Purpose: A function exercise for engaging the glutes, hamstrings and quads and to avoid excess stress on the low back or knees.
Instructions: Stand against the ball with your feet slightly our in front of you. Bend at the hips and knees to 90 degrees without leaning forward and without allowing your knees to go past your ankle/foot.
Common Errors: Knees buckling in, knees moving past toes - indicative of weak hip stabilizers. Bending too far forward - indicative of a weak core.