Can you do sport when you have flu?

You can, because you have the ability to, but it doesn't mean you will or you should. Most people don't feel like swimming with the flu. If you have the flu you should be resting in bed to allow your body to have all the energy it needs to fight the flu and heal yourself.

If you have a fever from the flu, swimming in a lake or cool pool can mask the symptoms and make you feel temporarily better, but that will only be temporary and the exercise will make you feel worse once you get out. If you get in a heated pool, it could make your fever worse. Don't use a hot tub when you have a fever.

If you are in a lake or pool without chemicals to kill germs, you could be shedding viruses that might live long enough to infect someone else in the same water. Don't swim with others when you are sick with any infectious disease.

Being out in public if you are still sick risks giving it to other people whether they are in the water with you or not. Stay home.

So, the bottom line is you can but you should not.