Head and arm positions that elicit maximal voluntary trunk range-of-motion measures

Relationships have been shown between spinal motion and head and arm postures, yet there has been little standardization of the head and arm positions that elicit maximal voluntary spine angles during maximal trunk flexion, lateral bend, and axial twist. This study aimed to determine the head and arm positions that facilitated maximum voluntary range of motion in various spinal regions during these movements. Twenty-four individuals performed maximal movements in each plane with different combinations of head and arm positions (flexion and lateral bend: four combinations; axial twist: six combinations). Generally, greater angles were elicited for the upper spine regions when the head was moved in the direction of trunk motion, while the angles of the lower regions were either unaffected or greater when the head was kept in a neutral position. Arm positions also affected maximum spinal angles, in that angles were greatest when the arms were hanging to the floor (flexion), abducted to 90° (axial twist), and either hanging to the floor or crossed over the chest (lateral bend). These findings provide insight into the interplay between the spine and adjacent segments and constitute an initial attempt to develop standardized positions during maximum range-of-motion trials.