When I do sit-ups I have a bulge in the middle of my chest just below the breast bone in the shape of a hot dog about 6 or 7 inches long when I go to the up position , when I return to the flat back position that bulge goes back down. I have no pain, the bulge is soft . I am in good health. A non smoker , I walk , I lift weights , not over weight etc. Could this be a Hiatal Hernia?