For the novice runner there are new terms to learn, and fartlek is amongst the strangest. You can run, you can do interval training, tempo training, and fartlek.
The word means “speed play” in Swedish, is continuous training with interval training. Fartlek runs are a very simple form of a long distance run. Fartlek training “is simply defined as periods of fast running intermixed with periods of slower running.”
Interval training is precise: you run quickly and recuperate for fixed intervals of running. Fartlek you decide on the go when you want to run fast, how far you want to run (to the next lamppost) and when you want to slow down. You can run faster than you median speed, or you can run very fast. The randomness assists your running, as you would in a race when you want to pass some-one, or speed up, or conserve your energy. Fartlek is definitely an aid to the novice.
Today I ran 10 miles: from Folkestone to Hythe and back along the promenade. It was an improvement on my previous long run as my leg muscles were not quite so stretched and sore. I plan to do a long run and incorporate parkrun into the middle of it. Once you have run that far it is a pity to waste it.