4.)
Because it helps with your immune system and your not putting so much on your lungs the more you use them
Answer:Doing fitness-gram testing and seeing how long you last through it.
Explanation:
3: immune system
4: antigens
1: not sure but maybe T-cell
2: how germs get inside our bodies
Well the reason we do it is because they wanna see if you can run normally for explain: if your a over weight kid and you can’t run a mile they get so worried that they might send you to the hospital right away. They also do this so if your a lazy kid and never get out of bed and you say your body hurts then will know you just lie In bed and do anything