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Double-Sided Mechanical Shocks Provoke Larger Seated Postural Reactions Compared With Single-Sided Mechanical Shocks
Tobias Carl Stenlund1, Fredrik Öhberg2, Ronnie Lundström2
1Department of Community Medicine and Rehabilitation, Physiotherapy, Umeå University, Umeå, Sweden.
Spine
|September 1, 2017
Summary
Fast double-sided mechanical shocks (DSMS) caused greater seated postural reactions than single-sided shocks (SSMS). However, the tested mechanical shocks did not appear to cause musculoskeletal overload in healthy adults.
Area of Science:
- Biomechanics
- Occupational Health
- Human Factors Engineering
Background:
- Mechanical shocks during driving may cause spinal injury and musculoskeletal pain.
- Little is known about seated postural reactions to mechanical shocks.
Purpose of the Study:
- To describe and contrast seated postural reactions to single-sided mechanical shocks (SSMS) and double-sided mechanical shocks (DSMS).
Main Methods:
- Healthy male adults were exposed to SSMS and DSMS while seated.
- Surface electromyography (EMG) and kinematics were recorded.
- Muscle activity was normalized to maximum voluntary contractions (MVCs).
Main Results:
- Fast DSMS elicited significantly higher EMG amplitudes compared to other shocks.
- Range of motion (ROM) was greater during DSMS than SSMS.
- External oblique muscles showed activity exceeding 10% MVC.
Conclusions:
- Fast lateral DSMS are more demanding, augmenting seated postural reactions.
- The tested mechanical shocks did not induce significant musculoskeletal overload in terms of ROM or muscle activity.
