Changes in the mean center of balance during balance testing in young adults.

BACKGROUND AND PURPOSE The analysis of standing balance is now possible using commercially available force platforms. In order to establish appropriate testing and treatment protocols for patient populations, we contend data should be collected relative to the typical response of nonpatient groups. More importantly, we need to better understand response characteristics of persons with intact nervous systems. The purpose of this study was to evaluate the typical response of young adults without known musculoskeletal or neurological impairments to balance testing with the Balance System. SUBJECTS Sixty-six subjects without known impairments (mean age = 23.6 years, SD = 4.5, range = 21-47) were evaluated in a single testing session. METHODS Center of balance (COB), a vertical force measurement, was evaluated under each of 18 conditions: 2 visual conditions (eyes open, eyes closed), 3 platform conditions (stable, vertical tilt, linear translation), and 3 foot positions (apart, together, tandem). RESULTS An effect was found for average displacement to the left along the x axis under all testing conditions. The COB locus along the y axis was dependent on the foot position, platform condition, and visual condition. CONCLUSION AND DISCUSSION Movement of the COB toward the center of the base of support accompanied closing of the eyes, narrowing of the base of support, and movement of the support surface. These findings are consistent with the need to move the center of gravity away from the limits of stability under more challenging stance conditions. This study contributes to the existing knowledge base related to standing balance function in young adults without musculoskeletal or neurological impairments and provides data that can be used for criterion-based comparisons of young adult patients. [Nichols DS, Glenn TM, Hutchinson KJ. Changes in the mean center of pressure during balance testing.