If your New Year's resolutions involve running a marathon or some other strenuous goal, experts warn that overexerting yourself could increase your risk of catching a cold or flu this season. Your best bet: exercise in moderation.
On the table at Friday's Association for Science Education (ASE) Conference, expert Mike Gleeson of Loughborough University in the UK adds that prolonged strenuous exercise, such as training for a marathon, can make you more susceptible to illness, especially upper-respiratory tract infections (URTI) -- including colds, tonsillitis, sinusitis, and flu.
"In the weeks following a marathon, studies have reported a two- to sixfold increase in the risk of developing an upper respiratory infection," Gleeson adds. "The heavy training loads of endurance athletes make them more susceptible to URTIs and this is an issue for them as infections can mean missing training sessions or underperforming in competitions."
However, avoiding activity altogether doesn't help matters, he notes. "If you have a tendency to be a couch potato then you probably have an average risk of catching an infection -- typically two to three URTIs per year." But he adds that research shows that taking a daily brisk walk, for example, can reduce your risk of catching a cold by up to almost a third.
Word to the wise: "It's all about finding a happy medium," Gleeson says.
Another recent study published in the British Journal of Sports Medicine reports that people who are physically fit and active have fewer and milder colds. Bouts of exercise spark a temporary rise in immune system cells circulating around the body, reported the authors. Yet the levels falls back within a couple of hours, but with frequent exercise, each bout can impact the number and severity of infections.