title: Suppression of endogenous testosterone production attenuates the response to strength training: a randomized, placebo-controlled, and blinded intervention study.
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.
authors.affiliation: Institute of Sports Science and Clinical Biomechanics, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark. thuekvorning@hotmail.com
authors.forename: Thue
authors.initials: T
authors.lastname: Kvorning
authors.forename: Marianne
authors.initials: M
authors.lastname: Andersen
authors.forename: Kim
authors.initials: K
authors.lastname: Brixen
authors.forename: Klavs
authors.initials: K
authors.lastname: Madsen
mesh_terms: D015502:Absorptiometry, Photon; D000328:Adult; D000726:Androgen Antagonists / Q000494:pharmacology*; D001823:Body Composition / Q000502:physiology; D004032:Diet; D004311:Double-Blind Method; D004967:Estrogens / Q000097:blood; D015444:Exercise / Q000502:physiology*; D017273:Goserelin / Q000494:pharmacology; D006728:Hormones / Q000097:blood; D006801:Humans; D007537:Isometric Contraction; D007866:Leg / Q000033:anatomy & histology; D008297:Male; D018482:Muscle, Skeletal / Q000254:growth & development* / Q000502:physiology*; D009929:Organ Size / Q000502:physiology; D013739:Testosterone / Q000037:antagonists & inhibitors* / Q000096:biosynthesis* / Q000097:blood; D014891:Weight Lifting / Q000502:physiology
chemical_list: D000726:Androgen Antagonists; D004967:Estrogens; D006728:Hormones; D017273:Goserelin; D013739:Testosterone