My favorite is:
60-minute fartlek run
My favorite running workout involving fartleks is a 60-minute run involving running 1 minute at hard effort followed with 1 minute of easy running.
This is a very demanding anaerobic workout but have found to be one of the best workouts you can add into your training routine that will pay you back ten fold come race day.
Come on Nate, I am a 5K runner. How is a 60-minute fartlek workout going to help me?
One, it is going to dramatically increase your lactate tolerance and you will be running over double the distance you will be racing at.