Glucoregulatory responses to intense exercise performed in the postprandial state.

A seven- to eightfold increment in hepatic glucose production (endogenous Ra) occurs in postabsorptive (PA) intense exercise (IE). A similar response is likely present in the postprandial (PP) state, when most such exercise is performed, because1) little evidence for increased intestinal absorption of glucose during exercise exists, and 2) intravenous glucose does not prevent it. We investigated IE in 10 PA and 8 PP fit, lean, young males who had exercised for 15 min at >84% maximum O2uptake, starting 3 h after a 412-kcal mixed meal. The meal induced a small rise in glycemia with sustained insulin and glucagon increases. Preexercise glucose total Ra and utilization (Rd) were equal and ∼130% of the PA level. Exercise hyperglycemia in PP was delayed and diminished and, in early recovery, was of shorter duration and lesser magnitude (P = 0.042). Peak catecholamine (12- to 16-fold increase) and Ra (PP: 11.5 ± 1.4, PA: 13.8 ± 1.4 mg ⋅ kg− 1 ⋅ min− 1) responses did not differ, and their responses during exercis...