Fahey, T.D. (1998). Anabolic-androgenic
steroids: mechanism of action and effects on performance. In: Encyclopedia of
Sports Medicine and Science, T.D.Fahey (Editor). Internet Society for Sport Science:
http://sportsci.org. 7 March 1998.
Anabolic steroids are
drugs that resemble androgenic hormones (sometimes called male hormones) such
as testosterone (Figure 1). Athletes consume them in the hope of gaining weight,
strength, power, speed, endurance, and aggressiveness. They are widely used by
athletes involved in such sports as track and field (mostly the throwing events),
weight lifting, and American football. However, in spite of their tremendous popularity,
their effectiveness is controversial. The research literature is divided on whether
anabolic steroids enhance physical performance. Yet, almost all athletes who consume
these substances acclaim their beneficial effects. Many athletes feel that they
would not have been as successful without them.
There are
several possible reasons for the large differences between experimental findings
and empirical observations. An incredible mystique has arisen around these substances,
providing fertile ground for the placebo effect. The use of anabolic steroids
in the "real world" is considerably different from that in rigidly controlled,
double-blind experiments (in a double blind study, neither the subject nor experimenter
knows who is taking the drug). Most studies have not used the same drug dosage
used by athletes. Institutional safeguards prohibit administration of high dosages
of possibly dangerous substances to human subjects. Subjects in research experiments
seldom resemble accomplished weight-trained athletes. Under these conditions,
we must assess the results of sound research studies, as well as clinical and
empirical field observations, in order to obtain a realistic profile of the use,
effects on performance, and side effects of these substances.
How Anabolic
Steroids Work
Male hormones, principally testosterone,
are partially responsible for the tremendous developmental changes that occur
during puberty and adolescence. Male hormones have androgenic and anabolic effects.
Androgenic effects are changes in primary and secondary sexual characteristics.
These include enlargement of the penis and testes, voice changes, hair growth
on the face, axilla, and genital areas, and increased aggressiveness. The anabolic
effects of androgens include accelerated growth of muscle, bone, and red blood
cells, and enhanced neural conduction.
Anabolic steroids
have been manufactured to enhance the anabolic properties (tissue building) of
the androgens and minimize the androgenic (sex-linked) properties. However, no
steroid has eliminated the androgenic effects because the so-called androgenic
effects are really anabolic effects in sex-linked tissues. The effects of male
hormones on accessory sex glands, genital hair growth, and oiliness of the skin
are anabolic processes in those tissues. The steroids with the most potent anabolic
effect are also those with the greatest androgenic effect.
Steroid Receptors
Steroid
hormones work by stimulation of receptor molecules in muscle cells, which activate
specific genes to produce proteins (see Figure 1). They also affect the activation
rate of enzyme systems involved in protein metabolism, thus enhancing protein
synthesis and inhibiting protein degradation (called an anti-catabolic effect).
| Figure 1: How a Steroid
Hormone Works |
|
 |
Heavy resistance training seems
to be necessary for anabolic steroids to exert any beneficial effect on physical
performance. Most research studies that have demonstrated improved performance
with anabolic steroids used experienced weight lifters who were capable of training
with heavier weights and producing relatively greater muscle tension during exercise
than novice subjects. The effectiveness of anabolic steroids is dependent upon
unbound receptor sites in muscle. Intense strength training may increase the number
of unbound receptor sites. This would increase the effectiveness of anabolic steroids.
Anti-Catabolic Effects Of Anabolic Steroids
Many
athletes have said that anabolic steroids help them train harder and recover faster.
They also said that they had difficulty making progress (or even holding onto
the gains) when they were off the drugs. Anabolic steroids may have an anti-catabolic
effect. This means that the drugs may prevent muscle catabolism that often accompanies
intense exercise training. Presently, this hypothesis has not been fully proven.
Anabolic
steroids may block the effects of hormones such as cortisol involved in tissue
breakdown during and after exercise. Anabolic steroids may prevent tissue from
breaking down following of an intense work-out. This would speed recovery. Cortisol
and related hormones, secreted by the adrenal cortex, also has receptor sites
within skeletal muscle cells. Cortisol causes protein breakdown and is secreted
during exercise to enhance the use of proteins for fuel and to suppress inflammation
that accompanies tissue injury.
