Acute Increases In Anabolic Hormones Do Not Enhance Protein Synthesis

[HawaiianPride.]

You are probably wondering "wtf", how do hormones NOT enhance pro synthesis...

Read on. It's interesting to say the least.

Hormones, such as human growth hormone (GH) and testosterone , have been shown to play a role in muscle hypertrophy and strength gains. Men suffering from either GH or testosterone deficiency have increased fat mass, reduced muscle mass, and reduced muscle force production. The anabolic effects of testosterone on muscle mass are dose- and concentration-dependent.1 Bhasin et al. demonstrated that supraphysiological doses of testosterone can induce increases in muscle size and strength in younger men, without exercise.2 Testosterone-induced increase in muscle mass is associated with a dose-dependent increase in cross-sectional areas of both type I and type II muscle fibers.3

The mechanisms by which testosterone increases muscle mass are not well understood. The prevalent dogma for the past 50 years has been that testosterone increases muscle mass by stimulating fractional muscle protein synthesis.4,5 Testosterone administration primes skeletal muscle for growth by increasing net protein synthesis, even in the fasted state.6,7 The logical extrapolation of continued increase in net protein synthesis is that it results in increased lean body mass and strength.

GH is also highly recognized for its role in muscle growth. Resistance exercise stimulates the release of GH from the anterior pituitary gland, with released levels being very dependent on exercise intensity. GH helps to trigger fat metabolism for energy use in the muscle growth process. GH also stimulates the uptake and incorporation of amino acids into protein in skeletal muscle.

GH is an anabolic hormone capable of increasing muscle mass.8 In humans, GH administration is known to increase both whole-body and muscle protein synthesis8,9 and almost unequivocally to increase lean body mass and decrease fat mass. GH also stimulates hepatic production of circulating IGF-1 concentrations, and may also stimulate IGF-1 production in other tissue such as skeletal muscle.10,11

Since GH and testosterone are potent stimulators of protein synthesis, it would seem logical that increases in anabolic hormones produced during resistance exercise will enhance protein synthesis. Researchers from the McMaster University designed an interesting study to determine if the acute anabolic hormone response to high-intensity exercise would enhance protein synthesis, in conjunction with a protein drink after exercise.

Subjects were assigned to a low-hormone, resistance-training group or a high-hormone, resistance-training group. Young male participants completed two trials on separate days. In the low-hormone trial, participants performed single-arm (unilateral) cable preacher-curl exercises aimed exclusively to activate the biceps muscle. In the high-hormone trial, participants performed the same single-arm exercise with their contralateral arm, immediately followed by a bout of high-volume, intense, heavy leg exercise using short rest intervals designed to elicit a large increase in systemic hormones.

Exercise with the unilateral arm consisted of 4 sets of 10 repetitions at a load that was ~95 percent of 10 RM, such that failure occurred during the final set. To elicit a large hormonal response, the same arm exercise was performed with the contralateral arm, followed by 5 sets of 10 repetitions of leg press at ~90 percent of 10 RM, and 3 sets of 12 repetitions of leg extension/leg curl supersets (1 set of each, back-to-back, with no rest between sets).

Between-set rest intervals for arm and leg exercises were 120 seconds and 60 seconds, respectively. All participants in both trials ingested 25 grams of whey protein after arm exercise. The whey protein drink served as a typical post-workout protein supplement, and provided essential amino acids as the substrate for the muscle protein's synthetic response to exercise. Immediately after the exercise trials, a muscle biopsy and a blood sample was taken.

No Increases in Protein Synthesis After Resistance Exercise in Conjunction With Acute Anabolic Hormones

As expected, the high-hormone group that combined both arm and leg exercise elicited larger increases in lactate, GH, IGF-1, and testosterone than the low-hormone group, yet there were identical increases in muscle protein synthesis. If acute anabolic hormones from resistance exercise were the driving mechanism for increasing protein synthesis, the researchers should have found increases in muscle protein synthesis in the high-hormone group, yet no differences were seen. If the acute anabolic hormones during exercise were the predominate factor for stimulating muscle hypertrophy and protein synthesis, then why do powerlifters demonstrate large increases in muscle mass despite taking prolonged rest periods between sets?

