Ernst van Aaken (16 May 1910 in Emmerich – 2 April 1984 in Schwalmtal-Waldniel) was a German sports physician and athletics trainer.
Van Aaken became known as the "Running Doctor" and was the founder of the training method called the Waldnieler Dauerlauf (German: "Waldniel endurance run").
He is generally recognized as the founder of the long slow distance method of endurance training.As a sports physician, trainer and advocate of new developments he directed himself fanatically to distance running and the training of "pure endurance" ("reine Ausdauer") with high mileage in the training program.
He was an opponent of the method of interval training that prevailed until halfway the sixties.
In the early 1960s, van Aaken trained among others the German athlete Harald Norpoth, who won silver in the 1964 Olympic Games in Tokyo on the 5000 meters.
In 1972 Van Aaken was hit by a car during his own training, which cost him both legs.
Since this accident he moved in a wheelchair and became also a champion for disabled sports and wheelchair racing.
He also held countless lectures, also in the United States and Japan, and organized running races, especially marathons for women, besides ultra running events.