Influence of sex on the reliability of cerebral blood velocity regulation during lower body negative pressure and supine cycling with considerations of the menstrual cycle

Objective. To evaluate sex differences in the reliability of absolute and relative cerebral blood velocity (CBv) during concurrent supine cycling with lower body negative pressure (LBNP). Approach. A total of 19 participants (11 females; aged 20 –33 years) completed five testing sessions, occurring on 7 d intervals. Visit 1 was a maximal-ramp-cycle test to ascertain peak CBv wattage. During visits 2–5, supine cycling protocol occurred at individualized peak CBv wattages with progressive decreases in LBNP from 0 to −20, −40, −60, − 70, and −80 Torr. Menstrual cycle day was self-reported via the Rhinessa Women’s Questionnaire. Transcranial Doppler ultrasound insonated bilateral middle cerebral artery velocity (MCAv). Two-way ANOVA assessed potential day- and sex-differences at each LBNP stage. Reliability was determined usi ng intraclass correlation coefficients (ICC) and coefficient of variation (CoV). Main results. For all physiological measures, no main-effects were present for day- or interaction-terms (p> 0.067; negligible-to-small effect sizes), while sex differences were noted for MCAv, blood pressure, and heart rate (p< 0.046). Across visits, males and females displayed excellent and good-to-excellent levels of reliability for MCAv metrics, respectively (ICC range: 0.745 –0.999; CoV range: 0.33%–9.90%). Significance. During the current investigation, both relative and absolute CBv demonstrated high reliability in both male and female participan...
Source: Physiological Measurement - Category: Physiology Authors: Source Type: research