In the early 1960s, van Aaken trained, among others, the German athlete Harald Norpoth, who won silver in the 1964 Olympic Games in Tokyo in the 5000 meters.

[citation needed] Van Aaken stated that human beings were able to reach the age of 100, if they would not live so "hopelessly unbiologically".

He also held the opinion that the female sex would eventually perform better in endurance events than the male, if all social barriers were dealt with that currently enhinder this.

[3] In 1967, van Aaken asked Anni Pede, a 27-year-old middle-distance runner and mother of two also from West Germany, and Monika Boers, a 19-year-old from the Netherlands, to participate in a marathon organized by his running club in Waldniel.

[4][nb 1] According to German sports historian Karl Lennartz, journalists skeptical of 13-year-old Maureen Wilton's recent world best in Toronto, Ontario, Canada asked van Aaken if women and teenagers were capable of such a performance.