An examination of the relationship between resting heart rate variability and heart rate reactivity to a mental arithmetic stressor

Resting heart rate variability can be art index of sympathetic or parasympa thetic dominance, according to the frequency of the variability studied. Sy mpathetic dominance of this system has been linked to increased risk of car diovascular disease (CVD), Similarly, rapid and dramatic increases in heart rate reactivity to a stressor task have also been suggested as indicating increased risk of CVD via atherogenesis. Although both of these variables h ave been related to the development of cardiovascular disease, and both may be related to increased sympathetic activity or parasympathetic withdrawal , most research studies have tended refocus on either variable independentl y of the other In order to investigate whether these two indices of stresso r reactivity were related in relatively young and healthy subjects, resting heart I-ate variability delta were collected from 80 volunteers for 20 min utes. in addition, heart rate reactivity data were collected during a 2-min ute mental arithmetic stressor, which has been previously shown to induce s ignificant increases in heart rate, After classifying subjects according to whether their heart rate variability data were above or below, the mean fo r their gender; heart rate reactivity data were examined via MANOVA to dete ct significant differences between subject groups. Females showed significa nt effects, and males showed nonsignificant trends, but these two sets of d ata were indifferent directions, suggesting that gender may be a confoundin g factor in the relationship between heart rate reactivity and heart rate v ariability.