Cardiovascular reactivity to psychophysiological stressors: association with hypotensive effects of isometric handgrip training

BACKGROUND: Isometric handgrip (IHG) training has been found to have hypotensive effects in normotensive and hypertensive samples. Mechanisms responsible for the reductions in arterial blood pressure have been suggested, but remain equivocal. OBJECTIVE: To investigate whether cardiovascular reactivity to cold pressor and serial subtraction stressors are associated with changes in resting systolic blood pressure found with IHG training. METHODS: After completion of an 8 week IHG training program and a 6 month detraining washout period, 17 healthy older participants (66 +/- 2 years) completed cold pressor (2 min at 4 +/- 1 degrees C) and serial subtraction (2 min) stressor tasks to assess cardiovascular reactivity. RESULTS: Compared with baseline, cold pressor and serial subtraction stressor significantly increased systolic blood pressure, diastolic blood pressure, and heart rate (P < 0.001). Heart rate reactivity was significantly different between the cold pressor and serial subtraction tasks (P < 0.001). Residualized reductions in systolic blood pressure from IHG training were strongly correlated with serial subtraction task reactivity scores [Systolic blood pressure: r(16) = -0.58, diastolic blood pressure: r(16) = -0.66, heart rate: r(16) = -0.53, P < 0.05], but not with cold pressor reactivity [r(16) < 0.14, P > 0.50]. CONCLUSION: The association between serial subtraction task reactivity and hypotensive effects of IHG training may hint at myocardial mediating mechanisms behind IHG training attenuations and may provide a method for identifying patients who stand to benefit from IHG training.