Pretty much every exercise class I've ever attended has followed the same basic structure: You begin with a series of warm-up stretches, sweat as much as possible, and then cool down by stretching once again.

The idea, most of us believe, is that stretching warms up and prepares the muscles so that they're ready to work hard and less likely to suffer injuries or strain.

But the research doesn't bear this out. Exercise experts and physiologists agree that stretching is an important component to fitness, but there's no consensus on whether it's more beneficial to stretch before a workout.

According to a sports medicine article, it's probably best not to stretch before exercising if injury prevention is your main priority. It makes sense that stretching when muscles are still cold would be dangerous, because it obviously puts so much strain on our muscles and ligaments.

If you seek a greater range of motion, however, the best approach may be to get your blood pumping (with a bit of cardio, I assume) and then stretch the major muscle groups for short durations of about 15-30 seconds.

Stretching after a workout, however, appears to be a wise idea. Muscles and joints are warm and pliable, therefore less likely to be pulled. Overall, the benefits are numerous: Improved flexibility, circulation, range of motion, posture, and injury prevention.

Personally, I'm comfortable when I stretch before a workout. Years of yoga have taught me how to pay attention to my threshold, and to get a sense of when a slight pull is likely to turn into pain.

In theory, I run through a quick series of stretches before going for a workout. In practice, however, I've noticed that I usually just jump in. Instead of limbering up stretching, I tend to start workouts at an easier pace until I'm warmed up.

The trouble is, I hardly ever stretch after a workout either. I'm convinced that it's a critical aspect of fitness, but I'm not in the habit of stretching after working up a sweat. I usually just grab my gym bag and make a beeline for the exit.

I'd like to think that one yoga class per week provides enough stretching. But, I know that I really should force myself to get in some post-workout stretching. Now the trick is making myself take that extra ten minutes instead of racing out the door.