As people age, they often experience a gradual decline in muscle mass, known as sarcopenia, which can lead to frailty, increased risk of falls, and fractures. This condition typically begins around age 30, with individuals losing approximately 3 to 5 percent of their muscle every decade, though symptoms often become noticeable after age 60. Beyond the well-documented physical limitations associated with sarcopenia, recent research has identified a potentially critical link between muscle loss and increased susceptibility to infections.

A large-scale study involving over 458,000 middle-aged adults in the U.K. Biobank examined the relationship between muscle health and infection risk. Participants, aged 40 to 69, were classified into categories of no sarcopenia, pre-sarcopenia (characterized by low muscle mass alone), or sarcopenia (combining low muscle mass with reduced muscle strength and performance). The analysis found that individuals with either pre-sarcopenia or sarcopenia had a higher likelihood of developing infections, particularly respiratory infections and sepsis, a severe reaction to infection or injury. Urinary tract and skin infections were also more common among those with diminished muscle health.

The study’s co-author Jinbo Chen of Xiangya Hospital noted that these findings reinforce the connection between skeletal muscle condition and immune system resilience. While the exact mechanisms remain uncertain, researchers suggest several underlying factors. People with sarcopenia often contend with chronic low-grade inflammation, nutritional deficiencies, and frailty, all of which may impair immune function and compromise the body’s ability to fight infections. The presence of systemic chronic inflammation, marked by elevated pro-inflammatory markers, may particularly exacerbate vulnerability to infectious diseases.

Although the study controlled for variables such as age, socioeconomic status, and other health conditions, it remains unclear whether muscle loss directly causes higher infection rates or if infections contribute to muscle deterioration. The research was limited by muscle assessments conducted at a single point in time, leaving the impact of muscle changes over time on infection risk undetermined.

Experts emphasize the importance of further longitudinal studies to clarify these relationships and to explore whether interventions like resistance training or dietary modifications could reduce infection risk. Previous research has shown that resistance training can improve immune function and reduce inflammation, although its effect on infection rates has yet to be firmly established.

In the meantime, health professionals recommend regular exercise to help preserve muscle mass and strengthen immune defenses. The U.S. Centers for Disease Control and Prevention advises adults to engage in two full-body strength-training sessions per week. Muscle-building efforts remain effective even in older adults, with studies demonstrating improvements in muscle strength and physical function in individuals aged 75 and above.

Maintaining muscle strength is one part of a broader strategy to support health in aging, which also includes vaccinations, hygiene practices, and managing chronic health conditions to reduce infection risks.