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The Long Fartlek: Another Option for Ultramarathon Training

Posted by on Jun 10, 2012 | 11 Comments

Over the years, my ultramarathon training has evolved from the common long, slow run to high intensity interval training to a weird hybrid between the two. I’ve tried running slow, running fast, intervals, tempo runs, and speed walking. After spending about eight years experimenting with all kinds of training methods, I’ve found the one method that appears to elicit the greatest benefit: the long fartlek.

Before I dive into the details of my training, it may be useful to define exactly what a fartlek run is and what it is not. Let’s start with a definition from the greatest collection of information the world has ever known: Wikipedia:

Fartlek, which means “speed play” in Swedish, is a training method that blends continuous training with interval training. The variable intensity and continuous nature of the exercise places stress on both the aerobic and anaerobic systems. It differs from traditional interval training in that it is unstructured; intensity and/or speed can be varied whenever the athlete wishes. Most fartlek sessions last a minimum of 45 minutes and can vary from aerobic walking to anaerobic sprinting.

Fartlek training was developed in 1937 by Swedish coach Gösta Holmér (1891–1983) and has been adopted by many physiologists since. It was designed for the downtrodden Swedish cross country running teams that had been thrashed throughout the 1920s by Paavo Nurmi and the Finns. Holmér’s plan used a faster-than-race pace and concentrated on both speed and endurance training.

Quite simply, it’s an unstructured run of varying intensity. The real key to a fartlek run is the unstructured part. To get the greatest benefit, we require the freedom to speed up and slow down at will. I’ve run with groups before that claimed to be doing fartlek runs. They would run at a predetermined pace for a certain time, then slow down for a recovery period, then repeat. This isn’t a fartlek run!!! It’s interval training. Removing the freedom to vary pace eliminated the real benefit of fartlek runs.

Okay, now that I got that off my chest, let’s take a look at my specific training. Almost all of my runs are done on trails, most of which are in mountainous terrain. Since we travel continuously, my schedule varies dramatically. I may have a week-long stretch where I have the ability to run every day. I may have weeks where I only have time for one or two short runs. Our schedule frequently changes with little notice, so it’s impossible to set a long-term schedule. We’re opportunistic runners- we run when we can where we can.

Without the guidance of a training plan, we have to run as much as we can whenever possible. It’s also difficult to schedule dedicated long, slow runs or speedwork sessions. This means each and every run must provide as much training benefit as possible without dramatically increasing the chance of injury. The fartlek run provides the aerobic benefit of the long, slow run and the benefit of fast-paced speedwork. It also provides an opportunity to practice walking and the transition from running to walking and back, which is useful for ultras.

The freedom to adjust pace based on feel allows me to run fast until I get tired, take enough time to recover, then repeat. The original fartlek runs were designed to reach a maximum heart rate of about 80% of a runner’ maximum. I will often push this to around 100% of max. I like the feeling of approaching that maximum, so my version of the fartlek can be a little more intense. I also stop on occasion to either take in the scenery, take pictures, or frantically gasp for air.

The very nature of the training closely mimics the change of intensity of a typical ultra. In a race, it’s common to speed up a bit when you feel good, slow down when you don’t, walk up the big hills, and bomb the downhills. The training sessions have a greater range of intensity (complete stopping all the way to 100% of maximum heart rate) than races (walking at maybe 60% of max heart rate up to running at about 85% of maximum on downhills). The occasional stopping during training mimics aid station stops during races. In short, the long fartlek closely resembles the actual race conditions of my typical ultra.

The distance of my runs varies from about four miles to over twenty. Again, it depends on the time I have to train on that particular day. Over the last six months, I’ve averaged around 35 miles per week with a low of zero and a high of 60 (excluding races).

