Influence of Fasting on Carbohydrate and Fat Metabolism during Rest and Exercise in Men,

摘要

Metabolic effects of an overnight fast (postabsorptive state, Pa) or a 3.5-day fast (fasted state. F) were compared in eight healthy young men at rest and during exercise to exhaustion at 45% maximum O sub 2 uptake. Glucose rate of appearance (Ra) and disappearance (Rd) were calculated from plasma glucose enrichment during a primed, continuous infusion of glucose, Serum substrates and insulin levels were measured and glycogen content of the vastus lateralis was determined in biopsies taken before and after exercise. At rest, whole-body glucose flux (determined by the deuterated tracer) and carbohydrate oxidation (determined from respiratory exchange ratio) were lower in F than PA, but muscle glycogen levels were similar. During exercise, glucose flux, whole-body carbohydrate oxidation, and the rate of muscle glycogen utilization were significantly lower during the fast. Keywords: Glucose flux; Muscle glycogen; Starvation; Glucose; Low-intensity exercise; Carbohydrate oxidation, Reprints. (SDW)