It's typical: you've been training religiously for months and all of sudden you get a cold or a bug. So do you continue training or rest up until you've got your strength back?
According to Dr Ross Tucker his advice is to rather rest your body and let it fight the bug without adding extra stress of strenuous exercise. It's good advice, considering if you have a viral infection, exercise literally could kill you.
"It's dangerous to exercise if you have influenza because a viral infection can very easily move to the heart muscle when you do strenuous activity (any stress can cause it and exercise counts as a stress). When this happens, you develop something called myocarditis, an infection of the heart muscle, which is easily fatal. Many runners have died as a result of this condition. So when you have flu, it's extremely dangerous to train," he said.
The 'neck test'
He suggested using what's known as the 'neck test' to check if you are healthy enough to exercise.
"If your symptoms are above the neck (stuffy nose, headaches, a bit of congestion, slightly sore throat), then it's usually okay to do a bit of exercise, but at a substantially reduced intensity and duration. In other words, if your training programme says to do 60 minutes of hard running followed by gym - forget that and rather do 20 minutes of running and no gym.
"If your symptoms are below the neck - sore joints, aching muscles, general fatigue, chest hurting, then under no circumstances should you exercise at all. It could be very, very risky, and it's not worth it. In this case, stay in and spend your energy fighting off the flu," he urged.
Rest is still best
However, while the 'neck test' is advised by most fitness guru's, Tucker admitted he's still more partial to advising people to rest and not exercise at all when they're sick.
"The reason is that being sick is another stress on the body and you need to deal with it, not add exercise to double that stress. So even though it may be safe to exercise when sick under some circumstances, I'm not convinced that it's the best in the long term, simply because it will delay your complete recovery.
"So two days off now may end up saving a forced one week later, if you follow my logic. Of course, this is easier said than done, but that's what I would try to do," he said.
(Advice taken from FitnessDoc expert forum. Compiled by Amy Henderson, Health24.com)