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.

Improvements in Lung Diffusion Capacity following Pulmonary Rehabilitation in COPD with and without Ventilation Inhomogeneity

“…Our results also confirm that the severity of ventilation inhomogeneity is an important index of reduced exercise tolerance [9,10,11], and that together with D LCO and static lung volumes it is capable of predicting baseline exercise performance [7,8]. None of the variables taken into consideration, however, was able to predict the improvements in 6MWT after the PR program.…”

“…While D LCO is a measure of total lung diffusing capacity, the V A , when corrected for total lung capacity (V A /TLC), represents the fraction of accessible inspiratory lung volume and provides valuable information about inspired gas distribution abnormalities and therefore of ventilation inhomogeneity [5,6]. In patients with COPD, D LCO represents one of the best predictors of oxygen consumption, exercise performance and intensity of daily physical activity [7,8,9]. Accordingly, ventilation inhomogeneity predicts reduced maximal exercise capacity better than forced expiratory volume in 1 s (FEV 1 ), and has been shown to limit exercise tolerance causing exercise ventilation inefficiency even in mild and moderate patients with COPD [10,11].…”

Interval training induces clinically meaningful effects in daily activity levels in COPD

“…COPD severity negatively impacts on DAL since patients with low DAL experience greater ventilatory, central hemodynamic and peripheral muscle oxygenation constrains during activities of daily living when compared to more physically active counterparts [2,3]. Although exercise training as part of Pulmonary Rehabilitation (PR) has shown to mitigate the aforementioned physiological constraints [4], there is no evidence of clinically meaningful improvement on DAL following PR [5] (manifested by a mean increase of at least 1000 steps/day [6]).…”

Smartphone-Based Physical Activity Telecoaching in Chronic Obstructive Pulmonary Disease: Mixed-Methods Study on Patient Experiences and Lessons for Implementation (Preprint)

“…This corroborates with the findings of the qualitative part of the study and should not be ignored as a reason for treatment failure. evidence that patients experiencing lower degrees of dynamic lung hyperinflation [25], along with greater central hemodynamic and peripheral muscle metabolic capacities, tend to be more physically active in daily life, exhibiting preserved exercise capacity compared to their physiologically impaired counterparts [26]. This is important for stratification in future trials.…”