Effect of 5 wk of detraining on epinephrine response to insulin-induced hypoglycemia in athletes.

Long-term endurance-trained subjects are known to have an enhanced 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 did not decrease significantly during the 4-6 wk of detraining (P greater than 0.05). Responses of other counterregulatory hormones, i.e., norepinephrine, glucagon, growth hormone, and cortisol, were identical in trained and detrained subjects (P greater than 0.05). Heart rate and blood pressure responses to hypoglycemia were similar in the two conditions (P greater than 0.05). In conclusion, in endurance athletes the enhanced capacity to secrete epinephrine is maintained during 5 wk of detraining.