Sudden Death Syndrome, exercise and flu

sudden death and flu

Cardiac arrest (heart attack) is responsible for 75% of sudden deaths on the sports field.

Every now and then a heartbreaking story hits the news of a seemingly healthy and young sportsman, or sportswoman, who drops dead in the middle of a sporting match or some bout of exercise. What makes this all the more shocking is that they usually have no history of heart problems.

Taking part in sport itself does not lead to cardiac arrest, but can act as a trigger in someone who already has an undetected heart problem.

What is Sudden Death Syndrome?

Sudden cardiac arrest has several causes and is generally known as Sudden Death Syndrome (SDS). A thickening or an abnormal structure of the heart muscle, as well as irregularities of the electrical impulses that control the heart rhythm, are usually to blame.

Undetected heart problems in young people

Many people find it shocking that this could happen to young people who appear to be healthy and fit, but underlying heart problems are not always obvious. An electrocardiogram (ECG) should be taken if a young person experiences any of the following during exercise:

• chest pain;

• excessive breathlessness;

• heart palpitations;

• dizziness; or

• fainting.

Link between heart attack and flu

There is another link between exercise and possible heart attacks: exercising when you have the flu.

It is important to distinguish between a cold and a flu, as you can safely exercise with a cold, but not if you have a flu-related fever, and/or muscle aches and fatigue.

A Canadian study found that in some cases there was a six-fold increase in the risk of people suffering a heart attack in the week after being diagnosed with flu. Strenuous exercise can put an additional strain on the heart that is already working hard to try and beat the flu. If you have a fever, it means your body is battling an infection. Dehydration is also an additional risk with both a fever and a workout.

It must be remembered that if you have a nasty flu, there could be inflammation in your heart muscle as well (known as myocarditis).. This in itself is a potentially dangerous side effect of a viral infection. The effects of this can last a few days after you are already feeling better. You can have myocarditis without having any symptoms at all.

Good to know

There is no hard-and-fast rule about when you can resume your normal exercise routine. However, you absolutely have to wait until the fever is gone. Get back into it slowly (low intensity and short duration) over a period of a few days. Stop at once if you get breathless.


By Susan Erasmus


Cardiac Risk in the Young (CRY) UK
National Institutes of Health
Harvard Medical School
Institute for Clinical Evaluative Sciences and Public Health Ontario

The Content on this site is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.

Related Posts