A client has mastered the single-leg squat on the floor.

NASM’s balance progression principles move from stable → less stable → unstable surfaces, while keeping proper form. A single-leg squat on a Dyna disc is more proprioceptively challenging than doing it on the floor or even on an Airex pad because the Dyna disc creates multidirectional instability.

Two-leg squats, even on unstable surfaces, are less challenging for balance than single-leg squats. Therefore, progressing from single-leg squat on the floor to single-leg squat on a Dyna disc follows the recommended instability progression.