Hi Sparrow,
MATRXR is "right on" about your activities. I remember this question coming up before, and I wrote to St Judes Medical for an answer. They clarified the issue stating that there are many professional atheletes and Olympians that are on Counadin. Coumadin will not restrict your activity level, however, other medications or medical conditions may. Your doctor should be the one to inform you based on your personal health condition.
The one thing that you want to be careful about though is high impact sports. You do not want to have any severe hits, bangs or falls when taking Coumadin.
Hope this helps,
Rob