Resistance training might have improved insulin resistance by attenuating sarcopenia.

Dear editor

We read the valuable article of Oliveira et al1 entitled “Resistance training improves isokinetic strength and metabolic syndrome-related phenotypes in postmenopausal women” with interest. In their well-designed prospective study, the authors observed improvement in metabolic syndrome-related phenotypes after 12 weeks of resistance training. We have some comments that could facilitate interpretation of the results of this study.

Because muscle mass is an important target for glucose uptake, sarcopenia seems to be an emerging risk factor for insulin resistance in elderly individuals.2,3 Resistance training is among the most important measures to attenuate sarcopenia.4,5 Thus, we suggest that there may be a close relationship between improvement in muscle mass and strength and reduction in insulin resistance in this study. At least some of the individuals in this study (90.3±24.1 Nm) seem to have sarcopenic muscle strength considering the muscle strength measurements of a sarcopenic obesity group (87.5±17.8 Nm) in a previous study from Brazil.6 After the resistance training intervention, the muscle strength of the study population (101.9±21.4 Nm) is similar to the non-sarcopenic obese group (96±23.4 Nm) in the previous study. Thus, transition from sarcopenia to normal muscle mass and functions is a rational explanation to the improvement in insulin resistance in this study. We suggest that the authors assess the relationship between delta-homeostatic model assessment-insulin resistance (delta-HOMA-IR) and delta-muscle strength. Furthermore, a multivariate regression analysis might also be performed to seek independent factors underlying improvement of insulin resistance (delta-HOMA-IR). These analyses may provide clinically relevant information.