Effect of expiratory airflow limitation on incremental exercise capacity and breathing responses during treadmill exercise in healthy individuals
Bibliographic record
Abstract
RATIONALE: Individuals with chronic obstructive pulmonary disease (COPD) have expiratory flow limitation (EFL) due to obstruction of the airways.Such individuals typically experience dyspnea on exertion and exercise intolerance.A Starling resistor (SR) can be used to simulate the EFL as occurs in COPD in order to evaluate its effect on exercise capacity.Although the SR has been evaluated during bicycle exercise, no studies have studied its effect during incremental treadmill walking. OBJECTIVES:The objective of the current study was to evaluate the effect of EFL, created by using a SR, on exercise capacity, metabolic parameters, breathing pattern, and exercise limiting symptoms in healthy participants during incremental treadmill exercise.METHODS: Healthy non-smoking individuals with no remarkable medical history were recruited in this cross-sectional repeated measures study.Participants performed two randomized incremental symptom-limited treadmill walking tests with and without a SR until exhaustion.Peak exercise workload (WLpeak) was assessed as the maximum exercise workload that was achieved and maintained during the last 30 seconds of exercise.Breathing pattern and metabolic parameters were measured breath-by-breath using a Vmax metabolic cart.Inspiratory capacity (IC) and Borg ratings of dyspnea and leg fatigue were measured every minute during exercise. RESULTS:Fifteen individuals (4 males, 11 females) aged 27 ± 12 years (mean ± SD) participated in the study.Mean expiratory flow with the SR was 0.5 ± 0.1 L/s (mean ± SD).Compared to treadmill exercise without the SR (no EFL), exercise with the SR resulted in a significantly lower WLpeak, as well as a lower peak minute ventilation, O 2 uptake and CO 2 production (P＜0.001for all).Tidal volume, which increased progressively during exercise with and without the SR, was observed to drop at end-exercise with the SR.The lower tidal volume at higher workloads was associated with an increased respiratory rate and a decreased IC indicating dynamic hyperinflation at end-exercise.Dyspnea was reported as the dominant exercise limiting symptom with the SR, while leg fatigue was the dominant symptom reported in the absence of EFL.CONCLUSION: During treadmill exercise, EFL resulted in a reduced exercise performance and severe dyspnea as exercise intensity increased.A SR can simulate in healthy individuals the exercise limitations that are typically observed in COPD.
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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 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 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".