javax.xml.bind.JAXBElement@632f4b41
Postexercise nutrition is paramount to the restoration of muscle energy stores by providing carbohydrate and fat as precursors of glycogen and intramyocellular lipid (IMCL) synthesis. Compared with glucose, fructose ingestion results in lower postprandial glucose and higher lactate and triglyceride concentrations. We hypothesized that these differences in substrate concentration would be associated with a different partition of energy stored as IMCLs or glycogen postexercise. javax.xml.bind.JAXBElement@6a1224ba The purpose of this study was to compare the effect of isocaloric liquid mixed meals containing fat, protein, and either fructose or glucose on the repletion of muscle energy stores over 24 h after a strenuous exercise session. javax.xml.bind.JAXBElement@7d971aa9 Eight male endurance athletes (mean ± SEM age: 29 ± 2 y; peak oxygen consumption: 66.8 ± 1.3 mL · kg javax.xml.bind.JAXBElement@1947b3f · min javax.xml.bind.JAXBElement@18f84d0f ) were studied twice. On each occasion, muscle energy stores were first lowered by a combination of a 3-d controlled diet and prolonged exercise. After assessment of glycogen and IMCL concentrations in vastus muscles, subjects rested for 24 h and ingested mixed meals providing fat and protein together with 4.4 g/kg fructose (the fructose condition; FRU) or glucose (the glucose condition; GLU). Postprandial metabolism was assessed over 6 h, and glycogen and IMCL concentrations were measured again after 24 h. Finally, energy metabolism was evaluated during a subsequent exercise session. javax.xml.bind.JAXBElement@63b48d5e FRU and GLU resulted in similar IMCL [+2.4 ± 0.4 compared with +2.0 ± 0.6 mmol · kg javax.xml.bind.JAXBElement@26b391d3 wet weight · d javax.xml.bind.JAXBElement@45c5bb9 ; time × condition (mixed-model analysis): javax.xml.bind.JAXBElement@5e16ee08 = 0.45] and muscle glycogen (+10.9 ± 0.9 compared with +12.3 ± 1.9 mmol · kg javax.xml.bind.JAXBElement@190f46e9 wet weight · d javax.xml.bind.JAXBElement@23886112 ; time × condition: javax.xml.bind.JAXBElement@456f7749 = 0.45) repletion. Fructose consumption in FRU increased postprandial net carbohydrate oxidation and decreased net carbohydrate storage (estimating total, muscle, and liver glycogen synthesis) compared with GLU (+117 ± 9 compared with +135 ± 9 g/6 h, respectively; javax.xml.bind.JAXBElement@2ce0b742 < 0.01). Compared with GLU, FRU also resulted in lower plasma glucose concentrations and decreased exercise performance the next day. javax.xml.bind.JAXBElement@4f3b9439 Mixed meals containing fat, protein, and either fructose or glucose elicit similar repletion of IMCLs and muscle glycogen. Under such conditions, fructose lowers whole-body glycogen synthesis and impairs subsequent exercise performance, presumably because of lower hepatic glycogen stores. This trial was registered at clinicaltrials.gov as NCT01866215.