Analysis of Rockers during the Stance Phase of Gait for Feature Extraction

As rockers are fundamental components of the walking gait, this study aims to reveal the individual differences in rockers and to examine the factors that cause these differences. We examined the relations among the percent duration of each rocker and important factors, such as age, sex, and the time-averaged floor reaction force (TAFRF). TAFRF has been subdivided into two components: the vertical component and the traveling direction component. We analyzed the gait data of 179 healthy individuals and determined the percent duration of each rocker during the complete stance phase. Individual differences in the percent durations of the ankle and forefoot rocker phases were larger than those in the heel rocker phase. Although, the individual differences in the duration of rocker phases did not correlate with age, a significant difference existed in the percent durations between the males and the females (p < 0.05). Strong correlations were observed between the percent duration of the ankle rocker and both the TAFRF components. Conversely, the duration of the forefoot rocker phase exhibited a weak correlation with both the TAFRF components. These results indicate that there exist no age-related differences in the use of rockers; however, the sex of an individual does cause significant differences. The high proportion of the ankle rocker phase in the total stance phase is relevant to the high efficiency of locomotion. This study suggests that the percent durations of the ankle and forefoot rocker phases could be a new feature value to assess gait, which would further aid in measuring the health conditions and physical declination of individuals.