Testosterone +/- Avodart (Dutasteride) vs Fat-Free Mass Part 2

Last Tuesday, we learned that dutasteride, and thus dihydrotestosterone, really has no impact on muscle mass and strength.  But within that short 20 week study published in JAMA, another result came out that could impact how we approach testosterone replacement.  Initial studies looking at the effect of anabolic steroids on muscle mass & strength failed to demonstrate any benefit at subphysiologic replacement doses.  Thus, for quite some time, most traditional mainstream physicians parroted the same party line, at least until the East German Olympic athletes, supported by trainers & coaches, demonstrated the benefit of anabolic steroids at 10-100 times physiologic doses.  Since then, it's become a well known secret in the world of bodybuilding that supraphysiologic doses of anabolic steroids lead to an increase in muscle mass & strength.  But this has all been word of mouth.

So let's take a moment to review this study where men average weight 80kg were randomized to receive either 50mg, 125mg, 300mg or 600mg of testosterone enanthate weekly (and at the same time randomized to receive either dutasteride daily or placebo).  To understand the implications of these testosterone doses, it helps to recall that testosterone cypionate and enanthate are typically dosed at 1mg/kg/week so that the 3 largest doses were really just that - high!  In fact, 50mg/wk of testosterone was able to achieve 519ng/dL in those who received dutasteride vs 385ng/dL who received placebo.  Those who received 125mg/wk achieved 895ng/dL & 822ng/dL, respectively, while 300mg/wk lead to 1,760ng/dL & 1,702ng/dL respectively.  Finally, 600mg/wk (that's 3cc at 200mg/cc) resulted in 3,898ng/dL & 3,578ng/dL on dutasteride vs placebo.  Keep in mind that normal testosterone levels were considered 300-1,200ng/dL by the lab used for before & after measurements such that the 2 largest doses lead to supraphysiologic levels.

In other words, this study really confirms what bodybuilders (and other athletes) have known for years:  there exists a testosterone dose-dependent increase in muscle mass & strength.  In the course of just 20 weeks, those randomized to the highest dose of testosterone gained 7-8kg(!) of muscle regardless of DHT.  Those randomized to just 50mg/wk gained 0.6-0.8kg, although statistically speaking, the confidence interval included zero, suggesting that this particular dose (and mid-range testosterone level) had no statistically significant impact.  Not so with the 3 other doses (and resultant high normal, if not above normal, testosterone levels), again regardless of DHT.  There was a similar testosterone dose- & level-dependent increase in both leg press and chest press strength, regardless of randomization to dutasteride or placebo.

Now, don't get me wrong.  I'm not suggesting for a minute that we supplement testosterone to supraphysiologic levels.  There are too many other issues at play here.  We have to monitor for mood change (possible 'roid rage), hair loss, prostate enlargement (not cancer), gynecomastia, (ironic) loss of libido, polycythemia, decrease in HDL, and increase in blood pressure.  The latter three combine to increase one's risk of thrombotic events, eg heart attack & stroke.  All I'm suggesting is that within the normal range, there is the potential for more muscle mass & strength without the side effects associated with supraphysiologic levels.  So make sure you follow your patients closely (or if you're the patient, make sure your doctor knows what s/he is following).

Follow @alvinblin
Tweet