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Exercising when unwell: A good idea?

You’re not feeling your best. Should you exercise when unwell or opt out? Here are some tips on how to decide.
WebMD Feature
Medically Reviewed by Dr Rob Hicks

You’ve been keeping up your new exercise routine, rarely missing a day since you started it, and then, all of a sudden, you’re laid low by a cold or flu.

What should you do? Should you avoid the treadmill or forsake those Pilates classes until you feel better? Will it be hard to start again if you miss a day or two?

Exercising when unwell: Should you or shouldn’t you?

"It really depends on what the illness is and the severity of the illness," says Dr Alastair Jordan, a lecturer in sport and exercise sciences at Leeds Trinity University. "It’s acceptable to exercise if you have a sniffle, but anything worse than that, it’s probably best not to exercise."

Certainly, exercising when you have a fever should be avoided. When you exercise, you raise your body’s temperature. If you already have a high temperature and you raise it further, you can make yourself even more ill. In adults, a fever is considered to be anything above 38C (100.4F).

The neck check

A rule-of-thumb about when it is or isn’t OK to exercise is called the “neck check”. If the symptoms are above the neck – a head-cold, say – it’s OK to exercise. Anything below the neck, such as bronchitis, tightness in your chest or muscle or stomach pains, it’s not OK to exercise.

However, Dr Jordan advises against following this advice too doggedly. "The problem is, if you have sinusitis, exercise might exacerbate the condition," he says. "So even things above the neck, you still have to be quite cautious of."

What exercise can you do?

If you are experiencing dizziness, avoid resistance exercising, such as weight lifting, because your coordination is likely to be poor. "You’re actually at risk of giving yourself an injury through poor movement patterns," says Dr Jordan. "I’d strongly recommend that if you do any kind of resistance exercises, they have to be very low resistance, preferably just using your own body weight."

So press ups, sit ups, leg raises, chin ups, etc., are in. Heavy weights are out.

If you prefer to do aerobic exercises, you’ve got to keep the intensity quite low. "Aerobic exercise can actually help at the start of a cold," says Dr Jordan. "It can open up the airways, improve mucus flow and generally make you feel better because your body releases endorphins [a neurotransmitter associated with pain relief and elevated moods]."

But, Dr Jordan cautions against overdoing aerobic exercise. "If you go for a long run, you put your immune system under stress and it can’t effectively fight the infection," he says. "So if you do aerobic exercise, it has to be of a lesser intensity and not as long as what you’d normally do."

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