Cardiovascular regulation: associations between exercise and head-up tilt

• Published in: Canadian journal of physiology and pharmacology Vol. 97; no. 8; pp. 738 - 745
• Main Authors: Koschate, J, Drescher, U, Werner, A, Thieschäfer, L, Hoffmann, U
• Format: Journal Article
• Language: English
• Published: Canada NRC Research Press 01.08.2019; Canadian Science Publishing NRC Research Press
• Subjects: Adult; Analysis; Blood Pressure; Cardiac patients; cardiorespiratory kinetics; Cardiovascular Physiological Phenomena; cardiovascular regulation; cinétique cardiorespiratoire; exercice physique; exercise; Exercise - physiology; expériences de basculement; forme physique; Head-Down Tilt - physiology; Heart beat; Heart Rate; Humans; Intolerance; Male; Muscles; orthostatic stress; orthostatic tolerance; Oxygen; Pharmacology; Physical fitness; Physical training; Physiology; Regulation; Respiration; régulation cardiovasculaire; stress orthostatique; tilting experiments; tolérance orthostatique; Vascular Resistance; Germany; exercice physique; cardiovascular regulation; cinétique cardiorespiratoire; exercise; expériences de basculement; stress orthostatique; tilting experiments; tolérance orthostatique; cardiorespiratory kinetics; forme physique; orthostatic stress; physical fitness; régulation cardiovasculaire; orthostatic tolerance
• ISSN: 0008-4212; 1205-7541; 1205-7541
• DOI: 10.1139/cjpp-2018-0742

It was hypothesized that faster cardiorespiratory kinetics during exercise are associated with higher orthostatic tolerance. Cardiorespiratory kinetics of 14 healthy male subjects (30 ± 4 years, 179 ± 8 cm, 79 ± 8 kg) were tested on a cycle ergometer during exercise with changing work rates of 30 and 80 W. Pulmonary oxygen uptake ( ) was measured breath-by-breath and heart rate (HR), mean arterial blood pressure (MAP), and total peripheral resistance (TPR) were measured beat-to-beat. Muscular oxygen uptake ( ) was estimated from HR and . Kinetic parameters were determined by time-series analysis, using cross-correlation functions (CCF max (x)) between the parameter and the work rate. Cardiovascular regulations of MAP, HR, and TPR during orthostatic stress were measured beat-to-beat on a tilt seat. Changes between the minima and maxima during the 6° head-down tilt and the 90° head-up tilt positions were calculated for each parameter (Δ tilt-up ). correlated significantly with ΔTPR tilt-up (r = 0.790, p ≤ 0.001). CCF max (HR) was significantly correlated with ΔHR tilt-up (r = –0.705, p = 0.002) and the amplitude in HR from 30 to 80 W (r SP = –0.574, p = 0.016). The observed correlations between cardiorespiratory regulation in response to exercise and orthostatic stress during rest might allow for a more differential analysis of the underlying mechanisms of orthostatic intolerance in, for example, patient groups.