Couch Potato or Elite Athlete? A Happy Medium Keeps Colds at Bay

http://www.sciencedaily.com/releases/2012/01/120105112158.htm

ScienceDaily (Jan. 5, 2012) — Battling colds and doing (or pledging to do) more exercise are familiar activities for most of us in January. But different levels of exercise can actually significantly increase or decrease your chances of catching a respiratory infection, says Professor Mike Gleeson from Loughborough University.

While regular moderate exercise can reduce the risk of catching cold-like infections, prolonged strenuous exercise, such as marathons, can make an individual more susceptible.

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Upper- respiratory tract infections (URTIs) are acute infections that affect the nose, throat and sinuses, and include the common cold, tonsillitis, sinusitis and flu. Viruses that circulate in the environment usually cause URTIs. While we are constantly exposed to these viruses, it is the status of our immune system that determines whether we succumb to infection or not. Exercise can have both a positive and negative effect on immune function, combined with genetics and other external factors like stress, poor nutrition and lack of sleep. Collectively these factors determine an individual's susceptibility to infection.

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There is a clear take-home message from our current understanding of the link between exercise and immune function. "Moderate exercise has a positive effect on the immune system. So to keep colds at bay, a brisk daily walk should help -- it's all about finding a happy medium," said Professor Gleeson.

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