Experts debate benefits of stretching with exercise

September 11, 2000

Web posted at: 11:53 AM EDT (1553 GMT)

WASHINGTON (AP) -- Common ideas about stretches may stretch the truth,

researchers say.

"Stretching recommendations are clouded by misconceptions and conflicting research

reports," said a report in a medical journal, The Physician and Sports medicine.

Stretching is supposed to reduce the risk of injury, relieve pain from exercise and

improve performance. But the benefits are only partly supported by the evidence, the

experts said.

Exactly what to stretch, for how long, and why are still up for scientific debate, said Drs.

Ian Shrier and Kav Gossal of Montreal. New research is challenging commonly held

ideas, they said.

The doctors checked the medical database Medline and the sports science database

SPORTDiscus for articles on stretching to help muscles relax and lengthen after being

tightened in a contraction.

The researchers found that, in general, only one post-exercise stretch of 15 to 30 seconds

per muscle group is needed for most people, although some people or muscle groups may

need more. There seems to be a limit -- after the fourth or fifth stretch, stretching seems

to make muscles tighter instead of more relaxed, they said.

Another expert finds some fault with that, however. Research suggests that 3 to 5

stretches of 30 seconds are optimal, said Lynn Millar of Andrews University, Berrien

Springs, Michigan. Larger muscle groups such as the hamstrings in the legs benefit more

from repeated stretches than do smaller muscles such as the biceps in the arm, she said.

If the stretches are intended to relieve post-exercise aches, additional stretching may

provide greater benefits, the article reported. Research indicates that part of the benefit of

stretching is in the mind, by increasing stretch tolerance "patients feel less pain for the

same force applied to the muscle," the doctors said.

The idea is that stretching reduces the perception of pain, although how this could work is

not known, Shrier said. And, although the benefit has been shown in research on healthy

tissue, people with injuries probably benefit as well, he said.

The benefit in pain relief might more than offset the cost in stretch-tightened muscles,

making greater stretching worthwhile, they said.

Stretching before exercise, a common way to prepare for sports or exercise, isn't as

valuable as exercisers think, the article reported. An active warm-up such as a jog is

better, it said. For instance, a warm-up run has been shown to decrease stiffness in the

calf muscle, although not in the hamstrings, it said. And warm-up has been shown to

decrease injuries.

Studies have found that an active warm-up followed by stretching increases range of

motion better than stretching alone does, the doctors said. But they feel the major value is

in the warm-up. They warn athletesthat the added stretching has not been shown to

reduce the injury rate.

"If injury prevention is the primary objective (e.g. recreational athletes who consider

performance a secondary issue), and the range of motion necessary for an activity is not

extreme, the evidence suggests that athletes should drop the stretching before exercise

and increase warm-up," the article said.

This may not be the case for competitive athletes, Millar said. Some preliminary research

has found soccer players reduced injury risks by stretching, although the number of

players studied was too small to draw a firm conclusion, she said.

Static stretching -- moving slowly into a position and holding it -- is generally considered

to be less risky than dynamic stretching, in which the athlete stretches while moving. But

the risk is probably overstated, because dynamic stretches still tax the athlete far less than

the activity for which the athlete is preparing, the article said.

And although textbooks commonly recommend static over dynamic stretching, "there

isn't any research to support the idea that there could be more injuries," Millar said. Her

feeling is that dynamic stretches may benefit competitive athletes because the movements

will be similar to movements they would use in their sports.

As for the best type of stretch, the researchers leave that to the athlete. "Individuals

should determine a strategy for themselves by simply holding a stretch until no additional

benefit is obtained," they said.