London, Oct. 27: Half an hour’s exercise a day cuts the risks of catching colds in half, a new trial suggests.
Brisk walking is all that is needed, and the longer you continue to exercise daily the greater the benefit.
The trial recruited 115 older women from Washington. All were sedentary and either overweight or obese. For a year they were asked either to exercise daily or take part in a 45-minute stretching class once a week.
The women were randomly allocated to one or other of these groups. Every quarter they filled in questionnaires regarding whether they had suffered colds or other upper respiratory infections in the previous three months.
The results, published in The American Journal of Medicine, show that the daily exercise group had only half as many colds as the weekly stretch-class group. Over the final three months of the study the gap was even wider, with the stretchers suffering three times as many colds as the exercisers.
“This adds another good reason to put exercise on your to-do list” said Cornelia Ulrich, the paper’s senior author.
But moderation was the key. Other studies had shown that excessive exercise could increase the risk of colds. She said that the likeliest cause of the benefit, if it proved to be real, was the enhancement of the immune system.
“It has been shown that just a 30-minute walk can increase levels of leucocytes, which are part of the family of immune cells that fight infection,” she said.