With fartlek training, you can experiment with pace and endurance, and experience changes of pace. (verywellfit.com)
My favorite way to do this is with fartlek workouts, which can be done running, biking, swimming or with any other endurance activity. (philmaffetone.com)
Nicola @ Running Happy recently posted... How fartlek running can make you a better runner (confessionsofamotherrunner.com)