OSAS Has an Additive Effect on COPD Muscle Weakness

COPD negatively impacts the muscles all on its own, but when combined with obstructive sleep apnea syndrome (OSAS), the problems are compounded, report Brazilian researchers who published their findings in Scientific Reports.

 They believe nocturnal oxygen levels may be to blame.

The study involved 44 patients, half of whom had isolated COPD and half of whom suffered from both COPD and OSAS. All underwent standard tests to assess muscle strength, and the researchers also examined how OSAS may be contributing to the problem. Specific results showed:

• Grip strength was significantly lower in the COPD-OSAS group, at an average of 26 kgf compared to 30 kgf in the group with isolated COPD.
• COPD-OSAS patients walked an average of 300 meters on the six-minute walk test, compared with 364 meters in those with COPD alone.
• Muscle quality loss was more strongly associated with the oxygen desaturation index than with the apnea-hypopnea index, suggesting that blood oxygen levels during sleep may underlie the additional muscle problems seen with COPD-OSAS.

“More than poor performance on the tests, the study results indicate that the magnitude of nocturnal oxygen desaturation during sleep is more strongly associated with muscle quality and functional performance than the frequency of respiratory events itself,” said study author Patricia Faria Camargo, from the cardiopulmonary physiotherapy laboratory at the Federal University of San Carlos.

She speculates that by compromising tissue oxygenation, intermittent nocturnal hypoxia may be a central pathophysiological mechanism in the loss of muscle mass and function in patients with COPD and OSAS, possibly through oxidative stress, systemic inflammation, and muscle metabolic dysfunction.

Since COPD and sleep apnea are both associated with systemic inflammation and increased oxidative stress, the combined effects of these factors may also exacerbate mitochondrial damage, compromising muscle contraction and regeneration. This leads to a cycle of progressive muscle weakening and functional limitation.

Screening COPD patients for OSAS and incorporating assessments of hypoxic burden into clinical follow-up could help identify patients at higher risk for functional impairment who could benefit from early referral to pulmonary rehabilitation. 

Highlighted in RC Buzz March 30, 2026