pro-Hormone und Muskelzuwachs

J Clin Endocrinol Metab 2000 Jan;85(1):55-9

Androstenedione does not stimulate muscle protein anabolism in young healthy men.

Rasmussen BB, Volpi E, Gore DC, Wolfe RR.

Department of Surgery, University of Texas Medical Branch, Galveston 77550, USA.

Androstenedione is the immediate precursor of testosterone. Androstenedione intake has been speculated to increase plasma testosterone levels and muscle anabolism. Thus, androstenedione supplements have become widely popular in the sport community to improve performance. This study was designed to determine whether 5 days of oral androstenedione (100 mg/day) supplementation increases skeletal muscle anabolism. Six healthy young men were studied before the treatment period and after 5 days of oral androstenedione supplementation. Muscle protein turnover parameters were compared to those of a control group studied twice as well and receiving no treatment. We measured muscle protein kinetics using a three-compartment model involving infusion of L-[ring-2H5]phenylalanine, blood sampling from femoral artery and vein, and muscle biopsies. Plasma testosterone, androstenedione, LH, and estradiol concentrations were determined by RIA. After ingestion of oral androstenedione, plasma testosterone and LH concentrations did not change from basal, whereas plasma androstenedione and estradiol concentrations were significantly increased (P<0.05). Compared to a control group, androstenedione did not affect muscle protein synthesis and breakdown, or phenylalanine net balance across the leg. We conclude that oral androstenedione does not increase plasma testosterone concentrations and has no anabolic effect on muscle protein metabolism in young eugonadal men.

Effects of anabolic precursors on serum testosterone concentrations and adaptations to resistance training in young men.

Brown GA, Vukovich MD, Reifenrath TA, Uhl NL, Parsons KA, Sharp RL, King DS.

Exercise Biochemistry Laboratory, Department of Health and Human Performance, Iowa State University, Ames, IA 50011, USA.

The effects of androgen precursors, combined with herbal extracts designed to enhance testosterone formation and reduce conversion of androgens to estrogens was studied in young men. Subjects performed 3 days of resistance training per week for 8 weeks. Each day during Weeks 1, 2, 4, 5, 7, and 8, subjects consumed either placebo (PL; n = 10) or a supplement (ANDRO-6; n = 10), which contained daily doses of 300 mg androstenedione, 150 mg DHEA, 750 mg Tribulus terrestris, 625 mg Chrysin, 300 mg Indole-3- carbinol, and 540 mg Saw palmetto. Serum androstenedione concentrations were higher in ANDRO-6 after 2, 5, and 8 weeks (p <.05), while serum concentrations of free and total testosterone were unchanged in both groups. Serum estradiol was elevated at Weeks 2, 5, and 8 in ANDRO-6 (p <.05), and serum estrone was elevated at Weeks 5 and 8 (p <.05). Muscle strength increased (p <.05) similarly from Weeks 0 to 4, and again from Weeks 4 to 8 in both treatment groups. The acute effect of one third of the daily dose of ANDRO- 6 and PL was studied in 10 men (23 +/- 4 years). Serum androstenedione concentrations were elevated (p <.05) in ANDRO-6 from 150 to 360 min after ingestion, while serum free or total testosterone concentrations were unchanged. These data provide evidence that the addition of these herbal extracts to androstenedione does not result in increased serum testosterone concentrations, reduce the estrogenic effect of androstenedione, and does not augment the adaptations to resistance training.

J Strength Cond Res 2001 Feb;15(1):144-7

The metabolism of orally ingested 19-nor-4-androstene-3,17-dione and 19-nor-4- androstene-3,17-diol in healthy, resistance-trained men.

Colker CM, Antonio J, Kalman D.

Department of Medicine, Beth Israel Medical Center, New York, New York 10006, USA.

The purpose of this investigation was to determine the metabolism of 2 over-the-counter steroids (Nortesten, which contains 36 mg of 19-nor-4-androstene-3,17-dione and 36 mg of 19-nor-4-androstene-3,17-diol) in healthy, resistance-trained men. Subjects were administered either low (72 mg) or high doses (144 mg) of Nortesten twice daily for 10 days. All subjects tested positive via urinalysis for the presence of nortestosterone at days 3, 5, 7, and 10. There was no change in the urine testosterone-epitestosterone ratio at any day. Furthermore, as determined by serum chemistry tests, there was no effect on renal, hepatic, hematological, or bone marrow function. Thus, short-term ingestion of 19-nor-4-androstene-3,17-dione and 19-nor-4-androstene-3,17-diol may result in a positive drug test result without any harmful side effect