I'm fairly certain that it's safe to say, this poor young girl will have a disposition for early on osteoporosis and arthritis.... .....Just sayin'..... 4951
Arching the back, as she does, distributes the weight away from the chest and shoulders. Powerlifters do it in order to lift more weight. It decreases the distance lifted, and allows the lifter to use the legs. But it does place pressure/strain on the lower back. 4951