Growth hormone, a kind of protein hormone produced and secreted by the somatotrophs in the anterior pituitary gland, plays an important role in human growth. GH's physiological functions are performed through two pathways, either binding growth hormone in target or binding hepatic cell membrane and then producing IGF-I, through which the physiological functions of growth hormone can be achieved. A great number of researches on human body have shown that apart from sleep, exercise is the most potent stimulus to GH secretion, and moderate intension and duration of exercise can stimulate GH secretion. However, the underlying mechanisms by which exercise induces the increase in GH secretion are still largely unknown. The classical mechanism of regulating GH secretion indicates that the secretion of GH is regulated through a complex neuroendocrine control system, especially by the functional interplay of two hypothalamic hypophysiotropic hormones, GH-releasing hormone (GHRH) and somatostatin (SS), exerting stimulatory and inhibitory influences respectively. A recently-discovered endogenous peptide ghrelin displays a stronger GH-releasing activity, but it still remains unclear whether ghrelin regulates the exercise-induced GH release. There has been abundant evidence that some athletes have used GH as doping in both resistance exercise and endurance exercise because of its protein anabolic actions and lipolysis. Based on the above reasons, there will be practical significance in the research on the effects of exercise and growth hormone on GH/IGF-I axis in order to understand the exercise adaptation mechanisms and fight against doping.The research aims to: (1) explore the mechanisms of GH release induced by endurance exercise, with the focus on discovering whether ghrelin is involved in regulating the exercise-induced GH release; (2) find out the effects of GH administration on the relational markers in GH axis, trying to offer a new approach to GH test, which is called scrum IGF-I/ghrclin; (3) explore the function mechanisms of GH, which includes the effects of endurance training and GH administration on GHR mRNA and IGF-I mRNA; (4) understand the effects and mechanisms of GH administration, combined with exercise training, on fat metabolism. The research is divided into four sections. The research methods and results of each section arc listed