BACKGROUND We investigated the inter-day repeatability of newly proposed indexes of cardiovascular health based on the absolute (PWVABS) or relative (PWVRATIO) difference in pulse wave velocity (PWV) between the carotid–femoral (PWVCF) and carotid–radial (PWVCR) segments compared with PWVCF alone and with systolic blood pressure (BPSYST) over multiple days. METHODS All variables were measured in triplicates in a group of 16 young, healthy individuals (8 men/8 women, body mass 66 ± 14 kg, height 1.7 ± 0.1 m, age 27 ± 3 years old, all mean ± SD) on 6 different occasions, always at the same time of the day (± 1 hour) and with at least 48 hours between assessments. RESULTS Values did not differ significantly over the 6 different visits for any of the parameters (all Ps > 0.08). Intraclass coefficients (ICCs) ranged from 0.52 (PWVRATIO) to 0.8 (PWVCF). The ICC 95% confidence interval of PWVRATIO (0.30–0.77) and PWVABS (0.33–0.78) did not overlap with that of PWVCF (0.79–0.95), indicating lower repeatability. The coefficient of variation (CV) of PWVABS was over 5-fold larger than the next largest one (46.7 vs. 8.1% for PWVABS and PWVRATIO, respectively), whereas PWVCF and BPSYST showed the lowest CVs (4.6 and 4.0%, respectively). CONCLUSION Between PWVABS and PWVRATIO, the relative method showed better repeatability and might be more sensitive to longitudinal changes in patients. Nonetheless, indexes of arterial stiffness-based PWV gradients between different segments show lower inter-day repeatability compared with PWVCF or BPSYST, suggesting that the latter are still preferable in clinical practice.

IntroductionThe chronic effects of respiratory muscle training (RMT) on the cardiovascular system remain unclear. This investigation tested to which degree a single sessions of RMT with or without added vibration, which could enhance peripheral blood flow and vascular response, or a 4-week RMT program could result in changes in pulse wave velocity (PWV), blood pressure (systolic, SBP; diastolic, DBP) and other markers of cardiovascular health.MethodsSixteen young and healthy participants (8 m/8f) performed 15 min of either continuous normocapnic hyperpnea (RMET), sprint-interval-type hyperpnea (RMSIT) or a control session (quiet sitting). Sessions were performed once with and once without passive vibration of the lower limbs. To assess training-induced adaptations, thirty-four young and healthy participants (17 m/17f) were measured before and after 4 weeks (three weekly sessions) of RMET (n = 13, 30-min sessions of normocapnic hyperpnea), RMSIT [n = 11, 6 × 1 min (1 min break) normocapnic hyperpnea with added resistance] or placebo (n = 10).ResultsSBP was elevated from baseline at 5 min after each RMT session, but returned to baseline levels after 15 min, whereas DBP was unchanged from baseline following RMT. Carotid-femoral PWV (PWVCF) was elevated at 5 and 15 min after RMT compared to baseline (main effect of time, P = 0.001), whereas no changes were seen for carotid-radial PWV (PWVCR) or the PWVCF/PWVCR ratio. Vibration had no effects in any of the interventions. Following the 4-week training period, no differences from the placebo group were seen for SBP (P = 0.686), DBP (P = 0.233), PWVCF (P = 0.844), PWVCR (P = 0.815) or the PWVCF/PWVCR ratio (P = 0.389).Discussion/ConclusionAlthough 15 min of RMT sessions elicited transient increases in PWVCF and SBP, no changes were detected following 4 weeks of either RMET or RMSIT. Adding passive vibration of the lower limbs during RMT sessions did not provide additional value to the session with regards to vascular responses.