Squat down and grasp dumbbells, with feet approximately shoulder width apart and arms at sides. Keep toes pointed forward or slightly out. Stand in good body alignment (abs tight, chest up, back straight - slight arch). Breathe in and hold. In a controlled motion, raise body by bending knees and hips, while keeping a slight arch in the back. Keep knees in line with toes; avoid turning knees in or out. Keeping feet flat on the floor, continue raising body up until it reaches a fully erect position without compromising form (back arched, abs tight, chest up). Hold breath past sticking point then exhale. While maintaining controlled motion, return to starting position. Do not allow muscles to relax before next repetition.