I used to do leg curls all the time but I had to stop. I kept getting pain in my lower abdominal area near the belly button. More recently I was doing seated dumbell overhead extentions and I felt the pain again. I didnt use any back support on the extentions. I was told that the pain was from stressing the muscles down there and that I should use lighter weight. I decreased the weight and also took time off from doing the leg curls. The pain was still there. Any thoughts?