KAN Akira Hiroshima International University, Dept. General Education, Lecturer, 保健医療学部, 講師 (80274033)
KOGA Shunsaku Kobe Design University, Applied Physiology Laboratory, Professor, 芸術工学部, 教授 (50125712)
FUKUBA Yoshiyuki Hiroshima Prefectural Women's University, Dept. Health Science, Professor, 生活科学部, 教授 (00165309)
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
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