weeks (2 sets of 8-12 repetitions in three dynamic exercises, plus three 1-min isometric planks), and the CG had a weekly meeting with lectures and stretching. Two-way ANOVA with repeated measures was applied to each variable. Regarding time comparisons, there was a significant increase for LniRR (F = 4.78; ω² = 0.046; p = 0.04), one repetition maximum (1RM) bench press (F = 8.06; ω² = 0,013; p = 0.01), and 1RM leg press (F = 17.3; ω² = 0,098; p < 0.01). There was a group*time interaction only for the index LnRMSSD (F = 5.11; ω² = 0.042; p = 0.03), and 1RM bench press (F = 9.52; ω² = 0,016; p = 0.01). No between-group main effect for any variable was found. The minimal dose RT protocol improved muscle strength, while cardiac autonomic and hemodynamic variables, as well as functional capacity, remained stable over 4 weeks in menopausal women.