Proper stretching is vital for ensuring good flexibility and muscle performance. You should avoid stretching “cold” muscles, which means that you should warm up before stretching. This is the reason that many athletes actually stretch after their athletic event. The muscles are already “warm” (meaning full of good circulation) and ready to elongate.
Stretching helps reduce pain and discomfort related to tendonitis as well as ensuring good range of motion at your joints. Oftentimes runners develop tight hamstring muscles and weight lifters develop tight chest and bicep muscles. Overtime the runner will no longer be able to sit with their legs fully extended in front of their bodies, and the weight lifter will walk with a slight bend in the elbow. With stretching, these issues can be totally avoided.