Androgen Profiles: Testosterone - Part I by David Tolson


This is the first article in an in-depth series on steroids, which will include both steroid profiles and articles that focus on particular side effects. In the first few articles, we’re going to talk about testosterone. This is for a few reasons. First off, it’s the most popular steroid, and many see it as essential for most or all steroid cycles. Secondly, there is more information on it than any other steroid, so knowing the ins and outs of testosterone will set the stage for discussion for the rest of the series.

One of the most frequently asked questions is, “what kind of gains can I expect?” Of course, the answer to this question depends heavily on a wide variety of factors, and one simply can’t make this prediction reliably. However, we can still make an effort to at least provide an approximate answer to the question by looking at the data that is available, and the changes in strength and body composition brought about by testosterone use will be the focus of this article.

Effects of Testosterone + Exercise

The most relevant information we have is research in which subjects are given testosterone and put on weight training routines. In research by Giorgi et al [1], 21 weight training men were given either 3.5 mg per kg of body weight of testosterone enanthate or an inactive placebo every week for 12 weeks. This dosage is equivalent to about 300 mg weekly in a 180 pound individual – approximately half of what most steroid users use. Over this three month period, those that were administered testosterone gained about 46 pounds on their bench press one rep maximum, while those administered placebo only gained about 20 pounds on their bench press one rep max. The men given testosterone also had increased body weight, increased arm and leg size, and lower body fat after the 12 weeks.

Another study, this one six weeks in duration, reported an even more dramatic strength difference – those given testosterone enanthate (same dose) increased their bench press one rep max by about 31 pounds, and those given placebo increased it by only about 8 pounds [2].

In another study conducted about a decade ago, 43 men were given placebo or 600 mg testosterone weekly for 10 weeks, and each of these groups was further divided into groups that either didn’t exercise or lifted weights three times a week. As expected, the greatest results were seen in those both using testosterone and exercising in terms of lean mass gain (increase of 13 lbs), muscle size, and strength (48 lb improvement on the bench press and 84 lb improvement on the squat) [3].

Dose-Response Curve

Another valuable source of information is research and a series of papers by a group of researchers that administered various doses of testosterone enanthate (25, 50, 125, 300, or 600 mg per week) for 20 weeks to 18-35 year old men with weight training experience (we will refer to this as the work of Bhasin et al). They followed a uniform, high protein diet and were also put on a GnRH agonist to suppress the natural production of testosterone and ensure more uniformity in the blood testosterone concentrations reached by subjects in each group. Although the subjects were not allowed to engage in heavy exercise during the study, some useful information about the dose-response curve was established from this research.

What was found is that the relationship between testosterone concentrations and improvements in body composition and strength was logarithmic [4]. For those that didn’t get too far in math, a logarithmic relationship looks like this:

So, as testosterone concentrations increase (from left to right), the results don’t increase in a linear fashion as some might think. Doubling the dose doesn’t double the results, and this is well in line with real world evidence. In fact, once the dose gets high enough, the increment by which you have to further increase the dose to see a significant increase in gains becomes quite large. These authors also speculate (based on typical dose-response curves) that a point will be reached (somewhere above the 600 mg dose) where the dose-response curve plateaus and increasing the dose no longer has any beneficial effect at all [5].

Interestingly enough, significant changes in body composition and strength were seen from testosterone use even without any heavy exercise stimulus (about a pound of lean mass gain a week on the 600 mg dose), contrary to the popular notion that steroids only “work” if diet and training are in order. Of course, the message still remains that using steroids without knowing and following the basics is a bad idea for a lot of reasons.

There are a few things that further complicate matters in predicting the response to steroid use, of course. One of the main ones is experience, and it is generally agreed upon by veteran steroid users that one must ramp up the dose to continue seeing the same gains. Also, to reiterate, the response is highly variable between individuals, and many of the potential reasons for this are genetic [4, 6]. Still, a first time user with an adequate dose is likely to gain a pound or more muscle per week and increase their strength level by a significant factor – and this is just with testosterone alone.

Specific/Regional Changes

While it is clear that testosterone increases strength, increases muscle mass, and reduces body fat, are these results similar in character to those that one would get from training alone? This is the question that we’ll now address.

