Muscle Strength as an Indicator of Longevity

By Eduardo André

Exercise Physiologist

In recent years, the view of muscle strength has changed, going beyond what it is as a mechanical property. It is undoubtedly fundamental to functionality, with its visible expression in physical fitness, but it is also fundamental in promoting health and longevity. A systematic review and meta-analysis published in the Archives of Physical Medicine and Rehabilitation in 2018, which included data from approximately 2 million people, reinforces the following idea: greater expression of muscle strength is associated with a lower risk of death from all causes.

Based on this article, I propose that you reflect on three key ideas presented by the authors. In my opinion, these reflect the most impactful aspects of the article in relation to the topic of muscle strength and longevity.

1. Muscle strength beyond the obvious

The expression of muscle strength depends not only on muscular characteristics, but also on neural factors. That's why it's more appropriate to talk about neuromuscular strength. With advancing age, adaptations occur that compromise this function: in the muscle, there is some replacement, albeit progressive, of contractile tissue by fat and connective tissue; in the nervous system, there is less capacity for motor recruitment and efficient innervation of muscle fibres. Together, these alterations significantly reduce the expression of neuromuscular strength and, with it, functional autonomy and the physiological reserve necessary for healthy ageing.

In the aforementioned meta-analysis, García-Hermoso and colleagues (2018) observed that adults with high levels of handgrip strength had a 31 per cent lower risk of mortality compared to those with lower levels of strength. This association was slightly more pronounced in women.

The researchers also assessed lower limb strength. Using the knee extension test, they observed that people with higher levels of strength had, similarly to the grip test, a lower risk of mortality (14 per cent).

Practical implication: muscle strength is a robust predictor of longevity and should be regularly assessed and trained.

2. Simple tests with impactful results

Handgrip and knee extension tests are easy to apply, non-invasive and inexpensive. They should be used in different contexts as a form of functional screening, risk of dependency or frailty. Their use in a training context (e.g. gymnasium) can be used as a criterion for prescribing exercise, simultaneously serving as a means of diagnosis and intervention.

Fun fact: Loss of muscle strength has been associated with chronic inflammation, mitochondrial dysfunction and changes in lipid metabolism, which may explain part of the impact on general health, and longevity in particular.

3. Muscular strength in women: a question of biological vulnerability?

Some of the studies included in this review suggest that the loss of muscle strength may be more pronounced in women. Some of the hypotheses proposed for this phenomenon include lower absolute muscle mass, hormonal changes in the post-menopause and closer proximity to the functional threshold of dependence.

Message: preserving and increasing muscle strength at a younger age can be even more relevant in the case of female longevity.

Conclusion

It's unequivocal: muscle strength has an impact on functionality, quality of life, health and longevity. As a trainable physical quality and a relevant clinical marker, it should be promoted from a young age. The most effective way to do this is through resistance training - commonly known as weight training - adjusted to the characteristics and needs of each person. By acting preventively and respecting this individuality, as well as the neural, muscular, joint and hormonal characteristics of each stage of life, it becomes possible to preserve more muscle mass and slow down the decline in neuromuscular strength. Thus, its progressive loss, common to the ageing process, although not avoidable, can be combated with adequate, regular and supervised training.

Message: May the force be with you - it's never too late to start.

Main reference:

García-Hermoso A, Cavero-Redondo I, Ramírez-Vélez R, et al. Muscular Strength as a Predictor of All-Cause Mortality in an Apparently Healthy Population: A Systematic Review and Meta-Analysis of Data From Approximately 2 Million Men and Women. Arch Phys Med Rehabil. 2018;99(10):2100-2113.