This lunge option is perfect for keeping your quadriceps, glutes, and hamstrings under constant tension throughout the entire range of a rep. Stand with one foot on a gliding disc. Carefully start to reach it out behind you while lowering the back knee toward the floor. Weight should be held on the non-glider foot, while the glider foot should be very light on the disc. Pull yourself back to standing with the strength of the non-glider foot, dragging through its heel. Complete all reps on one leg, then switch the glider to the other leg.