Warming up before you exercise helps to prevent injuries and lets you jump higher, run faster, lift heavier or throw further. Your warm-up should involve the same muscles and motions you plan to use in your sport. For example, before you start to run very fast, do a series of runs of gradually-increasing intensity to increase the circulation of blood to the muscles you will be using.

Muscles are made up of millions of individual fibers, just like a rope made from many threads. When you start to exercise at a very slow pace, you increase the blood flow to muscle fibers, increase their temperature, and bring in more oxygen, so the muscles are more pliable and resistant to injury. When you contract a muscle for the first time, you use less than one percent of your muscle fibers. The second time you bring in more fibers, and you keep on increasing the number of muscle fibers used in each contraction for several minutes of using that muscle. It