Sex-Based Differences in Peak Exercise Blood Pressure Indexed to Oxygen Consumption Among Competitive Athletes

Abstract

PurposeAlthough exercise testing guidelines define cutoffs for an exaggerated exercise systolic blood pressure (SBP) response, SBPs above these cutoffs are not uncommon in athletes given their high exercise capacity. Alternately, guidelines also specify a normal SBP response that accounts for metabolic equivalents (METs; mean [SD] of 10 [2] mm Hg per MET or 3.5 mL/kg/min oxygen consumption [V˙o2]). SBP and V˙o2 increase less during exercise in females than males. It is not clear if sex-based differences in exercise SBP are related to differences in V˙o2 or if current recommendations for normal increase in SBP per MET produce reasonable estimates using measured METs (ie, V˙o2) in athletes. We therefore examined sex-based differences in exercise SBP indexed to V˙o2 in athletes with the goal of defining normative values for exercise SBP that account for fitness and sex. MethodsUsing prospectively collected data from a single sports cardiology program, normotensive athlete patients were identified who had no relevant cardiopulmonary disease and had undergone cardiopulmonary exercise testing with cycle ergometry or treadmill. The relationship between ΔSBP (peak – rest) and ΔV˙o2 (peak – rest) was examined in the total cohort and compared between sexes. FindingsA total of 413 athletes (mean [SD] age, 35.5 [14] years; 38% female; mean [SD] peak V˙o2, 46.0 [10.2] mL/kg/min, 127% [27%] predicted) met the inclusion criteria. The ΔSBP correlated with unadjusted ΔV˙o2 (cycle: R2 = 0.18, treadmill: R2 = 0.12; P < 0.0001). Female athletes had lower mean (SD) peak SBP (cycle: 161 [15] vs 186 [24] mm Hg; treadmill: 165 [17] vs 180 [20] mm Hg; P < 0.05) than male athletes. Despite lower peak SBP, mean (SD) ΔSBP relative to unadjusted ΔV˙o2 was higher in female than male athletes (cycle: 25.6 [7.2] vs 21.1 [7.3] mm Hg/L/min; treadmill: 21.6 [7.2] vs 17.0 [6.2] mm Hg/L/min; P < 0.05). When V˙o2 was adjusted for body size and converted to METs, female and male athletes had similar mean (SD) ΔSBP /ΔMET (cycle: 6.0 [2.1] vs 5.8 [2.0] mm Hg/mL/kg/min; treadmill: 4.7 [1.8] vs 4.8 [1.7] mm Hg/mL/kg/min). ImplicationsIn this cohort of athletes without known cardiopulmonary disease, observed sex-based differences in peak exercise SBP were in part related to the differences in ΔV˙o2 between male and female athletes. Despite lower peak SBP, ΔSBP/unadjusted ΔV˙o2 was paradoxically higher in female athletes. Future work should define whether this finding reflects sex-based differences in the peripheral vascular response to exercise. In this athletic cohort, ΔSBP/ΔMET was similar between sexes and much lower than the ratio that has been proposed by guidelines to define a normal SBP response. Our observed ΔSBP/ΔMET, based on measured rather than estimated METs, provides a clinically useful estimate for normal peak SBP range in athletes.