# Impact of Trunk Versus Skeletal Muscle Mass Gain on Balance Improvement in Patients with Cerebral Infarction

## TL;DR

This study found that increasing trunk muscle mass, not overall skeletal muscle mass, is linked to better balance recovery in elderly patients with cerebral infarction.

## Contribution

The study identifies trunk muscle mass gain as a novel predictor of balance improvement in cerebral infarction patients.

## Key findings

- Trunk muscle mass index (TMI) gain was independently associated with improved balance function.
- Skeletal muscle mass index (SMI) gain showed no significant link to balance improvement.
- Subgroup analyses revealed no significant associations, suggesting confounding factors may influence results.

## Abstract

Increased muscle mass may positively influence the recovery of balance function. In this study, we aimed to investigate the relationship between changes in muscle mass and improved balance in patients with cerebral infarction.

This study included patients with cerebral infarction aged ≥65 years. The Berg balance scale (BBS) was used to evaluate balance function upon admission and discharge.

Participants were categorized into two groups based on BBS improvement: those who achieved the minimal clinically important difference (BBS improvement group; 213 participants, 73.4%) and those who did not (no BBS improvement group; 77 participants, 26.6%). Multiple regression analyses were performed, with increase in BBS score as the primary variable of interest and gains in skeletal muscle mass index (SMI) (Model 1), trunk muscle mass index (TMI) (Model 2), and SMI and TMI (Model 3) as explanatory variables.

A total of 290 participants were analyzed. BBS gain exhibited an independent association with TMI gain (coefficient = 3.72, 95% confidence interval [CI] = 0.99-6.45, p = 0.008); however, no significant association was observed with SMI gain (coefficient = 0.03, 95% CI = −2.28 to 2.33, p = 0.983). Furthermore, in Model 3, TMI gain (coefficient = 4.28, 95% CI = 1.35-7.20, p = 0.004) was independently linked to BBS gain. However, in the subgroup analyses stratified by tertiles of rehabilitation volume, this association was not statistically significant in any subgroup.

In patients with cerebral infarction, an increase in TMI was associated with greater improvements in balance function during hospitalization. These results suggest a potential role for trunk muscle mass in supporting balance recovery; however, owing to the observational nature of the study, the findings should be interpreted with caution and viewed as hypothesis-generating. In addition, the lack of association in the subgroup analyses underscores the potential influence of confounding factors, such as the amount and content of rehabilitation, and highlights the need for future studies to control for these variables.