Hi Coach Jay,

Can you help me understand a fartlek workout more clearly? First, in doing the “on” or fast intervals (miles) and then the “off” or slow miles, what system am I sharpening in my “runner’s tool belt”? I’ve been doing fartlek training on a weekly basis as follows:Total workout 5 miles:

fartlek is 3 on, 1 off for 2 miles, with 2-mile warm-up and 1-mile cool-down.

My goal is to run PRs in the 5k, 8k, and 10k this spring; therefore,  I want to be sure the fartlek is a workout that is effective in the “tool belt” of training so I can hit my goals. 

Thanks!
Jordy

Glad you’re asking this question, Jordy. I’ve had some email exchanges recently and this issue has come up: what exactly is a fartlek workout and why is it so hard to execute? Before we go into detail, let me reassure you that fartlek workouts are a must in any serious training program. You teach your body to deal with lactate during intense fartlek workouts, and you improve your lactate threshold and running economy in less intense fartlek workouts.

On one hand, the workout is very simple. "“Fartlek” is a Swedish term for “speed play” and that’s simply what you’re doing in a true fartlek workout—playing with a variety of speeds. However, it’s hard to conceptualize this workout at first, so most coaches break down the fartlek into two paces rather than have the athlete run four or five different paces. I like the “on” portion to be at a specific race pace. You mentioned you’d like to run 5k, 8k, and 10k PRs this spring. I would attempt to run your goal 5k pace for two minutes (which, if you think about it, shouldn’t be that hard…it’s just two minutes); then run for three minutes at a pace that is faster than your easy-day pace yet slow enough for you to recover from the two-minute “on” portion. These three minutes comprise the “off” portion. The “on” and “off” make a five-minute block of running that you simply repeat over and over. No reason you can’t build up to 40 minutes of running in this manner, which gives you 16 minutes at 5k pace. That’s good work, especially if, during the course of the workout, you can gently speed up the pace of the “off” portion.

Now you might be wondering: Why not run the “on” portion faster? Don’t I want to run a faster 5k? You want to teach your body the goal 5k pace…but remember, you’re not there yet because the “on” portion is your goal 5k pace, not the 5k pace you’re capable of today. By making the “off” portions slightly faster as the workout progresses, you ask your body to come back to that 5k goal pace when your body is fatigued. It’s a great stimulus metabolically, and it’s also a great opportunity to get in tune with posture and mechanics—so when the “on” portion starts again, you should feel as if you’re running faster, with a bit longer stride (and hopefully with turnover similar to what you had during the “off” portion).

So that's how to execute a simple fartlek. But as my favorite saying goes, courtesy of Thelonious Monk, “Simple ain’t easy.” It takes a great deal of practice to learn how to run a fartlek correctly because it’s a workout that is based on feel; however, there is something you can do. Go to the local track and run a simple workout of 800m at 10k pace; then do 800m steady. If you repeat this five times, you have 8k of running on the track and a great stimulus. Then, when you get back home, look at all 10 splits. Were the 800m “on” at 10k pace, or did you run them too fast, as most people do? Were the 800m “off” portions similar throughout the workout, or did they slow as the workout progressed? That’s what often happens…though it’s not what we want to happen. Some may find it boring to run 8k or 20 laps on a track, but it’s a great way to learn how to run a fartlek. 

Thanks for the question, Jordy—hope you have a better understanding of fartlek workouts now—and I wish you the best in your racing this year.

Jay