Starting Position: Stand with your feet hip-width apart, arms by your sides. Pull the shoulder blades down and back and engage your abdominal / core muscles) to brace your spine.
Downward Phase: Shift your hips back and down. This will create a hinge-like movement at your knees. Continue to lower yourself until you feel your heels about to lift off the floor. Try to maintain a flat back by bending forward at the hips. Keep your head facing forward and position your arms where they offer the greatest degree of balance support.
Jumping Movement: With ONLY a very brief pause at the bottom of your downward phase, explode up through your lower body, fully extending your hips, knees and ankles. As your jump into the air, try to keep your feet level with each other and parallel with the floor.
Landing: The most important components of the landing phase are correct foot position and avoiding excessive forward movement in your lower extremity, which places additional stress on your knees. 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.
Exercise Variation: Perform repeating jumps, or add the knee tuck to the forward linear jump.
Use your arms to help create momentum and propel you up into the air; when squatting down reach your arms behind you, then when you jump swing your arms forward and up while pushing your legs in to the ground to help generate extra power.