A person's physical fitness before contracting COVID-19 appears to significantly lower their chance of ending up in the hospital or needing breathing machines, according to recent findings. However, this same fitness level did not seem to make a difference in whether someone got infected with the SARS-CoV-2 virus in the first place.
Studies involving large groups of adults, such as the "HUNT study" and the "ETHOS study," both observed this pattern. Researchers looked at thousands of Norwegian adults, dividing them into categories based on how fit they were. Those in the "fit" and "high-fit" groups showed a markedly reduced risk of being admitted to the hospital or requiring intubation compared to those deemed "least-fit" or "low-fit."
No Shield Against Initial Infection
Crucially, neither cardiorespiratory fitness nor regular physical activity appeared to affect the likelihood of contracting the SARS-CoV-2 virus. The connection between fitness and health outcomes only emerged after infection.
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This suggests that while being in good shape might not stop the virus from taking hold, it plays a substantial role in how the body fares once infected. The research pointed to a "strong correlation between fitness and hospitalization risk."
Reduced Severity Across the Board
The "ETHOS study," which focused on patients already diagnosed with COVID-19, further illuminated this. Participants were categorized into five levels of cardiorespiratory fitness (CRF).
Least-fit
Low-fit
Moderate-fit
Fit
High-fit
Patients with higher CRF levels experienced more favorable outcomes, including lower rates of hospitalization and a reduced need for mechanical ventilation. This benefit was observed even when accounting for other health issues like cardiovascular disease, diabetes, obesity, and hypertension.
The findings also indicated that for individuals with pre-existing conditions, those in the "High-Fit" category had mortality rates roughly half those in the "Low-Fit" category. This benefit was seen regardless of age, body mass index, or the presence of specific comorbidities.
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Background Context
The connection between physical activity, cardiorespiratory fitness, and the risks associated with infectious diseases has been a subject of ongoing observation. However, the specific impact of cardiorespiratory fitness on COVID-19 related outcomes, particularly in populations with varying fitness levels and pre-existing conditions, required deeper investigation. The "HUNT study" and "ETHOS study" represent efforts to clarify this relationship within the context of the recent pandemic.