RESUMO
The purpose of this study was to investigate the circulation responses (heart rate (HR), systolic blood pressure (SBP) and second derivative of photoplethysmogram waveform index (|d/a|)) during 90 seconds continuous isometric contraction on trunk muscle. Subjects were 10 healthy male (22±1 years). Subjects performed 90 seconds continuous isometric contraction on Rectus Abdominus. Contraction intensity was 55.4±13.8% maximal voluntary contraction.HR and SBP were a significant increase after contraction beginning, immediately. |d/a| (one of the peripheral blood vessel contraction index) was a significant increase at 60 seconds after contraction beginning. After that, HR was an increase more, |d/a| showed a decline tendency. But, SBP was an increase more.The followings are suggestive by these results. When the contraction beginning, HR was increased immediately by central command, muscle mechano reflex and so on. The other hand, the peripheral blood vessel contraction was late by the accumulation of metabolism product from active muscle was late. When the prolong contraction time, the peripheral blood vessel was extension. But, SBP was increased more by increasing the cardio output, muscle tension and so on.
