Peripheral Waveforms in Humans: Detection of Age- and Exercise

26 We hypothesized that demographic/anthropometric parameters can be used to estimate effective 27 reflecting distance (EfRD), required to derive aortic pulse wave velocity (APWV), a prognostic 28 marker of cardiovascular risk, from peripheral waveforms and that such estimates can 29 discriminate differences in APWV and EfRD with aging and habitual endurance exercise in 30 healthy adults. Ascending aortic pressure waveforms were derived from peripheral waveforms 31 (brachial artery pressure, n=25; and finger volume pulse, n=15) via a transfer function and then 32 used to determine the time delay between forwardand backward-traveling waves (Δtf-b). True 33 EfRDs were computed as directly measured carotid-femoral pulse wave velocity (CFPWV) x 34 1⁄2Δtf-b and then used in regression analysis to establish an equation for EfRD based on 35 demographic/anthropometric data (EfRD=0.173*age + 0.661*BMI + 34.548 cm; BMI: body 36 mass index). We found good agreement between true and estimated APWV (Pearson’s R=0.43; 37 intraclass correlation ICC=0.64; both P<0.05) and EfRD (R=0.24; ICC=0.40; both P<0.05). In 38 young sedentary (22±2 years, n=6), older sedentary (62±1 years, n=24), and older endurance39 trained (61±2 years, n=14) subjects, EfRD (from demographic/anthropometric parameters), 40 APWV, and 1⁄2Δtf-b (from brachial artery pressure waveforms) were 52.0±0.5, 61.8±0.4 and 41 60.6±0.5 cm; 6.4±0.3, 9.6±0.2, and 8.1±0.2 m/sec; and 82±3, 65±1 and 76±2 ms (all P<0.05), 42 respectively. Our results demonstrate that APWV derived from peripheral waveforms using age 43 and BMI to estimate EfRD correlates with CFPWV in healthy adults. This method can reliably 44 detect the distal shift of the reflecting site with age and the increase in APWV with sedentary 45 aging that is attenuated with habitual endurance exercise. 46