Estimating Breathing Reserve at Peak Treadmill Exercise: Influence of Sex and Fitness
Bibliographic record
Abstract
PURPOSE: A low breathing reserve (peak ventilation [Epeak]/estimated maximum ventilation [Emax] ≤ 15%) is recommended as the decision node to indicate abnormal ventilatory limitation during incremental cycle ergometry. Given higher Epeak during weight-bearing exercise, we aim to establish which coefficients should multiply the forced expiratory volume in 1 second (FEV1) to reduce the prevalence of a low breathing reserve in healthy subjects undergoing treadmill exercise. METHODS: We determined the coefficients for FEV1 multiplication associated with <5% prevalence of a low breathing reserve in 3544 healthy individuals aged 20 to 80 years. We then contrasted their performance in differentiating healthy subjects (N = 148) from patients with chronic obstructive pulmonary disease (COPD) (N = 133) in an external validation sample. RESULTS: A low breathing reserve was found in 22% and 6% of women versus 48% and 17% of men when FEV1 was multiplied by 35 and 40, respectively. Sex-adjusted coefficients required to decrease the prevalence of a low breathing reserve ranged from 33 and 48 in women versus 36.5 and 50 in men in those showing peak oxygen uptake <80% and >120% predicted, respectively. Breathing reserve using the new sex- and fitness-adjusted coefficients were superior to previous values in differentiating health from disease, regardless of COPD severity. CONCLUSION: Higher coefficients for FEV1 multiplication are required to estimate Emax at peak treadmill exercise in men than in women, increasing as a function of cardiorespiratory fitness in both sexes. These data are poised to improve the yield of cardiopulmonary exercise tests in accurately indicating pathological ventilatory limitation in patients with respiratory diseases.
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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 | 0.002 | 0.008 |
| 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 | 0.000 | 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".