Exercise induced growth hormone and the effect of age and oxidative stress parameters in Iraqi subjects

ABSTRACT

Exercise is a potent stimulus for growth hormone [GH]. Age and oxidative stress are associated with a diminution of GH secretion. The aim is to explore the changes that occur in such parameters with exercise in an attempt to determine which one is more important for growth hormone production in order to set a milestone for overcoming such a cause in the future. This is one of many steps in trying to improve the life quality and style in elderly subjects. Sixty healthy Iraqi subjects were enrolled in this study. Divided into three groups according to age, group I [age range 20-29], group II [age range 30-39], and group III [age range 40-49]. They were asked to exercise according to modified Bruce protocol. Blood samples were taken from each subject pre and post exercise for biochemical tests. The test included were GH, creatin kinase, uric acid, malonedialdehyde [MDA], lipid profile [triglycerides, cholesterol, high density lipoprotein HDL]. Low density lipoprotein LDL was calculated. The same trend of having high triglyceride level had been shown in all groups in males and females before and after exercise and decrease after that. However the level is lower in the age group 20-29 and increases with increasing age. Same can be said about cholesterol. But HDL has a plateau pattern in all three groups but it decreases with increasing age. LDL on the other hand shows a significant decrease after exercise in both males and females in the small age group. Such a behavior can also be observed in the two other age groups but with less significance. The behavior of MDA and CK is the same in all age groups with a significant increase after exercise. One characteristic important finding is that the level of growth hormone in the females shows a significant increase after exercise in all age groups when compared with males although its level is less in the higher age group than in the lower. Mean serum levels of uric acid showed an elevation after exercise from its basic level before exercise. A significant difference was found between group I and group III. In conclusion regular exercise increases the secretion of growth hormone which in turns leads to an increase in physical fitness thus delays aging process despite the oxidative stress process that occur during these events. These conclusions have important clinical implications if we are to prevent the frailty and morbidity associated with old age