Locus of Symptom Limitation and Exercise Response to Bronchodilation in Chronic Obstructive Pulmonary Disease
Bibliographic record
Abstract
In Brief PURPOSE To evaluate the concordance between subjective and objective indices of muscle fatigue during exercise and to assess the significance of the perception of dyspnea and leg fatigue for the exercise response to bronchodilation in chronic obstructive pulmonary disease (COPD). METHODS Sixty-eight patients with COPD performed either 2 constant work-rate cycling exercises or 2 endurance shuttle walking tests. These tests were preceded by nebulization of placebo or 500 μg of ipratropium bromide. Changes in forced expiratory volume in 1 second and in endurance time with bronchodilation were measured. Changes in quadriceps twitch force after exercise were evaluated. In addition, the locus of symptom limitation was assessed. RESULTS Patients who stopped exercising because of leg fatigue showed a larger fall in quadriceps twitch force in comparison with patients who stopped for dyspnea. The proportion of patients who developed contractile fatigue of the quadriceps (postexercise fall in quadriceps twitch force >15% resting value) was substantially smaller in patients stopping exercise because of dyspnea than in those stopping because of leg fatigue or a combination of the 2 symptoms. The locus of symptom limitation modulated the exercise response to bronchodilation; patients stopping exercise because of leg fatigue or a combination of dyspnea/leg fatigue showed a smaller improvement in endurance time to constant work-rate exercise with bronchodilation compared with those stopping because of dyspnea. CONCLUSION Patients with COPD reporting leg fatigue as the main exercise-limiting symptom had a smaller increase in endurance time to constant work-rate exercise after bronchodilation compared with those reporting dyspnea as the main limiting symptom. Contractile leg fatigue prevents bronchodilation to fully translate into better exercise tolerance in patients with chronic obstructive pulmonary disease. Patients whose locus of symptom limitation during cycling or walking was leg fatigue had a smaller increase in exercise endurance following bronchodilation than those who stopped because of dyspnea.
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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 | 0.001 | 0.006 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".