There have been extensive discussion of the benefits, or more precisely the lack thereof, of Testosterone in numerous threads.
Much of this discussion is related to the Landis case, as well as the various assertions by the Landis camp in the ongoing PR
campaign (albeit not incorporated in his legal defense statements). There have been further assertions that finding any information was also a difficult to impossible task. Thus, it made sense to investigate further and post whatever actual research could be found on the subject.
Note that the research accessed here was neither difficult nor time-consuming to find. It involved simple search phrases such as "Testosterone performance in athletes". Far, far less time was reauired to to find this material than was required to actually type this post out. Some of it did cost me some money, but even that was minor. Moreover, the research all predates Stage 17 of last summer's Tour.
As noted in an earlier post, there has actually been a lot of research on Testosterone. Much or most of the research has been related to health issues -- resolving Testosterone deficiency, etc., particularly in older individuals. Not surprisingly, there has not been as much scientific research into performance enhancement for medical/ethical reasons among others. The use of Testosterone is known to be 'rampant' within the sporting world, and one must conclude that such use reflects extensive experimentation, and hence research, within sport. The research on health-related benefits has indicated benefits that would support a top cyclists interest in Testosterone as an enhancement agent.
Beyond those cited previously, such research includes(1)
Anabolic steroids are testosterone derivatives with three mechanisms of action. First, anticatabolic effects reverse the actions of glucocorticoids and help metabolize ingested proteins, converting a negative nitrogen balance into a positive one. Second, anabolic effects directly induce skeletal muscle synthesis. Third, there is a "steroid rush"--a state of euphoria and decreased fatigue that allows the athlete to train harder and longer.
All of which are completely consistent with Manzano's description of the benefit of Testosterone in his 2004 testimony about Kelme/Fuentes.
With respect to research on Testosterone benefit in athletes specifically, there are at least three studies of note:
A 1996 study (2) injected volunteers weekly over a period ten weeks with either 600 milligrams of testosterone enanthate or a placebo. Performance tests done at the end of this period showed the hormone had improved muscle size and strength in those doing strength training, and to a lesser extent in those who did not exercise. Strength increased in both testosterone groups, as well as in the exercise group receiving placebo, but was greater in the exercise group with testosterone than in the exercise group with placebo.(3)
A 2001 study (4) looked at the effects of different doses, with testing conducted only at the end of the 20 week study. This study concluded that changes in leg press strength, leg power, thigh and quadriceps muscle volumes, hemoglobin, and IGF-I were positively correlated with testosterone concentrations, whereas changes in fat mass and plasma high-density lipoprotein (HDL) cholesterol were negatively correlated.
A similar 2003 study (5) concluded that, "the effects of testosterone on muscle performance are specific; it increases maximal voluntary strength and leg power, but does not affect fatigability or specific tension. The changes in leg strength and power are dependent on testosterone dose and circulating testosterone concentrations and exhibit a log-linear relationship with serum total and free testosterone." In other words, it makes you stronger without fatiguing you.
In 2004, a study was conducted in Australia that utilized low dosages and weekly evaluation over the six week duration. Dosages of testosterone enanthate were 3.5 milligrams per kilogram of body weight (e.g. below 350 mg dose) for six weeks and compared with a placebo group. Tests included a cycling power ouput test (increasing the relevance to this forum and cycling related benefit), and the results were striking.
Discussion of the test and its results was provided in New Scientist(6):
EVEN a low dose of testosterone can give athletes a big performance boost - and in a fraction of the time thought necessary
There was, however, a dramatic improvement in the performance of the athletes taking testosterone. The most unexpected finding was that the greatest increases in muscle size and power occurred just three weeks into the trial
Taking testosterone for short periods only, taking smaller doses, or doing both, would reduce the chances of athletes getting caught by drugs testers. "Athletes have probably already figured this out, and we are just confirming that scientifically," says Randall Urban of the University of Texas at Austin
if athletes or coaches have learned by trial and error to use low doses for short periods only, there is less chance of them being caught. Their TE ratios should also return to normal faster, further reducing the chances of detection even under the new testing regime
Hopefully this material sheds some light on the possibility of Testosterone use as a realistic short-term aid for cycling performance, even at low doses.
(1) Haupt HA, Rovere GD. Anabolic steroids: a review of the literature. Am J Sports Med 1984;12:69-84.
(2) Bhasin S, Storer TW, Berman N, Callegari C, Clevenger B, Phillips J, et al. The effects of supraphysiologic doses of testosterone on muscle size and strength in normal men. N Engl J Med 1996; 335:1-7.
(4) Bhasin S, Woodhouse L, Casaburi R, et al. Testosterone dose-response relationships in healthy young men. Am J Physiol Endocrinol Metab. 2001 Dec;281(6):E1172-81.
(5) Storer TW, Magliano L, Woodhouse L, et al. Testosterone dose-dependently increases maximal voluntary strength and leg power, but does not affect fatigability or specific tension. J Clin Endocrinol Metab. 2003 Apr;88(4):1478-85.
(6) Cohen, D. Cheating is easier than you think. New Scientist. August 2004, 2460: 6-7.