How Estrogen Builds Muscle
This is certainly not a call for guys to go out and take estrogen pills – this could cause some big problems!
By William Llewellyn
Often, we learn things through observation long before we understand them from a scientific standpoint. The influence that estrogen has over muscle growth is a very good example. For a long time, bodybuilders have known through observation that this was an important hormone in men – just as it is in women. More to the point, this “female” sex steroid seemed to be a key supporter of the muscle-building process. This was most apparent when we examined traditional “bulking” steroids like oxymetholone, methandrostenolone and testosterone. While highly effective for this purpose, they have always been among the most problematic when it comes to estrogenic side effects. This seemed like too much of a coincidence. The assumption stuck – estrogen must play some role in muscle growth. It would take some time, however, for us to begin understanding why.
Years ago, I began looking into this relationship myself. I was able to find several studies linking estrogen to processes that support skeletal muscle growth. For example, estrogen was shown to increase levels of the enzyme glucose-6-phosphate dehydrogenase (G6PD). G6PD has been tied to the utilization of glucose for muscle tissue repair and growth. It also supports the pentose phosphate pathway, which helps regulate the synthesis of nucleic acids and lipids within cells. Estrogen has also been shown to influence the growth hormone/IGF-1 (insulin-like growth factor 1) axis. As such, it may indirectly support muscle growth by increasing the level or activity of other key anabolic hormones. If you’ve been reading my columns for a while, you’ve seen me cover this research before. I don’t mean to spend so much time on old information, but I do think it sets the background for our latest study.
The paper comes from the Institute of Sports Medicine at the Sports University in Cologne, Germany.1 The study was much more direct and detailed in comparison to previous papers that looked at the role of estrogen in muscle growth. To begin with, the German researchers utilized a variety of estrogen agonist/antagonist medications, as well as gene knockout (estrogen receptor negative) mice, to isolate the effects of estrogen from other hormones. These combination methodologies help eliminate error and spillover effects. During their investigation, they also measured nearly a dozen different markers of muscle growth. This included immunomodulatory substances, anabolic hormones and several important biological markers of protein synthesis and satellite cell activation. Their results were presented in what is probably the most detailed paper on estrogen and skeletal muscle growth yet released.
During their experiments, the researchers found links between estrogen and muscle repair/growth at several levels. First, they confirmed that estrogenic stimulation directly increases myosin heavy chain expression. These are motor proteins that are found in muscle fibers, and principally involved in skeletal muscle contraction. When we are talking about muscle size and strength, we’re talking about MHC proteins. Estrogen also reduced the output of creatine kinase after muscle injury, which is commonly used to measure the level of muscle damage. As such, it may help protect muscle proteins from breakdown during exercise, or have an anti-catabolic role. When it comes to other markers and hormones, estrogen was found to increase the expression of IGF-1, PCNA and MyoD. These are all involved in satellite cell activation and proliferation, which is a key process in ongoing muscle anabolism.
While there is still much research needed, this study does provide strong support for estrogen having an anabolic role, at least at some level. It also looks like one of the best papers we have to help explain why our traditional “bulking” steroids work so well. In a practical sense, however, this is certainly not a call for guys to go out and take estrogen pills – this could cause some big problems! It might give some people reason to pause over their use of aromatase inhibitors (AI), though. These drugs are popular these days, as they are the most effective for lowering estrogen and controlling side effects. But as we see, this may be counterproductive for the anabolic process (estrogen has distinct health benefits, too!). It is probably not a good idea to indiscriminately pack AI medications into your cycles. There are other ways to deal with estrogenic side effects. Take some time to weigh the benefits and drawbacks to each approach before making any decisions.
Deca Inhibits Exercise Benefit
It is no secret. Anabolic steroid abuse can have detrimental effects on the cardiovascular system. While we have known this for a few decades now, scientists are still trying to fully understand exactly how these drugs affect the heart and blood vessels at the cellular level. In furthering this understanding, scientists in Sao Carlos, Brazil examined the effect of nandrolone decanoate (Deca-Durabolin) and exercise on matrix metalloprotease MMP-2.2 MMP-2 is an enzyme involved in tissue remodeling. Its levels increase in certain body tissues in direct relation to exercise intensity, where it is believed to help facilitate tissue repair. This enzyme is also integrally involved in angiogenesis, or the formation of new blood vessels. As such, MMP-2 may help facilitate some of the beneficial effects of exercise on the cardiovascular system. In the Brazilian study, rats that were subjected to seven weeks of mechanical load exercise had a significant improvement in this marker of cardiovascular remodeling, as we’d expect. However, when Deca was also given to these animals, the MMP-2 improvements were blocked. This enzyme inhibition may help explain why long-term steroid abuse is associated with detriments in the cardiovascular system.
William Llewellyn is widely regarded as one of the world’s foremost authorities on the use of performance-enhancing substances. He is the author of the bestselling anabolic steroid reference guide ANABOLICS and CEO of Molecular Nutrition. William is an accomplished researcher/developer in the field of anabolic substances, and is also a longtime advocate for harm reduction and legislative change. He built the website anabolic.org, an extensive online database of information on anabolic steroids and other performance-enhancing drugs.
References:
1. Velders M, Schleipen B, et al. Selective estrogen receptor-B activation stimulates skeletal muscle growth and regeneration. FASEB J.
2. Marqueti RC, Micocci KC, et al. Nandrolone inhibits MMP-2 in the left ventricle of rats. Int J Sports Med.
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