Effects of ^<13>C-labeled carbohydrate ingestion on the cardiovascular responses to prolonged exercise

^ 13 C标记的碳水化合物摄入对长时间运动的心血管反应的影响

基本信息

批准号：
11680031
负责人：
SADAMOTO Tomoko
金额：
$ 2.24万
依托单位：
Nara Women's University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2001
项目状态：
已结题

项目摘要

Carbohydrate ingestion during prolonged exercise is known to improve endurance performance. It is, however, unclear whether carbohydrate ingestion also affects the cardiovascular adjustments to exercise. To verify this problem, we investigated time courses of oxidation of ingested glucose and fructose and the cardiovascular responses during prolonged exercise. Ten female volunteers exercised on a cycle ergometer at 60 % of maximal workload for first 40 miri (Ex 1) and then 60 min (Ex 2) on three occasions while subjects ingested water only (W) or 5 % of glucose (G) or fructose (F) solution. The subject drank a single bolus of W or G solution (3.4 ml/kg body wt) during 3.5-min resting period spaced between Ex 1 and Ex 2. In G or F solution, ^<13>C-labeled stable isotope glucose or fructose (8.5 mg/kg body wt) was dissolved as a tracer. Oxidation of the ingested glucose or fructose was evaluated by V^<13>CO_2 per V^<12>CO_2 ratio (^<13>C/^<12>-C ratio) in expired gases. Oxygen uptake, me … More an arterial blood pressure (MAP), heart rate (HR), and muscle blood flow (MBF) in thigh muscles measured by near-infrared spectroscopy were continuously recorded. The baseline value was defined as the average during the last 10 min of Ex 1, and the changes from the baseline was calculated for each variable during Ex 2. Rating of perceived exertion (RPE) was also monitored every 5 min during Ex 2. The oxygen uptake during Ex 2 was identical among G, F, and W. The ^<13>C/^<12>C ratio began to increase significantly from 15 mm in G and from!6 min in F and peaked at 37 min inG and at 53 min in F during Ex2. The MAP inG showed a significant decrease before the increase of ^<13>C/^<12>C ratio and sustained at the decreased level till the end of exercise, whereas the MAP in F showed similar levels as seen in W. The attenuated MAP responses in G were accompanied by lower RPE, HR, and MBF. These results indicated that the glucose ingestion had attenuating effects on the MAP adjustment to prolonged exercise whereas the fructose ingestion did not alter the MAP responses. The preceding decrease of MAP observed before the increase of ^<13>C/^<12>C ratio in G was independent of utilization of ingested glucose and probably mediated by insulin-induced vasodilatation in the gastrointestinal tract for digestion. The later sustained decreases in MAP in G were probably mediated by less activation in central command and/or the reduced activation of muscle fibers required to perform the identical exercise. Less

众所周知，长时间运动期间摄入碳水化合物可以提高耐力表现，但尚不清楚碳水化合物摄入是否也会影响心血管对运动的调节，为了验证这个问题，我们研究了摄入的葡萄糖和果糖的氧化时间过程以及运动期间的心血管反应。十名女性志愿者在自行车测力计上以最大负荷的 60% 进行锻炼，分别进行 3 次 40 米（Ex 1）和 60 分钟（Ex 2）锻炼。仅摄入水 (W) 或 5% 葡萄糖 (G) 或果糖 (F) 溶液受试者在 Ex 1 之间间隔的 3.5 分钟休息期内饮用单次推注的 W 或 G 溶液（3.4 毫升/千克体重）。和实施例2。在G或F溶液中，溶解13 C标记的稳定同位素葡萄糖或果糖(8.5mg/kg体重)作为示踪剂。摄入的葡萄糖或果糖的氧化通过呼出气体中的 V^<13>CO_2 与 V^<12>CO_2 比率（^<13>C/^<12>-C 比率）来评估，即吸氧量。连续记录近红外光谱测量的动脉血压（MAP）、心率（HR）和肌肉血流量（MBF），基线值定义为平均值。在实施例 1 的最后 10 分钟内，计算实施例 2 期间每个变量相对于基线的变化。在实施例 2 期间，每 5 分钟还监测感知用力 (RPE) 的等级。实施例 2 期间的摄氧量在实施例 2 期间是相同的G、F和W。^ 13 C/^ 12 C比率从G中的15mm和F中的6分钟开始显着增加，并在G中的37分钟和53分钟时达到峰值Ex2期间F中的MAP在^ 13 C/^ 12 C比率增加之前显示出显着下降，并维持在下降水平直到运动结束，而F中的MAP显示出与所见相似的水平。 G 中 MAP 反应减弱，RPE、HR 和 MBF 降低。这些结果表明，葡萄糖摄入对长时间运动的 MAP 调节有减弱作用，而果糖摄入则没有改变。在G中的^ 13 C/^ 12 C比率增加之前观察到的MAP降低与摄入的葡萄糖的利用无关，并且可能由胰岛素诱导的胃肠道中用于消化的血管舒张介导。后来 G 中 MAP 的持续降低可能是由于中枢命令激活减少和/或执行相同运动所需的肌纤维激活减少介导的。