Ergogenic aids: Human growth hormoneThe purpose of this review is to explore the effects of GH utilization in physiological and ergogenic responses to resistance training RT. The responses will be divided in seven groups: However, none of the studies reviewed regogenic additional gains in muscle strength and hypertrophy in response to RT due to GH administration. Additionally, there is no oxymetholone androlic cena human growth hormone ergogenic aid to support GH use in human growth hormone ergogenic aid to increase ergogenlc changes or reduce body fat with RT. The large evidence of side effects without a significant ergogenic effect, reinforces the orientations that this hormone should not be used as an ergogenic aid.
Ergogenic aids: Human growth hormone | SpringerLink
The purpose of this review is to explore the effects of GH utilization in physiological and ergogenic responses to resistance training RT.
The responses will be divided in seven groups: However, none of the studies reviewed showed additional gains in muscle strength and hypertrophy in response to RT due to GH administration.
Additionally, there is no irrefutable data to support GH use in order to increase bone changes or reduce body fat with RT. The large evidence of side effects without a significant ergogenic effect, reinforces the orientations that this hormone should not be used as an ergogenic aid. Its concentration is regulated by the hypothalamus via secretion of growth hormone releasing factor hormone GHRH and somatotropin release inhibiting factor hormone SRIH , which stimulate and inhibit GH release, respectively.
GH may act through two different ways: Until the mid 's treatment with GH was carried out with hormones directly extracted from the pituitary glands of human cadavers.
However, this practice exposed patients to transmissible brain diseases such as Creutzfedkt-Jakob Disease 13; 14; 33; 41; 46; 56 , which is fatal and could develop years after the cessation of the treatment In , human growth hormone recombined from DNA became available, augmenting its supply and decreasing the risk of the treatment 1. However, the accessibility of GH combined with the enthusiasm of scientists and retailers had stimulated its use in several situations where its efficacy and safety had not been proven.
Among other promises, there are anectodus claims that GH promotes increases in lean body mass, muscle mass, body fat and physical performance. Since the landmark investigation by Rudman et al 48 , recombinant human growth hormone has been prescribed to elderly people in order to promote changes in body composition and functionality.
Lately, its anabolic properties have been confirmed in animals 11; 47 and humans 31; Various studies reported that resistance training of different intensities and duration markedly stimulate GH release 34; 35; 42; 51 , this response along with the supposed physiological actions of GH brought the suggestion that this hormone may mediate some adaptations to resistance exercise and raised the theory that treatment with exogenous GH might enhance this response.
Based on this hypothesis, many athletes and fitness enthusiasts started using GH with the purpose of increasing muscle hypertrophy and strength. Hence, the purpose of this review is to explore the effects of GH utilization in physiological and ergogenic responses to resistance training. The following keywords were used: In addition to computer searches, cross-referencing from retrieved articles and original investigations were performed.
The following abbreviation will be widely used: GH may increase bone formation in two ways: Also, GH can control osteoclast formation, but both stimulatory and inhibitory mechanisms have been presented Some authors suggested that GH treatment has positive effects on bone mineral density 7; 53 , however controversy exists 5; 6.
Specifically with resistance training RT , Yarasheski et al 62 conducted an experiment to determine if GH treatment plus RT would increase whole body and regional bone mineral density BMD in elderly men more than RT alone.
The literature reviewed does not bring irrefutable data to support GH use in order to increase bone changes with RT. The controversy appears in a study by Deyssig et al 19 , where GH administration had no effect on body composition of well-trained male athletes.
Fat accumulation is characteristic of growth hormone deficiency and GH treatment is usually prescribed as a way of reducing body fat 4; In agreement with this practice, most of the reviewed studies showed an additive effect of GH in body fat reduction promoted by RT.
