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

已知在长时间运动过程中摄入碳水化合物可以提高耐力性能。但是，尚不清楚碳水化合物摄入是否也影响运动的心血管调整。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以及长期运动过程中心血管反应的时间。前40个Miri（EX 1）的最大工作量的60％在周期测力计上行使的十名女性志愿者，然后在三次中进行60分钟（EX 2），而受试者仅摄入水（W）或5％的葡萄糖（G）或果糖（F）溶液的5％。该受试者在3.5分钟的静止期间在EX 1和EX 2之间的3.5分钟静止期间饮用单个W或G溶液（3.4 mL/kg身体WT），在G或F溶液中， ^<13> C标记的稳定的同位素葡萄糖或果糖（8.5 mg/kg身体WT）被溶解为捕集剂。通过V^<13> CO_2每V^<12> CO_2比率（^<13> c/^<12> -c比率）评估摄入的葡萄糖或果糖的氧化。氧气吸收，我……更多的动脉血压（MAP），心率（HR）和肌肉血流（MBF）在大腿肌肉中通过近红外光谱进行了测量。基线值定义为EX 1的最后10分钟内的平均值，并且在Ex 2期间为每个变量计算了基线的变化。在EX 2期间，每5分钟的感知量度（RPE）也进行了一次监测。ex 2期间的氧气吸收在G，F中相同，从g，f，w。在EX2期间，在F中达到37分钟的峰值和53分钟的峰值。在 ^<13> c/ ^<12> C的增加之前，地图显示出显着降低，并在降低的水平上维持直到运动结束，而在F中的地图显示的水平与W相似。G中G中的MAP响应中的衰减MAP响应与下RPE，HR和MBF有关。这些结果表明，葡萄糖的摄入对地图调整为长时间运动有减弱的影响，而果糖摄入并未改变地图反应。在G中 ^<13> c/ ^<12> C的增加之前，观察到的MAP的下降独立于摄入的葡萄糖的利用，并且可能是通过胰岛素诱导的胃肠道中胰岛素诱导的加速延缓介导的，以消化。 G中心指挥中的激活和/或进行相同运动所需的肌肉纤维的激活减少，后来G中的MAP持续减少可能是通过较少的激活来介导的。较少的