Muscle weakness could be the new smoking

Since everyone ages at different rates, two 50-year-olds, for instance, despite living the same number of years, may have different biological ages, meaning that a variety of intrinsic and extrinsic factors have caused them to age at different paces, with different levels of disease and mortality risks. Lifestyle choices, such as diet or smoking, together with illness, contribute to accelerating biological age often well beyond one’s chronological age. Now, a team of researchers from the University of Michigan has found for the first time that muscle weakness marked by grip strength – a proxy for overall strength capacity – is associated with accelerated biological age.

The scientists modelled the relationship between biological age and grip strength of 1,274 middle-aged and older adults using three “age acceleration clocks” based on DNA methylation, which were originally designed to provide a molecular biomarker and estimator of the pace of aging in various health-related conditions, such as diabetes, cancer, cardiovascular disease, Alzheimer’s disease, or physical disability.

The analysis revealed that both older men and women showed a significant association between lower grip strength and biological age acceleration. “We’ve known that muscular strength is a predictor of longevity, and that weakness is a powerful indicator of disease and mortality, but, for the first time, we have found strong evidence of a biological link between muscle weakness and actual acceleration in biological age,” said study lead author Mark Peterson, an associate professor of Physical Medicine and Rehabilitation at the University of Michigan.

“This suggests that if you maintain your muscle strength across the lifespan, you may be able to protect against many common age-related diseases. We know that smoking, for example, can be a powerful predictor of disease and mortality, but now we know that muscle weakness could be the new smoking.”

Previous research has shown that low grip strength is an extremely strong predictor of adverse health effects, such as cardiovascular events. This evidence, coupled with the new study’s recent findings, could help clinicians adopt the use of grip strength as a method of screening individuals for future risk of functional decline, chronic disease, and even early mortality.

“Screening for grip strength would allow for the opportunity to design interventions to delay or prevent the onset or progression of these adverse ‘age-related’ health events,” Peterson explained. “We have been pushing for clinicians to start using grip strength in their clinics and only in geriatrics has this sort of been incorporated. However, not many people are using this, even though we’ve seen hundreds of publications showing that grip strength is a really good measure of health.”

Further research is needed to better understand the connection between grip strength and age acceleration, such as how inflammatory conditions contribute to age-related weakness and mortality. Moreover, scientists should also investigate how lifestyle and behavioral factors, such as diet or physical activity, could affect grip strength and thus age acceleration. “Healthy dietary habits are very important, but I think regular exercise is the most critical thing that somebody can do to preserve health across the lifespan,” Peterson concluded.

The study is published in the Journal of Cachexia, Sarcopenia, and Muscle.

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By Andrei Ionescu, Earth.com Staff Writer

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