Suppression of Endogenous Testosterone Production Attenuates the Response to Strength Training: A Randomized, Placebo-Controlled, and Blinded Intervention Study

Am J Physiol Endocrinol Metab. 2006 Dec;291(6):E1325-32. doi: 10.1152/ajpendo.00143.2006. Epub 2006 Jul 25.

Abstract

We hypothesized that suppression of endogenous testosterone would inhibit the adaptations to strength training in otherwise healthy men. Twenty-two young men with minor experience with strength training participated in this randomized, placebo-controlled, double-blinded intervention study. The subjects were randomized to treatment with the GnRH analog goserelin (3.6 mg) or placebo (saline) subcutaneously every 4 wk for 12 wk. The strength training period of 8 wk, starting at week 4, included exercises for all major muscles [3-4 sets per exercise x 6-10 repetitions with corresponding 6- to 10-repetition maximum (RM) loads, 3/wk]. A strength test, blood sampling, and whole body DEXA scan were performed at weeks 4 and 12. Endogenous testosterone decreased significantly (P < 0.01) in the goserelin group from 22.6 +/- 5.5 (mean +/- SD) nmol/l to 2.0 +/- 0.5 (week 4) and 1.1 +/- 0.6 nmol/l (week 12), whereas it remained constant in the placebo group. The goserelin group showed no changes in isometric knee extension strength after training, whereas the placebo group increased from 240.2 +/- 41.3 to 264.1 +/- 35.3 Nm (P < 0.05 within and P = 0.05 between groups). Lean mass of the legs increased 0.37 +/- 0.13 and 0.57 +/- 0.30 kg in the goserelin and placebo groups, respectively (P < 0.05 within and P = 0.05 between groups). Body fat mass increased 1.4 +/- 1.0 kg and decreased 0.6 +/- 1.2 kg in the goserelin and placebo groups, respectively (P < 0.05 within and between groups). We conclude that endogenous testosterone is of paramount importance to the adaptation to strength training.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Absorptiometry, Photon
  • Adult
  • Androgen Antagonists / pharmacology*
  • Body Composition / physiology
  • Diet
  • Double-Blind Method
  • Estrogens / blood
  • Exercise / physiology*
  • Goserelin / pharmacology
  • Hormones / blood
  • Humans
  • Isometric Contraction
  • Leg / anatomy & histology
  • Male
  • Muscle, Skeletal / growth & development*
  • Muscle, Skeletal / physiology*
  • Organ Size / physiology
  • Testosterone / antagonists & inhibitors*
  • Testosterone / biosynthesis*
  • Testosterone / blood
  • Weight Lifting / physiology

Substances

  • Androgen Antagonists
  • Estrogens
  • Hormones
  • Goserelin
  • Testosterone