Anabolic steroids may block
the binding of cortisol to its receptor sites, which would prevent muscle breakdown
and enhances recovery. While this is beneficial while the athlete is taking the
drug, the effect backfires when he stops taking it. Hormonal adaptations occur
in response to the abnormal amount of male hormone present in the athlete's body.
Cortisol receptor sites and cortisol secretion from the adrenal cortex increase.
Anabolic
steroid use decreases testosterone secretion. People who stop taking steroids
are also hampered with less male hormone than usual during the "off" periods.
The catabolic effects of cortisol are enhanced when the athlete stops taking the
drugs and strength and muscle size are lost at a rapid rate.
The
rebound effect of cortisol and its receptors presents people who use anabolic
steroids with several serious problems: (1) psychological addiction is more probable
because they become dependent on the drugs. This is because they tend to lose
strength and size rapidly when off steroids. To stave off deconditioning, athletes
may want to take the drugs for long periods of time to prevent falling behind.
(2) Long-term administration increases the chance of serious side-effects. (3)
Cortisol suppresses the immune system. This makes steroid users more prone to
diseases, such as cold and flu, during the period immediately following steroid
administration.
Psychological Effects
Some
researchers have speculated that the real effect of anabolic steroids is the creation
of a "psychosomatic state" characterized by sensations of well being, euphoria,
increased aggressiveness and tolerance to stress, allowing the athlete to train
harder. Such a psychosomatic state would be more beneficial to experienced weight
lifters who have developed the motor skills to exert maximal force during strength
training. Diets high in protein and calories may also be important in maximizing
the effectiveness of anabolic steroids.
Anabolic Steroids and Performance
The
effects of anabolic steroids on physical performance are unclear. Well controlled,
double blind studies have rendered conflicting results. In studies showing beneficial
effects, body weight increased by an average of about four pounds, lean body weight
by about six pounds (fat loss accounts for the discrepancy between gains in lean
mass and body weight), bench press increased by about 15 pounds, and squats by
about 30 pounds (these values represent the average gains for all studies showing
a beneficial effect). Almost all studies have failed to demonstrate a beneficial
effect on maximal oxygen consumption or endurance capacity. Anabolic steroid studies
have typically lasted six to eight weeks and have usually used relatively untrained
subjects.
Most changes in strength during the early part
of training are neural: increased strength is mainly due to an improved ability
to recruit motor units. Anabolic steroids affect processes associated with protein
synthesis in muscle. Studies lasting six weeks (typical study length) would largely
reflect neural changes and could easily miss the cellular effects of the drugs.
The
gains made by athletes in uncontrolled observations have been much more impressive.
Weight gains of thirty or forty pounds, coupled with thirty percent increases
in strength, are not unusual. Such case studies lack credibility because of the
absence of scientific controls. However, it would be foolish to completely disregard
such observations because the "subjects" have been highly trained and motivated
athletes.Please see the articles on pharmacology of sport and sports medicine
in the countries of the former Soviet Union for more information on anabolic steroids.
References
American
Medical Association, Council on Scientific Affairs. Medical and non-medical uses
of anabolic-androgenic steroids. J. Amer. Med. Assoc. 264: 2923-2927, 1990.
Bahrke,
M.S., C.E. Yesalosk, and J.E. Wright. Psychological and behavioural effects of
endogenous testosterone levels and anabolic-androgenic steroids among males: a
review. Sports Med. 10: 303-337, 1990.
Buckley, W.E., C.E.
Yasalis, K.E. Friedl, W.A. Anderson, A.L. Streit, and J.E. Wright. Estimated prevalance
of anabolic steroid use among male high school seniors. J. Amer. Med. Assoc. 260:
3441-3445, 1988.
Rogozkin, V. Metabolism of Anabolic Androgenic
Steroids. Leningrad: Nauka, 1988.
United States Olympic
Committee. USOC Drug Education Handbook. Colorado Springs: USOC, 1989.
Common misspellings of Steroid Mechanism: ateroid dteroid emchanism mchanism mecahnism mecanism mecganism mechabism mechaism mechamism mechanesm mechaniam mechanidm mechanim mechanims mechanis mechanisn mechanosm mechansim mechansm mechanusm mechnaism mechnism mechonism mechqnism mechsnism mecjanism mehanism mehcanism mevhanism mexhanism michanism mrchanism mwchanism nechanism seroid sreroid steeoid steoid steorid steraid sterid steriid sterod sterodi steroed steroi steroif sterois sterood steroud sterpid stetoid stiroid stroid strroid stwroid syeroid
