As athletes gear up for Sunday's New York City Marathon, falling world records have brought new attention to the distance event after a blockbuster year.
Ethiopian Tigst Assefa shattered the women's marathon record in Berlin in September, lopping more than two minutes from the previous best, with a time of two hours 11 minutes and 53 seconds.
Days later Kenyan Kelvin Kiptum beat compatriot Eliud Kipchoge's world record mark on the men's side with a stunning win in two hours and 35 seconds in Chicago.