Coaches and exercise gurus have long advocated stretching before exercise to avoid injuries. But what little research there is doesn’t support that idea. Instead, experts suggest stretching after you’re warmed up to increase overall flexibility.
In a paper published last year in the journal of the American College of Sports Medicine, researchers from the federal Centers for Disease Control and Prevention analyzed the limited number of studies available and concluded that “stretching had no effect in reducing injuries.”
A separate paper in the March issue of The Physician and Sports Medicine noted that stretching may even slightly impair performance because, as with weight lifting, muscle force decreases slightly, by 2 to 5 percent, immediately after stretching.
After your workout or race, when muscles and tendons are warm, is the time to really stretch to improve overall flexibility, said Dr. Edward Phillips, director of outpatient medical services at the Spaulding Rehabilitation Hospital. Or, use hot packs before stretching. Scientists demonstrated the value of hot stretching decades ago in rats, or more precisely, rat tails, which could be stretched farther and with less damage when they were warmer.
Physiologically, stretching increases the elasticity of muscles, and tendons and to a lesser extent, ligaments. Ideally, you should hold a stretch for 20 to 30 seconds without bouncing or pushing, said Dr. Brian Krabak, a physiatrist at Johns Hopkins. Then repeat this two or three times, several times a week at least, daily if you can.
Phillips makes a distinction between stretching and warming up. Instead of worrying about lengthening muscles at the beginning of a workout, he suggests jogging slightly or moving your limbs around to get your heart rate up a bit. The idea, he said, “is to go through the motions you will do in your event or workout.”