The Effects of Supraphysiologic Doses of Testosterone on Muscle Size and Strength in Normal Men

N Engl J Med. 1996 Jul 4;335(1):1-7. doi: 10.1056/NEJM199607043350101.

Abstract

Background: Athletes often take androgenic steroids in an attempt to increase their strength. The efficacy of these substances for this purpose is unsubstantiated, however.

Methods: We randomly assigned 43 normal men to one of four groups: placebo with no exercise; testosterone with no exercise; placebo plus exercise; and testosterone plus exercise. The men received injections of 600 mg of testosterone enanthate or placebo weekly for 10 weeks. The men in the exercise groups performed standardized weight-lifting exercises three times weekly. Before and after the treatment period, fat-free mass was determined by underwater weighing, muscle size was measured by magnetic resonance imaging, and the strength of the arms and legs was assessed by bench-press and squatting exercises, respectively.

Results: Among the men in the no-exercise groups, those given testosterone had greater increases than those given placebo in muscle size in their arms (mean [+/-SE] change in triceps area, 424 +/- 104 vs. -81 +/- 109 square millimeters; P < 0.05) and legs (change in quadriceps area, 607 +/- 123 vs. -131 +/- 111 square millimeters; P < 0.05) and greater increases in strength in the bench-press (9 +/- 4 vs. -1 +/- 1 kg, P < 0.05) and squatting exercises (16 +/- 4 vs. 3 +/- 1 kg, P < 0.05). The men assigned to testosterone and exercise had greater increases in fat-free mass (6.1 +/- 0.6 kg) and muscle size (triceps area, 501 +/- 104 square millimeters; quadriceps area, 1174 +/- 91 square millimeters) than those assigned to either no-exercise group, and greater increases in muscle strength (bench-press strength, 22 +/- 2 kg; squatting-exercise capacity, 38 +/- 4 kg) than either no-exercise group. Neither mood nor behavior was altered in any group.

Conclusions: Supraphysiologic doses of testosterone, especially when combined with strength training, increase fat-free mass and muscle size and strength in normal men.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adult
  • Affect / drug effects
  • Anger / drug effects
  • Behavior / drug effects
  • Biomechanical Phenomena
  • Body Weight / drug effects
  • Double-Blind Method
  • Gonadotropins, Pituitary / blood
  • Humans
  • Injections, Intramuscular
  • Lipids / blood
  • Male
  • Muscle, Skeletal / drug effects*
  • Muscle, Skeletal / physiology
  • Sex Hormone-Binding Globulin / analysis
  • Testosterone / administration & dosage*
  • Testosterone / blood
  • Weight Lifting / physiology*

Substances

  • Gonadotropins, Pituitary
  • Lipids
  • Sex Hormone-Binding Globulin
  • Testosterone