Effects of an anabolic hormone on striated muscle growth and performance
- 76 Downloads
Chronic administration of an anabolic hormone, nandrolone phenylpropionate, in sedentary female rats for 6 weeks gave a 20% increase in body weight and the same proportional increase in all muscles sampled (heart, diaphragm, soleus, TA, EHP and EDL), such that the muscle/body weight ratio was unchanged. Cardiac muscle was unresponsive to treatment. Acute stimulation of EDL via lateral popliteal nerve gave similar values for contraction time, 1/2 relaxation time and twitch: tetanus ratio in both groups suggesting no slowing of the muscle. Fatigue resistance of EDL was improved with 0.29±0.029 vs. 0.46±0.071 of maximum isometric twitch tension being developed after 10 min repetitive stimulation at 4 Hz. This improved endurance was not accompanied by any increase in strength and could not be explained on the basis of cellular hypertrophy, but appears to reflect an increased aerobic capacity of skeletal muscle. The proportion of FOG fibres in EDL increased, 38±1.1% vs. 46±1.1%, and this was paralleled in the other skeletal muscles. Specific hypertrophy of FOG and FG fibres could be conclusively demonstrated in soleus and TA, respectively.
Key wordsNandrolone phenylpropionate Durabolin Striated muscle Fibre types Growth Endurance
Unable to display preview. Download preview PDF.
- Egginton S (1986) Effects of an anabolic hormone on performance and composition of rat skeletal muscle. J Physiol 373:35PGoogle Scholar
- Fahley TD, Brown CH (1973) The effects of an anabolic steroid on the strength, body composition and endurance of college males when accompanied by a weight training program. Med Sci Sprots Exerc 5:272–276Google Scholar
- Freed DLJ, Banks AJ, Longston D, Burley DM (1975) Anabolic steroids in athletes: crossover double-blind trial on weight-lifters. Br Med J 2:477–473Google Scholar
- Gustafsson J-Å, Saartok T, Dahlberg E, Snochowski M, Häggmark T, Eriksson E (1984) Studies on steroid receptors in human and rabbit skeletal muscle — clues to the understanding of the mechanism of action of anabolic steroids. In: Gurpide E, Calandra LC, Soto RJ (eds) Hormones and Cancer. Liss, New York, pp 261–290Google Scholar
- Hervey GR, Hutchinson I (1973) The effects of testosterone on body weight and composition in the rat. J Endocrinol 57:XXIVGoogle Scholar
- Pearse AGE (1968) Histochemistry, theoretical and applied. 3rd edn, Churchill Livingstone, Edinburgh London New YorkGoogle Scholar
- Wright JE (1980) Anabolic steroids and athletes. In: Hutton RS, Miller DI (eds) Exercise and Sport Sciences Reviews, vol 8. Franklin Institute Press, Philadelphia, PA, pp 149–202Google Scholar