Objectives: Both central blood pressure (BP) and light-moderate exercise BP are independently associated with cardiovascular risk, and measuring central BP during exercise may have clinical relevance. Brachial-to-radial-systolic-blood-pressure-amplification (B-R-SBP_AMP) could influence the accuracy of central SBP estimation by radial tonometry during exercise. This study aimed to determine the influence of light-moderate exercise on B-R-SBP_AMP and consequent central SBP estimation. Independent correlates of B-R-SBP_AMP were also explored.

Methods: Sixty healthy participants (39±16 years, 50% male) underwent testing during light-moderate intensity (40W, 50RPM) semi-recumbent cycling. SBP was identified by brachial and radial ultrasound (1^st Doppler flow inflection = 1^st Korotkoff sound during cuff deflation). Haemodynamics were recorded by ultrasound and tonometry. Bra-Rad-SBP_Amp was defined as radial minus brachial SBP.

Result: Exercise radial SBP was significantly higher than brachial SBP (144±21 versus 134±17 mmHg; p<0.001). Exercise Bra-Rad-SBP_Amp was 10±11 mmHg and increased with advancing age (r=0.360, p=0.005). Exercise central SBP was significantly higher when radial tonometry was calibrated with radial SBP (accounting for Bra-Rad-SBP_Amp) versus brachial SBP (117±16 versus 110±13 mmHg, p<0.001). Low brachial peak flow velocity relative to radial velocity was negatively associated with exercise B-R-SBP_Amp (r=−0.439, p=0.001), independent of age, sex, heart rate and mean arterial pressure (β=−0.389, adjusted R²=0.273, p=0.003).

Conclusions: Significant Bra-Rad-SBP_Amp exists during light-moderate exercise. This will result in underestimation of central SBP unless Bra-Rad-SBP_Amp is considered and is influenced by variation in peak blood flow velocity magnitude between the brachial and radial arteries.