http://www.nytimes.com/2016/04/27/sports/aging-runners-find-help-for-a-question-how-slow-will-i-get.html?smid=nytcore-ipad-share&smprod=nytcore-ipad

Thanks to Ray Fair, a professor in the economics department at Yale, runners have an exact schedule that will predict how their performance will decline as they age.