Extremity Manipulation Impact on Postural Sway Characteristics

The focus of this study is to explore the effect of upper and lower extremity chiropractic
adjustments (manipulation) as well as surface condition (hard surface vs rocker board) on
multisegmental postural control as represented by postural sway. Using a rocker (tilt) board,
the participant cannot stand still, but has to adjust posture continuously to maintain
balance. Body sways are considered to be self-induced because the design of the rocker board
creates a natural instability without any external perturbation. This task provides a
self-driven sensorimotor condition in addition to amplifying the sway dynamics. Because the
rocker board has only one degree of freedom of motion, anteroposterior and lateral sways were
considered separately on the device.

The investigators had the following hypotheses.

Hypothesis 1: Lower extremity adjustments will lead to reduced postural sway magnitude
compared to upper extremity adjustments.

Hypothesis 2: Lower extremity adjustments will reduce sway variability of the rocker board,
trunk and head compared to upper extremity adjustments.

Hypothesis 3: Lower extremity adjustments will facilitate the organization of sway behavior
as assessed by the chaotic structure of sway.

Inclusion Criteria:

- student in Parker University's Doctor of Chiropractic program and patient at the
Parker University Wellness Clinic;

- available to take part in the study for all 3 test days;

- willing to forgo all non-normal daily activities and chiropractic treatments during
the test days;

Exclusion Criteria:

- pregnant;

- previous major injury involving the extremities;

- previous surgeries to an extremity joint; and

- known neurological or systemic diseases.