Stand tall with your core braced and a flat back. This is your start position. Take a big step backward with your right leg and bend at the knee, slowly lowering your body until your front knee is bent at least 90 degrees, whilst your rear knee should be hovering just off the floor. Inhale as you do so. Keep your torso upright the entire time and look forward. Pause at the bottom of the movement, then extend your knee as you push off from your right foot explosively. Bring your right leg through and your knee to your chest as you spring off the grounded leg into a small jump. Reverse the movement immediately and move the leg back into the reverse lunge. Perform all the required reps (or time) on one leg before changing to the other.