Hi Channy, It sounds like you might need to check with your doctor before you begin an exercise program. If you haven't worked out in a while, it could just be sore from the added work. Sometimes walking and the other movements Leslie incorporates into the walk can make the muscles around the knee stronger which in turn will do away with the pain. But if it feels like it's slipping, it's time to see the doctor to rule out any problems the might become worse if you continue to do the walk.

Best of luck.

I can't give you any helpful information but I would suggest trying water walking in a pool if you can. I you know the 4 basic steps the Leslie does you can try them in the water which should be better while you strengthen the knees. AnnofB is right seek out a doctor.