Short answers:
- bob sledders live 1.6 years longer
- ice hockey players live 4 years longer
- speed skaters live 5.6 years longer
This is only if you keep up your fitness level for your whole life (not an easy task).
Olympic medalists live an average of 2.8 years longer than their age-matched peers. More specifically, 8 percent more of the medalists than the non-Olympians were still living 30 years after they had won their medals.
References:
Live as Long as an Olympian, NYTimes, and BMJ.
http://well.blogs.nytimes.com/2012/12/19/live-as-long-as-an-olympian