Right, this is not a "I have selection next week and I can only do 6 sit ups" post: I can do 50 in 2 mins no drama so its just out of interest that I post. When I have done 40-50 sit ups with my feet under something or held down, my upper legs start to ache like hell! I dont really mind as I can still do the right number but it is driving me up the wall trying to figure out what exactly is happening here? Is it the quads, hip flexors or what that is being overworked? Whatever it is it is these muscle that always go first, if I didnt have this "problem" I think I could quite easily do 80 or 90 sit ups in the 2 minutes period as my abs always feel fresh after the test, just my legs are aching. Any physios, PTIs etc.. any idea what is going on? J.