Rolling

In my second aerobic session, I get to work out using ball. Big air-filled rubber ball. We sat on the balls each and keep ourselves bouncing while doing movements and exercises. We need to open our legs wide apart then closed up and doing steps while sitting on the ball, bouncing to the rhythm. At one point, we need to raise our knees up and down, up and down and man that was tough. I could feel my thighs 'bursting'. Haha. After about 40 minutes, we proceeded to the floor movements using balls. That was when we get to roll the ball, doing actions to tighten the tummy, the sides of our waist etc. It was rather difficult because you need to hold the ball in position but you could feel your muscles contracting.
My labmate performing
A difficult act. You need to roll the ball using your legs, and move it up to to this position from the 'stretching up legs' position.
That's me after the workout.