Pre-frontal Cortex Oxygenation Is Altered During 20km Time Trial (20tt) In Acute Hypoxia Vs. Normoxia
Notice bibliographique
Résumé
Recent research has shown that reduced muscle force and power during maximal voluntary contractions is related to both central and peripheral fatigue. Furthermore, some studies have investigated this central-peripheral relationship by comparing normoxia vs hypoxia during incremental exercise and found that a greater deoxygenation in the pre-frontal cortex likely contributed to exercise termination during hypoxia. We hypothesized that the response in pre-frontal cortex deoxygenation during endurance exercise would be greater during hypoxia and would contribute to a reduced power output. PURPOSE: To determine the effects of pacing strategy during intense cycling performance on pre-frontal cortex oxygenation under hypoxia and normoxia. METHODS: Eight competitive male cyclists (VO2max=57±5.8mL•kg−1•min−1) completed two 20TT in random order in a normobaric chamber on their own bicycles mounted on a Computrainer. In one trial, the 1st 10 km was normoxic (FIO2=21%) and the 2nd 10 km was hypoxic (FIO2=15% ∼2700 m). The order was reversed in trial two (21-15; 15-21). Subjects were blinded to the conditions. Near infrared spectroscopy was used to monitor pre-frontal cortex oxygenated (HbO2), deoxygenated (HHb) and total (tHb) hemoglobin concentration changes. RESULTS: ANOVA showed statistical (p≤0.05) differences between trials for all variables. There was a greater HHb during hypoxia, regardless of whether it was performed during the first (21-15) trial (0.29±0.24μM) or the second (15-21) trial (0.36±0.26μM). The HbO2 data showed a similar response in that a significantly greater HbO2 occurred under hypoxic conditions regardless of trial order. During the 21% trial HbO2 change was 0.31±0.48μM and 0.51±0.21μM change during the 15% trial. tHb demonstrated a similar pattern showing an increase during the hypoxic (0.87±0.33μM) vs normoxic condition (0.57±0.41μM). During each trial, there was a "cross-over" in the HHb, HbO2, and tHb response corresponding to the imposed condition (21% or 15%). Changes in power output (PO; Watts) were significantly correlated with HHb (r=-0.53), HbO2 (r=0.73), and tHb (r=0.57) during the 21-15 protocol, and moderately correlated with HHb (r=-0.47), and tHb (r=0.57) during the 15-21 protocol. PO was also lower during hypoxia vs normoxia and showed the same "cross-over" response as the pre-frontal cortex data. CONCLUSION: These data suggest that changes in pre-frontal cortex HHb and HbO2 correspond to changes in PO suggesting that central and peripheral factors contribute to the pacing strategy needed to complete this type of intense exercise. Support: NSERC Canada, Kingston University, University of Cape Town
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| 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) | 0,002 | 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 source (Gemma direct ou Codex distillé), 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 ».