Additionally, using skin fold measures, Deyssig et al 19 found that GH treatment had no influence in body composition changes during resistance training in highly trained males, who apparently had no excessive fat stores to be metabolized. However, the literature reviewed lends no support to the view that GH administration exerts a synergistic effect with resistance training on the muscle strength improvements observed in elderly 30; 55; 57; 64 and younger subjects 15; 19; Also, Deyssig et al 19 treated highly trained athletes with GH in a double-blind placebo controlled study and found that muscle strength, measured by 1 RM test, is not affected by GH administration.
Thus, based on current evidence we cannot conclude that GH confers any additional benefit on muscle strength compared to exercise alone.
In fact, besides positive changes in fat free mass, most of the studies reviewed did not show any additive effects of GH on muscle hypertrophy in exercising adults, either measured by nuclear magnetic ressonance imaging NMRI 36 , muscle biopsies 30; 36; 54 or rates of muscle protein synthesis 63; 64; Two similar experiments were conducted to determine whether GH administration enhances muscle anabolism associated with heavy-resistance training in young 63 and older 64 men.
However, fractional quadriceps muscle protein synthesis rate were not different between groups, suggesting no muscle protein accretion with GH treatment 63; In a similar work, Yarasheski et al 65 examined the effects of 14 days GH administration in protein metabolism of experienced weight lifters and found no difference in fractional rate of vastus lateralis muscle protein synthesis and whole body protein breakdown rate before and after GH administration, raising doubts if prolonged GH administration would result in additional muscle hypertrophy.
Later, Welle et al 57 found that GH administration has no acute 4 hours effect on myofibrilar protein synthesis compared to placebo. There were also no significant differences in the mean fractional rate of myofibrilar protein breakdown or mean postabsorptive fractional rate of myofibrilar synthesis between groups. However the author themselves admitted that the results raised question of how there could be an increase in muscle mass without alterations in protein metabolism.
One of the possible causes of the increase in FFM without muscle hypertrophy or gains in strength and power seen in most studies is that GH did not increase contractile protein. This hypothesis is supported by some studies 10; 12; 63; 64 , but not others Another possible explanation is soft-tissue overgrowth induced by GH treatment 15; 63; Although the lack of effect of GH in muscle hypertrophy might seem surprising, it is in accordance with the early work of Goldberg 26 , who demonstrated that work-induced muscle growth is independent of systemic GH.
Similarly, posterior studies in rats showed that skeletal muscle adaptation to mechanical stimulus occur independently of GH status 18; For example, Eliakim et al 24 found significant correlations between muscle leg volume and serum concentration of IGF-1 at baseline in young girls, however, in response to training, there were an increase in muscle volume without alterations in IGF-1 levels for the training group, while in control group, serum IGF-1 were elevated without an increase in muscle volume.
It is important to note that there is relative independence between the two forms of IGF-1 2; 18; The local effects of IGF-1 were clearly demonstrated either through localized infusion of small quantities of IGF-1 3 or through induction of increased IGF-1 response in specific tissues 8; 9; 37 , demonstrating that increases in muscle hypertrophy and strength occur with muscle-specific elevations in IGF-1, even in the absence of alterations in the level of the hormone in serum.
Crist et al 15 found two main adverse reactions associated with GH treatment: In a study conducted by Taafe et al 55 several participants experienced fluid retention, which was sufficient to cause three subjects to withdraw from the study and two others to require diuretic medication. Two subjects in the study conduced by Yarasheski et al 63 developed carpal tunnel syndrome symptoms compression and were withdrawn from the experiment.
Lately, GH treatment had to be discontinued in several subjects due to adverse reactions such as carpal tunnel syndrome compression, artrhalgia and fluid retention in hands and feet Because of side effects, GH dosage had to be reduced in many subjects in both studies 64; Symptoms of carpal tunnel syndrome and fluid retention were also seen by Deyssig et al 19 and Welle et al Hennessey et al 30 had to drop GH dose from 0.
In a recent study 36 , one subject in GH group abandoned the experiment because of intolerable side effects attributable to GH administration pitting leg edema. It is important to stress that the use of growth hormone as a performance aid is illicit. This, along with the large evidence of side effects without a significant ergogenic effect, reinforces the orientations that this hormone should be used only in the cases suggested by FDA.
