Eli5: How can you get more ill if you exercise vigorously with an underlying cold or fever?

Question

Eli5: How can you get more ill if you exercise vigorously with an underlying cold or fever?

In: 16

Answer 1

When you exercise, many of your body’s systems assume you must be running for your life, either to catch prey or to escape becoming prey.

It’s a red alert, all-hands-on-deck situation. Who cares if you will get sicker–there could be a bear about to eat you!

So almost all your energy goes to helping you outrun that bear or gazelle or whatever, leaving your immune system starved for energy.

We cannot consciously direct the allocation of energy or immune response. All we can do is rest, and give our body no other competing priorities except to fight illness.