To determine the effect of androgens on body composition and muscle strength, we measured fat-free mass (kg), fat mass (kg), and bone density (g/cm2) by dual x-ray absorptiometry, and muscle strength (Newton meters) by dynamometry in a controlled, prospective study involving 13 nonathletic men receiving testosterone enanthate 200 mg/week in for 6 months and 8 healthy controls. Biochemical markers of bone turnover were measured in the treated subjects at baseline and 6 months. In the treated subjects at 6 months, fat-free mass (mean +/- SEM) increased by 9.6 +/- 1.0% (P < or = 0.01) whereas fat mass decreased by 16.2 +/- 6.7% (P < or = 0.05). Changes in muscle strength 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%, decreasing 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 albumin decreased by 4.5 +/- 1.7% (P < 0.05). There were no detectable changes in fat-free mass, fat mass, muscle strength, or bone density in controls. The administration of testosterone enanthate in pharmacological doses for 6 months resulted in a modest reduction in fat mass and small increases in fat-free mass, muscle strength, and bone density. These changes do not support the use of androgens for enhancing athletic performance.
PIP: In Melbourne, Australia, physicians compared data on 13 healthy, nonathletic, 21-37 year old men receiving an intramuscular injection of 200 mg testosterone enanthate once a week for 6 months with data on 8 age-matched healthy controls to examine the effect of this androgen on body composition and muscle strength and to determine whether it may enhance athletic performance. Dual x-ray absorptiometry measured total body and regional bone density. Dynamometry measured muscle strength. Controls did not experience any detectable changes in fat-free mass, fat mass, muscle strength, or bone density. Between baseline and 6 months of testosterone enanthate treatment, the fat-free mass of cases increased 9.6% (about 6 kg; p .01), while fat mass fell by 16.2% (about 2 kg; p .05). When compared with the literature, however, these changes in body composition were modest. It is not sure whether an increase in lean muscle mass or fluid retention accounted for the increase in fat-free mass. Muscle strength changes varied from -1.6% to 19.2%. Body weight increased by about 5% (around 4 kg). Of the 6 movements, hip adduction was the only significant muscle strength change (increased 19.2%; p .05). Bone density decreased by 1.3% at the skull (p .05), while it increased significantly at the lumbar spine, ribs, pelvis, and femoral neck (p .05). It did not change significantly at the arms, Ward's triangle, trochanter, or legs. The increase in bone density were not enough to reduce the risk of bone fractures. Testosterone enanthate treatment increased serum testosterone levels by 91.1% (p .01), serum osteocalcin by 35.7% (p .05), and the serum immunoreactive parathyrin by 41.4% (p .05). It decreased testicular volume by 24% (p .01), serum calcium levels by 2.3% (p .05), and serum albumin levels by 4.5% (p .05). Based on these findings, androgens, at least in the administered dose range, should not be used to enhance athletic performance.