There is also an increase in the number of recreational runners participating in long distance races of 10 km or more, generally referred to as endurance races. 2013 was another record year for the classic distance with more than 1,100 marathons run across the country generating 541,000 finishers. Of those that finished, 57% were men (308,400, all-time high) and 43% were women (232,600, a new high overall and percent). Additionally, 47% were Masters – aged 40 and older (254,300, also a new high overall and percent). This represents greater than a 20-fold increase from the 25,000 finishers in 1976.
– Running USA. 2014 Annual Marathon Report. March 23, 2014