Israeli Study Finds Higher Muscle Mass but Lower Density in Obstructive Sleep Apnea Patients

Researchers in Israel have identified differences in muscle structure among people with obstructive sleep apnea (OSA).

A study published in the journal Sleep and Breathing showed that people with OSA have a higher muscle mass index, which reflects greater muscle area relative to height, along with lower muscle density. This suggests they may appear to have more muscle, but it is less dense and potentially less functional.

The researchers examined data from 209 adults who took part in an overnight sleep study and received chest or abdominal CT scans. Compared with a control group, those with OSA were older, more often male and heavier. They also had higher rates of hypertension, cardiovascular disease and lower oxygen levels during sleep.

The study revealed a significant association between OSA and higher muscle mass index. Lower muscle density, however, tied more closely to age and weight than to OSA itself. Greater OSA severity correlated with lower skeletal muscle density and higher skeletal muscle index, pointing to larger but less dense muscle.

Higher body mass index linked strongly to lower muscle density and higher muscle index, while older age tied strongly to lower density. People over age 60 and those with a body mass index over 30 showed much stronger associations with lower muscle density than OSA alone.

"These findings highlight that OSA is much more than a nighttime breathing disorder," said Dr. Wendy Troxel, a licensed clinical psychologist and senior behavioral scientist at RAND in Utah. She was not involved in the study but explained its results in an interview with Fox News Digital.

"Individuals with OSA may have more muscle mass, but that muscle may be less healthy because it contains more fat, which can impair strength and metabolic function," Troxel said. "This pattern overlaps with sarcopenia, a clinical condition where muscle becomes weaker and less efficient, even if muscle size doesn’t dramatically decline."

Troxel noted an association between OSA severity and muscle quality that was modest compared with risk factors like age and body mass. "[This indicates] that OSA may be one marker within a broader profile of metabolic risk," she said. "Clinically, these findings highlight that OSA is much more than a nighttime breathing disorder. It may signal underlying metabolic dysfunction affecting multiple systems, including muscle health."

Ariel Tarasiuk, a professor in the department of physiology and cell biology at Ben-Gurion University of the Negev in Israel and a co-author of the study, called the results paradoxical in an interview with Fox News Digital.

"Age and obesity appeared to have a stronger influence on muscle health than sleep apnea itself," he said. "This suggests that while sleep apnea may play a role, it is unlikely to be the primary factor driving these changes."

Patients should know sleep apnea goes beyond snoring or poor sleep and can affect overall health, including muscle function, Tarasiuk said. "Getting properly diagnosed and treated matters," he added. "CPAP therapy can make a real difference in improving breathing and sleep quality, but it’s only part of the picture."

"Maintaining a healthy weight and staying physically active are equally important for muscle health and for reducing the severity of sleep apnea," he continued. "In short, treating sleep apnea is about protecting long-term health, not just getting a better night’s sleep."

Tarasiuk stressed to clinicians that bigger muscles do not always mean healthier ones, as fat infiltration can reduce strength and performance. "This highlights the importance of looking beyond muscle size alone," he said. "Routine imaging, such as CT scans performed for other reasons, can sometimes provide additional insight into muscle quality."

"Overall, the findings point toward a more holistic approach: treating the airway while also focusing on weight, physical activity and metabolic health."

The study took place at a single center, so results may not apply to all populations, Tarasiuk noted. Researchers lacked data on lifestyle factors such as physical activity, diet, smoking or alcohol use, which affect muscle health.

"Looking ahead, larger studies across multiple centers will help confirm these findings and provide a broader picture," he said. "Future research will also focus more on outcomes that matter in real life, such as how patients respond to treatments like CPAP, and on understanding how muscle changes develop over time in people with sleep apnea."