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Neural respiratory drive in patients with COPD during exercise tests
1Guangzhou Medical College, State Key Laboratory of Respiratory Disease, Guangzhou, China. ym3698 @ yahoo.com.cn
Summary
Neural respiratory drive patterns differ between constant rate and incremental exercise tests in COPD patients. Both tests conclude at a similar, submaximal neural drive level, indicating comparable respiratory limitations.
Area of Science:
- Respiratory physiology
- Exercise science
- Pulmonary rehabilitation
Background:
- Assessing neural respiratory drive in chronic obstructive pulmonary disease (COPD) patients is challenging.
- Limited data exist comparing neural drive during constant rate versus incremental exercise.
Purpose of the Study:
- To compare neural respiratory drive between constant rate and incremental exercise in COPD.
- To determine if neural respiratory drive reaches maximal levels at the end of exhaustive exercise tests.
Main Methods:
- Sixteen moderate-severe COPD patients underwent incremental and constant work rate treadmill tests.
- Diaphragmatic electromyogram (EMG) and transdiaphragmatic pressure were measured.
- Minute ventilation and oxygen uptake were also recorded.
Main Results:
- Diaphragmatic EMG (RMS) increased without plateau during incremental exercise.
- Diaphragmatic EMG (RMS) plateaued during constant work rate exercise.
- End-exercise EMG RMS was similar (submaximal) in both protocols.
Conclusions:
- Neural respiratory drive increases differently during incremental versus constant work rate exercise.
- Both exercise types are limited by a similar, submaximal neural respiratory drive in COPD.
- This finding has implications for exercise testing and prescription in COPD.
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