Muscle Tension May be May Important than Acute Hormone Responses
This research also is in conjunction with Researchers at the Exercise Metabolism Group at McMaster's University who
recently reported that muscle hypertrophy took place without acute increases in anabolic hormone concentrations7. Ten
healthy young male subjects performed unilateral resistance training for 8 week (3 days/week). Unilateral resistance
exercise is basically where you train one leg, while the other leg is used as a control or untrained muscle. Exercises
performed in the study were knee extension and leg press performed at 80-90% of the subject's single repetition
maximum (1RM). Blood samples were collected before, immediately after, 30, 60, 90, and 120 minutes post-exercise.
The first training bout and following the last training bout were analyzed for total testosterone, free-testosterone, GH, and
insulin-like growth factor-1, along with other hormones. Thigh muscle cross sectional area of the (vastus lateralis) were
measured pre- and post-training. Acutely, no changes in GH, testosterone, or IGF-1 concentrations were observed in the
90 min period following exercise and there was no influence of training on the anabolic hormones measured. GH did
show a moderate increase 30 minutes post-exercise but returned to baseline values by 90 minutes. Training-induced
increases in muscle hypertrophy were observed in type IIb and IIa muscle fiber. No changes were observed in muscle
size in the untrained leg. In conclusion, unilateral training induced local muscle hypertrophy only in the exercised limb,
which occurred in the absence of testosterone, GH, or IGF-1 circulating levels. The moral of the story, don’t get so
caught up in the acute anabolic hormone response that you limit your poundage.
A light weight, high rep protocol does produce muscle hypertrophy, but light weight, however heavy resistance exercise
produces greater muscle mass gains. Muscle "burn" does not stimulate growth, overload stimulates growth.
“Muscle pumps” and "feeling the burn" are not really what building muscle is about nor is it a good indicator
of muscle growth as the study demonstrates. You can get a good "burn" by doing 20-30 repetitions; however, training at
that rep range does not efficiently overload the muscle. The bottom line of the study is that training loads less than 70%
of a 1-RM are not going to induce significant gains in muscle mass or strength. High rep training may be good for muscle
pumps but not good for increasing muscle size or strength.
? Light weight, high repetition workouts do not stimulate muscle growth effectively; heavy resistance exercise is a greater
stimulator of muscle growth.
? Muscle hypertrophy occurred despite increases in anabolic hormones; muscle growth factors (IGF-1, MGF) may be
more important than the acute hormone increases.
1. Hakkinen, K., and Pakarinen, A. Acute hormonal responses to two different fatiguing heavy-resistance protocols in
male athletes. J. Appl. Physiol. 74: 882-887, 1993.
2. Raastad, Truls., Bjoro, Trine., and Hallen, Jostein. Hormonal responses to high- and moderate-intensity strength
exercise. Eur. J. Appl. Physiol. 82:121-128, 2000.
3. Kraemer, W.J., Marchitelli, L.J., Gordon, S.E., Harman, E., Dziados, J.E., Mello, R., Frykman, P., McCurry, D., and
Fleck, S.J. Hormonal and growth factors responses to heavy-resistance exercise protocols. J. Appl. Physiol. 69:1442-
4. Hakkinen K, Pakarinen A. Acute hormonal responses to two different fatiguing heavy-resistance protocols in male
athletes. J Appl Physiol. 1993 Feb;74(2):882-7.
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5. Holm L, Reitelseder S, Pedersen TG, Doessing S, Petersen SG, Flyvbjerg A, Andersen JL, Aagaard P, Kjaer M.
Changes in muscle size and MHC composition in response to resistance exercise with heavy and light loading intensity.
J Appl Physiol. 2008
6. Hulmi JJ, Volek JS, Selänne H, Mero AA. Protein ingestion prior to strength exercise affects blood hormones and
metabolism. Med Sci Sports Exerc. 2005 Nov;37(11):1990-7.
7. Wilkinson SB, Tarnopolsky MA, Grant EJ, Correia CE, Phillips SM. Hypertrophy with unilateral resistance exercise
occurs without increases in endogenous anabolic hormone concentration. Eur J Appl Physiol. 2006 Dec;98(6):546-55.
8. Takarada Y, Sato Y, and Ishii N. Effects of resistance exercise combined with vascular occlusion on muscle function in
athletes. Eur J Appl Physiol 86: 308–314, 2002.
9. Takarada Y, Takazawa H, and Ishii N. Applications of vascular occlusion diminish disuse atrophy of knee extensor
muscles. Med Sci Sports Exerc 32: 2035–2039, 2000.
10. Takarada Y, Nakamura Y, Aruga S, Onda T, Miyazaki S, and Ishii N. Rapid increase in plasma growth hormone after
low-intensity resistance exercise with vascular occlusion. J Appl Physiol 88: 61–65, 2000.
11. Takarada Y, Takazawa H, Sato Y, Takebayashi S, Tanaka Y, and Ishii N. Effects of resistance exercise combined
with moderate vascular occlusion on muscular function in humans. J Appl Physiol 88: 2097–2106, 2000.
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