Sport performance
Half marathon training plan that keeps you strong
phase.fitness plans a half marathon as three phases and a taper: the long run gets the clean slot every week, tempo work at goal pace arrives in the build, and the lifting is heavy and short so it never eats the run that matters.
Updated
- Level
- All levels
- Length
- 10–14 weeks
- Days per week
- 4–6
- Modalities
- CardioStrength
- Equipment
- Road, a watch; barbell or dumbbells for the gym days
- Sessions go to
- Garmin, Intervals.icu, Strava, Hevy
The short answer
A half marathon plan in phase.fitness runs 10–14 weeks: a base phase of easy volume and strides, a build phase where a weekly tempo of 20–40 minutes and one interval session are added on an 80/20 distribution, a short peak with race-pace work and volume down 10–15%, then a two-week taper. Two gym sessions of 3–4 sets of 3–6 reps hold strength through all of it. phase.fitness writes the runs to your watch and reads them back to shape the next phase.
What decides a half marathon
The endurance document phase.fitness reads describes performance as three variables: VO2max, the fraction of it you can hold at threshold, and running economy. For 21 km the middle one dominates — how close to threshold you can sit for 90 minutes or more. That is why the build phase is organised around a weekly tempo run at or slightly faster than goal pace, and why the long run, which builds the base that makes threshold sustainable, is protected from everything else in the week.
Economy is the part most plans forget. Heavy, low-volume strength work improves it by a few percent and reduces injury risk, and it is lost quickly when dropped. So phase.fitness keeps two gym days through the base and build, and one in the final block — after easy runs, never before the tempo or the long run.
What is the 80/20 rule in running?
Eighty per cent of the running is easy and twenty per cent is hard. In a phase.fitness half marathon plan that is easy volume and strides on most days, one tempo of 20–40 minutes and one interval session in the build phase, and a long run held in zones one and two rather than raced.
How long should the long run be for a half marathon?
In a phase.fitness half marathon plan the long run sits at 90–120 minutes in zones one and two, prescribed by time rather than distance, and it grows through the base phase. It stays easy: the tempo and the intervals are separate sessions, so the long run stays aerobic volume and not a second workout.
When should I start tapering for a half marathon?
Two weeks out. phase.fitness trims volume 10–15% through the short peak, then runs a two-week taper that sheds fatigue while keeping the sharpness: race-pace touches stay in the week, total volume falls, and nothing new is introduced in the last fortnight.
What phase.fitness builds
A program is a sequence of phases, each with a job. These are the phases phase.fitness writes for this case, with the bands the generator has to respect — transcribed from the document it reads, not invented for this page.
Base
4–6
Build
4–5
Peak
2–3
Taper
2
| Phase | Weeks | Job | Band |
|---|---|---|---|
| Base | 4–6 | Easy volume, the long run grows, strides | ~90% Z1–Z2; volume +8–10% per week to the level's ceiling; strength 2×/week, 3–4 × 3–6 |
| Build | 4–5 | Tempo at goal pace, one interval session, volume flat | 80% Z1–2 / 10% Z3 / 10% Z4; tempo 20–40 min 1×/week; VO2max 3–8 min reps 1×/week |
| Peak | 2–3 | Race-specific sessions | Volume down 10–15%, intensity kept; one deload week per 3–4 weeks throughout |
| Taper | 2 | Shed fatigue, keep sharpness | Volume down 40–60%; 1–2 short quality sessions at race pace |
A sample week
One week from the first phase, as it would sit on the calendar. Your own week follows the days you say you have — 4–6 here — and the equipment you list.
- SStrength
- CCardio
- Rest
| Day | Modality | Session |
|---|---|---|
| Mon | C | Easy run 40–50 min + 6 × 20 s strides |
| Tue | C | Intervals: 5 × 4 min at 90–100% VO2max, 3 min jog |
| Wed | S | Squat, Romanian deadlift, step-up, calf raise — 3–4 × 3–6 |
| Thu | C | Tempo: 30 min at goal pace inside a 60-min run |
| Fri | Rest | — |
| Sat | C | Long run 90–120 min, Z1–Z2 |
| Sun | S | Second gym day, lighter; plyometrics 3 × 6–8 |
S = strength · C = cardio · K = calisthenics. The order is the point: hard days are kept apart and the long session gets the clean slot.
How it adapts when a phase ends
Between phases phase.fitness compares the plan with the runs that came back from your watch: weekly minutes, the long run's duration, heart rate on the tempo days, and which sessions were skipped. A long run that was cut short three weeks in a row makes the next phase's long-run fraction smaller and its ramp slower; tempo sessions run consistently under effort push the threshold estimate and the pace targets.
The engine's volume ramp is a property of the whole program, not of one phase, so the next phase resumes from where the ramp really is rather than from where the paper plan said you would be.
Where the sessions go
phase.fitness plans; you train in the app or on the watch you already use, and the completed session comes back. For this program:
What phase.fitness does not do here
phase.fitness plans the weeks and the sessions; it does not write race-day pacing or nutrition. The long run is prescribed by time and zone, not by a pace table, because the document phase.fitness reads keeps the base at an effort, not a number.
The evidence
The documents this page is built from
These are the knowledge-base documents the phase.fitness generator reads for this case. The phases, bands and weekly numbers above are transcribed from them.
- Physiological Optimization for Long-Distance Performance — updated 2026-02-21, endurance
- Strength Training Basics — updated 2025-01-07
- Deload Protocols and Recovery Strategies — updated 2025-01-18
Frequently asked questions
How long is a half marathon plan in phase.fitness?
Usually 10–14 weeks, in phases of roughly four weeks plus a two-week taper. phase.fitness sets the length from your race date and your current weekly minutes, and will say so if the date is too close for the ramp your level allows.
Will the plan include strength training?
Yes: phase.fitness schedules two heavy and short gym sessions a week in base and build, one in the final block. They are placed after easy runs or on separate days and never before the tempo or the long run.
Can I run the plan on Intervals.icu or a Garmin watch?
Yes. phase.fitness pushes each planned run with its intervals and zones to Garmin Connect and Intervals.icu, and reads the completed activity back.
The only app that plans strength, cardio and calisthenics together
For a half marathoner the calisthenics day is trunk and single-leg work — hollow holds, L-sit progressions, pistol-squat steps — that keeps the hips stable when the form starts to go at kilometre sixteen.
Right now, phase.fitness is the only training app that writes strength, cardio and calisthenics into one periodized program — same calendar, same phases, same recovery budget.
You choose the mix. A calisthenics-only plan, a cardio-only block, strength plus cardio, or all three: the phases, the end-of-phase analysis and the sync work the same way with one modality or three.
Why calisthenics is in the plan
Bodyweight skill work is strength training in a different shape. Straight-arm work, levers and handstands build scapular control, tendon capacity and relative strength that barbell and machine work leave untouched, and they transfer because they are closed-chain, whole-body patterns. Treated as a modality rather than a warm-up, they get sets, holds and progressions like a squat does.
No exercise catalogue on the market contains a tuck front lever, so those sessions run in the phase.fitness built-in player; strength goes to Hevy, Liftosaur or a Garmin watch, cardio to Garmin and Intervals.icu. How the skill work is programmed.
Free to start, no card. The first phase is yours to keep whatever you decide.
