Mitchell J B, Braun W A, Pizza F X, Forrest M
Department of Kinesiology, Texas Christian University, Fort Worth 76129, USA.
J Sports Med Phys Fitness. 2000 Mar;40(1):41-50.
The purpose of this study was to determine the influence of ingesting solutions containing mixtures of carbohydrate (CHO) types on pre-exercise glycemic response, exercise-induced hypoglycemia, metabolic responses, and 10-km treadmill running performance in a warm environment.
Ten trained runners completed 6, self-paced 10-km treadmill runs one hour after ingesting 900 ml of one of the following test solutions: a water placebo (WP), an 8 g 100 ml-1 high fructose corn syrup solution (HFG; 72 g CHO), a 6 g 100 ml-1 glucose solution (GLU; 54 g CHO), a 6 g.100 ml-1 sucrose/glucose mixture (SUG; 54 g CHO), or banana with water to equal 900 ml (BAN; approx. 54 g CHO). The sixth condition was 675 ml of an 8 g.100 ml-1 HFCS solution (LFG; 54 g CHO). Blood samples were taken prior to ingestion and every 15 min during rest and at 15 and 30 min, and at the end of the 10-km run. Blood was analyzed for glucose (BG) insulin (IN), glycerol, lactate, and percent change in plasma volume. Urine volume during the 1 hour of rest and change in body mass during exercise were also determined.
A significant (p < 0.05) correlation (r = -0.684) was seen between the pre-exercise glycemic response (PEGR = area under the resting BG curve) and the change in BG from pre-EX to 15 min of exercise. BG at 15 min of exercise was significantly higher in the WP (5.22 mM) versus the other conditions (HFG = 3.32, LFG = 3.91, GLU = 3.38, BAN = 3.74 & SUG = 3.63 mM). Pre-exercise IN was lower in the WP (6.54 U ml-1) condition versus the other conditions (HFG = 22.1, LFG = 16.2, GLU = 23.3, BAN = 18.8 & SUG = 12.8 U.ml-1). Ten km performance times were not different (WP = 41.87, HFG = 41.66, LFG = 41.79, GLU = 41.65, BAN = 41.53, and SUG = 41.75 min). A significantly greater body mass loss occurred due to urine production during the 60 min of rest in the WP compared to the other conditions. The degree of exercise-induced decline in blood glucose was related to the PEGR; however, the decline in BG did not affect 10-km running performance. In addition, there were no differences in the metabolic responses during exercise between the different CHO types, nor did the type of CHO influence running performance. Finally, the presence of CHO and/or electrolytes in the hydration solutions produced a better fluid retention during the 60-min pre-exercise rest period compared to water.
The results confirmed that if a competitive athlete consumed a breakfast prior to ingesting a CHO-electrolyte beverage, a practice that is common, the glycemic responses may be different.
本研究的目的是确定在温暖环境中摄入含有不同碳水化合物（CHO）类型混合物的溶液对运动前血糖反应、运动诱发的低血糖、代谢反应以及10公里跑步机跑步表现的影响。
10名训练有素的跑步者在摄入900毫升以下测试溶液之一1小时后，完成6次自行 pace 的10公里跑步机跑步：水安慰剂（WP）、8克/100毫升的高果糖玉米糖浆溶液（HFG；72克CHO）、6克/100毫升的葡萄糖溶液（GLU；54克CHO）、6克/100毫升的蔗糖/葡萄糖混合物（SUG；54克CHO），或加水至900毫升的香蕉（BAN；约54克CHO）。第六种情况是675毫升8克/100毫升的HFCS溶液（LFG；54克CHO）。在摄入前、休息期间每15分钟、运动15分钟和30分钟以及10公里跑步结束时采集血样。分析血液中的葡萄糖（BG）、胰岛素（IN）、甘油、乳酸以及血浆量的百分比变化。还测定了休息1小时期间的尿量和运动期间的体重变化。
运动前血糖反应（PEGR = 静息BG曲线下面积）与运动前至运动15分钟期间BG的变化之间存在显著（p < 0.05）相关性（r = -0.684）。与其他条件相比，WP组运动15分钟时的BG显著更高（5.22毫摩尔）（HFG = 3.32、LFG = 3.91、GLU = 3.38、BAN = ......完整译文请参考原文链接。）。运动前IN在WP组（6.54 U/ml）低于其他条件（HFG = 22.1、LFG = 16.2、GLU = 23.3、BAN = 18.8、SUG = 12.8 U/ml）。10公里跑步成绩无差异（WP = 41.87、HFG = 41.66、LFG = 41.79、GLU = 41.65、BAN = 41.53、SUG = 41.75分钟）。与其他条件相比，WP组在60分钟休息期间因尿液产生导致的体重损失显著更大。运动诱发的血糖下降程度与PEGR相关；然而，BG的下降并未影响10公里跑步表现。此外，不同CHO类型在运动期间的代谢反应无差异，CHO类型也不影响跑步表现。最后，与水相比，水合溶液中CHO和/或电解质的存在在运动前60分钟休息期间产生了更好的液体潴留。
结果证实，如果竞技运动员在摄入CHO - 电解质饮料之前吃了早餐（这是常见做法），血糖反应可能会有所不同。
