Symptoms That Limit Exercise Capacity in Patients With Obstructive Lung Disease
Bibliographic record
Abstract
Abstract Rationale: Obstructive lung disease can substantially impact quality of life, exercise capacity, and daily functioning. Breath effort alone is commonly assumed as the main limiting factor in the day-to-day activities of these individuals. The purpose of this study was to determine what symptoms limited exercise capacity during incremental cardio-pulmonary exercise testing (CPET) in individuals who had airflow obstruction with an impairment in ventilatory capacity. Methods: A cross-sectional, retrospective study of all patients >18 years of age with airflow obstruction (FEV1/FVC <70%) who performed CPET conducted at the McMaster University Medical Center between 1988-2012. Maximum power output (MPO) ranged from 0 to 2200 kpm/min. We analyzed data on those with a MPO between the 5th to 95th percentiles (200-1200 kpm/mim) to avoid potential outliers. At the end of the CPET, we queried patients on whether breath effort, leg effort, or a combination of both led to stopping the test. Results: 4429 patients had evidence of airflow obstruction (mean±SD age 61.3±14.8, FEV1 1.9±0.8, FVC 3.1±1.0). The main limiting symptom as MPO increased included leg effort alone (n=2025, 45.7%), followed by a combination of leg effort and breath effort (n=1497, 33.8%). Breath effort alone limited a smaller proportion of patients (n=1007, 22.7%). Figure 1 presents the results stratified by patients with an FEV1 % predicted of >80, 60-80, 40-60 and <40%. When FEV1% predicted was >80%, the limiting symptom was mainly leg effort (n=531, 48%), followed by both symptoms (n=428, 39%), and breath effort alone (n=138, 12%). As FEV1 % predicted worsened, limitation due to leg effort decreased while limitation due to breath effort increased. In those with FEV1% predicted <40%, leg effort, breath effort, and a combination of the two similarly limited individuals. Patients with lower FEV1 % predicted had weaker quadricep strength. Conclusion: In individuals with obstructive spirometry regardless of clinical diagnosis, leg effort predominantly limited exercise capacity. The effort required to breath was comparable to leg effort only in the lowest FEV1 category. This data highlights the importance of muscle strength, conditioning, and leg fatigue when assessing and evaluating patients with obstructive airways disease. The role of muscle strengthening exercise should be emphasised in rehabilitation.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.003 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".