Test-retest reliability of exercise blood pressure and the workload-indexed systolic blood pressure slope in healthy males and females

The reliability of blood pressure (BP) measured during submaximal and maximal exercise, and confounding effects of biological sex, remain to be fully established but have implications for using exercise BP as a cardiovascular risk factor. We hypothesize that exercise BP test-retest reliability will not differ between sexes but will be higher during submaximal compared to maximal exercise. Eighty-four participants (22 ± 5 yr; 36 females) completed two maximal treadmill tests (modified Bruce protocol) separated by ≥2 days. Exercise BP was measured every 90 s using automated auscultation (Tango M2 monitor). Breath-by-breath oxygen uptake was analyzed. Test-retest reliability was assessed using two-way, mixed-effects, consistency, single-rater intraclass correlation coefficient (ICC) analysis on the total group and separated by sex at submaximal and maximal exercise. Systolic BP during submaximal (ICC = 0.65 [0.49-0.76], <i>P</i> < 0.01) and maximal (ICC = 0.66 [0.52-0.77], <i>P</i> < 0.01) exercise both displayed substantial reliability between visits. In contrast, the SBP/MET slope showed poor submaximal (ICC = 0.12 [-0.09-0.33], <i>P</i> = 0.13) but substantial maximal (ICC = 0.63 [0.48-0.75], <i>P</i> < 0.01) exercise reliability. Females showed substantial reliability in submaximal systolic BP (ICC = 0.73 [0.53-0.85], <i>P</i> < 0.01) and peak systolic BP (ICC = 0.74 [0.54-0.87], <i>P</i> < 0.01) and SBP/MET slope (ICC = 0.78 [0.60-0.88], <i>P</i> < 0.01); the submaximal SBP/MET slope had fair reliability (ICC = 0.28 [-0.06-0.56], <i>P</i> = 0.05). Males showed moderate reliability in submaximal systolic BP (ICC = 0.53 [0.26-0.72], <i>P</i> < 0.01) and peak systolic BP (ICC = 0.41 [0.15-0.62], <i>P</i> < 0.01) and SBP/MET slope (ICC = 0.48 [0.22-0.67], <i>P</i> < 0.01); the submaximal SBP/MET slope had poor reliability (ICC = 0.06 [-0.18-0.31], <i>P</i> = 0.32). Systolic BP showed similar reliability during submaximal and maximal exercise, with females demonstrating higher reliability in exercise systolic BP compared to males.<b>NEW & NOTEWORTHY</b> Limited work has assessed the reliability of exercise blood pressure (BP) in young healthy males and females. Our results demonstrate that systolic BP test-retest reliability did not differ between submaximal and maximal exercise. Sex-specific analysis found that females had higher reliability in exercise systolic BP than males. Despite the acceptable average reliability, exercise BP measured using automated auscultation possesses wide confidence intervals, which impact sample size requirements in future trials.