Half marathon — Saturday 10 October 2026

Seven weeks. Written 26 August 2026, revised 27 August against 45 recorded runs, per-second heart-rate data and a 10.39 km best.

← Back to the data overview

Feasibility

2:20 is the target. 2:15–2:30 is the honest band.

Speed is not the problem. 2:20 needs 6:38/km and on 8 August you held 6:18/km for 10.39 km with even splits. The problem is durability: you have never run past 10.4 km, and the race is twice that. Everything below exists to close that gap, and nothing below asks you to run faster than you already have.

What the data says

Signal	Now	Reading
Longest run ever	10.39 km	49% of the race. The single limiting number.
Peak week	35.1 km	Enough to build on. Needs to reach ~45.
Intensity split, last 28 d	38% easy 62% hard	Still inverted, but moving. 471 min in Zone 3–5 against 294 in Zone 1–2 — up from 29% easy on 26 Aug. Two easy sessions shifted it nine points; keep going.
Resting HR	42–49	Excellent. Aerobic machinery is not the constraint.
HRV baseline	~150 ms	Very high and stable. You recover well — use that headroom for volume, not for more hard days.
Cardiac drift	+1.3 bpm/km	Measured on 8 Aug: HR 170→178 over the last 6 km at constant pace. This is why the race starts slow.
Cadence	150–162	Low for 189 cm. You are overstriding. Target 165+.
Terrain	flat	Every route ≤ 25 m gain. Hills are not a factor.

Riegel from the 8 August 10 km gives 2:19 at a trained exponent and 2:29 at one corrected for a thin base. Your base is nine weeks old, so trust the pessimistic end until the 18.5 km rehearsal on 19 September says otherwise.

Three rules that outrank every session below

Every commute leg is Zone 2 — HR 133–147, roughly 7:00–7:45/km. If HR crosses 150 on an easy leg, slow down; if it stays there, walk. You have started doing this — the 8.4 km on 26 Aug sat at HR 142 with 50 of its 62 minutes in Zone 2, which is exactly the session. Keep it there. Fixing this one habit is worth more than any workout in this plan.
Never skip the Saturday long run. If the week falls apart, drop the tempo, drop a commute leg, drop the optional run — the long run is the only session that actually buys you the second half of the race.
Ramp the long run by 2 km a week, never more. You are 189 cm and 82 kg going from a 10 km ceiling to 21 km in six weeks. That is the injury window. Shin or Achilles soreness that lasts past 48 hours means the next long run gets shorter, not skipped.

Paces and zones

Karvonen, max 192 / resting 45 — the same constants hr_config uses, so these match the zone charts on the overview. Heart rate is the instruction; pace is the sanity check, and it will drift with heat.

Effort	HR	Pace	Where it appears
Recovery Z1	<133	8:00+	Morning leg after a hard evening.
Easy Z2	133–147	7:00–7:45	Most of everything. All commute legs, all long runs.
Steady Z3	148–162	6:35–7:00	Closing kilometres of a long run.
Race pace	158–168	6:38	Race-pace segments. The number the whole plan aims at.
Threshold Z4	163–177	6:00–6:15	Tempo blocks, 20–30 min total.
Intervals Z5	177+	5:30–5:45	3–4 min reps, once a week at most.

The weekly shape

Two commute days a week, four legs. The morning legs are fixed at 4.7 km; the evening legs are where the training happens, because you can take the long way home. Commute days float with the office — the roles matter, the weekdays do not.

Slot	Session
Commute A	The volume day. Morning 4.7 km Zone 2. Evening: long way home, 7–10 km Zone 2.
Commute B	The quality day. Morning 4.7 km Zone 1–2, genuinely easy. Evening 5–7 km with the session inside it — the first 2 km of the commute is the warm-up, the last 1.5 km the cool-down.
Saturday	The long run. The session that decides the race.
Sunday	Rest, or 30–45 min walk or easy bike.
Other days	Rest by default. One optional 5 km easy only if the legs are fresh and the long run is more than 48 h away.

Week by week

Week 1 24–30 Aug · Base reset · 21.6 km done, ~38 km projected · long run 12 km

One job this week: prove you can run the commute slowly. No tempo.

Wed 26	done AM 4.7 km at 6:52, HR 145. PM 8.4 km at 7:25, HR 142, fifty of sixty-two minutes in Zone 2 — that is the session, run exactly as written. Plus a 3.8 km Zone 1 leg. 16.9 km on the day.
Thu 27	done AM 4.7 km at 6:52 — but HR 152 with 8 minutes in Zone 4–5 and a peak of 187, three beats off your maximum on a leg that was meant to cap at 147. One sprint for a crossing costs more than it looks: it is the whole reason this week is a reset. PM 4 km, Zone 1, deliberately slow. Shorter than the 5 km originally written — you are already at 21.6 km with the 12 km still to come.
Fri 28	rest
Sat 29	12 km long run at 7:30–7:50/km, HR under 155. Carry water. This is the longest run of your life by 1.6 km — start slower than feels sensible and you will finish it comfortably.
Sun 30	30–40 min walk or easy bike.

