Michael Morkos
Paul Sourial
Del Ingvaldson
Point - Growth Hormones/Somatotropin
Point hypothesis: Growth Hormone or somatotropin is a safe ergogenic aid to increase
body size by promoting protein synthesis and mobilizing lipids.
Counterpoint hypothesis: Growth Hormone or somatotropin is not a safe ergogenic aid
to increase body size by promoting protein synthesis and mobilizing lipids.
The purpose of this paper is to summarize the uses for growth hormone (GH), and to
support the conclusion that growth hormone or somatotropin is a safe ergogenic aid to
increase body size by promoting protein synthesis and mobilizing lipids.
Clinical Use and Recommended dose
GH is primarily used in a clinical setting to treat disorders that affect normal growth in
both children and adults. For adults with a GH deficiency, GH treatment has been shown to
decrease adipose tissue, increase muscle volume and stimulate bone and cartilage growth (1).
For children with Prader-Willis syndrome, GH treatment decreases percentage of body fat, and
increases height growth velocity (2). In a clinical setting, the recommended dose varies based
on use, but an accepted range is between 0.025 and 0.043 mg/kg/d (7). A natural
overproduction of GH can result in acromegaly, causing enlargement of various body structures
(2).
Mechanism of action
The hypothalamus secretes growth hormone-releasing hormone and this allows GH to
be synthesized and secreted by the anterior pituitary (4). GH binds to the GH receptor causing
JAK2 and STAT proteins to become phosphorylated thus initiating the JAK-STAT signaling
pathway. These pathways signal intracellular STAT proteins to translocate into the nucleus of
the target cell, where they regulate transcription factors and tissue specific genes. This effect
growth and metabolism and depending on the target cell, has different effects. For example, it
can lead to IGF-1 synthesis by the liver which results in an increase in protein synthesis in
muscle cells and fat mobilization in fat cells (4).
Point-GH
As we looked at GH, we found different studies to show the ergogenic effect that GH
employ. One study focused on the effects of GH on body composition and performance in
recreational athletes. They observed the effects of testosterone (T) alone, GH alone and a
mixed dosage of GH and T. These groups were compared with a placebo control group. They
concluded that GH helped to increase the subjects wingate values, increased lean body mass,
and decreased fat mass (8). Another study focused on the effects of GH on muscle growth with
resistance training (10). They detected an increased “whole body protein synthesis rate” (10)
compared to the placebo group (approximately 0.5g protein*kg/FFM/day) vs (approximately
0.1g protein*kg/FFM/day). Along with these results, synthesis and breakdown of protein was
increased with GH administration (10). Finally, a study observed anabolic effects employed by
GH while the subjects were at rest and in exercise (5). They determined three aspects: Rate of
leucine appearance (leucine Ra) (indication of protein breakdown), non-oxidative leucine
disposal (NOLD) (an indication of protein synthesis), and leucine oxidation. It was evident that
leucine Ra along with NOLD increased, but leucine oxidation was decreased. These effects were
augmented after the 4 weeks of the trial were complete. They concluded that GH given to
athletes had a net anabolic effect on whole body protein (5).
Counterpoint-GH
The rate of protein catabolism in rats was observed in muscles undergoing workinduced hypertrophy, muscles undergoing growth by GH administration and finally non-growing
muscles (3). Protein catabolism was measured through loss of radioactive labeled proteins, and
protein synthesis was measured through dilution of radioactive labeled proteins compared to
newly synthesized protein. Results showed that during the work-induced hypertrophy, protein
catabolism decreased whereas protein synthesis increased. In regard to the GH administered
rats, overall protein activity was substantially lower, similar to rates observed in the nongrowing muscles (3). Another study focused on the effects of GH in resistance training in elderly
men (9). In this double-blind experiment, a 14-week weight-training period was introduced, in
which the participants were given either GHs or placebo. In the 10 weeks of strength training
that followed, there was little improvement in leg/arm strength in both groups (9). Finally, the
last study focused on the physiological effects of GH intake in a double-blind study with GHdeficient adults (6). A placebo, physiological and supraphysiological doses of GH were
administered daily for 7 days. Results indicated that GH may be an unsafe aid due to
observations of increased Na+/fluid retention on the 7th day (6).
Counterpoint-GH refute
Study (3) was performed on rats, and thus may not be relatable to humans because of
anatomical/metabolic differences. Another study focused on elderly men (9). In aging, it is
typical that muscle mass declines while other health factors can affect the physical strength
levels of the subjects. This study also stated that “healthy elderly men” (9) were the subjects,
however there was no set definition of what constituted being healthy. Finally in study (6), even
though there was an increase in sodium/fluid retention, there was no increase in blood
pressure; this may suggest that GH is safe to consume.
Conclusion
As presented by the evidence of the point articles and the given critiques of the
counterpoint articles, it is observed that Growth hormone or somatotropin is a safe ergogenic
aid to increase body size by promoting protein synthesis and mobilizing lipids.
References
1. Bengtsson, B. A. Treatment of adults with growth hormone (GH) deficiency with
recombinant human GH. J. Clin. Endocrinol. Metab. 76: 309-317, 1993.
2. Davies, P. S., Evans, S., Broomhead, S., Clough, H., Day, J. M., Laidlaw, A., & Barnes, N.
D. Effect of growth hormone on height, weight, and body composition in Prader-Willi
syndrome. Arch. Dis. Child. 78: 474-476, 1998
3. Goldberg, A. L. Protein synthesis during work-induced growth of skeletal muscle. J Cell
Biol. 36: 653-658, 1968.
4. Han, Y., Leaman, D. W., Watling, D., Rogers, N. C., Groner, B., Kerr, I. M., Wood W. I.,
Stark, G. R. Participation of JAK and STAT Proteins in Growth Hormone-induced
Signaling. J. Biol. Chem. 271: 5947-5952, 1996.
5. Healy ML, Gibney J, Russell-Jones DL, Pentecost C, Croos P, Sönksen PH, Umpleby AM.
High Dose Growth Hormone Exerts an Anabolic Effect at Rest and during Exercise in
Endurance-Trained Athletes. J. Clin. Endocrinol. Metab. 88: 5221–5226, 2003.
6. Hoffman, D. M., L. Crampton, C. Sernia, T. V. Nguyen and K. K. Ho. Short-term growth
hormone (GH) treatment of GH-deficient adults increases body sodium and extracellular
water, but not blood pressure. J Clin Endocrinol Metab. 81: 1123-1128, 1996.
7. MacGillivray, M.H., Blethen, L.S., Buchlis, J.G., Clopper, R.R., Sandberg, D.E., Conboy.
T.A. Current Dosing of Growth Hormone in Children With Growth Hormone Deficiency:
How Physiologic? Pediatr. 102: 527-530, 1998.
8. Meinhardt U. The Effects of Growth Hormone on Body Composition and Physical
Performance in Recreational Athletes. Ann. Int. Med. 152: 568, 2010.
9. Taaffe, D. R., L. Pruitt, J. Reim, R. L. Hintz, G. Butterfield, A. R. Hoffman and R. Marcus.
Effect of recombinant human growth hormone on the muscle strength response to
resistance exercise in elderly men. J Clin Endocrinol Metab. 79: 1361-1366, 1994.
10. Yarasheski, K.E., Jill A. C., Kenneth S., Michael J. R., John 0. H., Dennis M. B. Effect of
growth hormone and resistance exercise on muscle growth in young men. Am. J.
Physiol. 262: E261-E267,1992.