Understanding ageing effects by approximate entropy analysis of gait variability.

Ageing influences gait patterns which in turn affects the control mechanism of human locomotor balance. The aim of this study is to investigate the relationship between approximate entropy (ApEn) and standard deviation (SD) of a gait variable (minimum toe clearance, MTC) for young and elderly gait patterns. MTC data of 30 healthy young (HY), 27 healthy elderly (HE) and 10 falls risk (FR) elderly subjects with balance problems were analyzed. The ApEn values of MTC were significantly correlated with SD of MTC in the three groups; however, such correlations were abolished in the randomly shuffled MTC data of HE and HY group. These findings have implications of understanding ageing effect on gait variability and the likely risks of tripping falls during gait. Results are also potentially useful for the early diagnosis of common gait pathologies.