WHEN DUANE KNUDSON, a professor of kinesiology at California State University, Chico, looks around campus at athletes warming up before practice, he sees one dangerous mistake after another. “They’re stretching, touching their toes. . . . ” He sighs. “It’s discouraging.”

If you’re like most of us, you were taught the importance of warm-up exercises back in grade school, and you’ve likely continued with pretty much the same routine ever since. Science, however, has moved on. Researchers now believe that some of the more entrenched elements of many athletes’ warm-up regimens are not only a waste of time but actually bad for you. The old presumption that holding a stretch for 20 to 30 seconds  known as static stretching  primes muscles for a workout is dead wrong. It actually weakens them. In a recent study conducted at the University of Nevada, Las Vegas, athletes generated less force from their leg muscles after static stretching than they did after not stretching at all. Other studies have found that this stretching decreases muscle strength by as much as 30 percent. Also, stretching one leg’s muscles can reduce strength in the other leg as well, probably because the central nervous system rebels against the movements.

“There is a neuromuscular inhibitory response to static stretching,” says Malachy McHugh, the director of research at the Nicholas Institute of Sports Medicine and Athletic Trauma at Lenox Hill Hospital in New York City. The straining muscle becomes less responsive and stays weakened for up to 30 minutes after stretching, which is not how an athlete wants to begin a workout.

Image Credit... Horacio Salinas

THE RIGHT WARM-UP should do two things: loosen muscles and tendons to increase the range of motion of various joints, and literally warm up the body. When you’re at rest, there’s less blood flow to muscles and tendons, and they stiffen. “You need to make tissues and tendons compliant before beginning exercise,” Knudson says.