- Image courtesy of davemendonca.com
"Why do I have to lift legs? I want bigger arms."
"Well,
if you lift your legs, you will get a greater base of anabolic hormones
to work off of later and that will allow you to build bigger arms."
I swear I have had this conversation with almost all of my male clients. Unfortunately, the advice I gave is dead wrong.
Check out my review of literature for
this study below!
Introduction
In
the lay fitness world it is often said that performing exercises that
increase anabolic hormone levels will increase hypertrophy everywhere
throughout the body (
2).
It is shown that exercise can acutely increase anabolic hormone levels (
3,
4,
8,
9). Additionally, it is shown that exercise can increase muscle protein synthesis (MPS) and intracellular signalling proteins (
5,
6,
7).
However, it has yet to be shown that an increase in anabolic hormone
levels leads to a concomitant increase in either MPS or the
phosphorylation of intracellular signalling proteins.
The
aim of this study is to determine whether an increase in anabolic
hormone levels after exercise leads to an increase in MPS and
intracellular signalling proteins in tissues that were not challenged
during the exercise (
1).
The authors hypothesized that an increase in anabolic hormone levels
would lead to an increase in both MPS and the intracellular signalling
proteins (
1).
Eight
healthy men aged 20 ± 1.1 years participated in the study. The
participants didn’t have any formal weight training experience. They
also had not consistently partaken in weight training during the
previous year.
Immediately before exercise, participants
were infused with l-[ring-13C6]phenylalanine. This was done so the
participants had amino acids that were available during the MPS process.
The
participants performed biceps curls unilaterally on one day. This was
the “Low Hormone” (LH) day. On another day the participants performed
the same volume of biceps curls using the contralateral arm. These
curls were followed by multiple leg exercises designed to acutely
increase anabolic hormone levels. This was the “High Hormone” (HH) day.
Muscle
biopsies were taken from the involved biceps of the participants after
both of the exercise days. These were analyzed for intracellular
signaling proteins. Western blots were used for this analysis. One
factor ANOVAs were used for the statistical analysis.
Blood
samples were taken at baseline and at the end of each of the exercise
days. These samples were analyzed for lactate, glucose, insulin,
cortisol, testosterone, growth hormone (GH), and insulin-like growth
factor 1 (IGF-1) levels. Two-factor repeated measures ANOVAs were used
for this statistical analysis.
All
of the anabolic hormones were at their highest levels 15 minutes after
completing the HH exercise. Except for cortisol, all of these levels
returned to the baseline levels within 60 minutes of completing the HH
exercise. Cortisol returned to the baseline level by 120 minutes after
the HH exercise.
There was no difference in the amount of MPS in the biceps brachii tissue between the LH day and the HH day.
The
phosphorylation of STAT3 and p70S6K were elevated after both exercise
days, but there was not an additive effect of the anabolic hormones.
The other signalling proteins were either unchanged after the different
exercise days or slightly decreased after the HH day.
Other Literature Findings
MPS is elevated for up to 36 hours after exercise (
5,
6,
7). IGF-1 levels are also elevated for up to 24 hours (
8). GH returns to resting levels two hours after exercise and testosterone returns one hour after exercise. (
8,
9).
Pharmacological doses of testosterone increases MPS (
10,
11), but there are conflicting findings on the effects of short-term GH supplementation (
12,
13).
There
are conflicting opinions in the research regarding the mechanism of
MPS. While some research cites the availability of amino acids as the
mechanism of MPS (
14), other research finds insulin to be the stimulatory agent (
15). By the same token, other research has found insulin to prevent protein breakdown instead of stimulate MPS (
16).
More recent research cites the contraction of a muscle as the mechanism that begins the process of MPS (
17). Following contraction, phosphorylation of mTORC1 occurs (
17).
This begins a series of biochemical reactions that ultimately leads to
the phosphorylation of rpS6, which is said to both increase the size of
cells as well as the proliferation of cells (
17).
Discussion
This study contradicts much of what is said in the lay fitness world (
2).
There are three important takeaways from this study.
The first is that
the acute increase in anabolic hormone levels does not increase muscle protein synthesis.
