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No "magic bullet" for building muscle.

Routine screening of athletes for anabolic steroid use has led some to seek untraceable substitutes. That search has drawn many to human growth hormone. Produced in the pituitary glands, it is responsible for spurring growth in muscles, bone, and connective tissue. Those athletes who use it believe that human growth hormone will give their muscles a "jump start" and add to the effectiveness of their regular workout.

However, Kevin Yarasheski, research instructor of medicine, Washington University School of Medicine, maintains that the hormone does not help muscles grow any faster or operate any more efficiently than exercise alone. He was the first to examine the combined effect of growth hormone and resistance exercise in a population of normal, healthy young men. He explains that the reason such a study hasn't been done before is that synthetic growth hormone is a relatively new development. For a long time, human growth hormone could be obtained only from cadavers and its use was limited strictly to short-stature children. In the last decade, however, recombinant DNA techniques have led to wider availability and given researchers the chance to examine other potential uses.

Yarasheski's study looked at 16 men between the ages of 21 and 34 who did 12 weeks of heavy resistance training on Nautilus weight-lifting machines, alternating daily between upper- and lower-body workouts. The participants "started lifting weights at about 75% of their max and worked up to about 85 to 90% of their maximum strength. This kind of high-intensity, low-repetition workout has been shown to improve muscle strength and enhance muscle growth."

When the workouts were over and the final measurements were taken, Yarasheski discovered no significant differences between the men who only had pumped iron and those who had lifted weights and taken growth hormone. Their muscles grew at about the same rate and their strength increased a similar percentage. The only discernible difference between the two groups was in the measurement of fat-free mass. Those who took growth hormone had less body fat, but they didn't get bigger muscles. Some of their increase in fat-free mass was due to fluid retention.

Yarasheski states that growth hormone is not the "magic bullet" that will improve quality of life by making people stronger and healthier. It does reduce body fat and increase fat-free mass, but seems to have no effect on muscle function. In addition, there are side effects. The most common appears to be a wrist ailment known as carpal tunnel compression, caused by pressure on the nerve in the wrist, triggering numbness or tingling in the fingers of the affected hand, he points out.

Another side effect is fluid retention that can lead to high blood pressure and cause problems for those who suffer from hypertension. The hormone also makes test subjects slightly glucose intolerant, but that condition ends when the injections stop. Moreover, evidence shows that people in the early stages of cancer could see more rapid tumor growth. In particular, too much growth hormone can be related to colon polyps or colon and stomach cancer.

There are potential uses for growth hormone other than improvement of muscle function. Researchers are studying its benefits to people recovering from surgery and /or burns or those with kidney failure. Because it may lower the amount of body fat, Yarasheski suggests it could have a future as a treatment for obesity. It does not appear, however, to provide any benefit to those athletes who are seeking a leg up on the competition.
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Title Annotation:hormones
Publication:USA Today (Magazine)
Date:Feb 1, 1993
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