| Keywords |
Prehypertensive ; Blood pressure ; Exercise pressor reflex ; Static handgrip exercise |
| Abstract |
Previous studies suggested that the exercise pressor reflex (EPR) plays an important role to regulate the cardiovascular responses during static exercise. However, the effects of the EPR on the cardiovascular responses to exercise have not been studied between young and middle aged prehypertensive men. Therefore, this study was to examine the cardiovascular responses in prehypertensive men between static handgrip exercise and post-exercise muscle ischemia (PEMI). Thirty subjects (15 young aged prehypertension: YAP and 15 middle aged prehypertension: MP) were recruited in this study. The maximum voluntary contraction (MVC) was obtained using a handgrip device in all subjects. Each subject performed static isometric handgrip exercise at 50% MVC for 2 min followed by 2 min of PEMI by inflating a cuff on the upper arm to 40 mmHg of resting systolic blood pressure (SBPrest). All subjects were continuously instrumented to measure cardiovascular variables that blood pressure (SBP, DBP), stroke volume (SV), heart rate (HR), cardiac output (CO), total vascular conductance (TVC) throughout the experiment by using of the Finometer device. From the baseline values, the increased in mean arterial pressure (MAP) was no significantly different between YAP and MP during SHE (YAP: Δ53 vs. MP: Δ48 mmHg) and PEMI (YAP: Δ36 vs. MP: Δ35 mmHg). In static handgrip exercise, the increase in cardiac output was significantly higher (YAP: Δ2.1 vs. MP: Δ0.8 L/min) than MP group, and in PEMI, total vascular conductance was significantly less decreased (YAP: Δ-21.7 vs. MP: Δ-12.9 ml/min/mmHg) than YAP group. This study indicates the reflex pressor response seen during static handgrip exercise and PEMI in men and may help to explain the neural mechanism where by prehypertensive men display excessive blood pressure response during static handgrip exercise and PEMI. |