People who are slow walkers - however healthy - are much more likely to die from coronavirus, according to The University of Leicester scientists, Report informs.
The study found that people of normal weight who walked slower than three miles per hour were almost 2.5 times more likely to develop severe COVID and 3.75 times more likely to die from the virus than normal-weight fast walkers.
In fact, normal weight slow walkers were found to be more at risk of both severe disease and death than fast walkers with obesity.
The study of 412,596 middle-aged men and women examined how both body mass index and self-reported walking pace related to the risk of contracting severe COVID and mortality.
They used data from UK Biobank, which has medical information about hundreds of thousands of UK citizens.
It remains unclear why fast walkers are less at risk but the scientists think it is because walking quickly is linked to having a healthy heart.
Fast walkers have been shown to generally have good cardiovascular and heart health, making them more resilient to external stressors, including viral infection, but this hypothesis has not yet been established for infectious disease.
The researchers warned there were a number of limitations to their study, saying that although self-reported walking pace has been shown to be associated with cardiorespiratory fitness within UK Biobank, it is subject to possible reporting bias.
They said that given this, and the observational design, no definitive causal conclusions could be derived from their results.