[Sportschosun Reporter Jang Jong-ho] A domestic study has found that restless legs syndrome, which causes discomfort in the legs at night and disrupts sleep, is significantly associated with reduced muscle mass.
A research team led by Professor Bae Hee-won of the Department of Neurology at Inje University Ilsan Paik Hospital and Professor Joo Eun-yeon of the Department of Neurology at Samsung Seoul Hospital analyzed body composition tests and polysomnography results from 5,752 adults. The team said that men with less muscle mass tended to face a significantly higher risk of developing restless legs syndrome. The study was published in the latest issue of Frontiers in Neurology, an SCI-level international journal in the field of neurology.
Restless legs syndrome is a neurological disorder in which unpleasant sensations occur in the legs during rest, usually in the evening or at night, along with an urge to move them for relief. Patients often complain of tingling, pain, or strange sensations such as insects crawling on the skin. If symptoms persist, the condition can lead to chronic insomnia and a reduced quality of life.
The study found that the overall prevalence was higher in women, at 6.6%, than in men, at 2.9%. However, the link with muscle mass was clear only in men. In particular, men with sarcopenia had a 8.7% rate of restless legs syndrome, about 2.7 times higher than the 3.2% seen in men with normal muscle mass. Periodic limb movements during sleep were also about 1.7 times more frequent.
The researchers also confirmed a relationship between muscle-related indicators and disease risk. As the Skeletal Muscle Index, or SMI, which shows how much muscle mass a person has relative to height, decreased, the risk of restless legs syndrome rose by 6.5%. The Fat-Free Mass Index, or FFMI, which reflects the amount of muscle, bone, water and other lean components, also showed a significant association, rising by 2.5% as it decreased. By contrast, men with sufficient muscle mass had a significantly lower risk of restless legs syndrome. In particular, men with a higher Skeletal Muscle Index were found to have about a 20% lower risk of developing the condition.
This suggests that even at the same body weight, a lower muscle-to-fat ratio and a higher body fat ratio may increase disease risk, while sufficient muscle mass may have a protective effect.
The team pointed to several possible mechanisms through which muscle loss may affect the onset of restless legs syndrome, including reduced oxygen delivery to peripheral tissues, a decline in muscle-derived anti-inflammatory substances known as myokines, and changes in the dopamine nervous system caused by increased oxidative stress.
In men especially, sleep deprivation can lead to lower testosterone levels and muscle loss, which in turn worsens sleep quality. This creates a vicious cycle, suggesting that the condition may be linked to a complex physiological structure in which muscle, sleep and nervous system function influence one another.
Professor Bae Hee-won of the Department of Neurology at Ilsan Paik Hospital said, "This study shows that restless legs syndrome may be closely linked not only to neurological symptoms but also to muscle condition." He added, "In men in particular, reduced muscle mass may be an important risk factor, so active management that combines strength training and aerobic exercise could be helpful."
He added, "If discomfort in the legs while resting, relief with movement, or unusual sensations that worsen at night continue, it is important not to dismiss them as simple fatigue and to consult a neurologist."
The study is significant because it was a large-scale analysis that simultaneously conducted polysomnography and body composition testing, confirming a meaningful association between reduced muscle mass and restless legs syndrome.
Jang Jong-ho, bellho@sportschosun.com
