Electromyographic and Kinematic Exploration of Whiplash-Type Left Anterolateral Impacts
Notice bibliographique
Résumé
BACKGROUND: Volunteer studies of the cervical muscular response and head-neck kinematics in response to frontal impacts are uncommon. Moreover, the effect of a frontal impact offset to the left on the resultant muscle responses is unknown. OBJECTIVE: The purpose of this study was to determine the response of the cervical muscles to increasing low-velocity frontal impacts offset by 45 degrees to the left and to compare the quantitative effects of expected and unexpected impact. METHODS: Nine healthy volunteers were subjected to frontal impacts, offset by 45 degrees to the subject's left, of 5.0, 8.7, 11.3, and 15.6 m/s2 of acceleration at two levels of expectation: expected and unexpected. Bilateral electromyograms (EMGs) of the sternocleidomastoids, trapezii, and splenii capitis were recorded. Triaxial accelerometers recorded the acceleration of the chair, torso at the shoulder level, and head of the participant. RESULTS: Subjects tended to exhibit lower percentages of their maximal voluntary contraction EMG when the impact was expected. When the impact was unexpected, and at an acceleration of 15.6 m/s2, the splenius capitis muscle contralateral to the impact (ie, right splenius in a left anterolateral impact) generated 95% of its maximal voluntary contraction EMG, whereas the left splenius (ipsilateral to the left anterolateral impact) generated only 43% of this variable. Under these same conditions, the trapezii responded symmetrically, generating approximately 80% of their maximal voluntary contraction EMG. At an acceleration of 15.6 m/s2, the sternocleidomastoids generated approximately 37% of their maximal voluntary contraction EMG in both the expected and the unexpected impact conditions. EMG (such as time to peak EMG) and kinematic variables were significantly affected by the levels of acceleration (P < 0.001) and expectation status (P < 0.05). The time to onset of the EMG for the splenii capitis and trapezii progressively decreased with increasing levels of acceleration. In response to left anterolateral impacts, muscle responses were greater with higher levels of acceleration and greatest for the splenius capitis muscle contralateral to the side of impact. The head acceleration response was greater in the unexpected than in the expected condition (P < 0.05). CONCLUSIONS: Because the muscular component of the head-neck complex plays a central role in the abatement of higher acceleration levels, this is likely a primary site of injury in the whiplash phenomenon in frontal collisions. More specifically, when a frontal impact is offset to the subject's left, it not only results in increased EMG generation in both trapezii, but the splenius capitis contralateral to the direction of impact also bears part of the force of the neck perturbation. Expecting or being aware of imminent impact may play a role in reducing muscle responses in low-velocity anterolateral impacts.
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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 ».