Experimentally Manipulating Mechanical Ventilatory Constraint During Exercise Does Not Influence Dyspnea in Older Men and Women
Bibliographic record
Abstract
During exercise at a standardized metabolic work load, the perception of dyspnea is higher in older women than older men, which is thought to be related to sex-differences in mechanical ventilatory constraint; however, this hypothesis has yet to be experimentally tested. PURPOSE: To determine the effect of manipulating the magnitude of mechanical ventilatory constraint during submaximal exercise on dyspnea in older men and women. METHODS: Thirteen healthy subjects (60-80 y; n=7 women) completed two days of testing. On Day 1, subjects performed pulmonary function testing and a maximal incremental cycle exercise test. On Day 2, esophageal pressure (Pes) and diaphragm electromyography (EMGdi) were recorded during three constant load cycle exercise tests (6 min each) at ventilatory threshold (VTh). Constant load exercise tests were performed under three conditions in a single blind, randomized, counterbalanced fashion: i) breathing normoxic helium-oxygen gas (HeO2) to reduce the work of breathing (W b ) and alleviate expiratory flow limitation (EFL); ii) inspiratory resistance (RES) of 5 cmH2O·l-1·s-1 to increase W b ; and iii) control (CON) breathing room air. During exercise on Day 2, Pes-derived measures of Wb, EMGdi, and EFL were assessed. RESULTS: During the HeO2 condition, there was a significant decrease in Wb (men=-20±4%, women= -16±5%) and EMGdi (men= -11±7%, women= -9±7%) relative to CON (both p<0.01). Moreover, if EFL was present during the CON condition (n=3 men, n=5 women), it was alleviated during HeO2. Conversely, during the RES condition, there was a significant increase in Wb (men= 34±11%, women= 50±12%) and EMGdi (men=32±15%, women= 23±12%) relative to CON (both p<0.01). The effect of condition on Wb and EMGdi was not significantly different between the sexes (both p>0.05). Across conditions, women reported significantly higher levels of dyspnea than men (3.3±0.4 vs. 1.9±0.4 Borg units, p<0.05). However, despite significant differences in the degree of mechanical ventilatory constraint between conditions, there was no effect of condition on the perception of dyspnea intensity, regardless of sex (p=0.46). CONCLUSION: Our results suggest that during short bouts of exercise at VTh, sex-differences in dyspnea in older adults are not related to sex-differences in mechanical ventilatory constraint.
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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 | 0.001 |
| 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".