Distinct contributions of muscle mass and strength stratified by nutritional status to physical activity in patients with chronic obstructive pulmonary disease.

Background: Physical activity is one of the most important prognostic factors for patients with chronic obstructive pulmonary disease (COPD). Physical activity correlates significantly with skeletal muscle mass and strength. Pulmonary rehabilitation has been conducted to improve physical activity, but its effectiveness has been inconsistent. Nutritional status is also related to physical activity in patients with COPD. The relationships between skeletal muscle mass, strength, and nutritional status evaluated using the Mini Nutritional Assessment Short Form (MNA-SF) were investigated. How nutritional status alters the relationships between physical activity, exercise capacity, skeletal muscle mass, and strength was also investigated.

Methods: This retrospective, cross-sectional study enrolled 81 outpatients with COPD. In all patients, physical activity, exercise capacity, body composition assessment, and MNA-SF were assessed. The relationships between physical activity, exercise capacity, skeletal muscle mass, and strength were examined according to the MNA-SF.

Results: The MNA-SF high group had significantly higher skeletal muscle mass than the MNA-SF low group when skeletal muscle strength was the covariate. In the MNA-SF low group, physical activity positively correlated with skeletal muscle mass. In the MNA-SF high group, physical activity positively correlated with skeletal muscle strength.

Conclusions: This study showed that the nutritional status of patients with COPD alters the relationship between physical activity and skeletal muscle mass or strength. Optimizing rehabilitation with nutrition interventions according to nutritional status might improve physical activity in patients with COPD.