Warming up

There is no sport where the workout doesn't start with a warm up.
With the warm up you reduce the risk for an injury,it improves your blood circulation,It boosts your oxygen level,it distributes the nutrients in your body,easier stretching,it prepares your heart for the increased activity,raised mental alertness,better coordination and nerve reaction through the training.
The stretching comes after the warm up,and many would advise to stretch after the training while the body cools down,the results of the stretching are similar to the warm up,with few exceptions it will improve your control over your own body,it will strengthen your skeletal structure and with that the risk of injury will decrease.