Effects of Resistance Training at Different Loads on Inflammatory Biomarkers, Muscle Mass, Muscular Strength, and Physical Performance in Postmenopausal Women.

Carneiro, MAS, de Oliveira Júnior, GN, de Sousa, JFR, Murta, EFC, Orsatti, CL, Michelin, MA, Cyrino, ES, and Orsatti, FL. Effects of resistance training at different loads on inflammatory biomarkers, muscle mass, muscular strength, and physical performance in postmenopausal women. J Strength Cond Res 36(6): 1582-1590, 2022-It has been suggested that the effect of resistance training (RT) on circulating proinflammatory biomarkers may be dependent on muscle mass gain. A few recent studies have suggested that lower-load RT (LLRT; loads <50% of 1 repetition maximum [1RM] and repetition performed until, or close to, voluntary concentric failure) may be superior to higher-load RT (HLRT; loads >70% of 1RM) in increasing muscle mass. Hence, this study aimed to test whether LLRT is superior to HLRT for increasing muscle mass (total fat-free mass [TFFM] and leg fat-free mass [LFFM]) and improving circulating inflammatory biomarkers (interleukin [IL]-6, IL1-ra, tumor necrosis factor [TNF]-α, and extracellular heat shock protein [eHSP]70) in postmenopausal women (PW) (primary outcome). The secondary outcome was to compare the changes in muscular strength and physical performance (4-meter walking test [4-M], timed-up-and-go [TUG] test, and sit-to-stand [STS] test) between the LLRT and HLRT. The PW were randomized into 2 groups: LLRT (n = 14; loads necessary to perform 30-35 repetitions) and HLRT (n = 15; loads necessary to perform 8-12 repetitions). The greater magnitude of increase in LFFM (p = 0.033) was observed in LLRT when compared with HLRT. Moreover, there was a trend for a greater increase in TFFM in LLRT over HLRT (p = 0.070). However, there were similar improvements in TNF-α and muscular strength (p < 0.001). Furthermore, there was no significant difference between the RT schemes on IL-6, IL-1ra, and eHSP70 levels. Thus, although performing LLRT until, or close to, voluntary concentric failure seems to provide a greater stimulus for an increase in muscle mass than HLRT, it does not seem to affect the responses in circulating inflammatory biomarkers, muscular strength, and physical performance in PW.