[Muscle strength and muscle blood flow of the quadriceps muscle]

This study was conducted to measure muscle blood flow changes during increased muscle strength in order to determine what characteristic parameters of muscle strength were most closely correlated with increased muscle blood flow. The muscle blood flow and muscle strength in the quadriceps femoris were measured simultaneously during isokinetic extension of the knee joints in two groups--one with knee-joint-disease and the other of healthy volunteers. Muscle blood flow was measured by the heated thermocouple technique, while parameters of muscle strength were evaluated utilizing curves calculated by a Cybex II. The test results showed a positive correlation between parameters of muscle strength (peak torque, total work and average power) and peak blood flow. However, both the muscle strength and the muscle blood flow values were less in the group with knee joint disease than in the group of healthy volunteers. In both groups, the muscle blood flow was greatest when the knee was extended at an increased angular velocity. Although the muscle blood flow was greatest at this time, only the parameter of average power increased while the parameter of peak torque and total work decreased. As a result, the average power was correlated most closely with the increased muscle blood flow. In patients with a knee joint disease, the increase in the muscle blood flow was much higher than expected despite the fact that there was little increase in average power during knee movement at an increased angular velocity. It appeared that the pathological condition in these patients' quadriceps femoris required increased blood flow despite an inability of the muscle to perform increased muscle work.