Modern Applications of Fartlek Training: A Hybrid Strategy of Structured and Unstructured Approaches

Introduction

“Fartlek,” a word of Swedish origin, literally means “Speed Play.” Invented in the 1930s by Swedish coach Gösta Holmér, it originally allowed runners to freely alternate between fast running and jogging on forest trails, adjusting intensity by feel to break free from the monotony of track intervals.

Today, Fartlek has evolved into two distinctly different forms: unstructured (traditional) and structured (modern). Understanding how to strike a balance between the two is the key to mastering this training tool.

Comparison of the Two Forms

Unstructured Fartlek: Rediscovering the Joy of Running

The essence of traditional Fartlek is “spontaneity”: sprint toward a tree you see ahead, push hard on the uphill, jog slowly downhill, and follow your instincts throughout.

How to do it:

1. Choose a park or riverside with terrain variation (e.g., the Xindian River riverside in Greater Taipei, or along the Love River in Kaohsiung)
2. Set a total time of 40–60 minutes
3. Run an easy 10-minute warm-up
4. In the middle 20–40 minutes, freely alternate fast and slow: sprint after stopping at a red light, pick a building as a target and push all the way to it, accelerate when climbing a bridge…
5. Finish with an easy 10-minute cool-down jog

Best times to use it:

• Maintenance training 2 weeks before a race
• “Recovery speed stimulus” after a high-volume week
• When mentally fatigued and don’t want to watch the clock

Structured Fartlek: The Precision of Modern Training

Modern coaches have standardized Fartlek to ensure consistency of training stimulus. Common formats:

Time-Based Fartlek

Sample workout (40-minute version):

• 10 minutes easy warm-up
• 3 minutes fast (10K pace) → 2 minutes easy × 5 sets
• 10 minutes easy cool-down

Sample workout (advanced 60-minute version):

• 15 minutes warm-up
• [1 minute hard → 1 minute easy] × 6 sets
• 5 minutes easy
• [2 minutes fast → 1 minute easy] × 4 sets
• 10 minutes cool-down

Distance-Based Fartlek

With the aid of a GPS watch, using specific distances as units:

• 200m fast + 200m slow × 8 sets
• 400m fast + 200m slow × 6 sets
• 1km fast + 400m slow × 4 sets

Intensity Reference Guide

The intensity of the “fast” segments in Fartlek can be adjusted according to training goals:

Applying Fartlek to Taiwan’s Terrain

Taiwan’s diverse terrain is highly suited to Fartlek:

• Greater Taipei Riverside Parks: Flat, straight sections suit time-based Fartlek, while bridge climbs provide natural terrain stimulus
• Around Taichung’s National Museum of Natural Science: Urban blocks allow traffic-light rhythms to naturally switch between fast and slow segments
• Kaohsiung’s Shoushan Trail: Natural gradients turn every climb into a natural interval stimulus
• Tainan Canal Route: Long straight sections plus corners suit unstructured, exploratory running

Practical Advice

• Beginners should start with unstructured Fartlek to first get used to “switching intensity” during a run, then introduce the structured version.
• Schedule Fartlek once per week, replacing an existing easy run to add stimulus without excessively increasing stress.
• Heart rate data from Fartlek tends to be erratic; it is not recommended to use average heart rate to evaluate training quality. Instead, analyze the “proportion of time spent in fast segments” or the “pace distribution of fast segments.”
• Doing unstructured Fartlek with running partners works even better: chasing and competing with each other naturally brings out speed stimulus.

Conclusion

The greatest appeal of Fartlek is that it breaks the myth that “training must be painful.” It shows us that speed can be acquired through play. Whether you adopt the traditional free-form approach or the modern precise structure, Fartlek can inject vitality into your weekly training while effectively improving speed and lactate tolerance. Next time you head out for a run, try turning off your watch’s “forced pace” mode and accelerate by feel—you might just discover that speed was always meant to be fun.

Related Reading

• Fartlek Training: Free-Form Speed Training Design for Unstructured Runs
• Fartlek Training for Road Running: The Scientific Benefits of Unstructured Speed Play
• Fartlek Workouts: A Free-Form Training Method to Play Your Way to Speed
• Road Running Speed Training: Differences and Applications of Tempo Run vs Intervals vs Fartlek