By the very word "supplements" depend upon your OWN particular needs. Taking what Norm, Tim and Peter are using isn't going to help your case.

Consult a nutritionist/coach.....

Thanks for the advice... however, I'm not looking to start using whatever supplements the pros are using, I'm just trying to get a feel for what advanced athletes are doing... I live on a remote island and don't have access to coaches or nutritionalist (at least not for face to face iteraction). Most of my learning about the sport comes through books and the internet, including this forum. From reading what other athletes write, it seems to me that the majority are using some sort of nutritional supplement... I was wondering if this is really necessary or similar to arguing about millimeters or grams of weight in cycling (which goes on a lot too).

I use glucosamine chondroitin. I think it works very well for my knees.

I also use Cytomax.