Muscular strength as a strong predictor of mortality, not just in the elderly

Recently grip strength has received a lot of attention for stratifying those at risk of sarcopenia and poor nutritional status¹, but multiple studies have suggested that lower limb strength testing in conjunction with hand grip can give a clearer picture of all causes of mortality and reduced functional capacity ⁷.

Meta-analysis by Jochem et al.^{3, 4} suggests that muscular strength is inversely and independently associated with death from all causes even after adjusting for cardiorespiratory fitness and other co-factors such as age, body fat, smoking and hypertension.

When looking at all-cause mortality Garcia-Hermoso and his colleagues found that those who scored in the upper quartile of grip strength had a 31% reduction in risk³, and those with higher knee extension strength had a 14% lower risk profile⁷.

Volaklis⁸ suggested poor strength measures in Peripheral Arterial Disease, certain Cancers, Renal Dysfunction, COPD and T2DM placed patients at greater risk of mortality. The authors also suggest that special attention must be afforded to cancer and heart failure patients, due to the progressive wasting nature of the conditions.

At this point, muscular strength and all-cause mortality are only associated. Studies are still being conducted to find a causal link. One theory is that decreased muscle strength and mass lead to reduced activity, which increases the risk of chronic disease, via several mechanisms.  These mechanisms include loss of coordination and balance, which can lead to falls, and reduced bone density which can increase fracture risk. Furthermore, there may be a hormonal mechanism, through skeletal muscle’s endocrine (6) function. It is suggested that muscle acts as an endocrine organ⁶, releasing hormones that act on tissue such as liver and adipose tissue facilitating the disposal of glycogen and stimulating insulin action. This is thought to help protect against low grade inflammation as well^{2, 4}.

Strength assessment can be conducted subjectively by way of manual muscle testing. This might be enough highlight potential issues, but a much more effective and objective measure is a handheld dynamometer. Once objective measures are found, Exercise Physiologists are well placed to develop effective interventions to affect muscular strength, mass and functional capacity and reducing mortality risk of being frail. At Advanced Physiotherapy, we have a private clinical gym, with a wide variety of tools and equipment to assess strength, as well as supervised Resistance Training and Pilates classes that allow us to cater to a vast spectrum of clinical patients.
 

 

References

1. Cruz-Jentoft, A., Bahat, G., Bauer, J., Boirie, Y., Bruyère, O., & Cederholm, T. et al. (2019). Sarcopenia: revised European consensus on definition and diagnosis. Age And Ageing, 48(4), 601-601. doi: 10.1093/ageing/afz046
2. Deutz, N., Ashurst, I., Ballesteros, M., Bear, D., Cruz-Jentoft, A., & Genton, L. et al. (2019). The Underappreciated Role of Low Muscle Mass in the Management of Malnutrition. Journal Of The American Medical Directors Association, 20(1), 22-27. doi: 10.1016/j.jamda.2018.11.021
3. García-Hermoso, A., Cavero-Redondo, I., Ramírez-Vélez, R., Ruiz, J., Ortega, F., Lee, D., & Martínez-Vizcaíno, V. (2018). 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. Archives Of Physical Medicine And Rehabilitation, 99(10), 2100-2113.e5. doi: 10.1016/j.apmr.2018.01.008
4. Hawkins, R., Raymond, S., Stortz, J., Horiguchi, H., Brakenridge, S., & Gardner, A. et al. (2018). Chronic Critical Illness and the Persistent Inflammation, Immunosuppression, and Catabolism Syndrome. Frontiers In Immunology, 9. doi: 10.3389/fimmu.2018.01511
5. Jochem, C., Leitzmann, M., Volaklis, K., Aune, D., & Strasser, B. (2019). Association Between Muscular Strength and Mortality in Clinical Populations: A Systematic Review and Meta-Analysis. Journal Of The American Medical Directors Association, 20(10), 1213-1223. doi: 10.1016/j.jamda.2019.05.015
6. Pedersen, B. (2010). Muscles and their myokines. Journal Of Experimental Biology, 214(2), 337-346. doi: 10.1242/jeb.048074
7. Reid, K., Naumova, E., Carabello, R., Phillips, E., & Fielding, R. (2008). Lower extremity muscle mass predicts functional performance in mobility-limited elders. The Journal Of Nutrition Health And Aging, 12(7), 493-498. doi: 10.1007/bf02982711
8. Volaklis, K., Halle, M., & Meisinger, C. (2015). Muscular strength as a strong predictor of mortality: A narrative review. European Journal Of Internal Medicine, 26(5), 303-310. doi: 10.1016/j.ejim.2015.04.013