Supplemental Growth Hormone Does Not Prevent Loss of Muscle Mass

There is much debate these days regarding the ethical considerations and performance enhancement associated with the use of supplemental growth hormone. Obviously, this is a sensitive topic as currently the use of supplemental growth hormone is illegal without a prescription and is banned by all governing bodies of sport. The use of supplemental growth hormone is not limited only to strength and power sports but is also suspected to be used in endurance sports such as professional cycling to help decrease time required for recovery from events. Some researchers also hypothesize that the use of supplemental growth hormone in elderly individuals may enhance quality of life by preventing the age-associated loss of muscle mass. This assertion is supported by a recently published paper (Marzetti E, Groban L, Wohlgemuth SE, Lees H, Lin M, Jobe H, Giovannini S, Leeuwenburgh C, Carter CS. Effects of short-term GH supplementation and treadmill exercise training on physical performance and skeletal muscle apoptosis in old rats. Am J Physiol Regul Integr Comp Physiol. 2007 Nov.) The purpose of the study was to investigate the effects of short-term growth hormone supplementation and exercise training on physical performance and skeletal muscle apoptosis in aged rats. According to the article, growth hormone supplementation in the elderly has been shown to decrease body fat but the effects on muscle performance have not been clearly shown, while it is well accepted that strength training can increase muscle mass and strength in elderly individuals.

Skeletal muscle apoptosis is a loss of muscle mass and in the case of this study, muscle loss is attributed to the aging process. Old male rats were assigned to one of three groups: Group 1 was supplemented with growth hormone for 4 weeks, Group 2 participated in 4 weeks of treadmill running, and the rats in Group 3 were used as sedentary controls for the experiment. Exercise training was shown to improve exercise capacity and muscle strength in old animals. Samples of the soleus muscle were used to measure apoptosis and neither age nor exercise was associated with significant changes in the muscle. Interestingly, DNA fragmentation, a measure of muscle apoptosis, in the extensor digitorum longus muscle in the old sedentary rats was shown to be offset by the exercise protocol. Growth hormone administration did not improve physical performance or prevent apoptosis in extensor digitorum longus muscle (EDL) and was associated with increased apoptosis in soleus. The conclusions of the research indicate that a short-term program of exercise training started at advanced age reverses age-related skeletal muscle apoptosis and represents an effective strategy to improve physical performance. In contrast, short-term administration of growth hormone late in life did not provide any protection against functional decline or muscle aging and may even accelerate apoptosis in slow-twitch muscles. The results of this study are by no means conclusive, since an animal as opposed to human model was used for data collection but it appears that exercise is a better prophylactic for age-associated muscle apoptosis than growth hormone supplementation.