Week 2 31 Aug–6 Sep · Build · ~39 km · long run 14 km

Commute A	AM 4.7 Zone 2 · PM 9 km Zone 2.
Commute B	AM 4.7 Zone 1–2 · PM 6.5 km containing 2 × 8 min at threshold (HR 168–175, ~6:05/km) with 3 min jog between.
Sat	14 km, easy, with the last 3 km at 6:38 race pace. First taste of finishing on tired legs.
Sun	40 min walk or bike.

Week 3 7–13 Sep · Build · ~42 km · long run 16 km

Commute A	AM 4.7 Zone 2 · PM 10 km Zone 2.
Commute B	AM 4.7 Zone 1–2 · PM 7 km containing 5 × 3 min at 5:40–5:50 (HR 177+), 2 min jog between.
Sat	16 km at 7:15–7:35/km. First fuelling rehearsal: 500 ml of drink, a gel at 45 min and another at 90 min. You have never run longer than 65 minutes, so you have never needed to eat mid-run. Find out now, not on 10 October.
Sun	40–50 min walk or bike.

Week 4 14–20 Sep · Peak · ~44 km · long run 18.5 km

The week that decides the race. Everything after this is taper.

Commute A	AM 4.7 Zone 2 · PM 10 km with the last 4 km at 6:38 race pace.
Commute B	AM 4.7 Zone 1 · PM 6 km very easy. Arrive at Saturday fresh — this is not the week to chase a session.
Sat 19	18.5 km dress rehearsal — race shoes, race kit, race breakfast 2.5 h before, gels at 45 and 90 min. Target 6:50–7:05/km with HR under 165. If this run goes well, 2:20 is on. If you fall apart after 14 km, race for 2:30 and enjoy it.
Sun 20	complete rest

Week 5 21–27 Sep · Holiday hold · ~32 km · long run 16 km

Away, no commute — four standalone runs. Unfamiliar ground, probably warmer. Run by heart rate and ignore the pace column entirely.

Run 1	6 km easy Zone 2.
Run 2	5 km with 6 × 1 min pickups, full recovery between.
Run 3	5 km easy.
Run 4	16 km by effort, HR ceiling 160. Second fuelling rehearsal.

Week 6 28 Sep–4 Oct · Taper · ~24 km · long run 12 km

Volume drops, intensity does not. Feeling twitchy and under-trained is what a taper is supposed to feel like.

Run 1	6 km easy.
Run 2	5 km with 4 × 90 s at threshold.
Run 3	12 km with 6 km at 6:38 in the middle. The last real session — it should feel controlled, not heroic.
Optional	4 km very easy plus 4 × 20 s strides.

Week 7 5–10 Oct · Race week · 13 km + the race

Mon 5	rest or bike commute.
Tue 6	8 km with 4 km at 6:38 — the calibration run. If 6:38 sits at HR 165 or below, race it. If it needs HR above 172, race at 6:50 and target 2:24 instead. Believe this run over your ambitions.
Wed 7	rest
Thu 8	5 km very easy plus 4 × 20 s strides.
Fri 9	rest · 20 min walk. Eat carbohydrate all day, drink more than feels necessary, lay the kit out.
Sat 10	HALF MARATHON

Race day

km	Pace	HR ceiling	Feel
1–5	6:50	158	Too slow. Deliberately. Let people go.
6–15	6:35–6:40	168	Settled and boring. This is the race.
16–19	6:35	174	Hard, but holding form and cadence.
20–21.1	everything left	—	Now you may hurt.

The one mistake that will cost you the race. On 8 August you opened at 5:58/km and 5:57/km, then spent the next 8 km at 6:18–6:38 with heart rate climbing to 178. Over 10 km you got away with it. Over 21 km you will not — that drift rate puts you above 185 bpm by km 16 and walking by km 18. Bank nothing. Start at 6:50.

Fuelling: at 82 kg over roughly 2h20 you need about 50 g of carbohydrate an hour after the first 45 minutes. Gel at 40, 80 and 110 minutes, water at every station. Practise this exactly on the 16 km and 18.5 km runs — whatever you use on race day must be something you have already run on twice.

Breakfast: 2.5 hours before the start, the same thing you ate before the 18.5 km rehearsal. Race morning is not the day to discover a new cereal.

How to know it is working

Four checkpoints. All four are readable straight off the overview page — none of them need a subjective judgement.

By 13 Sep: Zone 1–2 is above 60% of running time on the 28-day zone bar. It was 29% on 26 Aug and is 38% today.
By 19 Sep: 18.5 km completed with average HR under 165.
By 20 Sep: four-week volume above 150 km.
Throughout: resting HR stays under 50 and HRV stays near its baseline. A resting HR above 52 for three mornings running, or HRV 25% below baseline, means take the next quality session out and run it easy instead.

Written 26 August 2026, revised 27 August from export 20260827093674. This page is judgement, not a query — when new exports land, the numbers it argues from move and it has to be rewritten. The overview will say so. Weekly targets are not read from this page. They live in plan.csv and are charted against reality by v_plan_vs_actual, so a week's volume changed here has to be changed there too — see README.md, “Changing the weekly volume”.