Background:
The study aimed at examining the effects of body composition on respiratory function, muscle endurance, functional capacity, and sleep quality in healthy young adults.

Material and methods:
The study involved 59 participants, with body composition measured using Tanita DC-360, respiratory function and muscle endurance assessed via a digital spirometer, functional capacity evaluated through the 6-minute walk test, and sleep quality assessed with the Pittsburgh Sleep Quality Index.

Results:
A moderate correlation was found between the body mass index with forced vital capacity (r=0.395; p=0.002). A moderate relationship was also observed between respiratory muscle endurance and muscle mass (r=0.310; p=0.017), lean body mass (r=0.308; p=0.018), and total body water (r=0.285; p=0.045). Positive moderate correlations were found between forced vital capacity, forced expiratory volume in one second, between respiratory muscle endurance and muscle mass, lean body mass. There was a moderate relationship between body composition and functional capacity.

Conclusions:
Respiratory muscle endurance is linked to lean body mass, muscle mass, and total body water, while other respiratory functions relate to lean body mass and muscle mass. Increased fat mass and decreased muscle mass can negatively impact functional capacity. As muscle mass increases with exercise, our findings may guide future research on respiratory muscle endurance and exercise.