Abstract
Reduction in balance is an indicator of fall risk, and therefore, an accurate and cost-effective balance assessment tool is essential for prescribing effective postural control strategies. This study established the validity of the Kinect v2 sensor in assessing center of mass (CoM) excursion and velocity during single-leg balance and voluntary ankle sway tasks among young and elderly subjects. We compared balance outcome measures (anteroposterior (AP) and mediolateral (ML) CoM excursion and velocity and average sway length) to a traditional three-dimensional motion analysis system. Twenty subjects (10 young: age = 20.5\pm 2.3 y, height = \,{\text{171.8}}\,\pm\, {\text{7.2}} cm, weight = \,{\text{70.7}}\,\pm\, {\text{11.6}} kg; 10 elderly: age = \,{\text{70.6}}\,\pm\, {\text{9.5}} y, height = \,{\text{169.1}}\,\pm\, {\text{8.7}} cm, weight = \,{\text{74.0}}\,\pm\, {\text{17.8}} kg), with no history of lower extremity injury, participated in this study. Subjects performed six randomized trials; four single-leg stand (SLS) and two ankle sway trials. SLS and voluntary ankle sway trials showed that consistency (ICC(2, k)) and agreement (ICC(3, k)) for all variables when all subjects were considered, as well as when the elderly and young groups were analyzed separately. Concordance between systems ranged from poor to nearly perfect depending on the group, task, and variable assessed.
