[A hemodynamic comparison of cardiovascular stress responses during mental arithmetic and reaction time tasks]

The primary purpose of this study was to examine the covariation between preload (PL) and other cardiovascular stress responses during mental arithmetic (MA) and reaction time (RT) tasks. PL, stroke volume (SV), cardiac output (CO) and pre-ejection period (PEP) were obtained using impedance cardiography. Mean blood pressure (MBP) was measured by the vascular unloading method. Thirty-one male college students were given both MA and RT tasks with a counterbalanced order. Results indicated significant differences in heart rate reactivity which seems to provide evidence for a stronger vagal withdrawal in MA. Changes in CO and MBP were identical in these two tasks which might have resulted from a compensatory change in PL and SV. Specificity of PEP for the increased beta-adrenergic activity was supported by the correlation pattern among PL, MBP and PEP. The results were discussed in the context of cardiovascular regulating mechanisms.