Estrogen and the Male Athlete: Why Not to Avoid it at All Costs

If we believe in what supplement producers tell us, estrogen is to be avoided at all cost, to maximize strength and lean mass gains in male gymrats and competitive bodybuilders. Science on the other hand portrays a more diverse picture of the function/role of estrogen in muscle metabolism. In a recent review Enns & Tidus (Enns. 2010) write:

In skeletal muscle, studies with animals have demonstrated that sex and estrogen may potentially influence muscle contractile properties and attenuate indices of post-exercise muscle damage, including the release of creatine kinase into the bloodstream and activity of the intramuscular lysosomal acid hydrolase, beta-glucuronidase. (Enns. 2010)

They also highlight that

estrogen has also been shown to play a significant role in stimulating muscle repair and regenerative processes, including the activation and proliferation of satellite cells. (Enns. 2010)

The proliferation of satellite cells is however what most bodybuilders are striving for. This is the process behind muscle hypertrophy and some scientists think that it is also the beginning of muscle hyperplasia, i.e. an actual increase in the amount of muscle fibers.

Thus, although the "mechanisms by which estrogen exerts its influence upon indices of skeletal muscle damage, inflammation and repair have not been fully elucidated" even hobby athletes must not overlook its potential protective effects, which are

1. estrogen's action as an antioxidant
2. estrogen's acting as a membrane stabilizer by intercalating within membrane phospholipids
3. estrogen's role in the regulation of a number of downstream genes and molecular targets.

In even more recent study Kamanga-Sollo et.al. (Kamanga-Sollo. 2010) measured the effect of estrogen on bovine sattelite cells:

Figure 1: Effect of E2 concentration on protein synthesis rate in fused bovine satellite cell cultures. Cultures were treated with serum free medium (SFM) or with SFM plus the indicated amounts of E2. (Kamanga-Sollo. 2010. Figure 1)

They found a profound increase in protein synthesis (cf. Figure 1) that was accompanied by a concomitant decrease in protein degradation - in another words: an anabolic response to estrogen treatment.  Now keep that in mind before you start popping ATD-caps like candy ;o)