Fartleks are a well-known and popular running workout—or at least they’re something runners talk about all the time. But how many of us have gone out and said “I’m doing a fartlek today” and actually followed through with it? The original idea is that the workout is unstructured (the name means “speed play”) so it’s hard to plan one. Here’s what you need to know about fartleks, and some guidelines to setting yourself up for a fun and productive one.

What counts as a fartlek run? 

“Fartlek” comes from a Swedish term meaning “speed play,” and it’s usually described as something you just go out and do for funsies. You choose a landmark—say, a mailbox up ahead—and decide to run faster until you get to it. Then you slow down again. 

Most runners and coaches would agree on that description, but when you try to nail down a definition of the fartlek run, things start to fall apart. If you run fast for one minute and slow for four, is that a fartlek, or just a time-based interval? Can you run fartleks at a specific pace, or just off vibes? I even saw one post on Reddit that claimed it’s not a real farlek if you know how long you’ll be running each segment—you need a coach to blow a whistle when you least expect it. 

Still, these are some commonalities among the descriptions I’ve read, and we can use them to guide us: 

• A fartlek run includes short segments of faster and slower running.

• The slower running is still running, usually around your easy pace. So this isn’t a sprint-and-walk situation, more like jog-and-surge. (If you need to walk those recoveries, keep your pace strong and powerful.) 

• Precise paces and times are not required.

• The faster segments should be short, and the easy segments should be longer.

• Your cues to speed up and slow down may come from your environment, your training partners, your whims, or a loose plan you had when you set out.

• A fartlek run should feel harder than an easy run.

Why run a fartlek? 

The benefits of fartlek runs will depend on how you do them. Some fartleks are basically a threshold run, some end up being long runs with some marathon-pace work in the middle, and some are just standard speedwork with a different name. These will all have different benefits. If a coach or written program tells you to do a “fartlek run,” make sure to get clarification on what that’s supposed to mean. 

Here are some of the reasons commonly given for including fartlek runs in a program: 

• If the runner chooses their own intervals, it can be fun and playful, sort of a mental break from structured training. 

• Since there are no strict pace targets, it can serve as a transition between easy running and introducing more structured speedwork (for example, as you finish your off-season and start training for a race).

• The variety in the run can make it a little less boring than a standard threshold or long run.

• You can’t compare your times or paces to what you’ve done previously, since every fartlek is different. This can help if you get anxious about whether you’re “improving” enough. 

Examples of fartlek runs you can try today

So we have some guidelines, and we know when and why we might try a fartlek run. With that, you can pretty much put together your own version—but I’d like to give a few examples to start you off. There are no wrong answers, so feel free to add your own!

For any of these, plan to start and end your run with at least five to 10 minutes of easy jogging (or however you like to warm up and cool down). 

The music fartlek

You’ll need a good playlist for this one. (Fortunately, we have a guide from our resident spinning instructor on how to craft a great one.) When the song is slow, jog easy. When the chorus picks up the energy a bit, you can too. And if it hits a big, emotional bridge—you know what to do. 

You can also do this same idea song by song. Alternate chill songs with higher energy ones, and match that energy to your running speed. Remember, it’s a fartlek, so you can always skip or repeat a song as you see fit.

The hill fartlek

Do you have a route with some little hills or challenging parts here and there? Jog easy, but when you hit one of those special spots, put on a little extra speed and surge up that hill. Or, if the hills are too steep for that to be realistic, choose flat straightaways or downhills where you can really open it up and get your legs moving. 

The lightpole fartlek

This one is good for some distance-based guidelines if you run in a place with lightpoles, mailboxes, or some similar repetitive structure. Starting at one pole, run fast until you hit the next one, then jog easy until you pass two or three more. 

“Haul ass” triggers

I love this idea, which came from an old Reddit comment. The redditor says: “I learned about fartlek runs in the US Army, and still to this day I have certain spots in my routes that I consider ‘haul ass’ segments. I also have a rule that if certain songs come up in my play list when set to shuffle, that’s sprint mode or skip the song.”

This is like a speedwork version of the “run until” challenge. The “haul ass” segments could be a favorite hill or straightaway, as we discussed above, but you could come up with more creative options as well. Here are a few: If you pass a picnic with a boom box blasting, run faster for as long as it’s in earshot. If you see a cute dog or a cool-looking bird, run faster for 30 seconds. And of course, every park runner’s favorite, “pass that person in front of me.” They don’t have to know you think it’s a race. 

The partner fartlek

This one is like the “pick a mailbox” type of fartlek, but the catch is that you and your running buddy get to take turns. This can be playful, vicious, or anything in between, depending on how you and your buddy get along. (He made me run a real long one? OK, I’ll make him sprint up this hill!)

Time-based fartleks

Some will say these aren’t true fartleks, but sorry—plenty of people run time-based intervals with loose pace targets and call them fartleks. Here are a few I’ve seen: 

• 1 minute fast/4 minutes easy

• Pyramid up and down: 1 minute fast, 1 minute easy, then 2 of each, 3 of each, then 2, then 1. Jog easy for a bit before starting the next pyramid.

• Descending only: 5 minutes fast, 5 easy, then 4, 3, 2, and 1.

The treadmill fartlek

I’m now realizing that some of my ways to make the treadmill less boring are, in fact, fartleks. My favorite is the simple rule to “change something every quarter-mile.” That could mean an increase in speed, or a decrease in speed. A little bump to the incline. Maybe I just try to get this last quarter-mile over with as fast as possible. 

Again, make up your own rules. You could do time-based intervals as above, or choose triggers like sprinting for 30 seconds whenever a number 7 comes up on any of the readouts in front of you.