| It has been demonstrated in untrained individuals that acute antecedent exercise blunts the hormonal counterregulatory response to subsequent hypoglycemia. Purpose. To examine the effects of training for 1 week and 8 weeks on hormonal glucose counterregulation in response to hypoglycemia. Methods. Male Sprague-Dawley rats were randomly divided into long-term exercise (LT), short-term exercise (ST), and sedentary control (C) groups. Following the treatment period all rats underwent a hyperinsulinemic-hypoglycemic clamp. Plasma was taken during hypoglycemia for determination of counterregulatory hormone concentrations. Results. All groups exhibited similar concentrations in epinephrine (C = 28.97 +/- 2.4nmo1/L, LT = 37.86 +/- 4.2, ST = 47.08 +/- 9.1; p = NS), norepinephrine (C = 8.22 +/- 0.96, LT = 9.53 +/- 1.01, ST = 7.47 +/- 0.63nmol/L; p = NS), and glucagon (C = 623 +/- 117, LT = 593 +/- 129, ST = 631 +/- 191pg.m1; p = NS). The ST group displayed a higher corticosterone concentration at t = 50min of hypoglycemia (ST = 638 +/- 41 ng/ml vs C = 498 +/- 23 ng/ml p < 0.01). Conclusion. Voluntary training in rats has no effect on catecholamine or glucagon concentration, but there is an increased glucocorticoid response to hypoglycemia in the initial stage of training. |
