|Function:||Leg Ext (Vertical)|
Stand with shoulder width stance facing elevated platform with squat box positioned behind.
Squat down with arms extended forward while attempting to push rear end back as far as possible. Sit back on squat box and rock back until torso is positioned upright. Rock body forward, swing arms forward, and immediately jump off ground onto elevated platform. Land feet on top of elevated platform.
Try to keep knees from traveling forward while reaching rear end back onto squat box. Ideally, knees could be behind ankles (further back than what is shown). In this position, greater stretch reflex can be created through hips (via hamstrings) once torso rocks forward just before jump. However, other hip extensors can engage in stretch-shortening cycle in lieu of hamstrings' optimized involvement.
Movement is based on mechanics of Box Squats. A plyo-platform, bench, stool, or chair can be used. Increase height of elevated platform as ability improves. Plyometric boxes or stacked mats may be used as elevated platform. Also see similar Seated Box Jump.