Fartlek Training Is a Fun and Effective Way to Run Faster. Here's How to Do It

Sure, the word sounds funny, but a Fartlek workout is one of the greatest training techniques in the realm of distance running.

What is Fartlek running, exactly? It's a dynamic running method that blends steady running with bursts of intensity. Runners who have done Fartleks will agree, this practice that hails from Sweden provides incredible physiological improvements while actually being fun.

Perhaps the toughest part of Fartleks is knowing how to incorporate them into your training cycle. So, we chatted with a few experts to find out how to safely and effectively use Fartlek training.

Here, we'll explore the origins, physical adaptations, mental benefits, and practical applications of Fartlek training. Whether you're a seasoned runner or just starting your fitness journey, Fartlek training might be the extra spice you need in your running routine.

"Fartlek is Swedish for 'speed play,' says RRCA-certified run coach Erica Coviello, CPT. "It's a running workout in which you, quite literally, play around with different speeds."

The technique was invented in Sweden by Gösta Holmér in the 1930s. The Swedish Olympic coach needed an effective way to improve both the speed and endurance of his runners. The idea was that the training would work on steady-state running and quick bursts of speed simultaneously.

The world caught on to the effectiveness of this type of training when Holmér's runners started breaking world records. In 1942, one of these athletes, Gunter Hägg, set a whopping ten world records in seven different events in just 82 days.

In the traditional workout as conceived by Holmér, you'd run about seven miles with up to 3.1 miles at or faster than 5K race pace. But throughout the years, tweaks have been made. Fartlek training now is less of a prescribed workout and more of a loose and free run with some harder, quicker efforts sprinkled in.

"It's a form of speedwork that's relatively free and usually lower key," says exercise physiologist and RRCA-certified run coach Janet Hamilton, RCEP, CSCS. "I tend to use Fartleks as a lower-intensity form of speedwork."

Even though other types of speed workouts work similarly in your body to improve times and endurance, Fartlek workouts are very different from repeats and intervals. Coviello and Hamilton use the word "unstructured" to describe Fartlek training, whereas a track workout or tempo run requires runners to hit certain paces within 2 seconds or so and go specific distances.

"I don't usually give [runners] a real strict pace to follow," Hamilton, owner of Running Strong, says. "I'll tell them to go with what feels like whatever race they're after. So, for example, half- marathon pace or 10K pace, and hold that for 1 to 2 minutes and then drop back to your easy effort for 3 to 4 minutes. And I say that at the end of this workout, you should feel invigorated, not exhausted."

Hamilton explains that strict pacing during speed workouts comes later in an athlete's training cycle. These repeats, done at speeds similar to 5K race pace, can often be close to an athlete's VO2 max (maximal amount of oxygen you're able to use during exercise). Fartleks aren't meant to totally gas you, and they should be easier to recover from than these harder speed workouts.

Possibly one of the best Fartlek run benefits is its ability to make runners faster. A February 2018 study in ‌Physiological Reports‌ found that speed endurance training boosts running economy and speed. Runners did speed workouts over the course of 6 weeks and their average 10K time improved by 3.2 percent.

How do these improvements happen? When you perform high-intensity training, like track workouts, hill training, tempo runs and Fartleks, you recruit your fast-twitch muscles and elevate your heart rate so that it's working in the anaerobic zone (80 to 90 percent of your max heart rate). A June 2023 review in ‌Heliyon‌ says this greatly improves your VO2 max over time.

And, an October 2019 study in the ‌Think India Journal‌ concluded that 12 weeks of Fartlek training significantly improved the muscular endurance of cross-country runners when compared to a control group that did not incorporate Fartlek training into their running plans.

In addition to the physical adaptations that happen, you're also showing your body and brain how to get the speed you want.

"The goal is to teach your body to start moving faster, and Fartleks do that without the physical or mental stress of longer, harder running," Coviello says.

Plus, the physical stress of doing long or really fast-paced runs can lead to injury. So, Fartleks provide a way to include speedwork without having to run hard for your whole workout.

