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Too sick to exercise?

Regular exercise boosts your immune system and reduces your risk of illness. In fact, people who are deemed fit have a lower risk of contracting an upper respiratory infection than those who are mostly sedentary (note, however, that extreme exercise can actually suppress your immune system, making elite athletes more susceptible to some infections during intensive training periods, and this suppression can last between three to 24 hours). Exercise doesn’t make you completely bullet-proof though, so if you do catch a cold or get flu, caution is required. But how much caution and when does it become dangerous to exercise?


The general rule of thumb, according to Mayo Clinic’s Dr Edward Laskowski, a physical medicine and rehabilitation specialist, is that if you have the usual symptoms of a common cold, such as the sniffles, sneezing or congestion and a slightly sore throat, then you can still exercise. In fact, exercising can assist in opening up your respiratory passages and may bring some relief. But, keep the exercise mild – less than you usually do.

However, if your symptoms are below your neck and manifest as aching muscles, sore chest, hacking cough or an upset stomach, it’s best to stay away from exercising for a few days. Certainly if you have any kind of fever, you need to be extra careful. A fever is your body’s response to infection and indicates your immune system is doing its job. Your body temperature rises during exercise and if you already have a high temperature from a fever, then you could be putting yourself at unnecessary risk by contributing to the heat.


If you’ve experienced a severe illness or below-the-neck symptoms and have taken a break from your regular exercise regime, remember that you need to ease back in to it. So start slowly and allow your body time to build up to the level of intensity you’re used to.

If you don’t exercise regularly, the fact that a moderate regime can boost your immune system and reduce your risk of getting upper respiratory infections should motivate you to don your favourite gym clothes before the flu season hits this year.

References include

1 Nieman D. Moderate Exercise Improves Immunity and Decreases Illness Rates. American Journal of Lifestyle Medicine. Aug 2011;5(4):338-45
2 Nieman D, Henson D, et al. Upper respiratory tract infection is reduced in physically fit and active adults. Br J Sports Med. 2011;45:987-92
3 Gleeson M, Walsh N. The BASES Expert Statement on Exercise, Immunity and Infection. The British Association of Sport and Exercise Sciences. 2011
4 Laskowski E. Expert Answers. Exercise and illness: Work out with a cold? Mayo Clinic. Jun 2011

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