Fartlek

Fartlek is a middle- and long-distance runner's training approach developed in the late 1930s by Swedish Olympian Gösta Holmér. It has been described as a "relatively unscientific blending" of continuous training (e.g., long slow distance training), with its steady pace of moderate-high intensity aerobic intensity, and interval training, with its "spacing of [more intense] exercise and rest intervals". Simply stated, in its widely adapted contemporary forms, fartlek training is alternating periods of faster and slower running, often over natural terrain, including both "level and hilly terrain".

While Fartlek training is generally associated with running, it can be incorporated into almost any kind of exercise. The variable intensities and the continuous nature of the exercise stresses both the aerobic and anaerobic parts of the runner's physiology. It differs from traditional interval training by being less structured.

An example of its more modern manifestations in the training of serious runners is found in Mona fartlek, named for Australian distance runner Steve Moneghetti, devised by Olympian Chris Wardlaw. This training style injects speed into a 20-minute session, pairing alternating periods of effort and recovery: 90-seconds on, 90-seconds off (performed twice), then 60-seconds on-then-off, and 30-seconds on-then-off, and 15-seconds on-then-off (each of these performed four times), generally, with intensity (pace) increasing as the effort period shortens, with the specifics determined by coach and athlete.