Movie 1. Graphical illustration of semi-lunar process (SLP) motion during a kick. The charts in A and B are those shown in Fig. 8. A graphical representation of the metathoracic leg is shown to the right of the chart. The extensor muscle is colored red and the flexor is blue. The tibia is shaded gray whereas the SLP spring is in pink. As the joint rotates and moves, the center of the FT joint is traced using a series of black dots. When the FT joint began to rotate, the SLP torque was negative and caused the SLP to pull the FT joint into the femur. Once the extensor muscle rotated the tibia past the SLP force vector, the FT joint was rapidly pulled upwards. This accelerated the tibia upwards to provide energy for the jump. Figures in part C are for illustrative purposes only and are not drawn to scale.