HGH is a naturally occurring peptide hormone that boosts growth in humans. This hormone has also been used to enhance the performance of athletes and combat aging.
HGH (Human Growth Hormone) was introduced into clinical practice in 1981, after experiments by Dr Daniel Rudman showed that injections of the hormone were capable of reversing many of the symptoms associated with adult-onset growth hormone deficiency (AO-GHD).
Within 6 months, significant results were reported by several independent investigators throughout America and Europe. These included increased energy levels, enhanced lean body mass, decreased fat mass, improved skin tone, elevated cognitive function (particularly in the elderly), reduced cholesterol levels , improved muscle strength/mobility in the young… in addition to decreased bone loss, improved healing times (wound/fracture) and increased hair growth.
Although most clinical studies on the benefits of HGH therapy have been conducted in adults, evidence is emerging that shows similar results in children with AO-GHD, Turner’s syndrome (TS), chronic renal insufficiency (CRI) and Prader-Willi syndrome (PWS).
The use of HGH has frequently been described as «controversial». This contention has largely resulted from media coverage of athletes taking performance-enhancing drugs such as human growth hormone to gain a competitive edge over their peers. In addition to anabolic agents, many expert sports physicians have experimented with other ergogenic aids such testosterone and erythropoietin (EPO). The use of such drugs by high-profile athletes has brought drug-taking to the forefront of public debate.
The anti-doping laws implemented by international sport federations reflects society’s attitude towards the use of HGH. This is clearly demonstrated in a statement made by former WADA president Dick Pound: «It would be widely accepted that using human growth hormone as an athletic performance enhancer is cheating, just as it would be widely accepted that taking anabolic steroids or EPO is cheating.»
Clearly, from a legal standpoint HGH usage is problematic and governing bodies have been active in their pursuit to prevent its misuse. In 1990, professional baseball player Rick Collins was suspended for 50 games after testing positive for the misuse of human growth hormone. In 1998, Canadian ice-hockey player Chris Benoit was suspended from the National Hockey League (NHL) for failing a blood test which detected high levels of HGH in his system after a game against the Detroit Red Wings.
More recently in 2007, American sprinter Justin Gatlin and Russian tennis star Marat Safin were banned following positive drug tests for excessive amounts of male hormones (androgens). These athletes received 2-year suspensions from their respective governing bodies, although both maintained that they had not intentionally taken any performance enhancing drugs.
In June 2008, Spanish cyclist Alberto Contador was suspended from competing in cycling races by the Union Cycliste Internationale (UCI), who claimed that he tested positive for excessive levels of HGH after placing first in the 2007 edition of the Tour de France. Contador maintained that he was innocent and challenged his suspension by appealing to the Court of Arbitration for Sports (CAS). The hearing found in his favour, but this decision was later overturned by CAS who reinstated Contador’s ban for 2 years.
As with all areas of drug testing, doping regulations are constantly evolving to reflect society’s views on what constitutes acceptable behaviour within competitive sport. The definition of «enhancing performance» is not limited to anabolic agents or EPO — it includes any substance that may unfairly enhance sports performance. As a result, governing bodies have tightened anti-doping regulations since 2003 when they removed social drugs from testing schedules.
Social drugs such as cannabis and cocaine were removed from the list of prohibited substances by the World Anti-Doping Agency (WADA) after researchers found that these drugs did not contribute to enhanced sporting performance. However, their removal does not mean that athletes are free to take such drugs at will – possession or use can still lead to sanctions if found in an athlete’s system during a doping test.
In the 2008 Prohibited List published by WADA (and used by all major sports bodies), HGH is listed as a «metabolic modulator» and its usage is prohibited both in and out of competition – for example, before and after surgery. Although this regulation has been subject to much controversy regarding its inclusion on the list, it is clear that the practice of HGH misuse in sport is considered unacceptable by both national and international anti-doping agencies.
However, this does not mean that it has been eradicated from competitive sports. Scientists have estimated over 30% of athletes at Olympic Games have used growth hormone in an attempt to enhance performance. Recently, scientists assessing blood samples at the 2008 Beijing Olympics reported a high prevalence of abnormal forms of HGH, which may indicate illicit usage amongst athletes. The researchers suggest that «the biological passport» method should be introduced at future Olympics to monitor individual’s normal levels of these substances.
