Intense Exercise May Temporarily Weaken Immune System

A new study found that doing very tough workouts can weaken your body's defenses for a little while.

Scientists looked at samples from firefighters who were doing hard training.

They saw changes in the body's reactions during and after the exercise.

It's like when your body is working extra hard to fix itself.

People with intense jobs, like firefighters and athletes, might get sick more easily right after working out.

The study hopes to help people understand how to balance exercise and recovery to stay healthy.