If you ask experienced runners what their favorite training runs are, they'll probably say Fartlek runs. For so many runners, it truly does feel like playtime.

"Maybe it's the variation. Maybe it's that they're working but it's a little less of a high-intensity pace than a 5K repeat, and it feels a little easier. Or maybe it's just the fact that they know they're not tied to anything. That it's freedom," Hamilton says.

For some runners, it's a great way to break up the monotony of easy training miles, long runs or the doldrums of a long training cycle. Coviello says she likes to use them as part of a reset.

"When you're in a funk or on a day where you just don't feel like doing much, they're a good way to boost your fitness without feeling too overwhelming," she says.

Coviello is a big fan of Fartlek runs because any runner can learn to do them, complete them and improve on them over time.

"It's easy to tailor to any ability, fitness level or training style," she says. "You can turn the 'easy' part of the running into a walk, and the harder parts into an easy run. More advanced runners can bump it up a notch by adding a little more structure with timing and pace. You can do just a few in a short run or do a bunch in a longer run. There are so many possibilities, which is what makes Fartleks so enticing for so many people."

Fartleks aren't magic for everyone. Hamilton explains that there aren't many downsides to Fartlek training, but there are some circumstances for specific athletes where she won't use them.

"The only disadvantage is if an athlete is trying to work on strict pace awareness — that would usually require a more structured and disciplined approach to speedwork," she says.

Coviello has a similar take: "If you're a more experienced or advanced runner looking to hit big goals like [qualifying for the Boston Marathon] or a super fast 5K, there are other workouts that will be much more effective at getting you there, especially the further along you are in a training cycle."

Finally, it's important to remember that if you're injured or recovering from injury and just coming back, you should literally take it slow.

"As with any form of speedwork, you need to be healthy and injury-free to be doing this," Hamilton says. "So don't do speedwork just yet — even Fartleks."

For runners just starting out, Fartleks are a great way to get a feel for speedwork. And, after working to get your aerobic capacity to the point where you can sustain 30 minutes of running at a time, Farltek training can give you something a little different as you continue to work on your endurance.

"If you've got somebody who is wanting to make the transition from walking to running and they're at the point where they're able to continuously run for a reasonable distance — a mile, two miles, three mile — and they're like, 'Hey, can we do something fun or different?' Sure!," Hamilton says.

Hamilton advises the runners she coaches to find a nice shady path and gives them a loose structure to follow. For example, she'll say to alternate between a slow and medium-fast pace. She says to go telephone pole to telephone pole or mailbox to mailbox — whatever marker you want to choose to play around with speed.

The trick, Hamilton says, is not to do Fartlek running for every workout. Once per week for beginners is plenty. See how your body responds over the course of a few weeks.

"And if you find that you like the workout and you're having fun and your body's not barking at you, then you can probably get away with two," she says.

When Hamilton trains an athlete over the course of several months, she will build their base and then use Fartlek training as a way to "test the waters" of speedwork.

"I finally let you loose, because for weeks I've had you holding yourself back doing nothing but easy effort," she says. "Fartleks will give you the chance to be free."

After 4 to 8 weeks of base training, you can safely add a Fartlek workout to your weekly training schedule. Coviello echoes this strategy and adds that it's great for athletes as they begin to ramp up into the racing season. During this "pre-season," she says you don't have to do them that often.

"Once a week or every other week for a few weeks is usually enough to help you find your groove," Coviello says.

While it's best to talk with a running coach or trainer prior to implementing speedwork in your training plan, these workouts will give you an idea of how to do a Fartlek run. Remember, you should feel strong, happy and energized at the end — meaning don't go all out on the "hard" efforts.

Coviello recommends this 45-minute Fartlek workout:

• 5-minute warmup (jog or walk)
• 3 x 1 minute hard, 3 minutes easy
• 3 x 2 minutes hard, 2 minutes easy
• 3 x 1 minute hard, 3 minutes easy
• 5-minute cooldown

Hamilton says to follow this pattern to hit your time or distance goal for that day:

• Run at 10K race effort for 1 to 2 minutes
• Settle back to easy effort for 3 to 4 minutes