Jumping in Sand

Why is it harder to jump higher in sand than it is to jump on a court? This is the question I began to ponder as I grew exausted from playing beach volleyball. I then realized that Newton's Laws were the reason for my exaustion. In order to jump, the legs need to exert a force on the ground so that the ground exerts and equal and opposite force to push the body in to the air. In the gym, nearly all of the force exerted by the floor is transfered to the jump. On the beach however, tiny sand particles cushion the force of the jump by spreading outward. Therefore not a lot of the force is transfered to the jump because some force is needed to push the sand particles outward. The static friction of the sand is also relatively small compared to the solid, one-pieced court.