Sex-Related Differences in Motor Unit Firing Rates Between Muscles of the Upper and Lower Limb
Notice bibliographique
Résumé
Studies identifying sex-related differences in motor unit behavior are limited and show conflicting results. Differences across studies may depend on the muscle and contraction intensity being investigated. Therefore, it is necessary to identify sex-related differences in motor unit firing rates (MUFR) across muscles of the upper and lower limb and at various contraction intensities. The objective of this study was to compare MUFR between healthy males and females in the first dorsal interosseous (FDI) and tibialis anterior (TA) muscle. It was hypothesized that females would have higher MUFR during maximal contractions of the FDI, and submaximal contractions of the TA, while males would have higher MUFR during maximal contractions of the TA and submaximal contractions of the FDI. Twenty healthy males (age: 23.2 ± 2.7 years) and 20 healthy females (age: 22.7 ± 2.2 years) completed two testing sessions, one for the FDI and one for the TA. During each session, isometric maximal voluntary force (MVC) was recorded and participants completed three isometric contractions of index finger abduction or ankle dorsiflexion at 20% MVC, 50% MVC, and 100% MVC. A four-pin surface EMG electrode (Galileo wireless EMG, Delsys Inc.) was placed on the skin over the muscle to record the electrical activity of the muscle during each contraction. The EMG signal was decomposed into individual motor units and MUFR were calculated. Males had significantly greater MVC force than females in both muscles (p < 0.01). There were no main effects of sex on motor unit firing rates (p = 0.35, η 2 = 0.02), however, there was a sex by muscle interaction, such that males had significantly higher MUFR than females within the TA (p = 0.03, η 2 = 0.12). More specifically within the TA, males had higher firing rates than females at 20% MVC (p = 0.03) and 50% MVC (p = 0.02), but not 100% MVC (p = 0.25). There was a main effect of contraction intensity on MUFR (p < 0.01, η 2 = 0.96), such that MUFR were higher during the 50% MVC contraction compared to 20% MVC (p < 0.01), and higher during 100% MVC contraction compared to the 50% MVC contraction (p < 0.01). This pattern was observed within both males and females (p < 0.01, η 2 > 0.93), and within both muscles (p < 0.01, η 2 > 0.92). Sex-related differences in motor unit firing rates in healthy, young adults may be muscle and contraction intensity dependent. This work was supported by the Natural Sciences and Engineering Research Council of Canada Discovery Grant (RGPIN-2019-05127; Christie). This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.
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 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) | 0,000 | 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 ».