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Fartlek: HIIT For Runners

(Image credit: Unknown)

Long before HIIT (high-intensity interval training) became the world’s biggest fitness trend, runners were mixing up the paces in their training, switching between faster sprints and recovery sections. Swedish runners, to be more precise, because it was in the 1930s that the Fartlek system of running was developed. Fartlek means “speed play” in Swedish, and once you finish sniggering about the Swedish word for speed being fart (it’s fine, we’ll wait, it’s your own time you’re wasting), you’ll discover a training style sure to add a much needed injection of speed into your casual jogs.

Fartlek is a loose term that generally applies to a continuous run where you change your pace to include some high-speed sections. This can be done in a very free manner where you run a bit faster whenever the mood strikes or when you pass a certain landmark, or in more structured fashion where you hit certain distances with your intervals.

There are many reasons to include Fartlek sessions in your training, the first of which is that it’s an excellent way to avoid boredom, especially if you have one route you run regularly. Regular Fartlek sessions will also make you a better runner, because the faster efforts will improve your speed endurance, which is key for those looking to trim seconds or even minutes off their PBs. And if your primary aim with running is to lose weight then Fartlek is undoubtedly for you too, because interval runs that spike the heart rate will burn more calories than steady-paced runs.

Below you’ll find a variety of structured and unstructured Fartlek sessions that will work for runners of all abilities.

How To Fartlek

Fartlek is a blend of regular continuous running interspersed with higher-speed intervals. From there, what makes up a session is entirely up to you. You don’t have to go out all guns blazing on every sprint, or keep them all to a set distance, you just have to ensure you mix up your pace throughout the run. A good Fartlek run could involve you running at your target pace for all kinds of distances – from 400m or 800m sprints to marathon pace and slower recovery sections.

The lack of structure allows for plenty of variety. You can base fast sections around landmarks, terrain or other road users. If you do fancy something more defined then Fartlek allows for that too, with sprints and recovery sections clearly set out in minutes or metres before you start. Whichever way you choose to do it, building some Fartlek sessions into your running is always a good idea.

Five Unstructured Fartlek Runs To Try

1. Pass The Pooch

Head out to any big park at the weekend and you’ll be sharing the space with hordes of dog-walkers, which can be incorporated into your Fartlek training. Every time you pass a dog run a little faster than your 5K pace for 30sec.

2. Strava Segments

If you’re a Strava obsessive and know all the segments near your house, trying to set a PB on each of them is a great way to change the pace on your runs.

3. Hill Runner

A simple yet brutal way to mix up your runs. Every time you come across an uphill incline during your session, run faster.

4. Streetlights Sprints

Sprint the distance between two streetlights, then recover between the next two, then sprint again. Do this for the length of a street a couple of times during a run.

5. The Home Straight

If your favourite regular run involves completing several laps of a park, there are a couple of great ways to mix in some speed play. You can speed up and slow down for alternate laps, or mark out one section of the loop as your “home straight” where you open up and sprint for the line each time you come to it. You can even create a Strava segment for that section of your run, if you want to see how your sprint times are progressing.

Six Structured Fartlek Runs To Try

1. Long Run Fartlek

During your longer runs (anything over 10K), every 6min raise the pace for 2min. Don’t go for an all-out sprint, just increase your speed by 10sec per km.

2. Speedy Surges

To improve your 5K and 10K times, try going for a 25min run with surges. Run for 90sec at a pace 10sec per km faster than your desired 5K or 10K pace, then recover for a minute, then surge again.

3. Ladder Workout

This is great way to work on your race pace for a number of different distances in one session. Start with 2min at 5K pace, then 2min recovery. Then 3min at 10K pace, 2min recovery. Then 4min at half marathon pace, 2min recovery. Then reverse it. So 4min half marathon pace, 2min recovery, 3min 10K pace, 2min recovery, 2min 5K pace (or above, if you can), followed by a steady jog to cool down.

4. Effort Level Countdown

If you’re not sure on the exact pace you want to run, you can structure your Fartlek session around effort levels with a simple countdown workout. Start with 5min at 80% intensity. Then 4min at 85%, 3min at 90%, 2min at 95% and finish with 1min all-out effort.

5. Pick Up The Pace

Another good workout for training at different race paces, this session involves tough bursts of progressively faster running, with only 90sec rest between them. After a good warm-up, run for 2min 30sec, with the first 30sec at around your marathon race pace, or around 5sec per km faster than your normal training pace if you haven’t run any marathons lately. Each 30sec block from then on should get a touch faster with the aim of running the final 30sec at your 5K race pace. Take 90sec to recover, then run another 2min 30sec set. Aim for four 2min 30sec sets in total.

6. Miles And Miles

This is no fun whatsoever, but will do wonders for your 5K and 10K times. After warming up, run six one-mile bursts, with 3min recovery in between. Try to maintain a fast pace while keeping your mile times within 10sec of each other across the six efforts, rather than completely destroying yourself with a bid to match Roger Bannister first time out. Try to find a flattish one-mile loop – a park is a good bet – to help keep your times consistent.

7. Gerschler Fartlek

German running coach Dr Woldemar Gerschler was one of the sport’s great innovators and in the mid-20th century he developed a system of interval training that led to huge success for many of his athletes. This Gerschler Fartlek session designed by Jude Samuel, former MMA fighter and current BAMMA matchmaker, involves gradually reducing the amount of time you have to recover between sprints, resulting in a harrowingly tough climax to the workout.

Start with a 10min warm-up (treasure every second of this), then do three rounds of the following.

Sprint for 30sec, then jog for 90sec
Sprint for 30sec, then jog for 75sec
Sprint for 30sec, then jog for 60sec
Sprint for 30sec, then jog for 45sec
Sprint for 30sec, then jog for 30sec
Sprint for 30sec, then jog for 15sec
Sprint for 30sec, then jog for 15sec, then sprint for 30sec

Once you’ve done your three rounds, and maybe had a little cry at how hard it was, warm down for 10min.

Five Reasons To Try Fartlek

1. Improve your running

Adding in pacier intervals will improve your speed endurance, which will definitely tell next time you try and set a PB. Short sprint intervals are best for building your 5/10km race pace, while longer, medium-pace stretches will help when prepping for 10 miles plus.

2. Avoid boredom

Running can, whisper this quietly, sometimes be a tad monotonous. You’ll see that boredom disappear when you have to dash every time a dog appears on the horizon.

3. Good for sports training

Even the keenest runners might be left gasping by 20 minutes of six-a-side football, because the physical demands are different. Fartlek’s pacey intervals mirror the stop-start action of playing sport, so it’s the perfect way to train for the new season.

4. Fit for all

Endlessly variable, anyone can get the benefits of Fartlek. Just go a bit faster than your regular speed during the sprint sections.

5. Fast fat burning

Fartlek’s heart-pumping intervals will ensure you get your calorie-crushing fix in record time. A 25-minute run laden with sprints will torch calories more effectively than your regular steady speed jog.

Nick Harris-Fry
Nick Harris-Fry

Nick Harris-Fry is a journalist who has been covering health and fitness since 2015. Nick is an avid runner, covering 70-110km a week, which gives him ample opportunity to test a wide range of running shoes and running gear. He is also the chief tester for fitness trackers and running watches, treadmills and exercise bikes, and workout headphones.