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Cervical electromyographic activity during low-speed rear impact.
M L Magnusson1, M H Pope, L Hasselquist
1Iowa Spine Research Center, Department of Orthopaedic Surgery, University of Iowa, Iowa City, USA.
Summary
Neck muscles activate rapidly during whiplash injuries, challenging the belief they don't contribute. This rapid electromyographic (EMG) response suggests muscles play a key role in whiplash motion and injury patterns.
Area of Science:
- Biomechanics
- Neuromuscular Physiology
- Injury Mechanisms
Background:
- Whiplash-associated disorders (WAD) are common injuries.
- Previous assumptions suggested neck muscles do not contribute to whiplash injury.
- The role of muscle activation timing in whiplash remains unclear.
Purpose of the Study:
- To investigate the role of neck muscle activation in response to whiplash motion.
- To determine the onset latency of muscle activity during simulated whiplash.
- To challenge the assumption that muscles are passive during whiplash events.
Main Methods:
- Eight healthy males participated in a controlled sled-acceleration experiment.
- Electromyographic (EMG) activity of key neck and upper back muscles was recorded using wire and surface electrodes.
- Wavelet analysis was employed to precisely determine muscle activation onset relative to sled and head acceleration.
Main Results:
- Neck muscles exhibited very short reaction times, as low as 13.2 ms post-head acceleration and 65.6 ms post-sled acceleration.
- This rapid electromyographic (EMG) response indicates muscles actively participate in the neck's extension-flexion motion.
- The findings contradict the long-held belief of muscle passivity in whiplash injuries.
Conclusions:
- Neck muscles are capable of rapid activation during whiplash events.
- This muscular response suggests a significant role in influencing whiplash injury patterns.
- The study highlights the potential involvement of muscle and tendon injuries in clinical whiplash symptoms.