title: Intensity of daily physical activity is associated with central hemodynamic and leg muscle oxygen availability in COPD.
abstract: In chronic obstructive pulmonary disease (COPD), daily physical activity is reported to be adversely associated with the magnitude of exercise-induced dynamic hyperinflation and peripheral muscle weakness. There is limited evidence whether central hemodynamic, oxygen transport, and peripheral muscle oxygenation capacities also contribute to reduced daily physical activity. Nineteen patients with COPD (FEV1, 48 ± 14% predicted) underwent a treadmill walking test at a speed corresponding to the individual patient's mean walking intensity, captured by a triaxial accelerometer during a preceding 7-day period. During the indoor treadmill test, the individual patient mean walking intensity (range, 1.5 to 2.3 m/s2) was significantly correlated with changes from baseline in cardiac output recorded by impedance cardiography (range, 1.2 to 4.2 L/min; r = 0.73), systemic vascular conductance (range, 7.9 to 33.7 ml·min(-1)·mmHg(-1); r = 0.77), systemic oxygen delivery estimated from cardiac output and arterial pulse-oxymetry saturation (range, 0.15 to 0.99 L/min; r = 0.70), arterio-venous oxygen content difference calculated from oxygen uptake and cardiac output (range, 3.7 to 11.8 mlO2/100 ml; r = -0.73), and quadriceps muscle fractional oxygen saturation assessed by near-infrared spectrometry (range, -6 to 23%; r = 0.77). In addition, mean walking intensity significantly correlated with the quadriceps muscle force adjusted for body weight (range, 0.28 to 0.60; r = 0.74) and the ratio of minute ventilation over maximal voluntary ventilation (range, 38 to 89%, r = -0.58). In COPD, in addition to ventilatory limitations and peripheral muscle weakness, intensity of daily physical activity is associated with both central hemodynamic and peripheral muscle oxygenation capacities regulating the adequacy of matching peripheral muscle oxygen availability by systemic oxygen transport.
authors.affiliation: First Department of Critical Care Medicine and Pulmonary Services, GP Livanos and M Simou Laboratories, Medical School of Athens University, Evangelismos Hospital, Athens, Greece;
authors.forename: Zafeiris
authors.initials: Z
authors.lastname: Louvaris
authors.forename: Eleni A
authors.initials: EA
authors.lastname: Kortianou
authors.forename: Stavroula
authors.initials: S
authors.lastname: Spetsioti
authors.forename: Maroula
authors.initials: M
authors.lastname: Vasilopoulou
authors.forename: Ioannis
authors.initials: I
authors.lastname: Nasis
authors.forename: Andreas
authors.initials: A
authors.lastname: Asimakos
authors.forename: Spyros
authors.initials: S
authors.lastname: Zakynthinos
authors.forename: Ioannis
authors.initials: I
authors.lastname: Vogiatzis
mesh_terms: D000368:Aged; D005080:Exercise Test; D005260:Female; D006439:Hemodynamics; D006801:Humans; D007866:Leg; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology*; D053580:Muscle Strength; D010100:Oxygen / Q000097:blood; D010101:Oxygen Consumption; D029424:Pulmonary Disease, Chronic Obstructive / Q000097:blood / Q000503:physiopathology*; D052097:Quadriceps Muscle / Q000503:physiopathology; D016138:Walking / Q000502:physiology
chemical_list: D010100:Oxygen
keywords: activity monitoring; chronic obstructive pulmonary disease; near-infrared spectroscopy; quadriceps muscle oxygenation; walking intensity