IS RESPONSE ADAPTATION A THREAT TO THE HIGH-LOW REACTOR DISTINCTION AMONG FEMALE COLLEGE-STUDENTS

Examined cardiovascular-response adaptation patterns in high- versus low-cardioreactive women. Responses to a mental-arithmetic-plus-noise task were compared within trials (3 min each), across trials (three per session), and across two sessions separated by a 4-week interval. Forty-four normotensive women (mean age = 22.5 years) completed the study. Heart rate (HR), systolic blood pressure (SBP), and diastolic blood pressure (DBP) were monitored. Analyses of variance were employed to analyze the repeated-measures design and indicated consistent decreases in HR, SBP, and DBP response magnitudes across visits, trials, and minutes. Decreases in HR were greatest from Minute 1 to Minute 2 within each trial and, similarly, from Trial 1 to Trial 2 within each visit. BP responses showed a delayed onset of within-trial adaptation. Reactivity groups were formed for (a) SBP reactivity for HR and DBP analyses and (b) HR reactivity for SBP analyses. Although high reactors (top tercile) showed greater adaptation to task repetition in all responses compared to low reactors (lowest tercile), they also consistently displayed greater responses. Even during the final task, SBP and HR responses discriminated between high and low reactors.