Fartlek Training: Speed Workouts for Runners

Have you fartlekked recently?

I am not trying to be rude here... It's Swedish for speed play.

The principle is simple: warm up, then run faster for a while, slower for a while, and repeat as many times as you want. Then cool down. It mixes faster running and slower running without rigid structure.

I used to hate doing fartleks. I never did them.

I wanted structure in my runs. I didn't like just going out there and running by feel, deciding on the spot how fast to go and for how long. Because every fartlek workout differs — there's no way to compare two sessions. I really needed that comparison to track progress.

However, in the last few years I have mellowed a lot. I've lost a little bit of that competitive personality. Sure, I still want to run quickly. But I'm less number-bound. I learned that sometimes an unstructured session is exactly what you need.

Depending on your personality type you will think that is quite alright, or not good at all!

The playful nature makes it fun. It helps you connect with your body. That's why I recommend fartlek workouts for beginners wanting to try speed work — you decide, based on how you feel, how much you'll push yourself.

If you start doing structured speed workouts from a running program you picked up somewhere and you're actually not really ready for it, you risk injuring yourself. With fartleks the risk is smaller.

How Fartlek Compares to Other Speed Workouts

So how does fartlek compare to other speed work? Here's what you need to know:

Fartlek gives you flexible structure with effort levels that vary between 5K-10K pace. You recover by floating — not jogging slowly, but maintaining a purposeful rhythm. This makes it perfect when you're introducing speed work or want to break training monotony.

Intervals lock you into fixed distances and times at specific paces, usually 3K-5K effort with complete rest between efforts. They develop your VO2 max and speed, but demand more from your body.

Tempo runs hold one steady effort at your threshold pace with no recovery during the effort portion. They build your lactate threshold — the pace you can hold for an hour flat out.

Track repeats require precise distances and very specific paces with timed recovery. They develop pure speed and race preparation.

Hill repeats use uphill efforts at RPE-based intensity with downhill jog recovery. They build power, strength, and running form simultaneously.

You're not locked into one intensity with fartlek. Some efforts might hit 90% of your maximum heart rate, others 85%. This variation trains different parts of your aerobic and anaerobic systems within a single session while your mind stays relaxed about hitting exact splits. For more structured approaches to speed training for runners, fartlek serves as a perfect bridge between easy running and formal interval running sessions.

Step-by-Step Beginner Fartlek Session

When you start out, simply do a good warm-up, then pick a landmark and run there at a higher speed.

Total time: 35-40 minutes

Warm-up (10-15 minutes):
Start with 5 minutes easy jogging. Add 4-5 dynamic movements — leg swings, high knees. Gradually increase pace to comfortable running.

Main Set (15-20 minutes):

Pick a landmark 200-400m ahead — street light, mailbox, tree. Run to it at 7/10 effort. You should be breathing harder but able to say a few words. Float for 1-2 minutes at 5/10 effort. This isn't a jog — keep moving. Repeat 6-8 times, varying your landmarks and efforts.

Cool-down (10 minutes):

Easy running back to comfortable pace. Finish with light stretching.

Pacing guidelines:

Fast efforts should be 30-45 seconds faster per mile than your easy pace. Float pace runs 15-20 seconds faster per mile than your easy pace. If you can't talk at all during fast efforts, you're going too hard.

Your first session might cover 3-4 miles total. That's perfect. Focus on the rhythm of fast-float-fast-float, not the distance.

How Fartlek Fits Into Your Training Plan

Fartlek training integrates differently depending on your training phase within your overall running training program:

During base building (8-12 weeks): I'd recommend one fartlek per week maximum. Keep efforts controlled at 6-7/10 intensity. Focus on teaching your body to change pace smoothly with sessions of 15-20 minutes quality work. During this phase, fartlek complements your base running development perfectly.

In your build phase (6-8 weeks): Fartlek becomes more structured. I'd suggest introducing named sessions like Mona or Moose fartlek. Efforts can reach 8/10 with sessions lasting 20-30 minutes of quality work.

During peak sharpening (3-4 weeks): Short, sharp fartlek sessions work brilliantly. Mix race-pace efforts with faster surges — perfect for practising race tactics. Keep sessions to 15-25 minutes of quality work.

In recovery or off-season: Go completely free-form with your fartleks. Run by feel entirely. It's a sensible way to maintain fitness without pressure.

