What Is a Fartlek training? Farlek training is a type of fitness training that involves rowing continuously at varying paces. It challenges your body to adapt to various speeds, conditioning you to become faster over longer distances. The word “fartlek” is a Swedish term which means “speed play.” It is a training method that blends continuous (endurance) training with interval (speed) training. They are unique from most run workouts, which typically target one or two paces, and also differ from