If you’re a fan of bodybuilding or strength sports in general, you need to put down your remote, stop watching re-runs of “Girls Gone Wild,” and read the very cool and clever information that was just published in the American Journal of Physiology. (Of course, I’ll summarize and explain it to ya). 

Scientists found that testosterone enanthate (given in progressively higher doses) can increase satellite cell numbers in healthy men. Now, if you don’t know diddly about satellite cells, it’s high time you learned. ‘Cause these unique cells are one of the paramount cellular keys in your quest to gain skeletal muscle mass. Here’s the proof. But first, let’s take a crash-course on satellite cells.What Do Satellite Cells Do?Satellite cells are what scientists refer to as the “myogenic stem cells of skeletal muscle.”  In plain English, satellite cells are involved in the repair and regeneration of adult skeletal muscle fibers. Why is this important?

Keep in mind that mature adult muscle fibers no longer have the capacity to undergo mitosis or cell division. Unlike cells of your liver (which can divide and regenerate quite well), muscle cells just can’t do that. But— and this is important— satellite cells, which are located at the periphery of the muscle fiber, can divide and contribute to a variety of important things your muscle fibers are in dire need of, especially after training. What are the main things that satellite cells do?

1)    Repair of damaged muscle fibers
2)    Contribute more mass to existing muscle fibers. This is called muscle fiber hypertrophy.
3)    Contribute to an increase in muscle fiber number. This is called muscle fiber hyperplasia.

OK, for anyone who works out, satellite cells are clearly needed for #1; that is, you need them to repair damaged fibers. And for bodybuilders, satellite cells are definitely needed to contribute greater mass to your muscle fibers. That’s why your fibers get larger!  And the third one, in rare instances, satellite cell proliferation may result in muscle fiber hyperplasia. I’d guess that elite bodybuilders and strength athletes have undergone muscle fiber hyperplasia. 

So now you know what these cool cells do. But let’s get into this even further. If all this cell biology is causing you to sleep, then down some caffeine and do a few jumping jacks. And pay attention.

Muscle Memory and Satellite Cells
Ever wonder why you’re your initial efforts at gaining muscle mass are so difficult? Or why, once you have that muscle mass, and for whatever reason decide to detrain or stop training, it seems easier to regain that lost mass?  And to top it off, it seems that if you use androgens (i.e., anabolic-androgenic steroids), this “muscle memory” is present, and gaining that lost mass back is easier than the first go-round. 
Here’s how it might work. I say “might” because when we’re talking about cellular mechanisms, it’s difficult to say anything with 100 percent certainty. But heck, I’m givin’ it a shot. 

When you exercise, especially if you do negatives or eccentric contractions, the damage that ensues will cause satellite cell activation and proliferation. When satellite cells proliferate, they will do primarily two things; they’ll repair damaged fibers, as well as contribute new mass to make fibers bigger. But, when they do this, it will produce an increase in “myonuclear number” of the muscle fiber, meaning the number of nuclei located in each individual muscle fiber will increase. 

Why is this important? Well, think of the nuclei as the “brains” of the muscle cell. The nuclei decide how much protein to produce and which proteins to produce; obviously that is the critical element for bodybuilders. So with all that nuclei in muscle, you in essence have a muscle fiber with more “brains” to it. These nuclei control a finite segment of each muscle fiber. So, your muscle fiber is now “sensitized” to changes in training or detraining. 

Let’s say, for instance, that you take a three-month vacation from lifting.  You’ll probably lose a bit of size and strength. Now you start lifting again, and abracadabra, you end up regaining that “lost” muscle mass fairly quickly. Why so? It may be that with the greater number of nuclei sitting around your muscle fibers, they are more sensitive to changes in muscle fiber stress (i.e., an exercise stimulus). You end up re-charging your existing nuclei and they in turn start telling the muscle cell or fiber to start churning out protein faster than an Iraqi soldier can wave a white flag. 
Whew… OK, you passed cell biology 101. Let’s get to the meat and potatoes of the study from UCLA.

UCLA Study
This group from UCLA (led by Dr. Bhasin) has done perhaps the most interesting work on androgen administration. Admittedly, for those who have followed the strength sports, much of the “new” information really isn’t new.  We’ve known for years that progressively higher doses of androgens result in progressively larger muscle fibers (just look at the size of today’s strength athletes). And secondly, we’ve known that the harmful side effects have been exaggerated, to say the least. (Read the review paper co-authored by Chris Street and yours truly in a 1996 issue of the Canadian Journal of Applied Physiology). Nonetheless, the UCLA research team has done more than any other group of scientists to convince other scientists and physicians that androgen administration does indeed produce a profound ergogenic effect. 

