in 2001. The scientists state that while the reduction of concentration of somatotropin during aging is documented, there were several problems with previous researches as they did not exclude the various gonadotropic hormones that were also reduced with old age. The study was performed on two groups, a young group, consisting of 8 men and 8 women, and an aging group consisting of 11 women and 10 men. All the subjects had similar body mass indexes and blood samples were taken from each of the test subjects every 10 minutes for 24 hours. The results from the research showed a marked decrease of 32-56% of growth hormone concentration, each according to its sex. 81% of the young group secreted the highest amount of growth hormone during the night period, while 62% of the aging group secreted most of the growth hormone during the day period. The researchers reached the conclusion that there is a decrease in secretion of growth hormone as age increases for both sexes. The reduced concentration of growth hormone was, in turn seen as a lack of growth hormone releasing hormone. (Russel-Aulet et al.)
Another research focuses on the problem of sarcopenia, which represents a syndrome that manifests itself as a decrease in skeletal muscle mass, as well as in muscle work output. As the natural process of aging involves degradation of skeletal proteins, sarcopenia is expected to appear in most of the elderly, but this condition can be aggravated by the lack of exercise, leading to more frequent physical injuries such as hip fractures. Aware of the low concentration of several hormones that affect protein anabolism in old age, amongst them the growth hormone, the scientists researched the coupled human growth hormone replacement therapy with resistance exercise, which is known to reduce the effects of sarcopenia, in people aged 60 and over. Although the research can be viewed as retrospective, as it presents the various experiments, as well as the results, performed by other researchers, a case-control trial was described that was performed by the authors of the paper. The study involved men from 62-75 years of age which were involved in a 16 week exercise program, consisting of modest to high-intensity training in the form of weight lifting exercises with a small repetition. It encompassed muscles from both the upper and lower extremities. One group was given a dose of 12-24 g/kg/d of growth hormone, while the other, control, group performed the same exercises, but was not given anything. The result from their research, as well as results from other researches, led the scientists to conclude that there is not much difference in muscle mass and strength between the control group and the group that received somatotropin. An increase in muscle mass was present, however, but not focused on the skeletal muscles. Furthermore, the scientists concluded that there were significant side effects from the use of somatotropin replacement therapy in aging people, further criticizing the use of somatotropin as a means to prevent sarcopenia. (Zachwieja, Yarasheski).
Sarcopenia is but one of the many physiological