fartlek \FAH(r)T-lek\ (noun) - An athletic training technique developed in Sweden in the 1930s by the Swedish national coach, Gosta Holmer, comprising alternating periods of intense exercise with periods of less strenuous effort or any workout based on this technique.
"Jason, you can't study in fartleks; you have to work constantly and continuously on your studies if you are to succeed in school."
Today's word is actually the Swedish word for "speed play" based on fart "running, speed" + lek "play." "Fart" is the noun from Swedish fara "go, move," akin to German fahren "travel, journey" and English "fare" as in "fare thee well" or simply "farewell," from Old English faran "to journey, travel." Another derivate of the same root is "ferry" from earlier "ferian." In Greek, the original root emerged as poros "journey," seen lurking in "emporium" from Greek emporion "merchant," someone who did quite a bit of journeying in the days of ancient Greeks. In Latin it emerged in portare "to carry" which we see everywhere in English borrowings: "porter," "portfolio," "import," "deport," "important," and many, many more.