Fartlek works as a bridge. Too easy for intervals? Try fartlek. Too structured for your current mindset? Fartlek's got you covered.

What Fartlek Does to Your Body

Fartlek training hits multiple parts of your fitness simultaneously — that's what makes it so effective.

Your oxygen system improves:

Your maximum oxygen uptake gets better because you're pushing into that 5K-10K effort range repeatedly. The varied pace changes force your heart and lungs to adapt quickly, increasing your ability to deliver oxygen to working muscles. You're not locked into one intensity — some efforts might hit 90% of your max heart rate, others 85%.

Your lactate clearance gets better:

Those floating periods between fast efforts? They're not just recovery — they teach your body to clear lactate more efficiently while running at a decent pace. You can improve running performance significantly just by getting better at the float portions of fartlek sessions.

Your race brain develops:

Here's where fartlek really shines. You're making pace decisions constantly throughout the session. Should I surge now? Can I hold this pace to the next tree? How hard should I go up this hill? This decision-making under fatigue builds the exact mental skills you need for racing.

Your pace changes get smoother:

The constant pace changes improve how efficiently you run. Your body learns to shift gears smoothly, recruiting different muscle fibres as needed. This means better race performance when you need to respond to moves or vary your pace tactically.

Your First Month of Fartlek Training

Here's how I'd recommend you progress through your first month of fartlek training:

Week 1 — Foundation: Start with landmark fartlek as described above. Keep your quality time to 15 minutes at 6-7/10 intensity. Take 2-3 easy days between sessions.

Week 2 — Extension: Try 8-10 efforts of 45-90 seconds. Build your quality time to 18 minutes at 6-7/10 intensity. Float for 60-90 seconds between efforts.

Week 3 — Intensity: Attempt pyramid fartlek — 1-2-3-2-1 minutes. Your quality time reaches 20 minutes at 7-8/10 intensity. Include one longer 3-minute effort to build endurance.

Week 4 — Structure: Try modified Mona fartlek: 2 x 60s fast + 60s float, 4 x 45s fast + 45s float, 4 x 30s fast + 30s float. Quality time hits 22 minutes at 7-8/10 intensity.

Look for these signs of progress: Week 1 focus on completing the session comfortably. Week 2 maintain pace better during longer efforts. Week 3 handle the intensity without form breakdown. Week 4 float effectively — not jogging slowly.

Each week should feel challenging but achievable. If week 2 feels too difficult, repeat week 1. Build up progressively.

Choose Your Terrain Wisely

The terrain you choose completely changes the fartlek experience. Different surfaces work for different training goals:

Road Fartlek:

Perfect for pace awareness and speed development. Use landmarks like streetlights, intersections, or buildings. The consistent surface lets you focus purely on effort and pace. I'd recommend this for beginners learning to judge effort levels.

Trail Fartlek:

Brilliant for strength building and mental toughness. Hills naturally vary the intensity while the softer surface reduces impact stress. This forces you to run by effort, not pace.

Track Fartlek:

Ideal for precision and speed work. Use the straights and curves to structure efforts. Easy to measure progress by counting laps. Other runners provide natural competition.

Beach/Sand Fartlek:

Excellent for power development and injury prevention. Sand provides resistance training while the unstable surface improves your balance and stability. Lower impact on joints too.

Park/Grass Fartlek:

Great for form development and fun. The softer surface encourages longer strides while natural obstacles create variety. Perfect for group training.

Match terrain to your current needs. Feeling beat up? Hit the trails. Need speed work? Stick to roads or track.

Tools That Actually Help

While fartlek works well completely freeform, sometimes you want a bit of guidance. Here are my recommendations:

Smartphone Apps:

Runkeeper offers custom interval workouts with audio cues. Strava's segment hunting creates natural fartlek opportunities. Nike Run Club provides guided speed runs with coaching. Adidas Running includes interval training programs.

Low-Tech Options:

Create music playlists with fast songs for efforts, slower for floats. Use podcasts and change pace during different segments. Train with a running partner and take turns calling out effort changes. Try a heart rate monitor and use HR zones instead of pace. Are you interested in zone-based training? This is covered thoroughly in heart rate monitor running programs.

Online Resources:

Running forums often share creative fartlek sessions. YouTube has guided fartlek workouts you can follow. Training websites offer downloadable fartlek plans.

