Fig. 3

Six samples of takeoff velocities and corresponding CoM position trajectories from Participant 9, jumping to the 55% target. The line colours are the assigned jump grade and follow the convention outlined in Table 2. The dots (left) denote the end of the vector for viewing clarity where overlapping vector lines make it difficult to see where the vectors end. The circles (right) denote the CoM position when the feet left and regained floor contact. The dotted and solid vertical lines (right) show the location of the takeoff position and landing target. CoM trajectories behind, or forward of, the target distance exhibit early (legs extended), or late (legs partially collapsed) foot placement relative to on-target jumps. Average CoM forward position at landing is marked by the grey line at \(X_{fp}\). Some trajectories (yellow, red) show poor foot placement timing that is likely the cause of failing a jump, even though takeoff velocity and vector are similar to successful jumps.