I think that would be caused by the body's metabolism works less. She may feel tired and she must sit for long arm chair seat and changed to an activity that uses less power.
I think that would be caused by the body's metabolism works. She may feel tired and she had to sit on the chair arm. And to do things that are less and less.
I think should from the system of metabolism in the body a little work. She may feel tired easier and she must sit in the chair arm longer. And the change event, use less.