Speedwork typically increases the chance of injury because your body takes more of a pounding. These runs limit that by allowing the freedom to back off the intense stuff if I’m not feeling quite right. I can also increase the intense segments if I’m feeling especially good. It allows me to adjust the workout on the fly based on how I feel. In theory any workout can be cut short, but many people struggle with the guilt of ending a workout before the prescribed work is complete. After all, as ultrarunners we like to push through adversity, right?

The best advantage of this method is simple- it’s fun. Fartlek, after all, is a translation for speed play. here’s never a single point in time where I don’t want to do a training run. I know I’m going to have a blast. If I feel good, I know I can go as long as my available time allows. If I’m not feeling it, I know I have the freedom to cut it short. The actual runs themselves are awesome. This type of running, much like barefoot running, makes you feel like a kid again. It’s no surprise, watch kids run during play. They do Fartlek runs.

Is It Effective?

It can be difficult to measure the effectiveness of one training technique over another due to the sheer number of variables that affect running ability. Having said that, I have been performing significantly better since adopting this training technique. So far this year, I’ve:

  • Run two 50k’s, one with a friend and felt great afterward, and placed 8th (out of about 45) in the other,
  • Set a PR in a road 25k,
  • Set a 50 mile PR by well over an hour.

This was also more or less the same training plan I used prior to a sub-24 hour finish at last year’s Western States 100 miler, though my training volume has increased significantly over the last six months.

The true test of this training plan will be my race schedule for the rest of this year. It starts this upcoming weekend with the Bighorn 100, continues to the Grand Mesa 100 in July, the Trans-Rockies stage race in August, Hallucination 100 in September, Grindstone 100 in October, Chimera 100 in November, and Across the Years 72 hour race in December.

What are the Drawbacks?

Like any training method, there are some drawbacks. First, type “A” personalities may have some difficulty with the laxidasical nature of this training. My training log looks like it was generated with a table of random numbers. Additionally, things like average pace, average heart rate, and time really mean nothing. For those that feel inadequate if they don’t have a certain number of runs at a certain pace, this training will drive them crazy.

This training may not necessarily be the best training for any run where a consistent pace is desirable. I mentioned I set a 25k PR using this method… but the PR was an improvement by about 30 seconds. The original PR was set back in my “run a lot of tempo runs at a set pace over a set distance on flat roads” days, which was exactly the same condition as the road 25k. The long fartlek training works so well for ultras because of training specificity- it’s exactly what happens in the races I prefer to run. Since the training is much different that what is required for flat road races, I still sort of suck at those.


The idea of running without a dedicated training plan at varying intensities isn’t a new idea. In fact, elites like Geoff Roes have written extensively about the idea of more or less abandoning formal training plans in favor of “running for fun.” It’s definitely not a training “plan” for everyone. If your self-worth is tied to your training log, you’ll hate this method. If you need structure, this method isn’t for you. If you’re convinced you have to do very specific types of training runs to be effective, you won’t like this.

However, if you’re the type of person that loves variety, loves pushing yourself hard, understands when it’s appropriate to slow down, this method may be for you.

What do you think? Do you have any questions? Does anyone use this method now? What are your experiences?


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    […] stuff: Fartlek training for […]

  3. Bare Lee
    June 11, 2012

    Being a Swedish American, I look for any English vocabulary besides ‘smorgasbord’ that may harken back to the old country and give me a fleeting feeling of being ethnic, which usually only happens when we eat lye-treated rotting fish (Lutefisk) at X-mas.

