In reply to Arcticboy: I went to a physio when I did mine who very kindly isolated the muscle are re-tore the wound so it would heal up properly.
One thing he did say though is if you sit on the floor with the bottom your feet flat against each other, knees apart and put your elbows on your knees, then push your knees down using your elbows it stretches the groin muscles to loosen them up a bit.