[Impact of acute exercise intensity on plasma concentrations of insulin, growth hormone and somatostatin]. / Exercício físico e insulina, hormona do crescimento e somatostatina.

ABSTRACT

Obesity is increasing all over the world, its morbidity justifying a serious effort to improve the situation. Diet and physical exercise constitute major measures to fight obesity. We aimed to investigate the effect of acute exercise intensity over plasma insulin, growth hormone and somatostatin responses. Plasma levels of insulin, growth hormone, somatostatin and glucose were measured at baseline, after 15 minutes of moderate intensity exercise and after 15 minutes of high intensity exercise in a group of young healthy volunteers. Insulin, growth hormone and somatostatin were measured by immunoradioassay and glucose by a glucose oxidase method. After moderate intensity exercise plasma insulin levels tended to decrease, growth hormone tended to increase and somatostatin did not change. A similar period of high intensity exercise led to a similar decrease of plasma insulin, a much higher increase of growth hormone plasma level and no change of somatostatin. Glycemia suffered no significant change throughout the experiment. We conclude that hormonal changes induced by physical exercise depend on the intensity of exercise. When comparing moderate with high intensity exercise, a similar response of plasma insulin and a lower growth hormone/somatostatin ratio may support a healthier cardiovascular effect for moderate intensity exercise.