Figure 6.

A) Q₁ represents the initial measure of sagittal plane knee flexion angle while the subject performs the drop vertical jump. Q₂ represents the sagittal plane knee flexion angle taken at maximum knee flexion during landing. The displacement of knee flexion is found by calculating the differences in knee flexion position between positions (X = Q₁−Q₂). B) Q₁ and Q₂ are captured using the Dartfish angle tool in the video frame just before initial contact (Q₁) and at maximum knee flexion during landing (Q₂) of the drop vertical jump.