In the aging process, changes in body composition occur, with an increase in fat mass and a decline in lean mass, and this decline is closely related to functional dependence and the appearance of disabilities. Physical exercise can directly cause changes in body composition. However, studies show that a long time spent in sedentary behaviour (SB) can lead to a reduction in functional independence and an increase in mortality, regardless of physical exercise. Despite this, evidence is still needed to verify whether the reduction in CS can have positive effects on body composition.

To assess whether the adoption of self-management strategies (SMS) in multicomponent training (Multi) compared to isolated multicomponent training can improve the lean mass index of older adults who were physically active before the pandemic.

A single-blind, randomized, controlled clinical trial was performed. Forty-five elderly participants in a multi-component group physical exercise project were divided into two groups: Multi and Multi + AG. The Multi consisted of aerobic exercises, muscular resistance, balance, and flexibility (3x week, 50 minutes/session). The SMS consisted of setting goals and weekly telephone follow-ups by a professional trained in these strategies. The lean mass index (lean mass/height2) was evaluated by dual-energy X-ray absorptiometry (DXA). The intervention lasted 16 weeks, starting after the release of group physical exercises, due to the COVID-19 pandemic scenario, and reassessed shortly after 16 weeks of intervention. A generalized mixed linear model was used to analyze the data (fixed factors: time, group and interaction and random factor: subjects).

The sample had a predominance of 74% females, a mean age of 74.45 ± 6.1 years, body mass of 69.41 ± 15.43 kg. Both groups showed an increase in lean mass index (estimated marginal means: 0.217, CI: 0.01 to 0.42, p < 0.038). There was no group effect and no interaction between group and time. In this way, both groups obtained improvements in the lean mass index.

SMS to reduce SB did not potentiate the effects of Multi on the lean mass index of older adult participants in a group physical exercise project.

The provision of multicomponent physical exercise programs for the older adults, with characteristics similar to the sample of this study, may be sufficient to improve the lean mass index.