Continuous resistance is the key to the workout.  It is what builds the small muscles group, gives the small twitch muscles their endurance and your entire body the stamina your body needs.  The workout is intense without the high impact that strains your joints creating wear and tear on your body.  Slower is key to the workout, each movement is slow and controlled to provide optimum resistance during the push and pull (positive and negative movement), which create lean and defined muscles and also work the lengthening of muscles (flexibility).