Vascular Function Following An Acute Mental Stressor Among Fit Versus Non-fit Young Adults

Abstract

PURPOSE: Acute mental stress impairs vascular function. The purpose of this study was to investigate if stress-induced vascular impairment is moderated by physical fitness. METHODS: Nineteen young, healthy adults (21.6±2.7 y, 23.9 ± 3.1 kg/m2,10 F) were classified as fit (n=11) or non-fit according to ACSM physical activity guidelines (75 min vigorous, or 150 min moderate-intensity aerobic exercise). Across two randomized visits, subjects underwent an experimental (stress) and control (non-stress) testing session. A five-min mental arithmetic task was given to induce stress in the experimental session following baseline measurements. Measurements were taken throughout the 60 mins after the stress/control period. Measures included central blood pressure (cSBP), augmentation index (AIx), and brachial-radial pulse wave velocity (PWV). Mixed linear models were used to perform statistical analyses, covarying for baseline measures. RESULTS: There was a significant fitness x condition interaction for AIx (p=0.038), such that the greatest AIx of fit individuals following stress exposure was 3.3 percentage points less than non-fit individuals (95% CI -1.29, -0.09, d = -1.34). There was no interaction of fitness and condition on PWV (p=0.785; 95% CI -0.18, 0.16), but there was an inconclusive effect of fitness (p=0.143), such that fit individuals had a PWV 0.37 m/s less than non-fit individuals (CI: -0.27, 0.04; d=-0.43). For cSBP, there was no fitness x condition interaction (p=0.653; 95% CI: -1.14, 1.83), but there was a main effect of condition (p=0.045) where, regardless of fitness, stress elicited a 3.05 mmHg greater increase in cSBP after the stressor compared to the non-stress condition (95% CI 0.01, 3.06; d=0.69). CONCLUSION: Fitness was associated with a healthier wave reflection profile following a stressor, as well as better overall vascular function. These adaptive effects of fitness on hemodynamic and vascular measures ensued despite stress-induced increases in cSBP occurring regardless of fitness status.