Intertask consistency of blood pressure responses to laboratory stressors may increase with prolonged exposure[Note 1. This research was partly supported by Sapporo Gakuin University ...]

In this study, one of the predictions of the reactivity hypothesis was investigated: the intertask consistency of blood pressure (BP) responses. Twelve young male subjects underwent cold‐pressor (14°C) and digit‐scan (counting even numbers) tests in randomized order. Cardiovascular parameters were recorded during a 2‐min pretask baseline, a 10‐min stressful exposure, and over a 5‐min post‐task baseline. The intertask correlations between the cold pressor and digit scan increased with prolonged exposure and were higher for almost all of the systolic BP measurements than for the diastolic measurements. After prolonged exposure, the hemodynamic mechanisms of BP elevations during the digit scan shifted from an increase in both cardiac output and peripheral vascular resistance to solely an increase in peripheral vascular resistance. Increased peripheral vascular resistance was the consistent cause of the BP elevations with the cold pressor. Accordingly, the hemodynamic shift on the part of the digit scan seemed to heighten the intertask BP correlations. Some other factors influencing the intertask BP correlations are also discussed.