Stabilising function of the human diaphragm in response to involuntary augmented breaths induced with or without lower‐limb movements
Notice bibliographique
Résumé
New Findings What is the central question of this study? Is the stabilising function of the diaphragm altered differentially in response to involuntary augmented breaths induced with or without lower‐limb movements? What is the main finding and its importance? At equivalent levels of ventilation, the diaphragm generated higher passive pressure but moved significantly less during incremental cycle ergometry compared with progressive hypercapnia. Diaphragm excursion velocity and power output did not differ between the two tasks. These findings imply that the power output of the diaphragm during stabilising tasks involving the lower limbs may be preserved via coordinated changes in contractile shortening. Abstract Activity of key respiratory muscles, such as the diaphragm, must balance the demands of ventilation with the maintenance of stable posture. Our aim was to test whether the stabilising function of the diaphragm would be altered differentially in response to involuntary augmented breaths induced with or without lower‐limb movements. Ten healthy volunteers (age 21 (2) years; mean (SD)) performed progressive CO 2 ‐rebreathe (5% CO 2 , 95% O 2 ) followed 20 min later by incremental cycle exercise (15–30 W/min), both in a semi‐recumbent position. Ventilatory indices, intrathoracic pressures and ultrasonographic measures of diaphragm shortening were assessed before, during and after each task. From rest to iso‐time, inspiratory tidal volume and minute ventilation increased two‐ to threefold. At equivalent levels of tidal volume and minute ventilation, mean inspiratory transdiaphragmatic pressure () was consistently higher during exercise compared with CO 2 ‐rebreathe due to larger increases in gastric pressure and the passive component of (i.e., mechanical output due to static contractions), and yet diaphragm excursion was consistently lower. This lower excursion during exercise was accompanied by a reduction in excursion time with no difference in the active component of . Consequently, the rates of increase in excursion velocity (excursion/time) and power output (active × velocity) did not differ between the two tasks. In conclusion, the power output of the human diaphragm during dynamic lower‐limb exercise appears to be preserved via coordinated changes in contractile shortening. The findings may have significance in settings where the ventilatory and stabilising functions of the diaphragm must be balanced (e.g., rehabilitation).
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Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,001 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».