Dynamics of Low Speed Crash Tests with Energy Absorbing Bumpers

Szabo, Thomas J.; Welcher, Judson

doi:10.4271/921573

Cited by 39 publications

(14 citation statements)

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“…In the setting of controlled collision events, and in combination with other objective measurements, surface EMG studies have helped to model the mechanism of acute muscle injury in low-velocity collisions. Studies suggest a central role may be played by the cervical muscles in injury causation during low-velocity collisions [16,17].…”

Section: Discussionmentioning

confidence: 99%

Cervical muscle response to whiplash-type right anterolateral impacts

2004

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Frontal impacts are a common cause of whiplash injury. Yet, volunteer studies of the cervical muscular response and head-neck kinematics to frontal impacts are uncommon, and specifically, the effect of an offset (anterolateral) frontal impact on the resultant muscle responses is unknown. The purpose of this study was to determine the response of the cervical muscles to increasing low-velocity frontal impacts offset by 45°to the right, and to compare the quantitative effects of expected and unexpected impact. Ten healthy volunteers were subjected to frontal impacts, offset by 45°to the subject's right, of 5.1-, 8.7-, 12-, and 13.7-m/s 2 peak acceleration at two levels of expectation: expected and unexpected. Bilateral electromyograms 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. At a peak acceleration of 13.7 m/s 2 , with an unexpected impact, the contralateral trapezius (i.e., left trapezius in a right anterolateral impact) generated 83% of its maximal voluntary contraction electromyogram, whereas all other muscles generated 50% or less of this variable. Although it generated less EMG, the splenius capitis muscle also tended to show an asymmetric EMG response, with the left (contralateral) splenius capitis generating a higher percentage (46%) of its maximal voluntary contraction electromyogram than the ipsilateral (right) splenius capitis. In comparison, the sternocleidomastoid muscles behaved symmetrically and generated 25% or less of this variable under all impact conditions. Similarly, the times to onset and times to peak electromyogram for the contralateral (left) splenius capitis and (left) trapezius progressively decreased with increasing levels of acceleration (p<0.01). Subjects exhibited lower levels of their maximal voluntary contraction electromyogram when the impact was expected (p<0.01). The kinetic variables and the electromyographic variables regressed significantly on the acceleration (p<0.01). In response to right anterolateral impacts, muscle responses were greater with higher levels of acceleration, and more specifically, when a frontal impact is offset to the subject's right, it results in not only increased EMG generation in the contralateral trapezius, but the splenius capitis contralateral to the direction of impact also bears part of the force of the neck pertubation. Expecting or being aware of imminent impact plays a role in reducing muscle responses in low-velocity anterolateral impacts.

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Section: Discussionmentioning

confidence: 99%

Cervical muscle response to whiplash-type right anterolateral impacts

2004

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“…3,4 Because the muscles are the first in the line of defense for the cervical region, they are likely to be the first in casualty as well. In our study, the data reveal that the splenius capitis muscle contralateral to the side of impact is at greater risk for injury in low-velocity collisions that are offset.…”

Section: Discussionmentioning

confidence: 99%

“…1,2 Although most experimental studies have focused on the mechanism of whiplash-type injury in low rear impacts, [2][3][4][5][6][7][8][9] frontal impacts are also an important source for whiplash claims. 10 It thus seems as important to investigate the mechanism of injury in frontal collisions.…”

mentioning

confidence: 99%

Electromyographic and Kinematic Exploration of Whiplash-Type Left Anterolateral Impacts

Kumar

Ferrari²,

Narayan³

2004

Journal of Spinal Disorders &Amp; Techniques

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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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“…Even without knowing what the acute whiplash injury is, for example, knowing more of the human response to whiplash type impacts led to the introduction of head restraints in 1969[2] and further innovations of head restraints have followed as the knowledge has increased [3]. Most efforts to understand the whiplash injury mechanism have focused on rear impacts [4-11]. Although it has been traditionally reported that rear-impacts account for most cases of whiplash injury, epidemiological evidence suggests that rear, lateral, and frontal collisions account for whiplash injury in roughly equal proportions [12].…”

Section: Introductionmentioning

confidence: 99%

Analysis of right anterolateral impacts: the effect of head rotation on the cervical muscle whiplash response

Kumar

Ferrari

Narayan

2005

J NeuroEngineering Rehabil

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BackgroundThe cervical muscles are considered a potential site of whiplash injury, and there are many impact scenarios for whiplash injury. There is a need to understand the cervical muscle response under non-conventional whiplash impact scenarios, including variable head position and impact direction.MethodsTwenty healthy volunteers underwent right anterolateral impacts of 4.0, 7.6, 10.7, and 13.0 m/s2 peak acceleration, each with the head rotated to the left, then the head rotated to the right in a random order of impact severities. Bilateral electromyograms of the sternocleidomastoids, trapezii, and splenii capitis following impact were measured.ResultsAt a peak acceleration of 13.0 m/s2, with the head rotated to the right, the right trapezius generated 61% of its maximal voluntary contraction electromyogram (MVC EMG), while all other muscles generated 31% or less of this variable (31% for the left trapezius, 13% for the right spleinus. capitis, and 16% for the left splenius capitis). The sternocleidomastoids muscles also tended to show an asymmetric EMG response, with the left sternocleidomastoid (the one responsible for head rotation to the right) generating a higher percentage (26%) of its MVC EMG than the left sternocleidomastoid (4%) (p < 0.05). When the head is rotated to the left, under these same conditions, the results are reversed even though the impact direction remains right anterolateral.ConclusionThe EMG response to a right anterolateral impact is highly dependent on the head position. The sternocleidomastoid responsible for the direction of head rotation and the trapezius ipsilateral to the direction of head rotation generate the most EMG activity.

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Dynamics of Low Speed Crash Tests with Energy Absorbing Bumpers

Cited by 39 publications

References 1 publication

Cervical muscle response to whiplash-type right anterolateral impacts

Cervical muscle response to whiplash-type right anterolateral impacts

Electromyographic and Kinematic Exploration of Whiplash-Type Left Anterolateral Impacts

Analysis of right anterolateral impacts: the effect of head rotation on the cervical muscle whiplash response

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