1. (noun) A training technique used by runners and other endurance athletes that involves alternating between fast and slow paces during a continuous workout. The term comes from the Swedish word meaning “speed play,” reflecting the playful and unstructured nature of this type of training.


To improve her speed and endurance, the marathoner incorporated fartlek runs into her training schedule, alternating between sprints and slow jogs along the scenic trail.

Fun Fact

The fartlek training method was developed in the 1930s by Swedish coach Gösta Holmér. Holmér was tasked with improving the performance of the Swedish cross-country running team, and he believed that traditional interval training methods were too rigid and structured. Instead, he encouraged his athletes to incorporate periods of fast running into their longer, slower runs, allowing them to vary their pace based on how they felt. This more intuitive and flexible approach to training became known as “fartlek,” and it quickly gained popularity among runners and coaches around the world.