Answer:
je ne compred pas l,anglais
It is important to stretch before exercising because for example if you were to be doing a strenuous workout it causes the blood vessels in your legs to expand. Which then causes more blood into your legs and feet. If you were to stop after a while of exercising your heart rate slows down and blood can pool into your lower body which could cause you to possibly faint.
Those two are the muscular system and the excretory system because you use your muscles to push up and down and your excretory system produces the sweat you use while doing them