The data suggests that exercise-induced local mechanisms in muscle itself activate protein synthesis, rather than systemic increases in anabolic hormones being the activators of muscle protein synthesis.

References:

1. Bhasin S, Woodhouse L, Casaburi R, Singh AB, Bhasin D, Berman N, Chen X, Yarasheski KE, Magliano L, Dzekov C, Dzekov J, Bross R, Phillips J, Sinha-Hikim I, Shen R, and Storer TW. Testosterone dose-response relationships in healthy young men. Am J Physiol Endocrinol Metab, 281: E1172-E1181, 2001.

2. Bhasin S, Storer TW, Berman N, Callegari C, Clevenger B, Phillips J, Bunnell TJ, Tricker R, Shirazi A, and Casaburi R. The effects of supraphysiologic doses of testosterone on muscle size and strength in normal men. N Engl J Med, 335: 1-7, 1996.

3. Sinha-Hikim I, Artaza J, Woodhouse L, Gonzalez-Cadavid N, Shen R, and Bhasin S. Testosterone-induced increase in muscle size is associated with muscle fiber hypertrophy. Am J Physiol Endocrinol Metab, 283: E154-E164, 2002.

4. Brodsky IG, Balagopal P, and Nair KS. Effects of testosterone replacement on muscle mass and muscle protein synthesis in hypogonadal men—a clinical research center study. J Clin Endocrinol Metab, 81: 3469-3475, 1996.

5. Ferrando AA, Sheffield-Moore M, Yeckel CW, Gilkison C, Jiang J, Achacosa A, Lieberman SA, Tipton K, Wolfe RR, and Urban RJ. Testosterone administration to older men improves muscle function: molecular and physiological mechanisms. Am J Physiol Endocrinol Metab, 282: E601-E607, 2002.http://ajpendo.physiology.org/cgi/ij...sid=283/1/E154.

6. Ferrando, AA, Tipton KD, Doyle D, Phillips SM, Cortiella J, and Wolfe RR. Testosterone injection stimulates net protein synthesis but not tissue amino acid transport. Am J Physiol Endocrinol Metab, 275: E864-E871, 1998.

7. Sheffield-Moore, M, Urban RJ, Wolf SE, Jiang J, Catlin DH, Herndon DN, Wolfe RR, and Ferrando AA. Short-term oxandrolone administration stimulates net muscle protein synthesis in young men. J Clin Endocrinol Metab 84: 2705-2711, 1999.

8. Crist DM, Peake GT, Egan PA, Waters DL 1988 Body composition response to exogenous GH during training in highly conditioned adults. J Appl Physiol, 65:579-584.

9. Butterfield GE, Thompson J, Rennie MJ, Marcus R, Hintz RL, Hoffman AR 1997 Effect of rhGH and rhIGF-I treatment on protein utilization in elderly women. Am J Physiol, 272:E94-E99

10. DeVol, DL, Rotwein P, Sadow, J Levis, Novakofski J and Bechtel PJ. Activation of insulin -like growth factor gene expression during work-induced skeletal muscle growth. Am J Physiol, 259 (Endocrinol. Metab. 22): E89-E95, 1990.

11. Vandenburgh HH, Karlisch P, Shansky J and Feldstein R. Insulin and IGF-1 induce pronounced hypertrophy of skeletal myofibers in tissue culture. Am J Physiol, 260 (Cell Physiol. 29): C475-C484, 1991.

12. West DW, Kujbida GW, Moore D, Atherton PJ, Burd NA, Padzik JP, Delisio M, Tang JE, Parise G, Rennie MJ, Baker SK, Phillips SM. Resistance exercise-induced increases in putative anabolic hormones do not enhance muscle protein synthesis or intracellular signalling in young men. J Physiol, 2009 Sep 7.

[lovbyts]

Hmmmm so the theory of you should only rest xxx minutes or seconds between sets is a myth? Good because I have never followed any of those rules. I go by how I feel and when I think I'm ready for the next set.

[HawaiianPride.]

Same unless I'm implementing FST-7.

[tigerspawn]

Bump