Björkman O, Sahlin K, Hagenfeldt L, Wahren J
Clin Physiol. 1984 Dec;4(6):483-94. doi: 10.1111/j.1475-097x.1984.tb00134.x.
The aim of the present study was to examine the influence of glucose and fructose ingestion on the capacity to perform prolonged heavy exercise. Eight well-trained healthy volunteers exercised on a bicycle ergometer at 68 +/- 3% of their VO2 max until exhaustion, on three occasions, with 8-day intervals. During the exercise they ingested either glucose (250 ml, 7%), fructose (250 ml, 7%) or water (250 ml) every 20 min in a double-blind randomized study design. Arterial blood samples were collected at rest and during exercise for the determination of substrates and hormones. Muscle glycogen content (m. quadriceps femoris) was measured before and after exercise. The duration of exercise lengthened with repeated exercise (3rd test: 136 +/- 13 min v. 1st test: 110 +/- 12 min, P less than 0.01). Corrected for the sequence effect, total work time until exhaustion was significantly longer with glucose (137 +/- 13 min) than with either fructose (114 +/- 12 min) or water (116 +/- 13 min) (both P less than 0.01). When glucose or fructose was ingested, the arterial plasma glucose concentration was maintained at the normoglycaemic level; with water ingestion, plasma glucose values fell during exercise in seven subjects and remained at the resting level in the eighth subject. The muscle glycogen concentration was 467 +/- 29 mmol kg d.w.-1 at rest and fell to approximately half the initial value at exhaustion. In the subgroup of seven subjects in whom glucose values decreased with water intake, the mean rate of glycogen degradation was significantly lower (P less than 0.05) with the ingestion of glucose (1.3 +/- 0.4 mmol kg d.w.-1 min-1) as compared to fructose (2.1 +/- 0.5 mmol kg d.w.-1 min-1) or water (2.3 +/- 0.5 mmol kg d.w.-1 min-1). Intermittent glucose ingestion (3 X 17.5 g h-1) during prolonged, heavy bicycle exercise postpones exhaustion and exerts a glycogen-conserving effect in the working muscles. In contrast, fructose ingestion during exercise maintains the glucose concentration at the basal level but fails to influence either muscle glycogen degradation or endurance performance.
本研究的目的是检验摄入葡萄糖和果糖对进行长时间剧烈运动能力的影响。八名训练有素的健康志愿者在自行车测力计上以其最大摄氧量的68±3%进行运动，直至力竭，共进行三次，每次间隔8天。在运动过程中，他们在一项双盲随机研究设计中，每20分钟摄入葡萄糖（250毫升，7%）、果糖（250毫升，7%）或水（250毫升）。在静息状态和运动期间采集动脉血样，以测定底物和激素。在运动前后测量股四头肌的肌肉糖原含量。运动持续时间随重复运动而延长（第三次测试：136±13分钟对第一次测试：110±12分钟，P<0.01）。校正序列效应后，直至力竭的总工作时间，摄入葡萄糖时（137±13分钟）显著长于摄入果糖时（114±12分钟）或摄入水时（116±13分钟）（两者P均<0.01）。摄入葡萄糖或果糖时，动脉血浆葡萄糖浓度维持在正常血糖水平；摄入水时，七名受试者的血浆葡萄糖值在运动期间下降，第八名受试者的血浆葡萄糖值保持在静息水平。静息时肌肉糖原浓度为467±29毫摩尔/千克干重，力竭时降至初始值的约一半。在七名因摄入水而导致葡萄糖值下降的受试者亚组中，与摄入果糖（2.1±0.5毫摩尔/千克干重·分钟-1）或水（2.3±0.5毫摩尔/千克干重·分钟-1）相比，摄入葡萄糖时糖原降解的平均速率显著更低（P<0.05）（1.3±0.4毫摩尔/千克干重·分钟-1）。在长时间剧烈的自行车运动期间间歇性摄入葡萄糖（每小时3×17.5克）可推迟力竭，并对工作肌肉产生糖原保存作用。相比之下，运动期间摄入果糖可将葡萄糖浓度维持在基础水平，但对肌肉糖原降解或耐力表现均无影响。
