Well...although it sounds so boring now ;) All I was going to say is that it could be a situation where she just thinks she is being pushed too hard, because she is not in good health for the stated reasons and obviously is not an "overachiever" in the exercise dept. However, personal trainers can be anywhere from a kid right out of high school to a person with almost as much school ...or more...than a doctor! It is possible that the trainer is over doing it because of lack of knowledge/experience.

I would suggest she get a medical opinion from her doc as far as exercise with the knee.