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

Abstract

The study was undertaken to determine whether acute supplementation with zinc or vitamin E would modify neuroendocrine responses to physiologic stress. Specifically, the effects of exhaustive running on blood glucose, lactate, ACTH, cortisol, growth hormone, prolactin, catecholamine, and interleukin 6 (IL-6) concentrations were determined in 10 eumenorrheic runners after supplementation with zinc (25 mg), vitamin E (400 IU), or placebo. Subjects ran at 65-70% of their VO2max, to exhaustion, on a treadmill during the follicular phase of their menstrual cycles over three cycles. There were no significant differences associated with supplementation for any of the hormonal and metabolic measures. Exercise, however, significantly (P<0.05) increased plasma lactate, ACTH, prolactin, and catecholamine concentrations, all of which peaked immediately after exercise (POST). Plasma cortisol concentrations were significantly (P<0.05) elevated at POST, and a further increase was noted 1 h after exercise. IL-6 concentrations rose linearly throughout exercise and reached peak values at POST. Exercise-induced changes were transient in that all measures returned to baseline within 24 h. Acute supplementation with zinc or vitamin E did not influence the effects of exhaustive running on metabolic and endocrine responses in women. The effects of chronic supplementation on neuroendocrine responses to exercise remain to be determined.