FOOTBALL: Spain, Brazil, Germany and Italy.
BASKETBALL: USA, Argentina, Mexico and Spain.
HANDBALL: I can only really think of Spain.
TENNIS: UK, USA, Spain, Australia.
GOLF: At the moment, Northern Ireland.
SPRINTING: Jamaica, USA, Canada.
SWIMMING: USA, Australia, France.
In general, I would say the world's most sports-mad nation is Australia; they have the space, the climate, and the mentality to be really successful.