Investigating cervical muscle response and head kinematics during right, left, frontal and rear-seated perturbations.

Objective: Whiplash research has largely focused on rear collisions because they account for the majority of whiplash injuries. The purpose of this study was to evaluate the effects of 4 perturbation directions (anterior, posterior, right, and left) on muscle activity and head kinematics to provide insight into the whiplash mechanism of injury. Methods: The effects of 4 perturbation directions induced by a parallel robotic platform, with peak acceleration of 8.50 m/s2, were analyzed on 10 subjects. Surface electromyography (EMG) measures were collected from the sternocleidomastoid (SCM), trapezius, and splenius capitus muscles. Kinematics of the head, thorax, and head relative to thorax were also measured. Results: We observed stereotypic responses for kinematics and SCM EMG for the various perturbation directions; the trapezius and splenius capitus muscles showed amplitudes that were less than 5 percent maximum voluntary contraction (MVC). Rear perturbations elicited the smallest onset latencies for the ...