Muscle Loss Infection Risk: A Study Links Weak Muscles to Illness

Muscles do more than move the body. They may help defend it. A new study following more than 458,000 adults in the United Kingdom found that people with sarcopenia, the age-related decline of muscle mass and strength, faced a 34% higher risk of infection over roughly a decade. The finding puts muscle loss infection risk in front of anyone rethinking what counts as an immune-health habit.

The research, published in the journal MedScience, was led by investigators at Central South University in Changsha, China. The team drew on the UK Biobank, a large medical database tracking about half a million volunteers. Participants were sorted into three groups, no sarcopenia, pre-sarcopenia and confirmed sarcopenia, based on lean mass adjusted for body mass index. The researchers then tracked hospital records and death registries for a median of 12.5 years, counting infections including sepsis and respiratory, urinary tract, skin and soft tissue illness.

Compared with people without sarcopenia, those with pre-sarcopenia carried an 18% higher infection risk, and people with confirmed sarcopenia faced a risk roughly a third higher. The pattern held even after the team adjusted for age, sex, socioeconomic status, smoking status, alcohol use and physical inactivity, according to the study.

Why weak muscles may matter for immunity

The study is observational, so it shows the two move together without proving that losing muscle causes infections. Study co-author Jinbo Chen said the results support the concept that skeletal muscle health is closely tied to immune resilience and infection susceptibility. Chronic inflammation, poor nutrition and weakened immune responses that often accompany sarcopenia are possible explanations, the researchers reported.

One possible mechanism is chemical: scientists noted that muscles may release molecules that help regulate immune responses, which would explain why shrinking muscle mass leaves the body less defended. That dynamic is the core of the muscle loss infection risk story. Another route is behavioral. Elizabeth Landsverk, a geriatrician quoted in the Health.com report, pointed to a chain reaction that may link the two: sarcopenia raises the risk of falls, falls lead to broken bones and lost mobility, and hospital or long-term-care stays raise exposure to infection. The muscle-infection link may run through injury and immobility as much as through immunity itself.

Elizabeth Dulaney-Cripe, a board-certified orthopedic surgeon and integrative medicine physician at Valivera Health, told Health.com the study backs a suspicion clinicians had long held without strong evidence: that people with muscle loss face a higher risk of infectious disease. She praised the prospective design, which assessed muscle first and followed people forward, as more reliable than studies that look backward through old records.

Spotting early decline matters because muscle loss creeps in quietly. An expert cited by Newsweek listed warning signs: taking longer to climb stairs, struggling to open jars or carry luggage, walking more slowly, and finding it tougher to get out of a chair without using the arms. Any of these can be an early signal to act.

How to protect muscle as the years add up

Sarcopenia is common, affecting an estimated 10% to 16% of older adults worldwide. In the study data, younger adults with early muscle loss were hit hardest, a hint that premature decline may signal deeper health problems rather than simple aging.

The advice from physicians is straightforward. About two full-body strength sessions a week, using bands, light weights or bodyweight moves, can help preserve muscle after middle age. Dulaney-Cripe also suggested looking for everyday ways to load the bones and joints, such as taking the stairs instead of the elevator, and adding weight-bearing and resistance work three days a week.

Landsverk added that it is never too late to start, noting that the frailest adults often gain the most from physical activity or therapy. Enjoyable movement counts: dancing, walking, aqua aerobics and tennis all count as exercise.

For now, the message from the research is practical rather than alarming. Muscle strength is not about performance alone. With fresh evidence tying it to infection risk, keeping lean mass looks like a basic health habit, one worth the same attention given to sleep or diet.

Health.com has the full report: Losing Muscle as You Age May Be Linked to a Higher Risk of Infection, According to Research. The underlying study appeared in MedScience: Association of sarcopenia with the long-term risk of overall infections and infectious diseases.