The International Marathon Medical Directors Association physicians are recommending that you limit caffeine to 200 mg or lress (that is the amount in about two cups of diner coffee.)  Although the evidence is not conclusiive, there seems to be an association between large doses of caffeine and cardiac arrest with runners that do NOT have any blockage or heart abnormalities.

Read more: http://www.nydailynews.com/sports/more-sports/nyc-marathon-nears-resuscitation-caffeine-levels-hot-topics-race-doctors-article-1.963880#ixzz1cNjhb4Xs