MUSCLE GLYCOGEN RECOVERY AFTER EXERCISE DURING GLUCOSE AND FRUCTOSE INTAKE MONITORED BY C-13-NMR

The purpose of this study was to examine muscle glycogen recovery with glucose feeding (GF) compared with fructose feeding (FF) during the f irst 8 h after partial glycogen depletion by using C-13-nuclear magnet ic resonance (NMR) on a clinical 1.5-T NMR system. After measurement o f the glycogen concentration of the vastus lateralis (VL) muscle in se ven male subjects, glycogen stores of the VL were depleted by bicycle exercise. During 8 h after completion of exercise, subjects were orall y given either GF or FF while the glycogen content of the VL was monit ored by C-13-NMR spectroscopy every second hour. The muscular glycogen concentration was expressed as a percentage of the glycogen concentra tion measured before exercise. The glycogen recovery rate during GF (4 .2 +/- 0.2%/h) was significantly higher (P < 0.05) compared with value s during FF (2.2 +/- 0.3%/h). This study shows that 1) muscle glycogen levels are perceptible by C-13-NMR spectroscopy at 1.5 T and 2) the g lycogen restoration rate is higher after GF compared with after FF.