Influence of sex and aerobic fitness on blood pressure during maximal treadmill exercise in young healthy adults

Abstract

Exaggerated exercise blood pressure (BP) is a predictor of future hypertension but commonly observed in athletes despite their reduced cardiovascular risk. Normalizing exercise BP to metabolic or mechanical work may provide better discrimination between physiological and pathological responses. This study investigated the effects of sex and aerobic fitness on peak systolic BP (SBP) and peak SBP per metabolic equivalent (SBP/MET slope). One hundred and eleven healthy adults (22 ± 5 years; 51 female) performed a graded maximal treadmill exercise test (modified Bruce protocol) with brachial BP measured using automated auscultation (Tango M2, SunTech Medical). Peak oxygen uptake rate (V̇o_2peak) was assessed using indirect calorimetry. Males had a higher relative V̇o_2peak (P < 0.01) but not V̇o_2peak percentile (P = 0.16). Peak SBP was higher in males (208 ± 26 vs. 182 ± 23 mmHg, P < 0.01), while the SBP/MET slope did not differ between sexes (6.5 ± 2.4 vs. 6.3 ± 2.6 mmHg/MET, P = 0.60). Adjustment for differences in body mass index and V̇o_2peak did not alter these results. The SBP-V̇o_2peak regression slope did not differ between sexes (P = 0.92), with both slopes not different from zero (both, P > 0.47). The SBP/MET-V̇o_2peak regression slope did not differ between sexes (P = 0.43), but both slopes were different from zero (both, P < 0.001). The present cohort demonstrated sex differences in peak SBP but not the SBP/MET slope. The SBP/MET slope was lower in individuals with higher aerobic fitness, but the influence of V̇o_2peak did not differ between sexes. Using the SBP/MET slope in cross-sectional studies can reduce the confounding effects of sex on peak SBP, but differences in participant aerobic fitness should be considered.NEW & NOTEWORTHY Higher peak systolic blood pressure (SBP) during exercise is linked with an increased risk of developing hypertension. It has been suggested that exercise SBP should be normalized to mechanical or metabolic work to account for differences in aerobic fitness. We found that the influence of aerobic fitness on peak SBP or SBP per metabolic equivalent (SBP/MET slope) does not differ between sexes but that the SBP/MET slope is lower in participants with higher aerobic fitness.

Keywords: aerobic fitness; blood pressure; exercise; hypertension.