tiger woods and vijay singh both work out for 2-3 hours a day and practise for countless hours... they are athletes.
the art and act of swinging a club is also considered to be an athletic activity. and so anything that involves sporting equipment, is considered a sport.
So if you work out 2-3 times a day and play chess, you can be considered an athlete? As long as you work out though right?
A chess player who works out for 2-3 hours a day probably (and this is just a hunch, as I play chess regularly myself) doesn't do so to help themselves improve.