Kinematic gait stability index highly correlated with the margin of stability: Concept and interim report

Gait stability indices that are easy to measure and compute are necessary to enhance their commercial applications. We constructed a new kinematic gait variability index that is highly correlated with a popular kinetic stability index, i.e., the margin of stability (MoS). The new stability index was computed by using the velocity of the center of the human body mass, which can be easily measured by equipment such as inertial measurement instruments. A time-series extension of partial least squares regression was applied on the velocity series to construct the principal motions. These motions were independent of each other and were correlated with MoS. The linear combination of these principal motions exhibited a high correlation coefficient of 0.82 with the minimum values of MoS, suggesting that the proposed index can be used as an easy-tomeasure alternative of the MoS.