Previous studies have demonstrated that sensory and cognitive systems share some common neural substrate. The afferent neural impuleses of mechanoreception (also known as somatosensation) as produced by joint mechanoreceptors and adjacent muscle spindle cells may impact supraspinal centers. Few studies have been done to determine if the afferent impulses generated by spinal manipulative therapy (SMT) can impact the porcessing that occurs at supra-spinal centers. The relationship between postural control and cognition is studies using a dual-tak methodology, a primary (postural) task will often demonstrate degradation with the addition of a secondary, concurrent (cognitive) task. The current study seeks to determine the effects of SMT on postrual control using a dual-task paradigm, while monitoring autonomic state (using Heart Rate Variability analysis) during the course of therapy. It is thought that SMT can improve HRV status, and postural control within a dual-task situation, and that there will be differences in postural control related to a participant's HRV status. Activities of daily living often invole the coupling of a cognitive task with a complex postural task.