Training-induced changes in hormonal and metabolic responses to submaximal exercise.
Plasma glucagon and catecholamines increase during prolonged submaximal exercise, but the magnitude of the increase is less in endurance-trained individuals than in untrained subjects. We have studied the rapidity at which this adaptation occurs. Six initially untrained healthy subjects exercised vigorously (on bicycle ergometers and by running) 30-50 min/day, 6 days/wk, for 9 wk. Prior to the beginning of training and at 3-wk intervals thereafter, participants were subjected to 90-min bicycle ergometer test work loads that elicited 58 +/- 2% of the subjects' initial maximal oxygen consumption. The major proportion of the training-induced decrement in plasma glucagon and catecholamine responses to exercise was seen after 3 wk of training. We conclude that the hormonal component of the training adaptation occurs very early in the course of a vigorous endurance training program.
D000328:Adult; D004837:Epinephrine / Q000097:blood*; D005934:Glucagon / Q000097:blood*; D006801:Humans; D007328:Insulin / Q000097:blood*; D008297:Male; D009638:Norepinephrine / Q000097:blood*; D010101:Oxygen Consumption; D010806:Physical Education and Training; D005082:Physical Exertion; D013997:Time Factors
D007328:Insulin; D005934:Glucagon; D009638:Norepinephrine; D004837:Epinephrine