Prev NEXT  


How Performance-enhancing Drugs Work

Building Mass and Strength

Track star Marion Jones makes a statement prior to her sentencing for lying about steroid use.
Track star Marion Jones makes a statement prior to her sentencing for lying about steroid use.
Chris Hondros/Getty Images

Mass- and strength-enhancing drugs used by athletes include:

  • Anabolic steroids
  • Beta-2 agonists
  • Human chorionic gonadotropin (HCG)
  • Luteinizing hormone (LH)
  • Human growth hormone (HGH)
  • Insulin-like growth factor (IGF-1)
  • Insulin

Anabolic Steroids


A steroid is a chemical substance derived from cholesterol. The body has several major steroid hormones -- cortisol and testosterone in the male, estrogen and progesterone in the female. Catabolic steroids break down tissue, and anabolic steroids build up tissue. Anabolic steroids build muscle and bone mass primarily by stimulating the muscle and bone cells to make new protein.

Athletes use anabolic steroids because they increase muscle strength by encouraging new muscle growth. Anabolic steroids are similar in structure to the male sex hormone, testosterone, so they enhance male reproductive and secondary sex characteristics (testicle development, hair growth, thickening of the vocal cords). They allow the athlete to train harder and longer at any given period.

Anabolic steroids are mostly testosterone (male sex hormone) and its derivatives. Examples of anabolic steroids include: testosterone, dihydrotestosterone, androstenedione (andro), dehydroepiandrosterone (DHEA), clostebol, nandrolone.

These substances can be injected or taken as pills. Anabolic steroids have a number of possible and well-known side effects, including: jaundice and liver damage because these substances are normally broken down in the liver; mood swings, depression and aggression because they act on various centers of the brain.

In males, the excessive concentrations interfere with normal sexual function and cause baldness, infertility and breast development.

In females, the excessive concentrations cause male characteristics to develop and interfere with normal female functions. The drugs can stimulate hair growth on the face and body, suppress or interfere with the menstrual cycle -- possibly leading to infertility; thicken the vocal cords, which causes the voice to deepen, possibly permanently; interfere with the developing fetus in pregnant women.

Beta-2 Adrenergic Agonists

When inhaled, beta-2 agonists relax the smooth muscle in the airways of asthma patients by mimicking the actions of epinephrine and norepinephrine, substances that are secreted by sympathetic nerves. However when injected into the bloodstream, these drugs can build muscle mass (anabolic effect) and reduce body fat (catabolic effect). The anabolic effect appears to directly affect building proteins in the muscles, which is independent of nervous or cardiovascular effects. Some examples of beta-2 agonists include:

  • Clenbuterol
  • Terbutaline
  • Salbutamol
  • Fenoterol
  • Bambuterol

Some of these substances are permitted in inhaler forms with written medical consent.

The major side effects include: nausea, headaches and dizziness because these substances constrict blood vessels in the brain; muscle cramps because they constrict blood vessels in muscles; and rapid heartbeats or flutters because they stimulate heart rate. We'll look at human growth hormones in the next section.