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The Role of Estrogen in Muscle Growth
To sum this up IMO is to take enough to keep the bad sides such as water bloat
, fat deposits and the dreaded gyno away but just keep enough estrogen in your
system to keep IGF-1 production going, glucose metabolism, and especially muscle
growth!
Also in essence the stronger the anti-e the more it can possibly hinder gains..
So if taking one of the stronger anti-e's, one of two things should be
happening.
1.. your using less as to not hinder gains and or
2... You are very susceptible to gyno.
Stronger doesn't always equate to better
Can estrogen work to augment muscle growth? Is this hormone always unwanted when
we are taking anabolic steroids? Anecdotal reports from athletes suggest that
the use of estrogen maintenance drugs such as tamoxifen (anti-estrogen) or
aminoglutethimide (anti-aromatase) may slightly hinder muscle mass gains during
steroid therapy. An explanation or even clarification for this observation has
not been easy to come by. Here I would like to take a look at the comparative
effectiveness of certain aromatizable and non-aromatizable drugs, as well as the
possible mechanism in which estrogen can play a beneficial role to the athlete.
The Androgen Receptor
All anabolic/androgenic steroids promote muscle growth primarily via the
cellular androgen receptor (abbreviated as AR in this article). The steroid
attaches to and activates the androgen receptor, which ultimately gives the cell
an order to increase protein synthesis. This process is well understood. But it
has been suggested that other mechanisms may foster muscle growth during steroid
therapy as well, which lie outside of the androgen receptor. One way this is
evidenced is by the fact that steroids displaying a high affinity for the AR in
muscle tissue do not always promote an equally high level of muscle growth. In
other words, anabolic potency does not always correspond perfectly to receptor
affinity. Clearly there are some disparities that lead into question whether or
not the androgen receptor is the only thing at work concerning growth.
Testosterone, Nandrolone and Methenolone
Testosterone is without question one of the most effective steroids for building
muscle mass available to athletes. However it does not have the highest affinity
for the androgen receptor compared to some other steroids. For example, it has
been shown that by eliminating the 19-methyl group (nandrolone) the affinity of
the steroid for the androgen receptor is greatly enhanced[i]. Nandrolone thus
displays approximately 2-3 times greater affinity for the androgen receptor
compared to testosterone, yet its ability to promote muscle growth seems to be
considerably lower than testosterone at an equal dosage. One discussed
possibility for this occurrence is the reduced androgenic potency of nandrolone.
While testosterone converts to the more active steroid dihydrotestosterone (3-4
times greater AR affinity) upon interaction with the 5-alpha reductase enzyme in
various androgenic target tissues such as the skin, scalp, prostate, CNS and
liver, nandrolone drops to a third of its original potency by converting to the
weak steroid dihydronandrolone. However this action is very site specific, and
in muscle tissue nandrolone dominates as the active form of the steroid.
Therefore this explanation may not suffice.
Nandrolone also differs from testosterone in its ability to be converted by the
aromatase enzyme to estradiol (an active estrogen). In comparison, nandrolone
aromatizes at approximately 20% of the rate testosterone does, and as such is
not known as a very estrogenic steroid. It is likewise favored when reduced
estrogenic side effects such as water retention, fat deposition and gynecomastia
are desired. However athletes know that there is a trade off with the reduced
tendency for nandrolone to promote side effects, in that it is a less anabolic
steroid. With its known high affinity for the AR in muscle tissue, could this
suggest that estrogen may also be a key mediator of muscle growth?
When we look at Primobolan® (methenolone) we see a similar trend. Methenolone is
at least as good a binder of the androgen receptor as testosterone. By some
accounts it is on par with nandrolone. However it is known to be much weaker
than both steroids at promoting muscle growth. We know that methenolone does not
interact with 5-alpha reductase, and as such its affinity for the AR does not
increase or decrease in androgen target tissues. This would logically seem like
a more favorable trait for anabolism over the weakening we see with nandrolone.
However methenolone is a markedly weaker anabolic, and requires relatively high
doses to promote growth. This also brings into question the role of 5-alpha
reductase in promoting an anabolic state. Perhaps the fact that Primobolan® is a
non-aromatizable steroid is more relevant.
