Hi Joyce, you may not know me because I am a little new to the group. I don't notice pain so much but do notice cramping a lot of my lower back, upper leg muscles and right ankle. I do a moderate exercise of bike riding ( I position my seat so that my leg is almost extended when pedaling and the knee only so slightly bent) and don't suffer as of yet the knee problems (there is no weight on the knees when pedaling the bicycle). I limit my bike rides to 10 or 15 miles. This equates to 50 mins. for 10 miles and 1 hrs & 15 mins. of riding for 15 miles. Also while riding I can stop pedaling for a few seconds and take a break while still on the move.I believe that doing a low impact moderate exercise (like the one above or swimming pool) has helped me avoid some of the aches & pains of over excreted muscles or bone joint pressure associated with IBM.
But of course I am not a doctor and I could not diagnose a common cold let alone something as complex as IBM.