What the Fartlek?!
While it may sound like joke fodder for fifth graders, this type of workout can help runners, from beginners to seasoned vets, hit the ground running to better fitness or a faster PR.
http://breakingmuscle.com/endurance-sports/what-fartlek

What the Fartlek?!

While it may sound like joke fodder for fifth graders, this type of workout can help runners, from beginners to seasoned vets, hit the ground running to better fitness or a faster PR.

http://breakingmuscle.com/endurance-sports/what-fartlek