Stretching is an essential part of physical fitness. Routine stretching may slow the degeneration of joints, reduce the risk of injury, improve posture, enhance muscular relaxation, reduce or manage stress, improve functional performance, and promote circulation. There several different stretching techniques, including ballistic and static stretches.
Ballistic Stretching
In ballistic stretching, you use momentum to force your joints beyond their range of motion, with a bouncing action. For example, to stretch your lower back and hamstrings, you bend over to touch your toes and repeatedly bounce your fingers down towards them, from a standing position. The muscle your are trying to stretch is being used as a spring to bounce you back within your range of motion, while you are in turn trying to bounce your body back out of your range of motion.
Static Stretching
In static stretching, you extend your joints as far as you can, at or slightly beyond your range of motion, and hold it. For example, to stretch your lower back and hamstrings, bend over and reach down toward your toes as far as you can, and hold it for 30 seconds. Breathe deeply while holding the stretch. It is recommended that you hold the position for at least 20 seconds to achieve any lengthening of the muscle fibers and tissues.
Ballistic vs. Static Stretching
Ballistic stretching is no longer considered a safe way of stretching and may even cause injury, due to the quick forceful movement beyond your range of motion. A safer modification of this stretch is called dynamic stretching, in which you use movement and/or speed to gradually increase range of motion. It is done in a controlled fashion, however, as opposed to bouncing your body forcefully beyond it's range of motion. If you are choosing between ballistic and static stretching, then static stretching is the winner. It's a gentle and effective way to stretch when performed properly.
Tips and Warnings
The American Council on Exercise recommends that you do static stretching after your aerobic or strength training workout, because your muscles are warm, pliable and less prone to injury. As part of your warmup, do dynamic stretching. Whichever type of stretching you are performing, never stretch beyond the level of comfort. You should not feel any pain when stretching.