Rosset Robin, Lecoultre Virgile, Egli Léonie, Cros Jérémy, Dokumaci Ayse Sila, Zwygart Karin, Boesch Chris, Kreis Roland, Schneiter Philippe, Tappy Luc
Department of Physiology, University of Lausanne, Lausanne, Switzerland; and.
Department of Clinical Research and Radiology, University of Bern, Bern, Switzerland.
Am J Clin Nutr. 2017 Mar;105(3):609-617. doi: 10.3945/ajcn.116.138214. Epub 2017 Jan 18.
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. 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. Eight male endurance athletes (mean ± SEM age: 29 ± 2 y; peak oxygen consumption: 66.8 ± 1.3 mL · kg · min) 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. FRU and GLU resulted in similar IMCL [+2.4 ± 0.4 compared with +2.0 ± 0.6 mmol · kg wet weight · d; time × condition (mixed-model analysis): = 0.45] and muscle glycogen (+10.9 ± 0.9 compared with +12.3 ± 1.9 mmol · kg wet weight · d; time × condition: = 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; < 0.01). Compared with GLU, FRU also resulted in lower plasma glucose concentrations and decreased exercise performance the next day. 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.
运动后营养对于通过提供碳水化合物和脂肪作为糖原和肌内脂质（IMCL）合成的前体来恢复肌肉能量储备至关重要。与葡萄糖相比，摄入果糖会导致餐后血糖较低，乳酸和甘油三酯浓度较高。我们假设这些底物浓度的差异与运动后作为IMCL或糖原储存的能量的不同分配有关。本研究的目的是比较含有脂肪、蛋白质以及果糖或葡萄糖的等热量液体混合餐对剧烈运动后24小时内肌肉能量储备补充的影响。对八名男性耐力运动员（平均±标准误年龄：29±2岁；峰值耗氧量：66.8±1.3 mL·kg·min）进行了两次研究。每次，首先通过3天的控制饮食和长时间运动相结合的方式降低肌肉能量储备。在评估股四头肌中的糖原和IMCL浓度后，受试者休息24小时，并摄入提供脂肪和蛋白质以及4.4 g/kg果糖（果糖组；FRU）或葡萄糖（葡萄糖组；GLU）的混合餐。在6小时内评估餐后代谢情况，并在24小时后再次测量糖原和IMCL浓度。最后，在随后的运动过程中评估能量代谢。FRU组和GLU组的IMCL补充情况相似[分别为+2.4±0.4与+2.0±0.6 mmol·kg湿重·d；时间×组别（混合模型分析）：P = 0.45]，肌肉糖原补充情况也相似（分别为+10.9±0.9与+12.3±1.9 mmol·kg湿重·d；时间×组别：P = 0.45）。与GLU组相比，FRU组摄入果糖后餐后净碳水化合物氧化增加，净碳水化合物储存减少（估计总糖原、肌肉糖原和肝糖原合成）（分别为+117±9与+135±9 g/6小时，P < 0.01）。与GLU组相比，FRU组还导致次日血浆葡萄糖浓度较低且运动表现下降。含有脂肪、蛋白质以及果糖或葡萄糖 的混合餐引起的IMCL和肌肉糖原补充情况相似。在这种情况下，果糖会降低全身糖原合成并损害随后的运动表现，可能是因为肝糖原储备较低。该试验已在clinicaltrials.gov上注册，注册号为NCT01866215。
