Effect of badminton shoe sole on the lunge skill performance: in the viewpoint of coordination

Badminton lunge requires rapid coordination between the knee and ankle joints and it is accompanied by fast contact between the shoe's sole and the floor. Phase angle analysis is a protocol with high resolution and relating to the coordination, but how the shoe's sole would affect the lunge performance was not clear in terms of coordination. Thereby, the aim of this study was to applied phase angle analysis to insight the lunge process, then to disclose the effect of badminton shoe's sole on the lunge skill performance. Eleven elite badminton players performed five left-forward maximum lunge trials with wearing Rounded Heel Shoe (RHS), Flattened Heel Shoe (FHS), and Standard Heel Shoes (SHS). The motion capturing system was used to measure the knee and ankle kinematics information. The Phase Angle (PA), continuous relative phase (CRP) and variability of continuous relative phase (VCRP) between the knee and ankle joints were then calculated for both forward lunge phase and recovery phase in each of the three shoes. Current findings indicated that players wearing RHS had certain advantages on better movement coordination than other shoes, as indicated by better PA and CRP. The findings of this study would be helpful to understand the coordination of badminton lunges and explain the synergy between the lower extremity ankle and knee joint to minimize the possibility of injury in badminton. Furthermore, the coordination between the knee and ankle joints was greatly affected by the structure of the shoe heel design.