Muscle glycogen recovery after exercise during glucose and fructose intake monitored by¹³C-NMR

Abstract

The purpose of this study was to examine muscle glycogen recovery with glucose feeding (GF) compared with fructose feeding (FF) during the first 8 h after partial glycogen depletion using 13C-nuclear magnetic resonance (NMR) on a clinical 1.5-TNMR system. After measurement of the glycogen concentration of the vastus lateralis (VL) muscle in seven male subjects, glycogen stores of the VL were depleted by bicycle exercise. During 8 h after completion of exercise, subjects were orally given either GF or FF while the glycogen content of the VL was monitored by 13C-NMR spectroscopy every second hour. The muscular glycogen concentration was expressed as percentage of the glycogen concentration measured before exercise. The glycogen recovery rate during GF (4.2 +/- 0.2%/h) was significantly higher (P < 0.05) compared with values during FF (2.2 +/- 0.3%/h). This study shows that 1) muscle glycogen levels are perceptible by 13 C-NMR spectroscopy at 1.5 T and 2) the glycogen restoration rate is higher after GF compared with after FF.

Metabolic Effects of Fructose and the Worldwide Increase in Obesity

“…One study compared muscle glycogen recovery after exercise with glucose and fructose feeding. In this study, muscle glycogen repletion, evaluated with 13 C-NMR spectroscopy, was considerably more efficient with glucose than with fructose (227).…”

Heteronuclear Cross Polarization for Enhanced Sensitivity ofin Vivo13C MR Spectroscopy on a Clinical 1.5 T MR System

“…Furthermore, most carbons have attached protons, resulting in multiplet structures which further decrease sensitivity and complicate spectrum analyses. Most 13 C MR studies performed on humans use proton decoupling to remove the multiplet-splittings, thereby enhancing sensitivity and resolution (1)(2)(3)(4)(5). With nuclear Overhauser enhancement (NOE) the sensitivity of 13 C MR spectroscopy can be further increased (6 -8).…”

Dietary glycemic index influences lipid oxidation but not muscle or liver glycogen oxidation during exercise

“…As a result, the postprandial insulin response creates a fine balance between optimizing glycogen recovery vs. maintaining lipid availability, an essential fuel for endurance exercise. In line with this, studies have shown that carbohydrates, which are rapidly absorbed in the circulation and produce a large insulin response [termed high glycemic index (GI)] optimize the rate of glycogen resynthesis (31) and storage (2) after exercise. Conversely, we have recently demonstrated that short-term feeding of mixed meals differing by GI alone influence both lipid availability and oxidation (29).…”