The concentric action is hip and knee extension. The primary muscles used during hip extension are the gluteus maximus and hamstrings (semimembranosus, semitendinosus, and biceps femoris). During knee extension is quadriceps (vastus lateralis, vastus intermedius, vastus medialis and rectus femoris).
Begin the upward movement by stepping up with one leg. Keep trailing foot at start position and shift weight to the leg on the box. As the hip and knee extend on the box stand tall while simultaneously bring the opposite foot next to the starting foot. The downward movement starts with shifting the body weight to the same start leg and stepping off the box with the opposite leg. Shift the body to the the opposite leg and the start leg will follow to starting position.
- Keep torso erect and parallel to the tibia
- Initial contact of lead foot with top of the box must be made by the entire foot
- During upward extension push through the heels and squeeze the glutes
- Maintain hip flexion, knee flexion, and dorsiflexion of ankle at top of movement
- Do not allow the heel to hang off the edge of the box
Charles DeFrancesco, NFPT, USAW, NASM
President & CEO of Pure Fitness Club, Owner of Fit and Functional