Functional clustering of lower extremity kinematics changes across running speeds

Abstract

In this study, we investigated the relationship between changes in running speed and the movement patterns of the foot and three lower extremity joints (ankle, knee, and hip) during one step cycle of running. A hierarchical clustering analysis was performed using three-dimensional angular time series data of these joints at three running speeds (3.5, 4.5, and 5.5 m/s). Our results revealed that three distinct clusters of subjects based on their joint movement patterns were identified. Although Cluster1 and Cluster3 exhibited similar contact times across all running speeds, Cluster3 exhibited a significantly longer flight time than Cluster1. This suggests that the phase differences in the time series data of ankle plantar dorsiflexion angle and knee flexion-extension angle were the primary factor contributing to the formation of both clusters. In contrast, Cluster2 was formed due to the phase difference in the time series data of the plantar dorsiflexion angle and the knee flexion-extension angle between the different running speeds. These findings may have important implications for understanding the complex interplay between running speed and lower limb joint movement patterns in athletes.