I don't think I've ever directly been influenced in my fashion choices by clothes worn by sports personalities. I haven't ever purchased a particular item because I've seen a sports personality wear it. I do however think that people like David Beckham, in particular has indirectly influenced men's fashion hugely though- with the rise of the metrosexual, his highly publicised changing hairstyles and use of grooming procedures - moisturising e.t.c.
In terms of celebrities in general, I think I may have occaisonally tried to emulate someone's look to some extent - but it is more unconsious than something I do in a deliberately contrived way, I think they may influence fashion in subtle ways.