title: Influence of physical training on the fuel-hormone response to prolonged low intensity exercise.
abstract: The effects of physical training on the fuel-hormone response to prolonged (3 hr), low intensity cycle ergometer exercise (40% maximal aerobic power) which in the untrained state fails to produce a rise in blood lactate, was examined in six healthy male subjects. The training program consisted of one hour cycle ergometer exercise performed 4 times weekly for 6 weeks and resulted in a 19% increase in maximal aerobic power. Prior to training, prolonged low intensity exercise resulted in a 20% decline in plasma glucose, a 2.5-fold rise in plasma free fatty acids (FFA), a 7-fold rise in plasma epinephrine, a 3-fold elevation in plasma norepinephrine, and a 2.5-fold rise in plasma glucagon. Following training, the exercised-induced decline in glucose was 60% less than before training, the elevations in plasma FFA and norepinephrine were respectively, 45% and 90% less than before training and no significant increment in plasma norepinephrine and glucagon was observed. Training also blunted the exercise-induced elevations in circulating ketones and growth hormone and resulted in a lower respiratory exchange ratio during exercise. The data indicate that training markedly diminishes the fuel-hormone perturbations associated with low intensity exercise and in the face of a lessened increment in plasma FFA results in a greater utilization of fat and less dependence on carbohydrate during the exercise.
mesh_terms: D000293:Adolescent; D000328:Adult; D001786:Blood Glucose / Q000378:metabolism; D004734:Energy Metabolism; D004837:Epinephrine / Q000097:blood; D005230:Fatty Acids, Nonesterified / Q000097:blood; D006339:Heart Rate; D006728:Hormones / Q000097:blood*; D006801:Humans; D007328:Insulin / Q000097:blood; D007659:Ketones / Q000097:blood; D007773:Lactates / Q000097:blood; D019344:Lactic Acid; D008297:Male; D009638:Norepinephrine / Q000097:blood; D010101:Oxygen Consumption; D010806:Physical Education and Training; D005082:Physical Exertion
chemical_list: D001786:Blood Glucose; D005230:Fatty Acids, Nonesterified; D006728:Hormones; D007328:Insulin; D007659:Ketones; D007773:Lactates; D019344:Lactic Acid; D009638:Norepinephrine; D004837:Epinephrine