Stretching: The Truth
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PostPosted: Thu, Nov 6 2008, 8:24 am EST    Post subject: Stretching: The Truth Reply with quote

November 2, 2008
Phys Ed
Stretching: The Truth
By GRETCHEN REYNOLDS

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. Theyre stretching, touching their toes. . . . He sighs. Its discouraging.

If youre like most of us, you were taught the importance of warm-up exercises back in grade school, and youve 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 legs 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.

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 youre at rest, theres less blood flow to muscles and tendons, and they stiffen. You need to make tissues and tendons compliant before beginning exercise, Knudson says.

A well-designed warm-up starts by increasing body heat and blood flow. Warm muscles and dilated blood vessels pull oxygen from the bloodstream more efficiently and use stored muscle fuel more effectively. They also withstand loads better. One significant if gruesome study found that the leg-muscle tissue of laboratory rabbits could be stretched farther before ripping if it had been electronically stimulated that is, warmed up.

To raise the bodys temperature, a warm-up must begin with aerobic activity, usually light jogging. Most coaches and athletes have known this for years. Thats why tennis players run around the court four or five times before a match and marathoners stride in front of the starting line. But many athletes do this portion of their warm-up too intensely or too early. A 2002 study of collegiate volleyball players found that those whod warmed up and then sat on the bench for 30 minutes had lower backs that were stiffer than they had been before the warm-up. And a number of recent studies have demonstrated that an overly vigorous aerobic warm-up simply makes you tired. Most experts advise starting your warm-up jog at about 40 percent of your maximum heart rate (a very easy pace) and progressing to about 60 percent. The aerobic warm-up should take only 5 to 10 minutes, with a 5-minute recovery. (Sprinters require longer warm-ups, because the loads exerted on their muscles are so extreme.) Then its time for the most important and unorthodox part of a proper warm-up regimen, the Spider-Man and its counterparts.
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more:
http://www.nytimes.com/2008/11/02/sports/playmagazine/112pewarm.html?_r=3&oref=slogin&pagewanted=print
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