A concept that is often described in fitness magazines and blogs is
that by performing exercises that increase anabolic hormone levels,
hypertrophy of tissues that were not challenged will occur at a greater
rate (
2). This study shows that it is highly probable that this claim is false.
The second important takeaway
from this study also contradicts the lay conversation. An idea often
thrown around the corporate gym environment is that the spike in
anabolic hormones from exercise carries over from one day to the next.
What this study shows is that anabolic hormones return to resting levels within 60-120 minutes after completion of the exercise.
The third important takeaway is that in order for a tissue to hypertrophy it has to be challenged directly. This means that if somebody wants bigger biceps, they have to challenge their elbow flexor system.
One
application of this study is in regards to exercise design.
Understanding that a tissue has to be challenged in order for MPS to
occur within that tissue may lead to more appropriate exercise design.
If this information is not understood, an appropriate challenge may not
be created.
Another application of this study is to aid
in the defense against the misinformation circulating among the lay
regarding muscle hypertrophy. Understanding the conditions by which
muscle hypertrophy occurs will allow for more intelligent training and
discourse on the subject.
References
West D, Kujbida G, Moore D, Atherton P, Burd N, Padzik J, Lisio M, Tang J, Parise G, Rennie M, Baker S, Phillips S.
Resistance exercise-induced increases in putative anabolic hormones do
not enhance muscle protein synthesis or intracellular signalling in
young men.
The Journal of Physiology. 587(21): 5239-5247, 2009.
http://onlinelibrary.wiley.com/doi/10.1113/jphysiol.2009.177220/pdf.
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Kraemer W, Gordon S, Fleck S, Marchitelli L, Mello R, Dziados J , Friedl K , Harman E, Maresh C, Fry A. Endogenous Anabolic Hormonal and Growth Factor Responses to Heavy Resistance Exercise in Males and Females.
International Journal of Sports Medicine. 12(2): 228-235, 1991.
https://www.thieme-connect.com/ejournals/abstract/10.1055/s-2007-1024673.
Kumar V, Selby A, Rankin D, Patel R, Atherton P, Hildebrandt W, Williams J, Smith K, Seynnes O, Hiscock N, Rennie M.
Age-related differences in the dose-response relationship of muscle
protein synthesis to resistance exercise in young and old men.
The Journal of Physiology. 587: 211-217, 2009.
http://jp.physoc.org/content/587/1/211.short.
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Takarada Y, Nakamura Y, Aruga S, Onda T, Miyazaki S, Ishii N. Rapid increase in plasma growth hormone after low-intensity resistance exercise with vascular occlusion.
Journal of Applied Physiology. 88(1): 61-65, 2000.
http://jap.physiology.org/content/88/1/61.full.
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Urban R, Bodenburg Y, Gilkison C, Foxworth J, Coggan A, Wolfe R, Ferrando A. Testosterone administration to elderly men increases skeletal muscle strength and protein synthesis.
American Journal of Physiology. 269: E820-E826, 1995.
http://ajpendo.physiology.org/content/269/5/E820.
Yarasheski K, Zachweija J, Angelopoulos T, Bier D. Short-term growth hormone treatment does not increase muscle protein synthesis in experience weight lifters.
Journal of Applied Physiology. 34(6): 3073-3076, 1993.
http://jap.physiology.org/content/74/6/3073.short.
Fryburg D, Gelfand R, Barrett E. Growth hormone acutely stimulates forearm muscle protein synthesis in normal humans.
American Journal of Physiology - Endocrinology and Metabolism. 260: E499-E504, 1991.
http://ajpendo.physiology.org/content/260/3/E499.
Bohe J, Low J, Wolfe R, Rennie M. Latency and duration of stimulation of human muscle protein synthesis during continuous infusion of amino acids.
The Journal of Applied Physiology. 532: 575-579, 2001.
http://jp.physoc.org/content/532/2/575.full.
Biolo G, Williams BD, Fleming RY, Wolfe R. Insulin action on muscle protein kinetics and amino acid transport during recovery after resistance exercise.
Diabetes. 48(5): 949-957, 1999.
http://www.ncbi.nlm.nih.gov/pubmed/10331397.
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