why are stretching exercises good for?

I am going to a gym for some time. I want to tune-up my body. It helps me to be healthier and stronger. I want to work on my endurance also. Every time I go to the gym my friends there always insist that I should stretch my muscles for a while. Why is it necessary? Why are stretching exercises good for?

Your friends are right. It is important to warm-up your muscles and the best thing to do that are stretching exercises. You should stretch for 5-7 minutes before weight-lift. In that way you prepare your muscles for training and you reduce the possibility of injury. Also you can improve coordination, heart rate and increase of your body temperature. The most important: during stretching exercise do not bounce!

Stretching helps you function better all over! And like cheri said, you can cause some serious injury to yourself if you don't stretch out properly before any physical activity.

Most people dont know this but prior to stretching you must warm the muscles up. This can be done by 3 minutes on the treadmill walking at a slightly faster than normal rate or on the low bike at a relaxed pace. If the muscles are cold (and especially if you have just walked in from the cold outside) then you could possibly damage muscle strands. Think about play dough, when its cold and you stretch it, it will snap, but if you roll it around in your hand a little before stretching it out, the warmth allows it to stretch better. Stretching is very important, its even more important to do it right and safely!

It prepares your muscles to avoid injury during your upcoming exercises.