Chronic obstructive pulmonary disease, commonly called COPD, is a long-term lung condition that makes breathing difficult. It usually develops after many years of exposure to harmful particles, especially cigarette smoke, air pollution, or workplace dust and chemicals.
People with COPD often experience shortness of breath, coughing, and fatigue. The disease can slowly limit a person’s ability to perform everyday activities such as walking, climbing stairs, or even getting dressed.
Another condition that affects breathing is obstructive sleep apnea syndrome, often shortened to sleep apnea or OSAS. This disorder occurs when the airway repeatedly becomes blocked during sleep.
As a result, breathing stops briefly many times throughout the night. People with sleep apnea may snore loudly, wake up frequently, or feel very sleepy during the day because their sleep is constantly interrupted.
Although these two diseases are usually discussed separately, researchers have recently discovered that when they occur together, the health effects may be much more serious. A study published in the scientific journal Scientific Reports examined how the combination of COPD and sleep apnea affects muscle strength and physical performance.
The research was conducted by scientists at the Federal University of São Carlos in Brazil. The study was led by Audrey Borghi Silva, who coordinates the university’s Cardiopulmonary Physiotherapy Laboratory. The researchers wanted to better understand how these two breathing conditions interact and how they affect patients’ daily functioning.
COPD has traditionally been viewed as a disease that mainly damages the lungs. However, doctors now understand that it can also affect the entire body.
In addition to breathing problems, COPD is often linked with muscle weakness, fatigue, and reduced physical endurance. Scientists believe these effects may be related to chronic inflammation, poor oxygen supply to tissues, and reduced physical activity.
When COPD occurs together with sleep apnea, the effects on the body may become even more severe. Doctors sometimes call this combination the “overlap syndrome.” In the new study, the researchers compared patients who had both conditions with patients who had COPD alone.
The study included 44 participants. Half of them had both COPD and sleep apnea, while the other half had only COPD. The researchers measured several aspects of the participants’ physical performance, including muscle strength and walking ability.
One important measurement was grip strength. Grip strength is widely used by scientists as a simple way to estimate overall muscle strength. It is measured by asking participants to squeeze a special device with their hand.
The results showed that patients who had both COPD and sleep apnea had weaker grip strength. On average, their grip strength was about 26 kilograms of force, while patients with only COPD reached about 30 kilograms.
The researchers also tested functional capacity using the six-minute walk test. This test measures how far a person can walk in six minutes and is commonly used to evaluate patients with heart or lung disease.
Patients who had both COPD and sleep apnea walked an average of 300 meters during the test. In comparison, those who had COPD alone walked about 364 meters.
Doctors often consider walking distances below 350 meters in this test to be a warning sign. Patients who fall below this level may face a higher risk of hospitalization and even death. Because the group with both conditions walked much shorter distances, the results suggest that having both diseases significantly worsens physical ability.
To better understand why this happens, the researchers examined different measures of sleep apnea severity. One commonly used measure is the Apnea-Hypopnea Index, or AHI. This number shows how many times breathing stops or becomes shallow during sleep.
However, the researchers discovered that another measure seemed even more important. This measurement is called the Oxygen Desaturation Index, or ODI. The ODI tracks how often oxygen levels in the blood drop during sleep.
The study found that muscle weakness was more strongly linked with the number of oxygen drops during sleep than with the number of breathing interruptions. This finding suggests that repeated drops in oxygen levels may play a major role in damaging muscles.
According to the researchers, low oxygen during sleep may harm muscle tissue through several biological processes. These include increased oxidative stress, widespread inflammation in the body, and problems with how muscle cells produce energy. Over time, these effects can weaken muscles and reduce a person’s physical abilities.
Patricia Faria Camargo, the principal investigator of the study, explained that both COPD and sleep apnea can cause inflammation and oxidative stress even when they occur alone.
When the two diseases appear together, the damage may become worse. This may affect mitochondria, which are structures inside cells that produce energy. When mitochondria are damaged, muscles may not contract and repair themselves properly.
This creates a harmful cycle in which patients gradually lose muscle strength and become less physically active. Reduced activity can then lead to further muscle loss and worsening health.
The researchers emphasize that their findings highlight the importance of screening COPD patients for sleep apnea. Many patients may not realize they have sleep apnea, especially if they sleep alone and are unaware of breathing interruptions during the night.
Identifying sleep apnea early could help doctors provide treatments that improve oxygen levels during sleep. One common treatment is a device called continuous positive airway pressure, or CPAP. This machine keeps the airway open by delivering gentle air pressure through a mask during sleep.
Managing COPD also involves several strategies. Although the disease cannot be completely cured, its progression can be slowed through proper treatment. Doctors often recommend quitting smoking, using prescribed medications, exercising regularly, and maintaining a balanced diet.
Lifestyle changes can also help reduce the effects of sleep apnea. Losing excess weight, avoiding alcohol before bedtime, and maintaining good sleep habits can improve nighttime breathing.
Overall, this study provides important insight into how two common breathing disorders can interact in the body. The results suggest that poor oxygen levels during sleep may play a central role in weakening muscles and reducing physical performance in patients with both COPD and sleep apnea.
From a scientific perspective, the findings highlight the need for a more integrated approach to treating chronic respiratory diseases. Instead of focusing only on lung function, doctors may need to consider sleep quality, oxygen levels, and muscle health as part of a broader treatment plan.
However, the study also has limitations. The number of participants was relatively small, and larger studies will be needed to confirm the results. Future research may also explore whether treating sleep apnea earlier can prevent muscle weakness and improve long-term outcomes for COPD patients.
Even with these limitations, the study offers an important message for both doctors and patients. Paying attention to sleep quality and oxygen levels may help improve overall health and quality of life for people living with chronic lung disease.
If you care about sleep health, please read studies about foods that help people sleep better, and Keto diet could improve cognitive function in people with sleep loss.
For more health information, please see recent studies about the natural supplements for sound sleep, and how your diet can improve sleep quality.
Copyright © 2026 Knowridge Science Report. All rights reserved.
