Starting Position: Stand in an athletic ready position with your feet hip-width apart, your right leg forward, left leg back, with both arms bent at the elbows and the left arm in front of your body and right arm back behind your body. Prepare for the jump by leaning forward hinging at the hips, while simultaneously keeping your weight back in your thighs, depressing and retracting your scapulae (pull shoulders down and back) without arching your low back, and "brace" (engage your abdominal / core muscles) to stiffen your spine.
Jumping Movement: Quickly sink your weight back into your hips then explosively push both feet into the floor and driving your hips forward to accelerate your body into the air achieving triple extension (pushing and extending your ankles, knees and hips simultaneously) in both legs. As you jump into the air, keep your feet level with each other and parallel with the floor.
While you are in the air cycle your legs by moving your left leg forward in front of your body, your right leg backwards behind your body; cycle your arms with your legs so that as your left leg comes forward your right arm comes forward and as your right leg moves back your left arm moves back.
Downward phase: As you land your left leg should be in front of your body and your right leg back behind your body. The most important components of the landing phase are correct foot position and avoiding excessive forward movement in your lower extremity which places additional stresses upon your knees. Attempt to land softly and quietly on the mid-foot, rolling backwards quickly towards the heels. Always push your hips backwards and drop them downwards to absorb the impacting forces associated with jumping. Avoid locking out your knees or quads on your landing as this may lead to potential knee injuries. Land with your trunk inclined slightly forward, head aligned with your spine and back rigid or flat. Keep your abdominal / core muscles engaged, stiffening your torso to protect your spine.
Exercise Variation: Be sure to alternate the forward leg, when learning this exercise focus first on landing with control and resetting before another repetition, as you improve your strength and power progress to performing multiple jumps in a row.
It is suggested, you first learn how to squat and land before attempting to jump. Once you have mastered the hip-hinge mechanism, begin with small jumps, but emphasize your landing mechanics. Only progress to more explosive jumps once you have mastered your landing mechanics.