Starting Position: Stand facing a raised platform or a plyometric jump box. Place your right foot on the top of the step or box, keep your left foot on the ground, hinge forward from the hips. Arms are by your side and your head is level. Focus your gaze on the ground about two-to-three feet in front of you.
Upward phase: Jump straight up by pushing off with both feet and swinging your arms forward and up, making your body completely straight in the air. Imagine you are a rocket launching toward the ceiling. While in the air, your left foot must lift a little in order to keep your feet level with each other and parallel with the floor.
Landing phase: The most important components of the landing phase are correct foot position and control of the forward movement in your knees. Excessive forward movement in the knees places additional stress on the joint. Try to land softly and quietly on the mid-foot, rolling into the heels. Always push your hips back and down to absorb the impact of landing. Do not lock out your knees on your landing. Land with your trunk slightly forward, head aligned with your spine and back rigid or flat. Keep your abdominal / core muscles engaged, bracing your torso to protect your spine.
When jumping keep your spine straight and tall by contacting your abdominals (bracing). Be sure to perform the same number of repetitions on each leg.