Objective: To determine how precisely asymptomatic subjects can reproduce a neutral zero position of the head.
Study Design: Repeated measures of the active cervical neutral zero position.
Setting: Institute of Medical Biology (Center of Biomechanics) at Odense University.
Participants: Thirty-eight asymptomatic students from the University of Odense, male/female ratio 20:18 and mean age 24.3 years (range, 20 to 30 years).
Intervention: Measurements of the location of the neutral zero head position by use of the electrogoniometer CA-6000 Spine Motion Analyzer. Each subject's neutral zero position with eyes closed was measured 3 times. The device gives the localization of the neutral zero as coordinates in 3 dimensions (x, y, z) corresponding to the 3 motion planes.
Results: The mean difference from neutral zero in 3 motion planes was found to be 2.7 degrees in the sagittal plane, 1.0 degree in the horizontal plane, and 0.65 degree in the frontal plane.
Conclusion: We found that young adult asymptomatic subjects are very good at reproducing the neutral zero position of the head. This suggests the existence of some advanced neurologic control mechanisms. (J Manipulative Physiol Ther 1999;22:26–8)
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