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A recent study has provided evidence that testosterone increases muscle strength, but does this translate to enhanced performance?
MJA 1997; 166: 60
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Theoretically, anabolic-androgenic steroids should improve
athletic performance by increasing muscle mass (via increased
protein synthesis, nitrogen retention and antiglucocorticoid
actions), as well as by increasing aggression and motivation.
Moreover, recent isotope uptake studies in humans indicate that
androgens may increase muscle protein synthesis, possibly through
stimulation of intramuscular insulin-like growth factor-I (IGF-I)
gene expression. 4
However, clinical studies have, in general, been inconclusive,
partly because of the many unique methodological problems in
studying the effects of anabolic-androgenic steroids (see below).
In 1991, 16 randomised, placebo-controlled studies that
used objective measures of performance were analysed by Elashoff et
al. 5 They concluded that,
while the possibility of anabolic-androgenic steroids improving
sporting performance could not be excluded, "the data are
insufficient to allow any firm conclusion about the efficacy of
anabolic steroids in enhancing overall athletic performance".
Since then, apart from a non-placebo-controlled study that showed an
increase in lean body mass in healthy male volunteers receiving
weekly injections of testosterone enanthate, 6 there were few real developments in
the area until Bhasin et al. 7
published their study in July 1996. This study will probably become,
in time, one of the most-cited articles on drugs and sport. Funded by
the National Institutes of Health (US), the study examined the effect
of high doses of testosterone enanthate in sesame oil (600 mg/week
intramuscularly for 10 weeks); the authors made every attempt to
remove confounding variables (such as diet, training, and
weightlifting experience), and used standardised measures.
Forty-three experienced weightlifters were randomly assigned to
one of four groups (placebo with or without exercise, or testosterone
with or without exercise). Strength was measured by two single
weightlifts -- upper-body strength by benchpress, and lower-body
strength by squatting. Fat-free body mass was measured by underwater
weighing, and muscle size by magnetic resonance imaging. Forty
subjects completed the study.
Body weight increased only in the two testosterone-treated groups,
and fat-free body mass only in the exercise groups, with the greatest
change in fat-free mass in the testosterone plus exercise group
(increase, 6.1 kg). Percentage body fat did not change in any group.
Muscle size increased more in the testosterone groups than in either
placebo group. 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. No significant adverse drug reactions were reported.
Hence, for the first time, in a well designed study,
supraphysiological testosterone did appear to increase muscle
strength.
One other placebo-controlled study has used higher doses of anabolic
steroids (methandrostenolone, 100 mg/day for six weeks). 8 Reported 20 years ago, it used a
crossover design, with attempts to control for most variables. The
active drug was found to be no better than placebo in increasing
strength.
However, some caveats should be considered in assessing Bhasin et
al.'s data. A placebo response has not been completely eliminated. It
was not stated that the placebo was identical to the active drug in
terms of pH, viscosity and other factors that may have allowed the code
to be broken by either the administrator or recipient of the drug.
Indeed, in a controlled study of oral anabolic steroids, all subjects
correctly identified the active drug when directly asked. 9 The importance of the placebo
response was shown by Ariel and Saville, who found that strength
increased considerably in subjects who received placebo, but who
were told they were receiving anabolic steroids. 10 Bhasin et al.'s subjects were
experienced weightlifters. Although they reported that they had not
taken anabolic steroids, these medications are illicit, and thus
self-reporting may not be reliable. As 38%-58% of bodybuilders and
weightlifters have been reported to use anabolic steroids, 11,12 some of Bhasin et al.'s
subjects may well have been able to identify the active drug.
On considering the available evidence, it appears that anabolic
steroids definitely increase muscle size, and probably strength,
but the mechanism is unknown. Further studies, using a crossover
design, including inexperienced as well as experienced
weightlifters, and the same drug vehicle for both placebo and active
drug, with confirmation of subject blinding, should probably be
conducted to confirm these findings. In addition, whether
androgen-induced muscle hypertrophy translates into improved
performance in sports that require skill as well as strength remains
to be determined. But such studies should not overshadow the need for
significant research into the prevention of anabolic-androgenic
steroid abuse.
Michael C Kennedy
Anthony J O'Sullivan
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© 1996 Medical Journal of Australia.
strength increased considerably in subjects who
received placebo, but who were told they were receiving anabolic steroids
For almost half a century, athletes have believed that use of
anabolic-androgenic steroids can improve sporting performance.
The United States physician John Zeigler was so convinced of their
positive effects that on his return from the World Powerlifting
Championships in Vienna in 1954 he worked on the development of
methandrostenolone as a means of enhancing sporting performance.
1 This belief has persisted,
leading to the widespread and much-publicised use of these drugs at
all levels of sport (professional and amateur). It has been promoted
by the banning of these drugs by sporting bodies to ensure fair
competition. 2 Media reports
and "underground" guides to anabolic steroids have also propagated
the use of anabolic-androgenic steroids, which has spread from elite
athletes to recreational bodybuilders, amateur athletes and
adolescents. 3 Are the
athletes and their coaches mistaken in their belief?
Before generalising these results to athletes who use
anabolic-androgenic steroids in the community, it should be
remembered that they receive and use their supplies in very different
ways to the controlled circumstances of Bhasin et al.'s study. Street
supplies are often veterinary or illegally manufactured
preparations, often combined with other medications such as
diuretics and stimulants. Doses and duration are often well in excess
of those used in this study. Although no major side effects were
reported, the well documented long-term adverse effects of
anabolic-androgenic steroids on cardiovascular risk,
gynaecomastia, carcinogenesis, prostate and sexual function would
not have been evident in a study of this duration. 13
Department of Clinical Pharmacology and Toxicology,
St Vincent's Hospital; and Manly Hospital, Sydney, NSW.
Departments of Medicine and Endocrinology, St George Hospital,
Sydney, NSW.
Reprints: Dr M C Kennedy, Manly Non-Invasive Cardiac Laboratory,
Level 4, 22 Darley Road, Manly, NSW 2095.