Psychological flexibility is not associated with cardiovascular stress-response adaptation to recurrent stress

Psychological flexibility is a dynamic psychological construct representing a dispositional pattern of adaptive responding to changing situational demands and is associated with positive psychological functioning and stress resilience. Despite its relevance to stress regulation, it remains unclear whether psychological flexibility is associated with physiological indicators of stress adaptation. The present study examined whether psychological flexibility was associated with cardiovascular responses to, and adaptation following, repeated stress exposure. A total of 140 female participants underwent continuous cardiovascular monitoring while engaging in successive rest and task periods. The paced auditory serial addition task (PASAT) was used as the stress-task, with participants required to complete the PASAT on two occasions within a single laboratory session. Psychological flexibility was assessed using the self-reported six-item Psy-Flex scale. Multilevel modelling was used to examine cardiovascular responses across the session and adaptation to repeated stress exposure, with psychological flexibility examined as a between-person moderator of cardiovascular trajectories. Heart rate (HR) and cardiac output (CO) showed significant reductions in reactivity from the first to the second task, indicative of habituation, whereas total peripheral resistance (TPR) increased across tasks. No evidence of habituation was observed for systolic (SBP) or diastolic blood pressure (DBP). Across all models, psychological flexibility was not significantly associated with baseline cardiovascular levels, stress reactivity, within-session change, or adaptation to repeated stress exposure. Psychological flexibility was not associated with altered patterns of cardiovascular stress-response adaptation in a laboratory test of this construct, in a sample of young, healthy women.