The pituitary gland releases human growth hormone, HGH, into the bloodstream. This release occurs in brief pulses during the daytime hours. Growth hormone also responds to changes in sleep-wake cycle, exercise and diet. Chemists synthesize HGH so that patients can take it by intramuscular injection for a variety of ailments. Athletes abuse growth hormone to enhance skill and hasten recovery. Yet the risks of HGH use can outweigh these benefits, especially in women.
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Professional and recreational athletes take growth hormone as performance-enhancing drugs. Scientific data supporting this use remain sparse, yet some findings indicate that HGH can improve athletic abilities. A 2003 investigation described in the "Journal of Clinical Endocrinology & Metabolism" evaluated HGH intake in older women with HGH deficiency. Growth hormone enhanced leg and hand strength in most of the subjects tested. It also increased lean body mass and decreased total body fat. More importantly, the women reported few HGH-induced adverse events.
Growth hormone may affect other measures of athletic behavior as well. A 2010 investigation published in the "Annals of Medicine" looked at HGH-facilitated exercise in younger women. Subjects taking the hormone sprinted faster on a stationary bicycle, but they did not jump higher or have greater aerobic capacity. These effects of growth hormone disappeared within weeks of ending HGH treatment, and the women experienced no consistent side effects during the study.
Aging decreases growth hormone levels and increases arterial plaque development. These factors often co-vary which suggests that HGH intake could prevent cardiovascular disease in older adults. A 2004 investigation offered in the "Journal of Clinical Endocrinology & Metabolism" tested this hypothesis in younger and older women with HGH deficiency. The primary outcome measure in this study was cholesterol scores which predict cardiovascular risk. Results indicated that HGH injections reduced both total cholesterol and "bad" cholesterol levels. Growth hormone intake was well-tolerated, but it did increase ring size.
The positive effects of HGH intake often come at a price. For example, growth hormone use typically increases fluid retention or bloating. A 2005 investigation presented in the periodical "Clinical Endocrinology" evaluated body composition in younger women receiving HGH injections. Many subjects experienced greater fluid retention and complained of bloating. Detailed analysis revealed that most of the water retained was extracellular and not intracellular. These findings likely explain why HGH also reduced lean body mass in this study.
Injecting HGH may cause more serious side effects as well. Growth hormone use, for example, can produce symptoms of diabetes. A 2005 investigation published in the journal "Metabolism" looked at diabetic markers in middle-aged women. These subjects took growth hormone to correct their low HGH levels. Growth hormone intake decreased insulin sensitivity and thus increased fasting glucose in most of the women tested. Such changes may lead to the development of diabetes. Thus, growth hormone should be used with caution.
- Annals of Internal Medicine: Effects of Growth Hormone on Body Composition and Physical Performance in Recreational Athletes: A Randomized Trial
- Clinical Endocrinology: Supraphysiological Growth Hormone: Less Fat, More Extracellular Fluid but Uncertain Effects on Muscles in Healthy, Active Young Adults
- Metabolism: Long-term Monitoring of Insulin Sensitivity in Growth Hormone-Deficient Adults on Substitutive Recombinant Human Growth Hormone Therapy