Neuroendocrine responses to running in women after zinc and vitamin E supplementation

Purpose: The study was undertaken to determine whether acute supplementatio n with zinc or vitamin E would modify neuroendocrine responses to physiolog ic stress. Methods: Specifically, the effects of exhaustive running on bloo d glucose, lactate, ACTH, cortisol, growth hormone, prolactin, catecholamin e, and interleukin 6 (IL-6) concentrations were determined in 10 eumenorrhe ic runners after supplementation with zinc (25 mg), vitamin E (400 IU), or placebo. Subjects ran at 65-70% of their (V)over dot O-2max, to exhaustion, on a treadmill during the follicular phase of their menstrual cycles over three cycles. Results: There were no significant differences associated wit h supplementation for any of the hormonal and metabolic measures. Exercise, however, significantly (P < 0.05) increased plasma lactate, ACTH, prolacti n, and catecholamine concentrations, all of which peaked immediately after exercise (POST). Plasma cortisol concentrations were significantly (P < 0.0 5) elevated at POST, and a further increase was noted 1 h after exercise. I L-6 concentrations rose linearly throughout exercise and reached peak value s at POST. Exercise-induced changes were transient in that all measures ret urned to baseline within 24 h. Conclusions: Acute supplementation with zinc or vitamin E did not influence the effects of exhaustive running on metabo lic and endocrine responses in women. The effects of chronic supplementatio n on neuroendocrine responses to exercise remain to be determined.