Some more food for thought at the link:
http://www.geocities.com/biomorrow/sprinters.htmlBasically says a distance runner (pre-dominant slow twitch individual) cannot become a world class sprinter regardless of training but a sprinter (pre-dominant fast twitch individual) can become a good distance runner. It also says Rodgers was 70-80% slow twitch and Salazar was an amazing 95% slow twitch!