Stretching as a warm-up prior to exercise may be a practice you learned back in grade school gym class. Today, experts debate its effectiveness. While some studies show that stretching helps flexibility, others indicate that stretching as a warm-up may actually hinder athletic performance, decrease muscle strength and even increase the risk of injury.

The truth? Stretching is helpful, says Amy Ashmore, PhD, an exercise physiologist with the American Council on Exercise. Stretching benefits those with arthritis by lubricating joints and enhancing and maintaining range-of-motion. But, "Static stretching (stretch and hold) works best after a five to 10 minute warm-up or after you exercise," says Ashmore.

A warmed-up muscle can stretch longer and endure more, says Duane Knudson, PhD, professor and chair of the department of health, physical education and recreation at Texas State University. "Stretching at the end of the cool-down phase, after exercise, also helps to maintain long-term flexibility benefits," he says.

A New Way to Stretch

Replacing static stretching with dynamic or "active" stretching before exercise works better as a warm-up. Also known as "sports-specific" stretches, dynamic stretches mimic movements used in the sport or activity. Dynamic warm-ups prepare the body for activity by helping to increase blood flow and muscle temperature.

If you're preparing to play tennis, for example, you’ll want to practice side and front lunges as part of your warm-up – movements you'll use to reach for the ball.

If you're walking, you’ll want to start off at a slow pace and gradually pick up speed.

"Light, gentle rhythmic movements work best for the average person," says Ashmore. "Go through a shallow range of motion (i.e. a half-squat vs. a full squat) until you're thoroughly warmed up."

Even professional football players use dynamic warm-ups before a game. "You'll see players high-kicking down the field and going through a full range of motion instead of partner stretching for 10 minutes like they used to do," says Knudson.

Of course, you should always consult your physician or physical therapist before trying new stretches.