Higher muscle energy with much less danger of COVID-19 hospitalization
The range of results after infection with the severe coronavirus 2 (SARS-CoV-2) with acute respiratory syndrome, which causes coronavirus disease 2019 (COVID-19), is astonishing. The reason for this extreme variety of clinical manifestations is not clear. However, cardiovascular disease, obesity, and diabetes, and other comorbidities, are associated with a higher risk of serious illness.
A new preprint research report posted on the medRxiv * server discusses the results of a study examining the relationship between increased muscle strength and hospitalization for severe COVID-19.
Muscle strength is a marker of muscle function, a critical component of health. As such, it is a powerful predictor of many pathological conditions, as well as death for any reason. This led the researchers in the current study to believe that muscle strength was independently and negatively correlated with hospitalization for COVID-19.
The study used data from the European Health, Age and Retirement Survey (SHARE), which was collected every two years from 2004 to 2017. A sample of SHARE participants answered a questionnaire between June and September 2020 as to whether they were infected with COVID-19 and whether they were hospitalized with the disease.
This group of adults is older than 50 years and comes from 27 European countries. Everyone has participated in SHARE at least once. There were 3,600 people in this group with a mean age of 69, of whom more than half were female (> 2,000). There were 83 hospital admissions for COVID-19, which was 2% of the group.
Using hospitalization as a marker for the severity of COVID-19 may have led to an overestimation of the severity of the disease, which could have been corrected by asking about the length of hospitalization or ICU admission. Second, the most recent measure of handle strength, dated two years prior to the start of the pandemic, and the occurrence of disease during this gap cannot be ruled out. Such disease states could also have affected the risk of COVID-19 hospitalization.
Third, SHARE participants who were actually hospitalized with COVID-19 at the time of the survey were typically not part of this study, nor were patients who died from COVID-19. However, they represent the most severe form of this infection. Such exclusions could explain why the researchers did not find significant associations between already established risk factors such as cardiovascular disease, respiratory disease and diabetes and COVID-19 hospitalizations.
Muscle strength and hospital risk
The researchers found that people at higher risk for hospitalization were typically older, more severe, more likely to have cardiovascular or chronic kidney disease, and with less muscle strength.
Elderly patients were 70% more likely to be hospitalized because of COVID-19, while obese patients were twice as likely. Other risk factors showed no significant associations with hospitalization for COVID-19.
However, the most recent measurement of maximum handle strength correlated closely with the risk of COVID-19 hospitalization. For each increase in grip strength by one standard deviation (SD), the likelihood of hospitalization decreased by ~ 35%.
What are the effects?
The results of this study show that physical fitness is a significant correlate of the risk of severe COVID-19 following SARS-CoV-2 infection. The measure used in this study was handgrip strength while a history of COVID-19 hospitalization was a substitute for serious illness.
The observations showed that lower muscle strength was linked to a higher risk of severe COVID-19. This is consistent with the hypothesis that muscle strength is a marker of disease severity in COVID-19.
This, in turn, is due to the important role muscle tissue plays in human health. Skeletal muscle is important for the body's movement, mediates the proper functioning of the respiratory system, and is vital for the immune response. Weak skeletal muscle is also a risk factor for metabolic stress during severe infection.
All of these relationships carry the risk of SARS-CoV-2 infection as well as severe COVID-19 infection.
Conditions associated with muscle weakness or sarcopenia, such as advanced age, chronic disease states, or cancer, have been found to increase the risk of severe COVID-19. This is also the case with respiratory functions, which are reduced in patients with sarcopenia and also in severe COVID-19. This provides indirect support for this hypothesis.
The results of the current study also agree with other recent research suggesting a close association between physical fitness and a lower risk of COVID-19 hospitalization.
The association of muscle strength with severe COVID-19 demonstrates the usefulness of hand grip strength measurements as an important factor in monitoring the disease in COVID-19 patients and in achieving a prognosis as part of a composite score.
* Important NOTE
medRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be considered conclusive, guide clinical practice / health-related behavior, or treated as established information.