specialized
• all LevelFartlek Training
Fartlek (Swedish for "speed play") is unstructured interval running where you vary pace based on feel, terrain, or spontaneous decisions. It combines the benefits of intervals with the freedom of continuous running.
Physiology & Adaptations
Trains multiple energy systems in one session: aerobic base (easy running), lactate threshold (tempo), and VO2 max (hard surges).
Key Benefits
Develops race-specific pacing and surges.
Mentally less demanding than structured intervals.
Adapts to terrain and how you feel.
Builds aerobic and anaerobic systems simultaneously.
Fun and exploratory approach to speed work.
Sample Session
Blueprint
45 min run: Easy pace baseline, then surge hard for 1-3 min whenever you feel good, jog easy until recovered, repeat. No set structure—go by feel.Common Pitfalls
Making it too structured (defeats the "play" aspect).
Going too hard on every surge (turns into all-out intervals).
Not including enough easy running between efforts.
Skipping it because it seems too simple or unscientific.
Specifications
Duration20-60m
Intensityall
Focusspecialized
Progressive Overload
Increase total duration, include more surges, or make hard efforts faster/longer.
Setup Checklist
1
Run continuously for set duration (30-60 min).2
Vary pace naturally: easy, tempo, hard, sprint.3
Use landmarks, terrain, or time as cues (e.g., "sprint to that tree").4
No strict structure—respond to how you feel.5
Include easy running between efforts for recovery.