In this study, they determined the number of satellite cells and myonuclear number in the vastus lateralis muscle obtained at baseline and after 20 weeks of treatment with a GnRH (Gonadotropin Releasing Hormone) agonist, and 125, 300, or 600 milligrams weekly dose of testosterone enanthate (let’s abbreviate it as TE from now on). TE administration was found to significantly increase myonuclear number in the men receiving 300 and 600 milligrams of TE weekly. Also, the percent satellite cell number (i.e., percentage of total myonuclei) was greatest in the 600-milligram group (15 percent), second highest in the 300-milligram group (five percent) compared to baseline (2.5 percent). Also, the absolute number of satellite cells was greater in both the 300- and 600-milligram groups! 

The change in satellite cell number correlated with changes in total and free testosterone concentrations. Satellite cell and mitochondrial areas were also higher in the 300- and 600-milligram groups.
According to the authors, “T-induced muscle fiber hypertrophy is associated with an increase in satellite cell number, a proportionate increase in myonuclear number and changes in satellite cell ultrastructure.”

AAAhhhhh… What Does this Mean?
I know your head is spinning, but this really is fairly simple. By taking TE (we don’t yet know if other androgens do the same thing, but my guess is they do), we can activate satellite cells. And taking more seems to be even better. 

Since TE directly impacts satellite cells, this, of course, explains in part the huge hypertrophic response seen as you progressively increase androgen dosage. With an even greater number of satellite cells, I’d speculate that your muscle fibers are now “sensitized” to changes in exercise stimuli; meaning, if you train like a madman and take TE, you’ll grow! 

In essence, TE alters the “structure” of your muscle fibers both in a quantitative and qualitative sense. Bottom line: TE profoundly affects satellite cell activity and morphology in skeletal muscle fibers; this can dramatically impact your muscle’s ability to enlarge.
And here’s an interesting side note. We also now (at least based on one rodent study) that Creatine can also activate satellite cells. Would stacking Creatine and let’s say a legal OTC prohormone have a similar effect? That sounds like a good thesis project… Any takers?
Reference

Sinha-Hikim I, Roth SM, Lee MI, Bhasin S. Testosterone-induced muscle hypertrophy is associated with an increase in satellite cell number in healthy, young me.  AmerJ Physiol: Endocrin & Metabol. Apr.1, 2003. 10.1152/ajpendo.00370.2002.

T and Health
You’ve heard the endless drumbeat of “steroids will kill you.” What’s so odd about this statement and those of a similar vein is the enormous body of scientific literature that just completely contradicts this. Besides, as with any hormone, there are risks versus benefits that any clear-thinking individual should see. For instance, the use of androgens to treat wasting conditions (e.g., AIDS, post-surgery, burn patients, etc.) would at least convince those who are open-minded that there’s a legitimate use for androgens. Nonetheless, there will always be a cadre of narrow-minded nitwits for whom the data will never alter their a priori conclusions.
 

Singh and co-workers looked at varying doses of testosterone enanthate administration in various health parameters in 61 normal young men (ages 18-35). They looked at different doses of TE ranging (25, 50, 125, 300, or 600 milligrams weekly for 20 weeks). They made sure subjects were consuming similar calories and protein. They found that plasma HDL-cholesterol (the good cholesterol) decreased in the 600-milligram per week group only. On the other hand, serum total cholesterol, LDL-cholesterol (the bad cholesterol), triglycerides, VLDL-cholesterol, apolipoprotein B (high levels indicate high risk for clogged arteries and heart attack), C-reactive protein (measure of stroke risk) did not change in any of the groups. 

Bottom line observation? According to the authors, “significant increments in fat-free mass, muscle size and strength were observed at doses that did not affect cardiovascular risk factors.” Interestingly, only at the highest dose (600 milligrams weekly) was there a negative effect (a drop in HDL).  However, it should be noted that exercise, especially aerobic exercise, is a potent stimulus for increasing HDL concentrations. Would doing aerobic exercise offset this drop? Perhaps.

Nevertheless, it must be made clear that the effects of androgens are dose-specific as well as androgen-specific. Just like the fact that not all carbs, proteins or fats are created equally; the same can be said for androgens. 
Reference
Singh AB et al. The effects of varying doses of T on insulin sensitivity, plasma lipids, apolipoproteins, and C-reactive protein in healthy young men.  J Clin Endocrin & Metabol, 2002 87(1):136-43.

 

Jose Antonio, PhD, CSCS is a co-editor and contributor to Sports Supplements (Lippincott Williams & Wilkins) and the Sports Supplement Encyclopedia (Nutricia), Supplements for Strength-Power Athletes (Human Kinetics) and Supplements for Endurance Athletes (Human Kinetics). More information at www.supplementbooks.com or www.Humankinetics.com