fartlek

/ˈfɑrtlɛk/
noun
  1. A training method for runners that alternates between fast running and slow jogging, often used to build speed and endurance.
    • Many runners enjoy fartlek because it feels less structured than interval training.
    • The coach included fartlek runs in our weekly training schedule to improve our speed.
    • During fartlek, you might sprint to a tree and then jog to the next lamppost.
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