This exercise requires a partner. 
- Start position is kneeling on the floor with the partner behind holding onto your heels to keep the legs in place.
Lean forward from the waist slightly for three repetitions, returning to the starting position each time. Do not bend at the waist and keep the trunk and the thighs in line.
After the first three repetitions, increase the forward lean a bit more for every movement until you reach an angle from which you are unable to return, then fall forward keeping the trunk rigid and use a push-up to return to the starting position.