The blood pressure (BP) response during exercise testing is a robust correlate of hypertension in middle-to-older White people, but whether this extends to a healthy, young-to-middle-aged multiethnic population is unknown. Moreover, it is unclear what constitutes an exaggerated BP to submaximal exercise, which is a more reliable and stronger correlate of hypertension than maximal testing. The NHANES dataset was used to interrogate the association of submaximal exercise BP with current hypertension and to provide multiethnic norms for BP responses in young-to-middle-aged adults. The analyses combined NHANES cycles wherein treadmill exercise testing was conducted with an analytic sample of 2544 participants aged 12-49 years (Female: White = 467
Black = 324
Hispanic = 439
Male: White = 493, Black = 351
Hispanic = 470). Weighted logistic models were fitted to test associations between exercise BP and hypertension. Age, sex, and race-specific percentiles were estimated. Exaggerated systolic BP (SBP) responses to exercise testing were defined as readings ≥90th percentile, and ≥ROC-derived cutoff. Regardless of race, sex, exercise workload, clinical and socioeconomic characteristics, a 5-mmHg increase in SBP and diastolic BP during stage 1 of exercise testing was associated with a 15% (aOR: 1.15, 95% CI: 1.08-1.21), and 31% (aOR: 1.31, 95% CI: 1.22-1.40) higher odds for hypertension, respectively. Black males had the highest proportion of exaggerated SBP responses (44%, 95% CI: 36-53%) when defined only via ROC-derived cutoffs. BP responses during submaximal exercise were associated with hypertension, irrespective of race in young-to-middle adulthood. Still, the exaggerated SBP response to exercise of Black males suggests uncontrolled high BP not detected at rest.