Work of breathing influences muscle sympathetic nerve activity during semi‐recumbent cycle exercise
Bibliographic record
Abstract
Abstract Reducing the work of breathing during exercise improves locomotor muscle blood flow and reduces diaphragm and locomotor muscle fatigue and is thought to be the result of a sympathetically mediated reflex. Aim The aim of this study was to assess muscle sympathetic nerve activity (MSNA) when the work of breathing is experimentally lowered during dynamic exercise. Methods Healthy subjects (n = 12; age = 29 ± 9 years) performed semi‐recumbent cycling trials at 40%, 60%, and 80% of peak workload. Exercise trials consisted of spontaneous breathing, reduced work of breathing (proportional assist ventilator), followed by further spontaneous breathing (post‐ventilator). MSNA was recorded from the median nerve. Results There was no difference in work of breathing between PAV and post‐PAV at 40% peak work. At 60% peak work, the ventilator significantly ( P < 0.05) reduced work of breathing (103 ± 39 vs 144 ± 47 J min −1 ), sympathetic nerve activity (35 ± 5 vs 42 ± 8 burst min −1 ), and (2.4 ± 0.5 vs 2.6 ± 0.5 L min −1 ) without influencing ventilation (86 ± 9 vs 82 ± 10 L min −1 ; P > 0.05), for PAV and post‐PAV respectively. During 80% peak work (n = 8), the ventilator significantly ( P < 0.05) reduced work of breathing (235 ± 110 vs. 361 ± 150 J min −1 ), MSNA (48 ± 7 vs 54 ± 11 burst min −1 ), and (2.9 ± 0.6 vs 3.2 ± 0.7 L min −1 ) but not ventilation (121 ± 20 vs 123 ± 20 L min −1 ; P > 0.05), for PAV and post‐PAV respectively. There was a significant relationship between MSNA and ( P < 0.0001) with a significant interaction due to the ventilator ( P < 0.05). Conclusion Lowering the normally occurring work of breathing during exercise results in commensurate reductions in MSNA. Our findings provide evidence of a sympathetically mediated vasoconstrictor effect emanating from respiratory muscles during exercise.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| 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) | 0.000 | 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 teacher head, 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".