Response of blood pressure during isometric-incremental handgrip exercise -Difference between intermittent and continuous loading-

Abstract

The purpose of this study was to measure blood pressure and heart rate (HR) during isometric-incremental handgrip exercise (IHG), and to clarify the difference between the effects of intermittent (Imt) and continuous (Cont) loading in IHG. To accomplish this, eighteen male subjects aged 20 years old attended this study as volunteers, and preformed two kinds of IHG on the same day (or on two different days respectively.). The IHG consisted of five incremental stages, whose intensities were set at 20, 30, 40, 50 and 60 percent (%) of maximal voluntary contraction (MVC) with IHG. The IHG was done at 20%MVC of load at first, the load was increased in 10% increments by 60%MVC. During Cont loading, contraction was maintained for ten-second intervals, continuously increased work load and kept IHG without a rest between exercise stages. During Imt loading, contraction was maintained for ten-second, subjects took sufficient time to recover until the next stage of exercise, and began the next exercise stage. Subjects carried out the IHG in a sitting posture. The target load was checked and adjusted through the display of a personal computer by a subject himself. During the IHG, arterial blood pressure and HR were continuously measured. During both Imt and Cont IHG, blood pressure and HR gradually increased according to increasing intensity of load. However, over 30%MVC, blood pressure and HR increased more significantly during Cont IHG than Imt trial. Pressor response of Cont IHG strongly correlated enhancement of blood pressure and HR with intensities, even though those makers of Imt IHG did not correlate significantly. According to those results, incremental continuous handgrip exercise induces a more obvious change in blood pressure even at 30%MVC for ten seconds than that of intermittent handgrip exercise. Therefore, continuous handgrip exercise would seem to be more effective in evaluating hypertension in the future.