Lie on your back with one of your ankles on a ball, the other leg straight off the ball and your back in neutral position (slightly arched).
Activate your lower abdominals (transversus abdomini) by bringing your belly button inward and by activating your pelvic floor muscles (inner thigh) 20 to 30% of a maximal contraction. Maintain steady abdominal breathing while you lift your pelvis off the floor keeping your back straight and your knee slightly bent. Return to floor and repeat.