How Anabolic Steroids Work

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Thomas D. Fahey
Exercise Physiology Laboratory
California State University, Chico
Chico CA 95929 USA

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: Sportscience. 7 March 1998.

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.

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