High intensity interval training or HIIT is all about very intense exercise followed immediately by low intensity exercise. The slower pace for the recovery period offers a more efficient workout. The Quest Fitness HIIT is sometimes combined with weights and at other times a purely cardio based workout. Maximum effort is the key to effective HIIT that pushes up the number of calories that are burnt during and after the session. The other benefit of this kind if training is that muscle loss that usually accompanies weight reduction is limited to a minimum.