NHANES-based, Sex-Specific Reference Values for Systolic Blood Pressure during Moderate-to-Vigorous-Intensity Treadmill Exercise

Abstract

Purpose: The systolic blood pressure (SBP) response to moderate-to-vigorous intensity exercise (xSBP) is associated with cardiovascular health and future disease. We investigated the relationship between exercise intensity and xSBP and generated reference values for xSBP for healthy Americans performing moderate-to-vigorous intensity treadmill exercise. Methods: We analyzed data from 7,447 healthy participants, aged 12–49 years, in the 1999–2004 National Health and Nutrition Examination Survey (NHANES). Participants completed two 3-minute treadmill stages eliciting ~64% and ~76% of their estimated maximum heart rate (%HR MAX ). SBP was measured during the third minute of each stage. Absolute work rate (metabolic equivalents, MET) was estimated from treadmill speed and grade. Mixed-model ANOVA accounting for the complex survey design was used. Results: Sex-specific normative values for xSBP and xSBP indexed to work rate were generated. Age was only weakly related to xSBP (r = -0.019 to -0.024, P<0.001), so data were not stratified by age. Overall, males exhibited significantly greater increase in SBP at Stage 1 and Stage 2 (~22 and ~27 ΔmmHg, respectively; P<0.0001). Absolute work rate ( i.e., MET) was related to xSBP (r = 0.404 to 0.494, P<0.001). Accounting for differences in resting SBP (rSBP) and MET blunted but did not eliminate the sex difference in xSBP (P<0.0001). Furthermore, males exhibited a greater increase in SBP per MET than females (+5.58 ± 0.47 ΔmmHg·ΔMET -1 , P<0.0001). Conclusions: Biological sex and absolute work rate are independently associated with the blood pressure response to moderate-to-vigorous intensity exercise. The sex-stratified, absolute, and work-indexed reference values generated in this study provide context for interpreting exercise blood pressure in clinical and research settings.