Periodization is the practice of dividing your training season into phases — each with distinct volume, intensity, and recovery goals — so fitness peaks on race day instead of plateauing mid-season.
Who this is for
Any athlete training toward a specific event date — from a local 5K to a full Ironman.
Works for single-sport and multi-sport schedules when weekly hours are limited.
The five main phases
Most endurance plans follow a macro-cycle of five phases, including post-race recovery:
| Phase | Duration | Focus | Intensity mix |
|---|---|---|---|
| Base | 4–8 weeks | Aerobic volume, technique | ~80% easy |
| Build | 4–6 weeks | Race-specific intensity | More threshold/VO2 |
| Peak | 2–3 weeks | Sharpening, race simulation | High quality, moderate volume |
| Taper | 1–3 weeks | Freshness | Volume down, short openers |
| Recovery | 2–4 weeks | Post-race reset | Low volume and intensity |
Micro-cycles and recovery
Within each phase, training is organized into 3:1 or 2:1 load patterns — three hard weeks followed by one recovery week with 30–40% less volume.
Recovery weeks are not optional. They let your body absorb training stress and prevent chronic fatigue.
12-week marathon example
Weeks 1–4: Base — build aerobic mileage, one tempo session per week.
Weeks 5–8: Build — add intervals, extend long run to 18–20 miles.
Weeks 9–10: Peak — race-pace work, highest long-run distance.
Weeks 11–12: Taper — reduce volume 25–40%, keep short race-pace touches.
Common mistakes
- Skipping base and going hard too early.
- No recovery weeks — chronic high load without absorption.
- Tapering too much or too little (both hurt race performance).
Sources
Using Vo2Max
Vo2Max automates periodization from your race calendar — generating Base, Build, Peak, and Taper weeks with appropriate TSS targets for each phase.