THE EFFECT OF MUSCLE TENSION AND BODY POSITION ON LEG BLOOD FLOW

本研究的目的是确定肌肉张力（长与短行程长度）对人体仰卧和直立伸膝运动期间股动脉血流的影响。<In 2002>6名健康受试者（22-46岁）参加了本研究。采用标准程序估算伸膝运动功率-持续时间双曲线关系的LT和临界功率（CP）。受试者在仰卧位和直立位以60 rpm以三种不同的WR进行6 min方波膝关节伸展运动。WR为40%LT、80%LT和LT-CP（LT和CP之间的一半）。使用多普勒超声连续测量股动脉的平均血流速度并逐秒平均。平均血流量（MBF）通过使用超声心动图在运动过程中测定的股动脉直径计算。在运动过程中测量通气和气体交换反应、股动脉水平的平均动脉压（MAP）和心率（HR）。 关于我们 rcise。稳态MBF，氧摄取量，和HR线性增加的功能，增加WR。在稳态MBF [静息，568 ± 76 ; 40%LT，1948 ± 210 ; 80%LT，2958 ± 150 ; LT-CP，3973 ± 303 ml/min，平均值± SE]中，每个WR之间存在显著差异（P&lt;0.05，通过ANOVA）。而在相同的功率输出下，仰卧位和直立位的MBF相似。<In 2003>6名健康受试者（22-47岁）在两种条件下（仰卧短行程，SS ;仰卧长行程，SL）进行膝关节伸展运动。长冲程的冲程位移固定在10（短）和20（长）cm，与短冲程的锻炼相比，每次输出功率仅需要一半的肌肉张力。每次运动包括2分钟休息，5分钟踢，2分钟恢复。对每种条件进行3 - 11瓦的3个工作率阶段，其与最低强度下最大自主收缩的5%至最高强度下的30%相关。收缩频率设定为40 kick/min。股动脉的平均血流量（MBF）连续测量，并通过使用多普勒超声心动图在一个心动周期内取平均值。各WR的稳态MBF在SS和SL条件下无显著性差异（P&gt; 0.05），提示伸膝运动时股动脉稳态平均血流量与功率输出有关，而与肌张力和体位无关。少

The purpose of this study was to determine the effect of muscle tension (long vs short stroke length) on femoral artery blood flow during supine and upright knee extension exercise in humans.<In 2002>Six healthy subjects (22-46 years) participated in this study. The LT and critical power (CP) of the power-duration hyperbolic relation of knee extension exercise were estimated by standard procedures. Subjects performed 6 min square-wave knee extension exercise at three different WR in supine and upright position at 60 rpm. The WR were 40%LT, 80%LT, and LT-CP (halfway between the LT and CP). Mean blood velocity of the femoral artery was continuously measured and averaged second-by-second using Doppler sonography. Mean blood flow (MBF) was calculated by using the diameter of the femoral artery determined during exercise using echo ultrasound. Ventilatory and gas exchange responses, mean arterial pressure (MAP) at the level of the femoral artery, and heart rate (HR) were measured during exe … More rcise. Steady-state MBF, oxygen uptake, and HR increased linearly as functions of increasing WR. There were significant differences (P<0.05, by ANOVA) between each WR in steady-state MBF [rest, 568 ± 76 ; 40%LT, 1948 ± 210 ; 80%LT, 2958 ± 150 ; LT-CP, 3973 ± 303 ml/min, mean ± SE]. However, MBF during supine and upright position were similar at the same power output.<In 2003>Six healthy subjects (22-47 years) performed knee extension exercise under two conditions (supine short stroke, SS ; supine long stroke, SL). Stroke displacements were fixed at 10(short) and 20 (long) cm with the long stroke, only half the muscle tension would be required for each power out put compared to exercise with the short stroke. Each exercise consisted of 2 min rest, 5 min kicking, and 2 min recovery. 3 work rate stages ranging from 3 to 11 watts, which correlated with 5% of maximum voluntary contraction at the lowest intensity to 30% at the highest intensity, were performed for each condition. The contraction frequency was set at 40 kicks/min. Mean blood flow (MBF) of the femoral artery was continuously measured and averaged over a cardiac cycle by using Doppler sonography. There were no significant differences (P<0.05, by ANOVA) between SS and SL condition of each WR in steady-state MBF.These result suggested that steady-states mean blood flow of femoral artery during knee extension exercise is related to the power output, irrespective of the muscle tension and body position. Less