Walking stability using portable acceleration measurement system

It is important that we analyze walking stability of physically unimpaired persons as one aspect of preventive medicine. There are many cases of unstable walking even if people think they are in good health. It is considered that if they continue to walk unstably, this may cause lower-back pain or knee pain; this burden also exerts bad influences upon other physical parts. We assessed walking stability, quantitatively, using an acceleration measurement system. Using this system, we measured the acceleration displacement at the COG of a normal walking subject and evaluated walking stability quantitatively. The center of gravity (COG) plays an important role in evaluation of stability for both standing posture and walking. By using the seasonal adjustment model it was possible to predict the periodic fluctuations observed, decomposing the original data into factors representing stability and instability. We assessed walking stability, quantitatively, using the ratio of the variance of the noise component vs. the variance of periodic component. This study provides useful information for understanding walking systems in preventive medicine and rehabilitative medicine.