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）对人类仰卧和直立膝关节伸展运动中股动脉血流的影响。< 2002年b> 6名健康受试者（22-46岁）参加了本研究。采用标准方法估计膝关节伸展运动的功-时双曲线关系的极限功（LT）和临界功（CP）。受试者在仰卧位和直立位以60 rpm的速度进行三种不同WR的6分钟方波膝关节伸展运动。WR分别为40%LT、80%LT和LT-CP（介于LT和CP之间）。用多普勒超声连续测量股动脉平均血流速度，逐秒取平均值。平均血流量（MBF）由运动时超声超声测定的股动脉直径计算。在运动过程中测量呼吸和气体交换反应、股动脉水平的平均动脉压（MAP）和心率（HR）。稳态MBF、摄氧量和HR随WR的增加呈线性增加。稳态MBF各WR间差异有统计学意义（P<0.05，经方差分析）[其余，568±76；40%lt, 1948±210；80%lt, 2958±150；LT-CP, 3973±303 ml/min，平均值±SE]。然而，在相同的功率输出下，仰卧位和直立位的MBF相似。< 2003年> 6名健康受试者（22-47岁）在仰卧短卒中（SS）和仰卧长卒中（SL）两种状态下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，与短冲程相比，每次输出能量只需要一半的肌肉张力。每次锻炼包括休息2分钟，踢腿5分钟，恢复2分钟。在每种情况下，进行了3至11瓦的3个工作速率阶段，与最低强度时最大自愿收缩的5%到最高强度时的30%相关。收缩频率设定为40次/分钟。用多普勒超声连续测量股动脉平均血流量（MBF），取一个心动周期内的平均血流量。各WR在稳态MBF中的SS和SL状态之间无显著差异（P<0.05，经方差分析）。这些结果表明，在膝关节伸展运动中，股动脉的稳态平均血流量与力量输出有关，而与肌肉紧张程度和体位无关。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