If your fitness regime has been thrown off course by a bout of flu, a cold or the dreaded norovirus, you are certainly not alone. But how, in that sluggish post-viral period, do you gauge whether it is safe to start exercising again?
Your resting heart rate can be a good indicator of whether exercise is appropriate — providing you know what it is when you are 100% well. “Elite athletes check their resting heart rate daily,” says Dr Mark Wotherspoon, a sports physician with the English Institute of Sport. “If the resting level is 10 beats per minute above normal, this would be an indicator not to train.”
For the rest of us, the nature — and location — of our symptoms are an important determinant of whether we should don our slippers or our running shoes. “We differentiate between ‘above the neck’ symptoms, such as a runny or stuffy nose, watery eyes or a mild sore throat,” says Wotherspoon, “and ‘below the neck’ ones, such as a cough, a congested or tight chest, an upset stomach, muscle aches or fever.” If your symptoms are above the neck and you feel OK, a light workout is fine.
Research from Ball State University in Indiana found that infecting people with a mild cold virus did not affect their ability to exercise moderately. The infected people’s lung capacity was the same as that of healthy people, and running on a treadmill for 15 minutes felt no harder to the infected people.
Is there any truth in the old “sweating out a cold” adage? “Bringing your body temperature up is a way of fighting a virus,” says Dr Alex Nieper, club doctor for Chelsea Football Club. “But keep the activity light to moderate — and brief.”
Research from the Common Cold Centre at Cardiff University in the United Kingdom shows that symptoms normally last around a week — though in about 25% of cases they can linger for up to 14 days.
“Hard exercise compromises the immune system, allowing a virus to strengthen its hold,” says Nieper. “The body is already under stress in fighting the infection, so piling on additional stress through vigorous exercise is counterproductive.” Studies have found that a long, hard workout can lower immunity for up to nine hours.
If your symptoms are below the neck, give your workout a miss regardless of how you feel or how much you think you need it. Exercising with major cold symptoms, particularly a fever, will prolong your illness and can be dangerous.
“A fever is an indication that your body is fighting a virus,” explains Ron Eccles, director of the Common Cold Centre. “If you are feverish or feeling really rough, then don’t force yourself to exercise as you may faint or, in very rare cases, cause some damage to your heart.”
Eccles is referring to a heart condition called myocarditis, which can result from overexerting yourself when you have a virus. It can cause shortness of breath, heart arrhythmias and, in extreme cases, sudden cardiac death.
Stopping exercising for up to a fortnight can be tough for fitness fanatics or those training for a specific event with a looming deadline, but Wotherspoon says it is important not to panic. “The quality of your training is at least as important as the quantity,” he says. “Training when you’re not 100% well isn’t going to give you that quality.”
It is important to return to exercise with caution. Monitor how you feel, make sure you stay well hydrated (particularly if you have had a stomach bug), avoid getting wet and cold and look out for telltale signs that you are overdoing it, such as a workout feeling harder than it should, shortness of breath, weakness or dizziness.
“From a sports medicine point of view, there are no specific signals that you’re ready to return,” says Nieper. “Once your symptoms have gone, try a gentle 10minute workout and see how it feels. If that’s OK, gradually increase the challenge the next day, and again the day after. If you’re still feeling fine, you can gradually work your way back to where you were.”
But, he warns, “don’t try to make up for lost time. Push too hard, too soon, and you might end up back where you started.” —