Effect of endurance training on glycerol kinetics during strenuous exercise in humans

Glycerol kinetics were evaluated during high-intensity exercise in five untrained and five endurance-trained subjects. Glycerol rate of appearance (Ra) in plasma was determined by infusing [H-2(5)]glycerol during rest and 60 minutes of cycle ergometer exercise performed at 70% Vo(2) peak. Mean plasma glycerol concentration was greater in trained than untrained subjects throughout exercise (P < .05). The average glycerol Ra during exercise and the integrated lipolytic response to exercise, expressed as total glycerol Ra above baseline, were both greater in trained (7.85 +/- 0.72 mu mol . kg(-1). min(-1) and 289 +/- 50 mu mol . kg(-1). h(-1), respectively) than in untrained (5.68 +/- 0.90 mu mol . kg(-1). min(-1), and 198 +/- 31 mu mol . kg(-1). h(-1). respectively) subjects (P < .05). We conclude that whole-body lipolytic rates are greater in endurance-trained athletes than in sedentary controls during high-intensity exercise performed at the same relative intensity. Copyright (C) 1996 by W.B. Saunders Company