Regular aerobic exercise is linked to a significantly lower risk of death from flu or pneumonia, according to US national data published yesterday in the British Journal of Sports Medicine. The study was based on 577,909 adults who had taken part in the US nationally representative National Health Interview Survey (NHIS) between 1998 and 2018.
Respondents were asked how often they did 10 or more minutes of light-, moderate- or vigorous-intensity aerobic activities, including jogging, swimming, or brisk walking. They were also asked how often they performed muscle-strengthening exercises.
Participants were classified as meeting physical activity guidelines if they reported 150 minutes or more per week of moderate-intensity aerobic physical activity and two or more sessions per week of muscle-strengthening activity.
Aerobic activity lowered risk by 36%
The researchers grouped responses into five categories: people who performed below 10 minutes per week, 10 to 149, 150 to 300, 301 to 600, or more than 600 minutes per week of moderate to vigorous physical activity; and less than 2, 2, 3, 4 to 6, or 7 or more sessions per week of muscle-strengthening activities.
During the monitoring period of 9 years, the researchers assessed 577,909 participants, of whom 81,431 died. Of those deaths, 1,516 were attributed to flu and/or pneumonia.
The authors said cardiovascular activity below the recommended goal was still inked to a lowered risk of mortality from flu and pneumonia.
"Compared with participants meeting neither guideline, those meeting both [aerobic and strength-training] guidelines had 48% lower adjusted risk of influenza and pneumonia mortality," they wrote. "Relative to no aerobic activity, 10–149, 150–300, 301–600 and >600 min/week were associated with lower risk (by 21%, 41%, 50% and 41%)."
Meeting only the aerobic activity target was associated with a 36% lower risk.
Some strength training helped
Strength training was also associated with significant risk reduction—to a point. When compared with those who did fewer than two sessions per week, participants who participated in two sessions per week had a 47% lower risk of death from flu or pneumonia. But participants who did seven or more strengthening sessions per week had a 41% higher risk of death from those causes.
Although the outcome was influenza and pneumonia mortality, the pathophysiologic principles may apply to COVID-19 and other infectious respiratory diseases.
The authors say this could be because of a number of factors, including insufficient activity classification or recall among participants, or the dynamics of blood flow caused by high-intensity exercise.
The authors aid their findings build on studies going back to the 1950s, which show that more active workers were less likely to die from flu than sedentary workers. The authors also emphasize that protective health gains were made even for adults who reported only 10 to 150 minutes of aerobic activity per week.
"Although this level is often labelled 'insufficient' because it falls below the recommended duration, it may confer health benefits relative to physical inactivity," the authors wrote.
US adults are advised to clock up at least 150 minutes per week of moderate intensity, or 75 minutes of vigorous intensity, aerobic physical activity, or an equivalent combination, plus muscle-strengthening activity of moderate or greater intensity at least twice a week.
"Although the outcome was influenza and pneumonia mortality, the pathophysiologic principles may apply to COVID-19 and other infectious respiratory diseases," the authors concluded. "This protective association may warrant additional clinical and public health efforts to decrease the prevalence of aerobic inactivity."