Nicholas C W, Tsintzas K, Boobis L, Williams C
Department Sports Science, Loughborough University, Leicestershire, United Kingdon.
Med Sci Sports Exerc. 1999 Sep;31(9):1280-6. doi: 10.1097/00005768-199909000-00008.
The purpose of this study was to examine the effects of ingesting a carbohydrate-electrolyte beverage or a noncarbohydrate placebo on muscle glycogen utilization during 90 min of intermittent high-intensity running.
Six trained games players (age 24.6 +/- 2.2 yr; height 179.6 +/- 1.9 cm; body mass 74.5 +/- 2.0 kg; VO2max 56.3 +/- 1.3 mL x kg(-1) x min(-1); mean +/- SEM) performed two exercise trials, 7 d apart. The subjects were university soccer, hockey, or rugby players. On each occasion, they completed six 15-min periods of intermittent running, consisting of maximal sprinting, interspersed with less intense periods of running and walking. During each trial, subjects consumed either a 6.9% carbohydrate-electrolyte solution (CHO-E: the CHO trial) or a noncarbohydrate placebo (the CON trial) immediately before exercise (5 mL x kg(-1) BM) and after every 15 min of exercise thereafter (2 mL x kg(-1) BM). Drinks were administered in a double-blind, counter-balanced order, and the total volume of fluid consumed during each trial was 1114 +/- 30 mL. Needle biopsy samples were obtained from the vastus lateralis muscle before and after 90 min of exercise. Venous blood samples were collected from an antecubital vein at rest and every 30 min during exercise.
Muscle glycogen utilization in mixed muscle samples was lower (P < 0.05) during CHO [192.5 +/- 26.3 mmol glucosyl units (kg x DM(-1))] than CON [245.3 +/- 22.9 mmol glucosyl units (kg x DM(-1))]. Single fiber analysis on the biopsy samples of the subjects during the CON trial showed a greater glycogen utilization in the Type II fibers compared with Type I fibers during this type of exercise [Type I: 182.2 +/- 34.5 vs Type II: 287.4 +/- 41.2 mmol glucosyl units (kg x DM(-1)); P < 0.05). After 30 min of exercise, blood lactate was significantly greater (P < 0.05) and serum insulin concentration lower (P < 0.05) in CON.
In summary, when trained games players ingested a carbohydrate-electrolyte beverage, muscle glycogen utilization was reduced by 22% when compared with a control condition.
本研究旨在探讨在90分钟间歇性高强度跑步过程中，摄入碳水化合物 - 电解质饮料或非碳水化合物安慰剂对肌肉糖原利用的影响。
六名训练有素的运动员（年龄24.6±2.2岁；身高179.6±1.9厘米；体重74.5±2.0千克；最大摄氧量56.3±1.3毫升·千克⁻¹·分钟⁻¹；平均值±标准误）进行了两次运动试验，间隔7天。受试者为大学足球、曲棍球或橄榄球运动员。每次试验时，他们完成六个15分钟的间歇性跑步阶段，包括全力冲刺，其间穿插强度较低的跑步和步行阶段。在每次试验期间，受试者在运动前（5毫升·千克⁻¹体重）以及此后每15分钟运动后（2毫升·千克⁻¹体重）立即饮用6.9%的碳水化合物 - 电解质溶液（CHO - E：碳水化合物试验）或非碳水化合物安慰剂（对照试验）。饮料以双盲、平衡顺序给予，每次试验期间摄入的液体总量为1114±30毫升。在运动90分钟前后从股外侧肌获取针吸活检样本。在静息状态下以及运动期间每30分钟从前臂肘静脉采集静脉血样本。
混合肌肉样本中的肌肉糖原利用率在碳水化合物试验组[192.5±26.3毫摩尔葡萄糖基单位/（千克·干物质⁻¹）]低于对照组[245.3±22.9毫摩尔葡萄糖基单位/（千克·干物质⁻¹）]（P<0.05）。在对照试验期间对受试者活检样本进行的单纤维分析显示，在此类运动中，II型纤维的糖原利用率高于I型纤维[I型：182.2±34.5对II型：287.4±41.2毫摩尔葡萄糖基单位/（千克·干物质⁻¹）；P<0.05]。运动30分钟后，对照组的血乳酸显著更高（P<0.05），血清胰岛素浓度更低（P<0.05）。
总之，当训练有素的运动员摄入碳水化合物 - 电解质饮料时，与对照情况相比，肌肉糖原利用率降低了22%。
