New research indicates strength and muscle mass may reduce the severity of COVID-19 infections

Building muscle strength and mass may offer more than a physical armour for the human body. Recent research has indicated that strength and muscle mass may also offer significant immune health benefits, protecting individuals from severe bouts of COVID-19 infection.

As the COVID-19 pandemic continues to unfold, much has been reported on the dangers associated with certain co-morbidities, such as diabetes, hypertension and obesity. These have served as predictors of hospital admission, intensive care, the need for respiratory support such as the use of a ventilator, and even death in the most severe cases.

Two recent studies investigated a number of potential preventative factors in COVID-19 patients — common features associated with milder infections and shorter hospital stays. The results indicated a strong and inverse correlation between strength and muscle mass, and the length and seriousness of hospital admissions associated with COVID-19.

Put more simply, those who exhibited greater strength and muscle mass either avoided hospital admission, or saw less severe infection and significantly shorter hospital stays.

The research

Gil, S. et al., (2021) analysed data from 3,600 adults in the first study, with 316 confirmed with severe infection and 83 hospitalised due to COVID-19.

The researchers used different measures of handgrip strength as an indicator of patient strength and took cross sectional measurements of the thigh muscle as indicators of muscle mass.

Kara, O. et al (2021) classified 312 patients (140 Female and 172 Male) into mild, moderate and severe disease groups in the second study. The researchers also observed cough, fever, shortness of breath, hypertension, obesity, cardiovascular disease (CVD) and chronic obstructive pulmonary disease (COPD) and took measurements of absolute grip strength across groups.

The results

Results from the first study showed that length of stay was shorter for the strongest patients, by almost two days. The authors also found an association between the size of the thigh muscle and hospital stay, with patients having a larger cross-sectional area of the muscle seeing shorter hospital stays by more than three days.

In the second study, absolute grip strength values were lowest in the severe group and highest in the less severe cases, with strength shown to be an independent and reliable predictor for severe COVID-19 disease.

The researchers observed the association, even after controlling for established risk factors for severe COVID-19. This suggests that low muscle strength was a stable predictor for COVID-19 hospitalisation, independent of older age and other health-related factors such as obesity, cardiovascular disease, respiratory disease and diabetes.

The authors reflected on the association between muscle strength and COVID-19 severity by pointing to the essential role of muscle in health and disease. Skeletal muscle weakness has been shown to affect the motor and respiratory function and has been linked to poor immune response and metabolic stress when facing acute infection.

This highlights the importance not just of physical fitness for our immune health, but more specifically resistance training and the goal of building strength and muscle mass to prevent the serious health effects associated with COVID-19 infection.

As the COVID-19 pandemic continues to unfold and with much of the country still in lockdown and many gyms unable to open to the public, this research highlights the importance of finding other avenues to strength and resistance training in the interim. And when gyms become accessible again, all trainees are encouraged to continue on their fitness journeys with a focus on building strength and muscle mass.

Journal references:

Gil, S. et al., (2021). Muscle Strength and Muscle Mass as {Predictors of Hospital Length of Stay in Patients with Moderate to Severe COVID-19: A Prospective Observational Study. medRxiv.

Kara, O. et al (2021). Grip strength as a predictor of disease severity in hospitalised COVID-19 patients. The Journal of Cardiopulmonary and acute care.

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