Exercise blood pressure indexed to workload provides insight into pathological versus physiological hypertensive response to exercise in men and women
S Jones, S T Chiesa, M G Schultz, A D HughesAbstract
Background
A hypertensive response to exercise (HRE) is a recognized predictor of future cardiovascular disease (CVD). However, individuals with high aerobic fitness may demonstrate an HRE without incurring elevated CVD risk. Indexing exercise blood pressure for exercise workload may improve risk stratification, but limited evidence exists for men and women separately and sex-differences in the mechanisms underlying HRE remain poorly delineated.
Purpose
This study aimed to compare workload-adjusted and unadjusted exercise BP across fitness quartiles in non-athletic men and women and describe physiological differences that may underpin the HRE by sex.
Methods
Individuals enrolled in the Avon Longitudinal Study of Parents and Children (ALSPAC) undertook a cardiopulmonary exercise test (CPET) where systolic BP (SBP) was measured at rest and during incrementally loaded exercise. The slope of SBP against workload was calculated using linear regression (SBP/Wattslope). Fitness (VO2peak) was measured from expired gases. Cardiac output (CO) was measured using impedance cardiography and total peripheral resistance (TPR) calculated from BP and CO. Data are summarised using univariable linear regression to calculate marginal means (95%CI) by fitness group. Analysis was stratified by sex a priori.
Results
1404 participants were included (782 females(56%), mean age 31±0.8). In women, maximum exercise SBP was highest in the lowest fitness quartile with 10% classified as having a HRE. In men, there was no strong evidence that maximum exercise SBP differed by fitness (Table 1). However, SBP/Wattslope was steepest in the lowest fitness quartile, becoming progressively less steep with increasing fitness in both sexes (Table 1). CO increased the most in the highest fitness quartile in men and women. There was weak evidence of a smaller exercise-induced reduction in TPR among low-fit women, but no indication that TPR responses differed by fitness in men (Table 1).
Conclusion
The slope of SBP relative to workload may provide a clearer distinction between physiological and pathological hypertensive responses to exercise than peak SBP alone in both men and women. TPR may contribute to the HRE in men with high aerobic fitness and women with low aerobic fitness.