Instead of approaching COVID with the mindset of ‘what doesn’t kill you makes you stronger,’ what if we used ‘become strong first so you don’t have to worry about being killed?’
A bit of a mouthful — I need to work on the exact wording — but the principle remains.
A new study concluded, “muscle strength and mass assessed upon hospital admission are predictors of length of stay in patients with moderate to severe COVID-19.” Basically, muscle mass and strength were protective effects, reducing the length of stay in a hospital due to COVID-19.
Whenever health claims are made, it is important to understand the details. What are the characteristics of the population being tested (e.g. age, comorbidities, location, etc.)? What is the magnitude of difference (i.e. how much stronger)? Were other variables at play?
As a researcher and healthcare provider, I can help answer those questions, assisting you with applying this information to the real world.
Who was the study conducted on?
All patients included in the study were at least 18 years old, COVID positive, and hospitalized due to respiratory distress. The study was conducted from March 2020 to October 2020, meaning the vaccine was not yet available.
This is a key point.
These results may be irrelevant for vaccinated individuals — no added benefit of muscle mass and strength — or there may be a compound effect. I would presume the latter but we don’t have the research to draw firm conclusions.
How did they measure strength and muscle mass?
The researchers measured grip strength and quadriceps muscle mass via ultrasound imaging. Both targets make sense based on current research.
Handgrip strength has been associated with many health outcomes, including depression, cognitive function, suicidal ideation, mobility limitations, falls, cardiovascular disease, diabetes, renal outcomes, osteoporotic factors, multimorbidity, and mortality (again, harder to kill).
A 2021 study found higher handgrip values are associated with a minor reduction in mortality risk in the general population; cardiovascular death in mixed populations (e.g., diabetes, general, and other conditions), and incidence of disability. Handgrip strength may be an indicator of overall health and strength.
As for the quadriceps, it is one of the most important muscles for function and assessing mortality. Research suggests quad strength is a primary predictor of mortality. Our muscle size is directly correlated with our strength. It is not the sole indicator, but it plays a role. The quadriceps is a primary muscle for walking, squatting, and other vital tasks.
While both of these markers are for individual body regions — hands, forearms, and upper legs— they are good markers for total body strength and muscle mass.
What was the outcome of the study?
The primary research question was whether strength and muscle mass influence the length of hospital stays resulting from COVID-19. The researchers ranked patients by their handgrip strength and quadriceps size into sex-specific tertiles. Then it became a comparison game.
Highest tertile (High) versus the combined mid and lowest tertiles (High vs. Other)
Lowest tertile (Low) versus the combined mid and highest tertiles (Low vs. Other)
In total, 186 patients met the inclusion criteria, with 174 surviving COVID-19. If you want a better picture of the demographics of the patients (average age, BMI, comorbidities, etc.) then check out table 1 in the study.
Were the results meaningful?
This question is rarely addressed in mass media articles. When reporters don’t understand statistics and home-in on headlines, we are left with misinformation.
This study found significant differences between groups, but significance simply means the statistics show the difference is likely true, not due to error or chance.
The strongest patients stayed in the hospital 7.5 days on average compared to 9.2 days for the rest. Patients with the lowest muscle mass stayed in the hospital 10.8 days on average compared to 7.7 days for the others. Not a large difference in days, but an indicator that the severity of the symptoms and their impact differed amongst the groups.
With the small sample size, it is important to note the range of values is great. On several occasions, weaker patients left the hospital sooner. Same for the amount of muscle mass. There are too many variables to boil down the risk to a single factor. The human body is complex. Life is complex.
But if we are playing the odds and aiming to stack the deck in our favor, building muscle and strength is likely in our interest.
Final thoughts
This is not the first study to highlight the importance of muscle mass. Muscle is vital for strength and metabolic health, playing a direct role in glucose metabolism and metabolic rate. We can build muscle for aesthetics, but that is not its primary purpose.
Building muscle and strength requires discipline and effort, but it is attainable at any age. Studies have shown elderly and very elderly individuals are able to build muscle and strength with 2–3 sessions per week.
This study didn’t directly address mortality, looking at hospital length instead, but the outcomes are related. You don’t need to have bulging muscles and the ability to deadlift 500 pounds to be healthy — there is no specific threshold for health — but adding moderate to high-intensity resistance training to your routine will likely be beneficial.
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