Abstract
Both convective O2transport to, and diffusive transport within, skeletal muscle are markedly diminished in patients with chronic obstructive pulmonary disease (COPD). However, it is unknown how these determinants of peak muscle O2uptake (V̇MO2peak) respond to exercise training in patients with COPD. Therefore, the purpose of this study was to assess the plasticity of skeletal muscle O2transport determinants of V̇MO2peakin patients with COPD.
Adaptations to 8 weeks of single-leg knee-extensor exercise training were measured in 8 patients with severe COPD (forced expiratory volume in 1 s (FEV1)±sem=0.9±0.1 l) and 8 healthy, well-matched controls. Femoral arterial and venous blood samples, and thermodilution-assessed leg blood flow were used to determine muscle O2在最大exerc运输和利用率ise pre- and post-training.
Training increased V̇MO2peakin both COPD (by ∼26% from 271±29 to 342±35 mL·min−1) and controls (by ∼32% from 418±37 to 553±41 mL·min−1), restoring V̇MO2peakin COPD to only ∼80% of pre-training control V̇MO2peak. Muscle diffusive O2transport increased similarly in both COPD (by ∼38% from 6.6±0.9 to 9.1±0.9 mL·min·mmHg−1) and controls (by ∼36% from 10.4±0.7 to 14.1±0.8 mL·min·mmHg−1), with the patients reaching ∼90% of pre-training control values. In contrast, muscle convective O2transport increased significantly only in controls (by ∼26% from 688±57 to 865±69 mL·min−1), leaving patients with COPD (438±45versus491±51 mL·min−1) at ∼70% of pre-training control values.
While muscle diffusive O2transport in COPD was largely restored by exercise training, V̇MO2peakremained constrained by limited plasticity in muscle convective O2transport.
Footnotes
This manuscript has recently been accepted for publication in theEuropean Respiratory Journal. It is published here in its accepted form prior to copyediting and typesetting by our production team. After these production processes are complete and the authors have approved the resulting proofs, the article will move to the latest issue of theERJonline. Please open or download the PDF to view this article.
Conflict of interest: Dr. Broxterman reports grants from National Heart, Lung, and Blood Insitute, grants from U.S. Department of Veterans Affairs, during the conduct of the study;.
Conflict of interest: Dr. Wagner reports grants from National Heart, Lung, and Blood Insitute, grants from U.S. Department of Veterans Affairs, during the conduct of the study;.
Conflict of interest: Dr. Richardson reports grants from National Heart, Lung, and Blood Insitute, grants from U.S. Department of Veterans Affairs, during the conduct of the study;.
- ReceivedNovember 10, 2020.
- AcceptedJanuary 5, 2021.
- ©The authors 2021. For reproduction rights and permissions contactpermissions{at}ersnet.org