Warm-up stretch no longer a winner

I stretch before I do cardio or lift weights because I thought it was supposed to improve my workouts and reduce my chances of getting injured. However, my friend recently told me that this is not true, that stretching before working out may actually do the opposite. Can you tell me which one of us is right?

CLARK

Newport Beach

For years, exercisers stretched before their workouts in an effort to prepare themselves and reduce the risk of injury, but the latest research indicates that this may not be the best approach. Evidence now suggests that stretching before a workout may actually decrease performance and increase the risk of injury.

Stretching properly on a regular basis can have benefits, but the actual act is quite stressful on the muscles and joints. For example, stretching the chest immediately before a chest press may temporarily reduce the amount of weight you can press. And stretching leg muscles before a run may temporarily reduce overall running speed. In general, the normal stress of exercise combined with the stress caused by stretching beforehand might well put the body at greater risk of injury than if you did not stretch at all.

Researchers have yet to actually prove that pre-activity stretching will impede exercise and sports performance or that it will increase the risk of injury. Evidence does suggest, however, that it probably does not enhance performance or reduce the risk of injury.

The best time to stretch appears to be after a workout or activity (when the body is warm and the muscles and tendons are more pliable) or in a stand-alone workout that won’t be followed by anything too intense. You could stretch at your desk for as little as 10 minutes a day, for example, or stretch at the end of a vigorous soccer game.

For a warmup before weightlifting or a run, however, just do an easier version of whatever you are getting ready to do. If you are going for a run, try walking a few minutes, then jogging, before you get into your base running pace. Or, if you are doing a weight-training workout, start by lifting lighter weights before progressing to heavier ones. Slow progression into more intense exercise or activity appears to be the best preparation of all.

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Jay Blahnik, a Laguna Beach-based personal trainer and IDEA Health & Fitness Assn. spokesman, has appeared in more than 25 videos and is the author of “Full-Body Flexibility.” He can be reached at jay@jayblahnik.com or health@latimes.com.