Yet , despite these obstacles , he has become one of the world 's leading multi-marathon runners , having run over 700 official marathon races in the fastest ever average finish time .
He also has a congenital blood disorder that directly compromises athleticism .
Despite these obstacles , he has become one of the world 's leading multi-marathon runners , having run over 700 official marathon races in the fastest ever average finish time .
He also has a congenital blood disorder that directly compromises athleticism .