In terms of muscular function, there are three main factors to consider – strength, power, and fatigability. Strength is simply how much force one can exert, and is measured by the one rep maximum. Power refers to not only the force exerted, but the rate at which it is done – so, with an increase in power, one can lift a heavy weight much more quickly. Fatigability is self-explanatory, and can be measured by the number of repetitions one can perform at a certain percentage of the one rep maximum. While one can make improvements in all of these areas with weight lifting, Bhasin et al found that testosterone administration led to increases in strength and power, but not fatigability [5]. However, this may not have been the case if subjects were allowed to engage in heavy exercise during the study period.

Another measure of muscle function is specific tension – in simple terms this refers to the strength per unit of muscle mass. The muscles of those that train for strength tend to have a higher specific tension than for those that primarily train for muscle mass. Bhasin et al also found that testosterone did not influence specific tension (in other words, the gains in strength corresponded to the gains in muscle mass) [5]. Additionally, they found that testosterone did not change the ratio of type I to type II muscle fibers [7].

The changes in muscle architecture caused by testosterone along with weight training have also been examined, by Giorgi et al. They found that the combination of the two brought about increases in muscle pennation relative to exercise alone (pennation refers to the angle at which muscle fibers reach the bone). Also, there was an increase in muscle fiber length in the exercise-only group, but not the exercise plus testosterone group. These differences in muscle architecture seen in the subjects given testosterone are characteristic of muscles adapted to a high degree of force production [2].

Another question is whether or not the reductions in body fat associated with testosterone use are region specific. This is actually quite a complicated question, and one has to differentiate between short-term and long-term use. For now, we’re just going to talk about region-specific changes induced in the short-term. Bhasin et al found that increases in testosterone dose correlated to decreased fat mass, with a loss of about a pound of fat every five weeks (despite significant body weight increases) in the 600 mg group. While fat loss in the trunk and extremities was proportional, in the thigh, a greater degree of fat was lost from intermuscular (deep) fat deposits than from the subcutaneous area [8].


We’ve discussed the magnitude of the effects testosterone has on body composition and strength, including specific characteristics of these changes. In the next few articles we’ll talk about the mechanism of action, the different types of testosterone and their pharmacokinetics, and some of the side effects (both good and bad) of testosterone use.


1. J Sci Med Sport. 1999 Dec;2(4):341-55. Muscular strength, body composition and health responses to the use of testosterone enanthate: a double blind study. Giorgi A, Weatherby RP, Murphy PW.

2. Med Sci Sports Exerc. 2001 Oct;33(10):1688-93. Effect of testosterone administration and weight training on muscle architecture. Blazevich AJ, Giorgi A.

3. N Engl J Med. 1996 Jul 4;335(1):1-7. The effects of supraphysiologic doses of testosterone on muscle size and strength in normal men. Bhasin S, Storer TW, Berman N, Callegari C, Clevenger B, Phillips J, Bunnell TJ, Tricker R, Shirazi A, Casaburi R.

4. Am J Physiol Endocrinol Metab. 2001 Dec;281(6):E1172-81. Testosterone dose-response relationships in healthy young men. Bhasin S, Woodhouse L, Casaburi R, Singh AB, Bhasin D, Berman N, Chen X, Yarasheski KE, Magliano L, Dzekov C, Dzekov J, Bross R, Phillips J, Sinha-Hikim I, Shen R, Storer TW.

5. J Clin Endocrinol Metab. 2003 Apr;88(4):1478-85. Testosterone dose-dependently increases maximal voluntary strength and leg power, but does not affect fatigability or specific tension. Storer TW, Magliano L, Woodhouse L, Lee ML, Dzekov C, Dzekov J, Casaburi R, Bhasin S.

6. Am J Physiol Endocrinol Metab. 2003 May;284(5):E1009-17. Epub 2003 Jan 7. Development of models to predict anabolic response to testosterone administration in healthy young men. Woodhouse LJ, Reisz-Porszasz S, Javanbakht M, Storer TW, Lee M, Zerounian H, Bhasin S.

7. Am J Physiol Endocrinol Metab. 2002 Jul;283(1):E154-64. Testosterone-induced increase in muscle size in healthy young men is associated with muscle fiber hypertrophy. Sinha-Hikim I, Artaza J, Woodhouse L, Gonzalez-Cadavid N, Singh AB, Lee MI, Storer TW, Casaburi R, Shen R, Bhasin S.

8. J Clin Endocrinol Metab. 2004 Feb;89(2):718-26. Dose-dependent effects of testosterone on regional adipose tissue distribution in healthy young men. Woodhouse LJ, Gupta N, Bhasin M, Singh AB, Ross R, Phillips J, Bhasin S.

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