The most efficient way to cycle box jumps is to try to stay upright and close to the box. You should spend very little time on the ground and very little time on the box. Anticipating the bottom and the top and pushing the ground and the box away with your feet and ankles will make you very powerful. Keep in mind that no matter what you are doing in the gym holding your belly tight and using your air in the appropriate way are essential.
21-15-9 reps for time of:
135 pound Clean