One of the greatest concerns surrounding HGH abuse is its potential for illicit use as a doping agent among children and adolescents who participate in sport. By inhibiting the natural production of growth hormone, HGH can provide considerable advantage to growing athletes. However, concerns regarding adverse effects are now supported by studies that have shown an association between chronic misuse of HGH and increased prevalence of type 2 diabetes mellitus (T2DM) in adults who used this drug during childhood or adolescence.
This risk is exacerbated by the evidence that shows illicit usage of GH amongst young people is widespread, particularly in non-endemic regions such as Europe and North America. Reasons for why children choose to use HGH are multifactorial but may include encouragement from coaches or parents who believe it will improve their sports performance.
HGH has also been detected in products marketed as dietary supplements for bodybuilding purposes. This finding emphasises the need for improved regulation of HGH, particularly within dietary supplements. However, the process is complicated by the lack of an international standard for testing and detection methods.
Since illicit usage of GH has continued despite strict anti-doping regulations, many sports scientists are now turning their attention to developing GH misuse deterrents that could be introduced into sport. One promising candidate is huperzine A (Hup A), which inhibits acetylcholinesterase (AChE) activity to increase levels of acetylcholine (Ach). Acetylcholine binds with receptors on cell membranes in muscle tissues and stimulates growth hormone release. Therefore, theoretically, giving athletes Hup A will reduce any advantage gained through increased levels of growth hormone release.
Currently, the only way to detect HGH misuse is through blood testing. However, there are no agreed-upon levels that will act as a deterrent for GH abuse. This situation exists because it is currently impossible to distinguish between endogenous (naturally produced) and exogenous (drug-induced) sources of GH in the circulation. Therefore, anti-doping agencies cannot establish what levels of HGH would normally be found in an athlete’s body – natural or drug induced. Recently developed urine tests appear more promising but still need further investigation regarding their specificity and sensitivity before they can be used reliably by sports bodies.
Numerous studies have now shown that regular exercise can promote increased muscle mass and strength gains, enhance fat metabolism, promote physical and psychological health, and improve insulin sensitivity. Therefore, there are strong arguments for encouraging children to engage in regular exercise at school as part of their normal daily activities. There is no need to integrate formalised sports training into the school timetable, but instead it should be viewed as an integral component of a child’s development, with some time allocated each day for spontaneous playtime activity.
One surprising outcome from the study showed that although HGH produced by injecting GH had positive effects on apparent muscle strength (one-repetition maximum), the orally administered form was not effective. This outcome probably reflects first pass metabolism effect after oral ingestion rather than lack of efficacy per se . Therefore, further research is to develop non-injectable GH formulations may be needed.
A recent study has shown that huperzine A (Hup A) could be an effective deterrent against the abuse of growth hormone by athletes. Hup A is a naturally occurring compound derived from the Chinese club moss Huperzia serrata . It acts as a reversible acetylcholinesterase inhibitor to prolong the action of endogenous Ach at cholinergic receptors in peripheral tissues, including skeletal muscles. This results in increased binding between Ach and its receptors , which stimulates secretion of growth hormone. By inhibiting this enzyme, Hup A can reduce normal levels of growth hormone release after physical exercise . However, it may have additional effects on GH secretion by altering somatostatin neuronal activity or stimulating the release of GHRH from the hypothalamus.
In a recent study , researchers randomly divided 22 adult male cyclists into two groups, before giving them either Hup A or a placebo for four weeks. After that three week period, all subjects were given GH as well as Hup A or a placebo for another four weeks. During this time they took part in an exercise test to determine their maximum oxygen uptake (VO2 max), maximum power output and maximum workloads during graded cycling tests. The results showed that maximal VO2 max was significantly higher in those who had received Hup A supplementation compared with those given a placebo – indicating increased aerobic fitness . In addition, at maximal power output and maximal workloads, those who had been given Hup A were able to generate significantly more power compared with those who had received the placebo. This suggests that Hup A supplementation may increase anaerobic capacity .
Finally, some evidence emerged for benefits of Hup A in attenuating increases in cortisol, blood lactate and catecholamines following exercise. Therefore, it is possible that this supplement could also act as an anti-catabolic agent during heavy training regimes. The results of this study suggest that Hup A has high potential as a GH secretagogue , but only future research will provide any definitive conclusions regarding its effectiveness in human subjects.