Growth Hormone In Sport
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Slide 1 - Source: Growth Hormone in Sport: Beyond Beijing 2008 (Segura et al. 2009)
- Growth Hormone In Sport
Slide 2 - Introduction
- Growth Hormone (GH):
- A natural peptide hormone produced endogenously mostly by the anterior pituitary gland.
- Hormones of hypothalamic (hGH-releasing hormone, somatostatin) and alternative (ghrelin) origin are involved in its secretion (Mihoces 2014).
- Mainly bound to binding proteins.
- Most abundant form of Human Growth Hormone (hGH) is 22 kDa and 191 amino acids are involved (Widdowson et al. 2009).
- Figure 1. Location of the Anterior and Posterior pituitary gland within the brain (Holt & Sönksen 2008)
Slide 3 - hGH Secretion
- Highest level of secretion observed at puberty and decreases with age around 14% per decade.
- Secretion varies under different conditions.
- Greater secretion of hGH observed during:
- Slow-wave sleep
- Low concentration of blood glucose
- Presence of androgens and estrogens
- Figure 2. The amount of GH secreted (in micrograms) at different ages (in years) (Mihoces 2014).
Slide 4 - Sources of hGH
- Figure 3. Serum growth hormone response profiles for women (A) and men (B) for 30, 60, and 120 min of exercise. Values are means ± SD (Bosch et al. 2012).
- Previously, the only source of human growth hormone was human cadavers, but the potential to transfer the dreaded kreutzfeldt-Jacobs disease made this practice obsolete (Cox, Rampton & Eichner 2013).
Slide 5 - The Recombinant Product (rhGH)
- Figure 4. Creating a cDNA that contains the Human Growth Hormone Gene (McHugh et al. 2005).
- hGH and rGH initially used in the late 1980s to treat patients with hormone deficiency.
- The recombinant product is prepared by inserting the gene for hGH in suitable culture of mammalian cells or bacteria, that is, E.coli, and collecting and purifying the expressed protein.
Slide 6 - Putative Benefits of GH Administration
- The anabolic and lipolytic effects reported after hGH treatment in hGH-deficit patients made it highly appealing to athletes, especially when combined with anabolic steroids (Bosch et al. 2012).
- Also increases lean body mass.
- hGH involved in the stimulation of protein synthesis and restriction of protein breakdown (Segura et al. 2009).
- Its popularity is based on the widespread knowledge that it is efficient, hard to detect and without major side-effects if well dosed.
Slide 7 - hGH Levels After Ingestion
- Figure 5. Growth Hormone Levels (% from baseline) by time (minutes after ingestion) (Mihoces 2014).
Slide 8 - Drawbacks of GH Administration
- Heat muscle damage
- Unfavourable changes in lipid profile in blood
- Figure 6. Acromegaly- Enlargement of the fingers, bones and organs (Bosch et al. 2012)
Slide 9 - Influenes on Sport Performance
- hGh secretion increases the elimination of lipids.
- Works on muscle and muscle-specific growth.
- Effectiveness of rhGH as a single doping agent has been questioned due to lack of scientific evidence (McHugh et al. 2005).
Slide 10 - Clinical Trials With Recombinant GH
- Claims on hGH enhancement of athletic performance may be unsubstantiated.
- From >200 studies, authors chose only 44 (correct selection of participants with respect to age and health condition) (Holt & Sönksen 2008).
- rGH regimens: 3-100mg kg21 d21.
- Treatment duration: 4-84 days.
Slide 11 - rGH Clinical Trials
- Increased lean body mass, while decreasing fat.
- Stimulated basal metabolic rate, with preferential use of lipids rather than carbohydrates catabolism at rest.
- Increased biochemical parameters linked to exercise capacity (e.g. lactate, free fatty acids and glycerol concentrations in plasma) and functional markers such as forced expiratory volume, forced vital capacity and maximum inspiratory & expiratory pressure.
