Slow walkers are more likely to fall seriously ill and die if they catch COVID-19, a new study has found.
It's believed people who walk quickly are likely to have better overall fitness and cardiovascular health, perhaps giving them some protection against the virus which has killed more than 2.6 million people since the start of last year.
"We know already that obesity and frailty are key risk factors for COVID-19 outcomes," said Prof Tom Yates of the University of Leicester, who led the research.
"This is the first study to show that slow walkers have a much higher risk of contracting severe COVID-19 outcomes, irrespective of their weight."
Researchers used data from more than 400,000 middle-aged volunteers enrolled in the UK Biobank, including their body-mass index (BMI), risks of contracting severe COVID-19 and dying from it, and self-reported walking pace.
"Walking pace is a central indicator of whole-body physical fitness, frailty, reserve and resilience," the study, published in the International Journal of Obesity, said.
"Self-reported walking pace consistently found to be strongly associated with cardiorespiratory fitness, cardiovascular mortality and all-cause mortality, along with being a powerful marker of longevity."
Amongst the 412,596 individuals' data analysed, the researchers found 1001 severe cases of COVID-19 and 336 deaths.
"Both obesity and self-reported walking pace are independently associated with the population level risk of severe COVID-19 and COVID-19 mortality in UK Biobank," the study found. "However, self-reported slow walkers had the highest risk regardless of their obesity status, with normal weight slow walkers having over twice the risk of severe disease and almost four times the risk of COVID-19 mortality compared to normal weight brisk walkers."
The conclusion being that if you're a slow walker, there's a good chance you don't have overall fitness - increasing your risk of severe illness or death from COVID-19, even if your weight is in the healthy range.
"With the pandemic continuing to put unprecedented strain on health care services and communities, identifying individuals at greatest risk and taking preventative measures to protect them is crucial," said Prof Yates.
"It is my view that ongoing public health and research surveillance studies should consider incorporating simple measures of physical fitness such as self-reported walking pace in addition to BMI, as potential risk predictors of COVID-19 outcomes that could ultimately enable better prevention methods that save lives."