J Manipulative Physiol Ther. 1999 Jan; 22(1): 26-8.

The ability to reproduce the neutral zero position of the head.

Christensen HW, Nilsson N.

Nordic Institute of Chiropractic & Clinical Biomechanics, Odense, Denmark.

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, v, 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.