Aside from anecdotal evidence, some scientific studies display that HGH has little or no affect on athletes. One early study done in 1988 tested eight athletes for six weeks and showed that body fat decreased by a significant amount, however, muscle levels were not tested.5 In 1992, Kevin Yarasheski led a major study of athlete's performance done on 18 young men at the Washington University School of Medicine. Each man went through 12 weeks of resistance training.6 The muscles were measured at the end of the test, and all of the men had muscle gains.6 However, there were no differences in gained muscle size between the group who received the growth hormone, and the group who received the placebo.6 In 1995, Yarasheski headed another test on growth hormone. This time the strength of men was tested, but on a group of men averaging 67 years of age.6 The same results occurred with the older men; there were gains in muscle size and strength, but the group that actually received HGH did not have any better gains than those who did not use the hormone.6
Another study of 18 healthy men with ages ranging from 65-82 years, went through 14 weeks of weight training before receiving HGH or a placebo.7 The group that received human growth hormone saw significant increases in lean body mass, and a loss of fat.7 However, this did not translate into better performance. The two groups' overall muscle size gains were the same, as tested by using needle biopsies.7 Even though the muscular gains were the same, the significantly greater decrease in fat by the group that used HGH could be seen as a great benefit of the hormone for many people.
5. Crist DM, et al. "Body composition response to endogenouis GH during training in highly conditioned adults." Journal of Applied Physiology 1995;268:E268-E276.
6. Yarasheski KE, et al "Effect of growth hormone and resistance exercise on muscle growth in young men." American Journal of Physiology 1992;262:E261-E267, E268-E276.
7. Taaffe DR, et al. Effect of recombinant human growth hormone (GH) on the muscle strength response to resistance exercise in elderly men. J Clin Endocrinol Metab 1994;79:1361-1366.
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