Abstract

Long-term endurance-trained subjects are known to have an enhandced capacity to secrete epinephrine. It is, however, unknown to what extent this is a reversible phenomenon, i.e., whether the adrenal medullary secretory capacity is diminished during a period of abstinence from training. Hormonal responses to insulin-induced hypoglycemia were studied in seven endurance-trained young male athletes at the onset and the termination of a 31- to 44-day period of detraining necessitated by a sports injury that required leg casting. During insulin infusion, plasma glucose decreased to a mean range of 2.0-2.1 mM for the two conditions. The epinephrine response to hypoglycemia didnot decrease significantly during the 4-6 wk of detraining (P>0.05). Responses of other counterregulatory hormones, i.e., norepinephrine, glucagon, growth hormone, and cortisol, were identical in trained and detrained subjects (P>0.05) Heart rate and blood pressure responses to hypoglycemia were similar in the two conditions (P>0.05). In conclusion, in endurance athletes the enhanced capacity to secrete epinephrine is maintained during 5 wk of detraining. Verf.-Referat