Slide 12 - rGH Clinical Trials
- Change in different parameters correlated with administered dose and were more evident after prolonged treatments.
- However, hGH intake did not change muscle strength , exercising energy expenditure, or power output.
- Ultimate conclusion:
- - On trained healthy athletes: at the dose regimens and the durations periods used, hGH intake has limited activity on athletic performance.
Slide 13 - History of GH In Sport
- Listed as a forbidden substance with international federations and the International Olympic Committee (IOC) since 1989.
- hGh belongs on the category S2 “hormone and related substances” of the 2006 FIFA list of prohibited substances.
Slide 14 - Future Cheating Alternatives
- It is quite feasible that we will see the emergence of other cheating alternatives to mimic or improve the ‘‘presumptive’’ performance enhancement effect of GH.
- They will focus to use directly the recombinant growth factors such as insulin-like growth factor-I (IGF-I) or to administer GH metabolic precursors such as ghrelin-like synthetic pharmaceuticals, known as GH secretagogues (GHS) (Holy, Erotokritou & Sönksen 2009)
Slide 15 - Growth Hormone In Sport
- Potentially beneficial in enhancing athletic performance due to its anabolic and lipolytic effects. Works on muscle and muscle-specific growth factors.
- Objective results from scientific studies and subjective reports from user are not in agreement.
- Hence, difficult to draw conclusions regarding the true effects of excessive hGH doses on muscle function and other factors affecting performance (Segura et al. 2009).
Slide 16 - Bibliography
- Bosch, J, Ueki, M, Such-Sanmartin, G, Segura, J & Gutierrez-Gallego, R 2012, Tracking growth hormone abuse in sport: Performance of marker proteins in a controlled setting, viewed 11 May 2015, <http://www.sciencedirect.com.ezproxy.uws.edu.au/science/article/pii/S000326701200623X>
- Cox, H, Rampton, J, Eichner, D 2013, ‘Quantification of insulin-like growth factor-1 in dried blood spots for detection of growth hormone abuse in sport’, Analytical and Bioanalytical Chemistry, vol. 405, no. 6, pp. 1949-1958.
- Green, G, Thevis, M, & Trevorrow, P 2009, ‘Growth hormone: Barriers to the implementation of human growth hormone testing in sport’, Drug Testing and Analysis, vol.1, no. 9, pp. 455-456.
- Holt, RIG, Erotokritou, ML & Sonksen, PH 2009, ‘The history of doping and growth hormone abuse in sport’, Growth Hormone & IGF Research, vol. 19, no. 4, pp. 320.
- Holt, RIG, & Sönksen, PH 2008, ‘Growth hormone, IGF‐I and insulin and their abuse in sport’, British Journal of Pharmacology, vol. 154, no. 3, pp. 542-556.
- McHugh, CM, Park, RT, Sonksen, PH & Holt, RIG 2005, Challenges in detecting the abuse of growth hormone in sport, Clinical Chemistry, vol. 51, no. 9, pp. 1587.
- Mihoces, G 2014, ‘Human growth hormone testing begins’, USA Today, 12 May, p. 08C.
- Saugy, M, Giraud, S, Scottas, ED, Robinson, N 2006, Growth hormone doping in sport, viewed 12 May 2015, <http://www.sciencedirect.com/science/article/pii/S1773035X08717568>
- Segura, J, Gutiérrez-Gallego, R, Ventura, R, Pascual, JA, Bosch, J, Such-Sanmartín, G, Nikolovski, Z, Pinyot, A & Pichini, S 2009, ‘Growth hormone in sport’, Therapeutic Drug Monitoring, vol. 21, no. 1, pp. 3-13.
- Widdowson, WH, Healy, M, Sonksen, PH & Gibney J 2009, The physiology of growth hormone and sport, viewed 13 May 2015, <https://www-clinicalkey-com-au.ezproxy.uws.edu.au/#!/content/playContent/1-s2.0-S1096637409000513>
Slide 17 - Any Questions?