Base, Build, Peak, Taper — what each phase is for and when it kicks in.
Every Pheidi plan moves through four phases in order. Each one has a different job, and the workouts inside it are shaped to match.
| Phase | % of plan | What it's for |
|---|---|---|
| Base | ~25% (min 2 weeks) | Aerobic foundation. Easy mileage only — your body is laying down capillaries, mitochondria, and tendon resilience. |
| Build | Remainder of the plan | Race-specific intensity gets layered on top of base fitness. Tempo, intervals, hills, and progressively longer long runs sharpen the engine. |
| Peak | ~15% (min 1 week) | The hardest, most race-specific block. One or two weeks of your highest fitness — race-pace work and your longest long runs land here. |
| Taper | ~20% (min 2 weeks) | Volume drops by 40–60% so accumulated fatigue clears while fitness holds. Workouts stay sharp but short. Trust it — the gains are already in the bank. |
Phase length is computed from total plan weeks, with floors so short plans still get a meaningful Base and Taper. Build absorbs whatever's left after Base, Peak, and Taper claim their share — so longer plans get more Build, not more of everything.
Within each phase, weekly volume is shaped by the plan's overall progression curve. See How Plan Generation Works for the full math, and How Load Distribution Works for how each week is built.
When your plan crosses into Build, Peak, or Taper, Pheidi sends a single email — what the new phase is for, which week of the plan you're on, and a link back here. At most three phase emails per plan; Base doesn't get one because it's where every plan starts.
The first time the system observes you on a plan, it stamps your current phase without sending an email. That stops a "Welcome to Build" arriving in week 8 just because the feature shipped, or just because you signed up mid-plan.
Sender: mnemea@mail.pheidi.training.
New accounts are opted in by default. To turn the emails off, either uncheck Email me when my plan enters a new phase in Settings, or use the unsubscribe link in any phase email.
Each email also carries an RFC 8058 List-Unsubscribe header, so the
one-click unsubscribe button in Gmail, Apple Mail, and Yahoo works without you
needing to visit the site.