Clinical determinants of maximal aerobic capacity in patients with obstructive sleep apnea syndrome

Investigating the clinical determinants of maximal aerobic capacity in patients with obstructive sleep apnea syndrome (OSAS) may help better understand the systemic effects of the disease, improve clinical management, and predict long-term risks of cardiovascular mortality and morbidity.

This cross-sectional study aims to identify the fundamental clinical determinants of maximal aerobic capacity in patients with OSAS.

Physical and demographic characteristics and polysomnography results of 60 OSAS patients (54 M, 6 F; AHI: 30.3 ± 20.6) were recorded. We evaluated handgrip strength, inspiratory and expiratory respiratory muscle strength (MIP, MEP), the 6-min walk test (6MWT), exercise capacity (cardiopulmonary exercise test), sleep quality (Pittsburgh Sleep Quality Index, PSQI), and daytime sleepiness (Epworth Sleepiness Scale, ESS).

VO₂max was negatively correlated with age (r = -0.447, p < 0.001), BMI (r = -0.295, p = 0.023), arousal count (r = -0.374, p = 0.004), arousal index (r = -0.286, p = 0.028), and ESS score (r = -0.322, p = 0.013), and positively correlated with 6MWT distance (r = 0.380, p = 0.003). No significant associations were found between VO_2max and disease severity (AHI), nadir SpO₂, or muscle strength. In regression analysis, age (β = -0.32, p = 0.006) and arousal count (β = -0.26, p = 0.023) were independent predictors (R² = 0.441).

Aerobic capacity in OSAS is associated with age, sleep fragmentation, functional capacity, and subjective sleep parameters, but not with disease severity or nocturnal oxygenation. These findings support the multifactorial nature of aerobic capacity in OSAS.