The ability to reproduce the neutral zero position of the head

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 positio n. Setting: Institute of Medical Biology (Center of Biomechanics) at Odense Un iversity. Participants: Thirty-eight asymptomatic students from the University of Ode nse, 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 positio n by use of the electrogoniometer CA-6000 Spine Motion Analyzer. Each subje ct's neutral zero position with eyes closed was measured 3 times. The devic e 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 plan e, and 0.65 degree in the frontal plane. Conclusion: We found that young adult asymptomatic subjects are very good a t reproducing the neutral zero position of the head. This suggests the exis tence of some advanced neurologic control mechanisms.