Concurrent Validity between a Portable Force Plate and Instrumented Walkway when Measuring Limits of Stability

Background: Balance deficits underlie a number of disorders and can exacerbate the primary condition if not addressed. Limits of stability, usually evaluated via force plates, can provide valuable information about balance and associated insufficiencies. A portable instrumented mat used clinically to measure gait characteristics has recently shown potential for limits of stability assessment. The mat also affords the ability to measure proactive control of limits of stability and quantitative information specific to stepping when limits of stability are exceeded. This study examined concurrent validity between the Bertec BalanceCheck Force Plate, an established instrument for measuring limits of stability, and the ProtoKinetics Zeno Walkway.

Methods: A total of 51 adults (mean age 25.5 [standard deviation: 7.5] years; 72.5% female) without known disabilities leaned as far as possible in anterior, posterior, rightward and leftward directions while standing in narrow and natural stances on the force plate and walkway.

Results: Pearson correlations for the force plate and walkway showed significant positive agreement for all directions tested in the narrow (r range = 0.657–0.878) and natural stances (r range: 0.928–0.936).

Conclusions: Findings lend evidence of instrument interchangeability when measuring limits of stability. The results demonstrate evidence of concurrent and construct validity in support of the use of the Zeno Walkway as a measure of limits of stability.