Beginner's guide to stretching: you always hear how important it is to stretch—but is it really, and if so, why?

How many times have you heard the advice "Don't forget to stretch!"? But when it comes to stretching, there are so many mixed messages--from when you're supposed to do it (before exercise? after? before and after?), to how long to hold a stretch, to the best ways to do it, to why to do it in the first place. Here's a primer to help you get to the bottom of all those claims and unanswered questions.

Why stretch?

* A systematic review of studies that addressed the impact of stretching on sports injury risk published in the March issue of Medicine & Science in Sports & Exercise notes that the jury is still out on whether or not stretching can prevent injury among competitive or recreational athletes. However, flexibility exercises--when done after a workout or at least after a brief cardio warm-up--do help to maintain circulation around the joints, keeping muscles healthy where they're most apt to get injured.

* Stretching allows the body to move more efficiently and perform at its peak. According to Jim Wharton, musculoskeletal therapist and owner of Wharton Performance in New York City, during the course of a workout, muscles begin to shorten as they fatigue. This impedes your ability to generate speed and power and leads to a less efficient, shorter, more shuffling stride. Stretching keeps muscles elongated, reducing this tendency.

* It can make you stronger. According to research conducted by Wayne Westcott, Ph.D., fitness research director of the South Shore YMCA in Quincy, Mass., stretching after a workout--or even between resistance exercises--can increase strength gains by up to 20 percent.

* It's an incredibly soothing way to connect your mind and body, and it simply feels great!

When to stretch

You can stretch anytime you feel like it, or you can do so in conjunction with other activities. Just remember: Stretch after any type of physical activity: cardio, strength training or sports. Muscles are warmer and more pliable then, making it easier to lengthen them. According to Westcott, vigorous stretching before exercise, when muscles are cold and less pliable, will produce less benefit and may leave tendons more susceptible to injury. A good rule of thumb is to start your workout with a five-minute cardio warm-up, stretch gently, follow your usual routine, then do more serious stretching after.

Mistakes to avoid

* Don't bounce. Using momentum to increase your stretch can activate the body's protective reflex, causing the muscles to contract instead of stretch, which can lead to small tears.

* Don't stretch to the point of pain. While you may experience a little discomfort in an area that is tight, actual pain is your body's way of letting you know something is wrong.

* Don't forget to breathe. Not only is oxygen exchange necessary for the muscle to respond in a beneficial way to a stretch, but holding your breath may temporarily increase blood pressure. Focus on inhaling as you get in position for the stretch and exhaling as you move into it. Keep your breathing slow and regular.

THE STRETCHES

1. side bend Stand with right foot crossed over left, both feet flat on the floor. Bring your upper right arm alongside head, pointing elbow toward ceiling, then move your right palm to your upper back and place left hand over right elbow. With abs tight, gently lean to the left [shown]. To get more of a triceps stretch, gently pull right elbow over with left hand. Switch feet and repeat on opposite side. Stretches middle back, rear shoulders, triceps, oblique abdominals, some spine extensors

2. chest opener Stand with feet hip-width apart, abs tight and chest lifted. Bring arms out to sides at shoulder height, wrists bent with palms facing out and fingers pointing up. Keeping arms straight, use upper-back and triceps muscles to open chest and pull arms back, still at shoulder height [shown]. Stretches chest, front shoulders, biceps

3. standing runner's lunge Stand a foot away from a wall and place palms on wall at shoulder height. Bend right knee in line with right ankle and step back 2-3 feet with left foot, left leg straight and left heel on floor, feet hip-width apart and toes facing forward. Tighten abs and keep pressing left heel into floor to stretch calf. Hold for 30 seconds, then press hips forward to stretch hip flexors for another 30 seconds [shown]. (If your hips are more flexible, your right heel may need to lift slightly off the floor to get a full stretch.) Switch legs and repeat. Stretches quadriceps, hip flexors, calves

4. seated hamstrings stretch Sit with your buttocks on the edge of a chair, knees bent, feet flat on floor, chest lifted and abs tight. Lift and extend right leg at hip height, toes up, and hinge torso forward from hips, keeping spine in a neutral position. (If you're inflexible, begin with right leg extended and heel on floor. When you've achieved enough flexibility, lift leg to hip height.) Place hands on your lower leg [shown] or reach for your toes, depending on your flexibility; at the same time, slightly lift tailbone to get more of a stretch. Switch legs and repeat. Stretches hamstrings