I think it depends on the sport, we see a lot of cross pollination particularly with training methods and conditioning. Boxers training footballers, rugby players training GAA players and Football players etc. There are plenty of mutually exclusive sports though, a javelin thrower wouldst automatically have an aptitude for swimming and so on.
A good grounding in lots of different sorts would on the face of it make sense in developing a core strength and co-ordination. Its probably at the elite level that focus on one sport is key and focus on many is a dis-advantage. I suppose thats why dual-code players in the GAA are a rarity now.
Of course you always get freaks as in the indo piece.
