Taking regular, moderate exercise cuts the risk of colds,according to a study in the American Journal of Medicine.

A trial of the effect of exercise in post-menopausal women found up to a three-fold reduced risk of cold in those who did more physical activity with the ability to ward off colds getting stronger over time. Though the Seattle research team advised 30 to 45 minutes of moderate daily exercise could in some cases be overdoing and may weaken the immune system. .

Half of 115 previously sedentary, overweight women who had gone through the menopause were asked to do moderate aerobic exercise for 45 minutes five times a week.

The other half attended a weekly stretching class.

The women in the exercise group chose to do brisk walking either in the gym or at home, and during the 12 month study, those in the non-exercise group had twice as many colds as those who increased their physical activity. The effect was seen despite the fact that the women in the exercise group only averaged 30 minutes of exercise five days a week.

The improved immune function was greatest in the last three months of the study, where those who didn't do exercise had a three-fold increased risk of colds, additionally the women who exercised also had lost a significant amount of weight and total body fat.

The researchers said previous research had shown exercise could increase levels of leukocytes, a type of white blood cell that helps fight infection.

Risk of upper respiratory infection, however, was not different between the two groups but more women in the non-exercise group had a flu jab which could have affected the results.

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