Stronger muscles, longer lives? Study highlights benefit for older females

• A new study suggests that stronger muscles may be associated with a lower all-cause mortality in older females.
• The association was independent of activity levels, with muscle strength linked to longer life, even among females who did not meet recommended aerobic exercise guidelines.
• In particular, the study found a consistent association between grip strength and lower mortality. 

Healthcare professionals often recommend that older adults engage in regular physical activityTrusted Source to promote healthy aging and longevity.

In fact, the Physical Activity Guidelines for AmericansTrusted Source advises at least 150 minutes of moderate-intensity aerobic activity and muscle-strengthening activities at least 2 days a week for older adults. 

Physical activity can significantly help to prevent or reduce disease, extend health span, and enhance physical function. Exercise influences the drivers of biological aging and can slow aging rates, underscoring its foundational role in geroscienceTrusted Source.

As people age, they begin to lose muscle mass and strength, a condition known as sarcopenia. However, a decline in strength with aging can be substantially slowed by exercise. Maintaining strength through exercise may also be instrumental for optimal aging.

A large U.S. study of females ages 63 to 99, published in JAMA Network OPENTrusted Source, suggests that greater muscle strength is associated with a significantly lower risk of death.

The findings add to growing evidence that muscle strength is a key marker of healthy aging and may play an independent role in longevity.

The analysis included 5,472 ambulatory females enrolled in the Objective Physical Activity and Cardiovascular Health (OPACH) study, an ancillary study of the Women’s Health Initiative.

Participants had a mean age of 78.7 years, and the cohort consisted of 33.8% Black, 16.7% Hispanic, and 49.5% white individuals.

Between 2012 and 2014, the participants completed an in-home physical performance test and wore an accelerometer for 7 consecutive days to objectively measure movement and sedentary time. They were followed for an average of 8.3 years. During that time, 1,964 individuals died.

Researchers assessed muscle strength using chair-stand time and grip-strength tests.

For chair stand time, participants were timed while completing 5 consecutive sit-to-stands without using their arms, with faster times indicating greater lower-body strength. Grip strength was measured with a hand dynamometer. Individuals were divided into 4 groups based on strength levels.

The researchers found a clear inverse relationship, as higher strength was associated with lower mortality.

After adjusting for age, race and ethnicity, education, body weight, smoking, alcohol use, blood pressure, comorbidities, and other health factors, the researchers found that females in the highest grip strength group had a 33% lower risk of death compared with those in the lowest group.

Additionally, those with the fastest chair stand times had a 37% lower risk of death.

Importantly, muscle strength was associated with lower mortality, even among individuals who did not meet the recommended 150 minutes per week of aerobic activity.

Kristen Lettenberger, PT, DPT, CSCS, medical advisor at Uresta, was not surprised at the association between muscle strength and longevity:

“Muscle mass and strength as we age is important for a few reasons. One, muscles are more metabolically active, they help us manage our insulin levels and improve some of our biggest risk factors for cardiovascular disease and type 2 diabetes,” explained Lettenberger.

“Two, being strong improves our balance and mobility, reducing our risk of injury, and helps us maintain our independence. Three, a high muscle mass may also be correlated to reduced inflammation, which can aid in better mortality. Muscle is the greatest gift we can give ourselves,” she added.
 

Although both measures were associated with mortality, grip strength appeared to be a more consistent predictor.

The correlation between grip strength and chair stand performance was relatively small, suggesting the tests capture different aspects of physical function.

After extensive statistical adjustments, grip strength remained robustly associated with lower mortality across nearly all subgroups, including individuals of different ages, racial and ethnic groups, and BMI categories, as well as those with varying levels of physical activity and females who used walking aids.

After accounting for other health indicators, chair stand time showed somewhat weaker associations.

The researchers suggest that stronger muscles might be a sign of better overall health, rather than muscle strength itself being the direct cause of longevity.

Additionally, a notable finding was that strength remained protective even after objectively accounting for total daily movement and sedentary behavior.

The researchers believe that muscle quality, not just muscle mass, may be especially important as people age. Muscle strength may affect the body in different ways, including how it controls metabolism and the immune system, not just inflammation.

Previous research suggests that changes during the aging process may exacerbate muscle loss by promoting chronic low-grade inflammation, as long-term inflammation is known to cause muscle loss and increase the risk of death.

However, taking inflammation into account only slightly weakened the connection between muscle strength and longer life. This indicates that muscle strength may help people live longer for reasons beyond reducing inflammation alone.

While the findings are promising, the study was observational. This means that it cannot prove that increasing muscle strength directly reduces mortality.

Additionally, the study estimated muscle mass rather than directly measuring it, and nutritional status was not comprehensively assessed. Furthermore, the study only included females, so the results may not be generalizable to males.

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