The trick is picking the tool you'll actually use consistently. Don't let technology complicate what should be playful training.

Named Fartlek Workouts for Structure Lovers

Some of us need structure. Here are proven fartlek sessions with names and reputations:

Mona Fartlek (Steve Moneghetti):

Steve Moneghetti is a famous Australian marathon runner who won several big marathons and picked up medals in Commonwealth Games and World Championships. Mona had that same problem mentioned before: he needed structure. His workout is 2 x 90 seconds fast + 90 seconds float, 4 x 60 seconds fast + 60 seconds float, 4 x 30 seconds fast + 30 seconds float, 4 x 15 seconds fast + 15 seconds float. This is tough. The key skill is learning to "float" between intervals.

Moose Fartlek (Julian Spence):

5 sets of 3 minutes at 10K-HM effort + 1 minute jog + 1 minute at 5K effort + 1 minute jog. That's 30 minutes of quality work. The contrast between the longer threshold efforts and shorter speed bursts is brilliant for race preparation, especially when training for a half marathon.

Portsea Fartlek:

3 x 5 minutes fast + 1 minute float, 3 x 3 minutes fast + 1 minute float, 4 x 1 minute fast + 30 seconds float. This is 36 minutes of quality — definitely advanced territory. I have used this as part of half marathon and marathon preparations.

Michigan Fartlek:

1-2-3-4-3-2-1 minute pyramid with equal recovery between each effort. Perfect for building both speed and endurance.

Kenyan Hills Fartlek:

2 minutes moderate uphill + 1 minute easy downhill, repeated 8-10 times. Builds power and teaches efficient downhill running.

Elite athletes tested each of these. Don't let that intimidate you — adjust speed, modify the times and intensities to match your current fitness level.

Common Fartlek Mistakes and How I'd Fix Them

I see these fartlek mistakes frequently. Here's how I'd recommend avoiding them:

Running the "fast" parts too fast:

You turn every effort into an all-out sprint, then struggle to maintain any quality for the float portions. Use the talk test — during fast efforts, you should be able to say 3-4 words with some difficulty.

Floating too slowly:

The floats become slow jogs or walks, which defeats the purpose. Float pace should be roughly your normal training pace — maybe slightly easier, but still purposeful running.

Making every session different:

While variety is good, having zero consistency makes it impossible to track improvement. Use a core session like Mona fartlek once every two weeks, then vary your other fartlek sessions.

Skipping the warm-up:

You jump straight into fast running without proper preparation. Always start with 10-15 minutes of gradual warm-up. Your first fast effort should feel controlled and smooth.

Going by pace instead of effort:

You get fixated on hitting certain splits rather than running by feel. Cover your watch during fartlek sessions. Learn to judge effort by breathing, muscle tension, and overall sensation.

Doing fartlek too often:

Because it feels less structured, you think you can do it more frequently than other speed work. I'd recommend treating fartlek like any quality session — once or twice per week maximum.

Your Fartlek Questions Answered

How fast should I run the "fast" parts of a fartlek? Run by effort, not pace. On a scale of 1-10 where your easy pace is about 4-5, your fartlek efforts should be 7-8. You should be breathing harder but not gasping. If you can chat normally, go a bit faster. If you can't say anything, back off.

How often can I do fartlek workouts? I'd recommend treating fartlek like any speed work — once or twice per week maximum. You need recovery days between quality sessions. A typical program includes one structured speed session (intervals or tempo) and one fartlek per week.

Is fartlek better than regular interval training? They serve different purposes. Fartlek is brilliant for beginners, mental freshness, and learning to run by feel. Intervals work better for specific pace work and measurable progression. Both belong in sensible training programs.

Can I do fartlek during marathon training? Absolutely. Fartlek helps you practise surging and responding to moves during races. It also breaks up the monotony of long runs. Try adding 10-15 minutes of gentle fartlek in the middle of your long runs.

What if I can't maintain the float pace between efforts? That's normal when starting out. Your aerobic system is still developing. It's better to jog slowly and complete the session than to stop completely. Gradually work on making your recovery pace faster over several weeks.

How do I know if I'm improving at fartlek? For unstructured sessions, you'll notice running faster efforts feels easier. After your cool-down, complete some light running stretches to help with recovery and maintain flexibility for your next session.

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