HEALTH TOPICS 
Activities that lengthen and stretch muscles can help you prevent injuries, back pain, and balance problems.
A well-stretched muscle more easily achieves its full range of motion. This improves athletic performance — imagine an easier, less restricted golf swing or tennis serve — and functional abilities, such as reaching, bending, or stooping during daily tasks. Stretching can also be a great way to get you moving in the morning or a way to relax after a long day. Activities such as yoga combine stretching and relaxation and also improve balance, a wonderful combination.
However, note that experts no longer recommend stretching before exercise. Newer recommendations suggest that you start your workout routine with a warm-up, such as an easy walk or a sport-specific routine, such as serving some tennis balls and practicing ground strokes before a match. This gets blood and oxygen flowing to your muscles. After five to 10 minutes of warm-up, your muscles are warm and supple. This is a good time to stretch. You can even do your flexibility exercises as a post-workout cool-down.
To get more tips on starting a successful exercise program, buy Starting to Exercise, a Special Health Report from Harvard Medical School.