Moreover, GH use by athletes is often accompanied by other dangerous practices making it difficult to assess its side effects in these cases. However, the literature submits some reports of GH abuse by bodybuilders presenting diverse pathological conditions 20; 21; The exact mechanisms of muscle adaptation to overload are still not completely understood; however, there is much evidence that systemic GH does not play a major role in this process 2; 18; Furthermore, in acromegaly, muscles appear hypertrophied but are often functionally impaired Besides some speculative hypothesis for the augmentation in FFM without correspondent increases in contractile structures and function, it is not clear what changes occur during GH treatment.
Thus, requirements for future studies in this area should include expression of non-contractile protein and precise measurements of water retention. This study does not question the potential benefit of GH to specific groups and we are not able to determine if GH have a synergistic effect with resistance training in cases such as GH deficiency, HIV, burn-induced wasting or sarcopenia as the literature reviewed only addressed the effects in apparently healthy persons.
Although GH does seem to have no synergistic effect on muscle anabolism promoted by resistance training, it is possible that GH response to training is statistically correlated to muscle hypertrophy, since training protocols frequently used for this purpose also induce expressive elevations in GH levels 27; 34; 35, 42; This, however, could be attributed to a relation between GH and metabolic stress, instead of a direct relation between GH and muscle anabolism, since protocols that induced higher elevations in GH also produced higher elevations in lactate 27; 35 , and according to some authors metabolic stress is an important stimulus to muscle hypertrophy 49; The increase in FFM without a concomitant improvement in muscle performance and hypertrophy in conjunction with a wide variety of side effects and the high cost of treatment make GH an unviable alternative as an ergogenic aid to resistance training for healthy subjects.
Despite some positive results observed in fat mass, the magnitude of the results are not enough to justify the high incidence of side effects and the elevate cost, making GH treatment not recommended in this cases too. It is important to note that FDA had approved GH as a treatment for several conditions, but not as a therapy for ageing or as an ergogenic aid for sports.
AACE clinical practice guidelines for growth hormone use in adults and children. Adams GR, Haddad F. Body composition and quality of life in adults with growth hormone deficiency; effects of low-dose growth hormone replacement. Treatment of osteoporosis with calcitonin, with and without growth hormone. Coherence treatment of postmenopausal osteoporosis with growth hormone and calcitonin.
Calcif Tissue Int Effects of growth hormone in osteoporosis. J Clin Endocrinol Metab Muscle-specific expression of insulin-like growth factor I counters muscle decline in mdx mice. Viral mediated expression of insulin-like growth factor I blocks the aging-related loss of skeletal muscle function. Treatment of adults with growth hormone GH deficiency with recombinant human GH. J Clin Endocrinol Metab. J Appl Physiol Growth hormone administration conserves lean body mass during dietary restriction in obese subjects.
Degenerative neurologic disease in patients formerly treated with human growth hormone. Early cognitive decline in Creutzfeldt-Jakob disease associated with human growth hormone treatment. J Neurol Neurosurg Psychiatry. Body composition response to exogenous GH during training in highly conditioned adults. Daughaday WH, Rotwein P. Insulin-like growth factors I and II. Peptide, messenger ribonucleic acid and gene structures, serum, and tissue concentrations.
Activation of insulin like growth factor gene expression during work-induced skeletal muscle growth. Am J Physiol Effect of growth hormone treatment on hormonal parameters, body composition and strength in athletes. Related Articles, Links Bilateral median neuropathy and growth hormone use: Arch Phys Med Rehabil.
Dickerman RD, Jaikumar S. Secondary partial empty sella syndrome in an elite bodybuilder. Increased physical activity and the growth hormone-IGF-I axis in adolescent males. Ernst M, Froesch ER Growth hormone dependent stimulation of osteoblast-like cells in serum-free cultures via local synthesis of insulin-like growth factor I.