Estrogen Blockers: Vascularity Killers

Simplified Explanation:

As someone working toward their master’s degree in exercise physiology, it is mind blowing some of the things I see done (sometimes needlessly) that impact the athlete’s health. Bodybuilding often results in the use of Aromatase Inhibitors (AI’s) because they are thought to create a hardening and more vascular appearance. The blocking of estrogen is a very complex physiological interaction. Simply stated, the use of AI’s in excess can contribute to a decrease in vascular function. This decrease over time can lead to increases in arterial stiffness making them less elastic and increasing blood pressure. Furthermore, micro and macrovascular dysfunction can lead to end organ damage and are contributors’ morbidity and mortality.

The Nerdy Stuff

Estrogen is often thought of with a bad reputation in the world of bodybuilding. As previously stated it is often associated with a softer and less vascular appearance. The reality is, this hormone does play a vital role in many physiological functions of the body including vasodilation. Estrogen itself has vascular effects through the production of nitric oxide. It does this by binding to cells through their specific estrogen receptors. Once it does this, it is transported to the nucleus of the cell where it causes gene expression and creates variations of proteins and enzymes. The relevant enzyme for this article is endothelial nitric oxide synthase (eNOS). This enzyme leads to the breakdown of the amino acids arginine and citrulline to form the vasodilator nitric oxide. Estrogen additionally causes smooth muscle cell relaxation which is another physiological pathway to vasodilation.

Vascular Dysfunction

Aerobic exercise is often used as the first line of treatment and can reverse impairments in men but show inconsistencies in women. This has been in large part due to estrogen deficiency due to menopause. In a study conducted by Santos-Parker et al, the blood flow of 57 subjects was examined. The subjects were separated into pre and post-menopausal sedentary and post-menopausal aerobically trained groups. The study infused vasodilatory compounds in each of the groups to observe micro and macrovascular function through forearm blood flow (FBF). Shockingly, they found that post-menopausal aerobically trained women had less vasodilation when infused with the compounds compared to pre-menopausal sedentary women. This means that for groups of women who have not gone through menopause and do next to no aerobic exercise have better blood flow than that of aerobically trained post-menopausal women.  The key takeaway here is that reduced estrogen is has a negative impact on vascular function.

R, Santos-Parker, Sarah et al, 2016. J Applied Physiology

Proper PED Cycling

The reason AI’s are often needed or at least thought to be needed are because high doses of testosterone convert over to both DHT and to estrogen through different pathways. I have often seen other competitors block estrogen as a protocol without even getting labs done. The only time you should be even considering this is when labs show estradiol as being too high. Most of these competitors and coaches do not even have the athlete on doses that would warrant the use of AI’s. The simple logic here is to not escalate anabolic doses to high levels until it is needed. Does this mean that AI’s will never be needed or should never be used? No, but if other compounds are regulated safely, it can mitigate the use of these agents and the preservation of vascular function which is both aesthetically appealing and crucial for our vital organs. Get your labs done regularly, especially on cycle, your hormones regulate so many important functions in your body and should be measured carefully. If you are someone who is taking AI’s just because, and have not even had your hormone panels done recently, it maybe time to inquire why you are taking them.