    But actually, as Jason knows from my BRS post last week, I stumbled on fartleking last week.
    The fart-like spontaneity of my fartlek had its basis in the fact that I used to be reasonably fast growing up, and had stayed in decent shape until middle age, then got out of shape for several years, but now want to recapture that feeling of going (relatively) fast again. But most recreational runners, barefoot or shod, do long and slow, so I adopted that approach when I got back into running in 2010. Then it occurred to me that there was nothing stopping me from running intervals or sprints or whatever I damn well wanted. The do-such-and-such-distance-at-a-certain-steady-pace paradigm fell by the wayside. “I’m a recreational runner damn it,” I said to myself, “so let me recreate.” And faster running is definitely more recreational for me than long and slow.
    So I did something of a fartlek over my short, 3.5 mile run down by the Mississippi River. A slightly faster pace, then a jog, some sprinting, some walking–overall it was a lot of fun. I particularly like running flat out and gasping for air afterwards. Very exhilarating.
    The idea now is to do one hills run per week, on fartlek run, and one long-n-slow. Like you, I like variety, and don’t seem to need so much structure to stay motivated. It’s really been a minor revelation that a casual runner like me can keep mixing it up all the time. I don’t know why it didn’t occur to me earlier.
    One question, with your schedule and use of fartleks, you obvious don’t adhere to any sort of Maff training. Do you think there’s any validity to this approach? I was thinking of trying a few months of it over the winter, when running fast(er) will become harder.

    • Jason
      June 11, 2012

      I have yet to see convincing empirical research that unequivocally supports Maff, but enough people have used it successfully to give it some validity.

      I don’t know all of the physiological details Phil uses to explain the concept, but my n=1 experimentation shows I seem to burn more fat when heart rate is below a certain threshold. The slower I run, the longer before I hit the gycogen-depletion crash. The big question- does training below that threshold improve your ability to run faster in that ‘fat burning’ mode?

      For me, it’s a moot point. I eat during races, so I can afford to burn a higher percentage of glycogen.

      As far as the outcomes people experience using Maff, there are alternative explanations. Training at low intensity decreases the chance of injury, which leads to longer sustained training periods. Longer periods allows for better endurance base-building on a physiological level. A better endurance base usually results in better performance. Occam’s razor would seem to favor this explanation.

      My biggest objection to Maff is personal preference- running in the appropriate heart rate zone is really, really boring. This is especially true in mountains. If I were to follow it for any length of time, motivation would severely wane.

      • Bare Lee
        June 11, 2012

        Thanks, that was really helpful.

  4. bryan
    June 10, 2012

    I have a question; how do you (or did you) determine your maximum heart rate? Do you just rely on 180 since that’s what Maffetone relies on to determine the aerobic threshold? Or did you do something else?

    I too have a very erratic running schedule due to lifestyle but also due to injury. If I put too much speed work in to a given week, I’ll be paying for it later. I’ve already been working this sort of running in to my training; i.e. run fast til I can’t, then run fast some more; where “fast” means as fast as I can go without my form breaking down, so really not a determined speed at all.

    • Jason
      June 10, 2012

      Bryan- I use a decidedly less scientific method. I sprint uphill until I cannot maintain the pace because the “I’m blacking out” circle interferes with the ability to see the trail. That heart rate = close to max. 🙂

  5. Kenneth
    June 10, 2012

    Thanks for the great post, Jason. I have been feeling lately like my training has had been getting dull. Working some fartleks into my training runs might be just the thing to spice it up.

  6. Rob Y
    June 10, 2012

    This is sort of how my wife and I have executing our long runs for many years. Run 7-10 miles at an easy pace to a local 5-10km race, race as hard as we can, then run back home at an easy pace, even mixing in walking as well. You get quantity and quality all mixed into one prolonged session. Very effective in our experience.

  7. Thomas
    June 10, 2012

    Being a Swede, I like the fact that “fartlek” is one of very few Swedish words that has become a part of the English vocabulary. Another well-known (?) Swedish word is Smorgasbord. One could make an interesting analogy since both words are about variation, individualism, picking what you like for the moment and combining what is best for you.
    One could even argue that fartlek is like a smorgasbord for the runner, combining the best dishes/ways of training for your own taste 🙂

    • Dave
      June 11, 2012

      Thanks to the Muppet’s Swedish Chef, many Swedish words have made it into the English lexicon. However, I’m still not exactly sure what “Her de boor de boor” or “bork bork bork bork” mean exactly…