Study Suggests Long Term Anabolic Use Will Generate New Muscle Fibers

In depth study of anabolic usage.

Andy Galpin is a PHD in Human Bioenergetics. In October, he took to Mark Bell’s Supertraining Youtube Channel to discuss many topics, one of which was the influence of testosterone on the body. Many of the claims he makes are quite controversial, like that exogenous testosterone will not significantly increase strength for those who already have natural levels, but another is worth closer examination – that long term anabolic use can lead to hyperplasia, or the generation of muscle fibers.


Galpin states that increase in muscle happens in two ways, hypertrophy, expansion of individual muscle fibers, or, theoretically, an increase in the number of muscle fibers –called hyperplasia.

Galpin says, “We’ve been told for decades hyperplasia doesn’t happen in humans- it’s impossible. Well some pretty awesome data and some papers came out of Europe where they took a bunch of powerlifters who acknowledged that they took anabolic steroids for decades at a time- extended use none the less- well when they actually looked at these people’s muscle what they found was that they have really small fibers and a lot of them. Now this doesn’t prove anything but it really suggests that long term testosterone use could actually induce hyperplasia.”


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The study that he appears to be referring to comes out of Sweden and has been published with the NIH. It’s long, but worth the read. In a nutshell they tested 17 elite lifters, asked them to record all use of anabolic androgen steroids (AAS) and then tested and examined their muscle tissue in various ways. The athletes who claimed to be clean were only accepted if they were routinely tested by a competitive organization.

The results demonstrated that while the long-term users of AAS did have more lean muscle mass, they did not present larger fibers, suggesting the muscle mass is accounted for by a greater number of fibers. Again, this cannot be proven – that would require counting all the fibers in a muscle.

The study presents the result like this:

“In previous studies on subjects with long term AAS supplementation (9±3.3 years), we observed significant higher frequency of newly formed myofibers in AAS users than in the non-AAS users, indicating that steroid can induce both muscle hypertrophy and hyperplasia In the present study, long term AAS supplementation was only associated with higher lean leg mass, but not with larger fiber size, indicating that muscle fiber hyperplasia may play a role in the muscle mass enhancement. Coincidently, the number of myonuclei in type I fibers in the doped athletes was significantly higher than in the clean athletes, which may indicate satellite cell activation for muscle fiber hyperplasia.”


Very interesting result, as Galpin states, there is more work to be done, but this is an extremely provocative finding that could help lead us to a better understanding of anabolics.

“On basis of the results, we concluded that intake of anabolic steroids in combination with strength training induced both fiber hypertrophy and fiber hyperplasia (formation of new muscle fibres), in which the activation of satellite cells is a key process.”

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