Estrogen and GH/IGF-1
>To date the most common explanation for why anti-estrogens may be slightly
counterproductive to growth in the sports literature has been the suggestion
that estrogen plays a role in the production of growth hormone and IGF-1. IGF-1
(insulin like growth factor 1, formerly known as somatomedin is of course
an anabolic product released primarily in the liver via GH stimulus. IGF-1 is
responsible for the growth promoting effects (increased nitrogen retention, cell
proliferation) we associate with growth hormone therapy. We do know that women
have higher levels of growth hormone than men, and also that GH secretion varies
over the course of the menstrual cycle in direct correlation with estrogen
levels. Estrogen is likewise often looked at as a key trigger in the release of
GH in women under normal physiological situations.
It is also suggested that the aromatization of androgens to estrogens in men
plays an important role in the release and production of GH and IGF-1. This was
evidenced by a 1993 study of hypogonadal men, comparing the effects of
testosterone replacement therapy on GH and IGF-1 levels with and without the
addition of tamoxifen. When the anti-estrogen tamoxifen was given, GH and IGF-1
levels were notably suppressed, while both values were elevated with the
administration of testosterone enanthate alone. Another study has shown 300mg of
testosterone enanthate weekly (which elevated estradiol levels) to cause a
slight IGF-1 increase in normal men, whereas 300mg weekly of nandrolone
decanoate (a poor substrate for aromatase that caused a lowering of estradiol
levels in this study) would not elevate IGF-1 levels. Yet another study shows
that GH and IGF-1 secretion is increased with testosterone administration on
males with delayed puberty, while dihydrotestosterone (non-aromatizable) seems
to suppress GH and IGF-1 secretion, presumably due to its strong
anti-estrogenic/gonadotropin suppressing action. All of these studies seem to
support a direct, estrogen-dependant mechanism for GH and/or IGF-1 release in
men. It is difficult to say at this point just how important estrogen is to
IGF-1 production as it relates to the promotion of anabolism in the steroid
using athlete, however it remains an interesting subject to investigate.
Glucose Utilization and Estrogen
Estrogen may play an even more vital role in promoting an anabolic state by
affecting glucose utilization in muscle tissue. This occurs via an altering the
level of available glucose 6-phosphate dehydrogenase. G6PD is an important
enzyme in the support anabolism, as it is directly tied to the use of glucose
for muscle growth and recuperation. During the period of regeneration after
skeletal muscle damage, levels of G6PD are shown to rise dramatically. G6PD
enzyme plays a vital role in what is known as the pentose phosphate pathway, and
as such this rise is believed to enhance the PPP related process in which
nucleic acids and lipids are synthesized in cells; fostering the repair of
muscle tissue.
A 1980 study at the University of Maryland has shown that levels of glucose
6-phosphate dehydrogenase rise after administration of testosterone propionate,
and further that the aromatization of testosterone to estradiol is directly
responsible for this increase.[x] In this study neither dihydrotestosterone nor
fluoxymesterone could mimic the affect of testosterone propionate on levels of
G6PD, an affect that was also blocked by the addition of the potent
anti-aromatase 4-hydroxyandrostenedione to testosterone. 17-beta estradiol
administration caused a similar increase in G6PD, which was not noticed when its
inactive estrogen isomer 17-alpha estradiol (unable to bind the estrogen
receptor) was given. An anti-androgen could also not block the positive action
of testosterone. This study provides one of the first palatable explanations for
a direct and positive effect of estrogen on muscle tissue.
What does this all mean?
It is a long held belief among athletes that estrogen maintenance drugs can
slightly hinder muscle gains during steroid therapy with a strong aromatizable
steroid such as testosterone. Whether or not we have plausibly explained this
remains to be seen, however the above evidence certainly does provide strong
support for a direct and positive affect of estrogen on growth. Does this mean
we should abandon estrogen maintenance drugs? I don’t think that should be the
case. It is important to remember that estrogen can deliver many unwanted
effects such as increased water retention, fat deposition and the development of
female breast tissue when it becomes too active in the male body. Clearly if we
plan a high-dose cycle with an aromatizable steroid, anti-estrogens will be an
important inclusion. However we cannot ignore the suggestion of using estrogen
maintenance drugs only when they are necessary to combat visible side effects
during mild to moderately dosed cycles, especially if bulk is the ultimate goal
of the athlete.
by William Llewellyn
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