BODY-COMPOSITION AND MUSCLE STRENGTH IN HEALTHY-MEN RECEIVING TESTOSTERONE ENANTHATE FOR CONTRACEPTION

To determine the effect of androgens on body composition and muscle st rength, we measured fat-free mass (kg), fat mass (kg), and bone densit y (g/cm2) by dual x-ray absorptiometry, and muscle strength (Newton me ters) by dynamometry in a controlled, prospective study involving 13 n onathletic men receiving testosterone enanthate 200 mg/week im for 6 m onths and 8 healthy controls. Biochemical markers of bone turnover wer e measured in the treated subjects at baseline and 6 months. In the tr eated subjects at 6 months, fat-free mass (mean +/- SEM) increased by 9.6 +/- 1.0% (P less-than-or-equal-to 0.01) whereas fat mass decreased by 16.2 +/- 6.7% (P less-than-or-equal-to 0.05). Changes in muscle st rength ranged from -1.6-19.2%. Only hip adduction increased 19.2 +/- 9 .5% (P < 0.05). Changes in bone density ranged from -1.3-5.2%, decreas ing significantly at one site and increasing significantly at four of the nine sites measured (P < 0.05). Serum testosterone increased by 91 .1 +/- 7.5% (P < 0.01), and testicular volume decreased by 24.0 +/- 3. 2% (P < 0.01). Serum osteocalcin increased by 35.7 +/- 17.3% (P < 0.05 ), serum immunoreactive PTH (iPTH) increased by 41.4 +/- 15.1% (P < 0. 05), serum calcium decreased by 2.3 +/- 1.0% (P < 0.05), and serum alb umin decreased by 4.5 +/- 1.7% (P < 0.05). There were no detectable ch anges in fat-free mass, fat mass, muscle strength, or bone density in controls. The administration of testosterone enanthate in pharmacologi cal doses for 6 months resulted in a modest reduction in fat mass and small increases in fat-free mass, muscle strength, and bone density. T hese changes do not support the use of androgens for enhancing athleti c performance.