5150 · Hoorn · Last raced 21 Jun 2026
How to train for 5150 Westfriesland
The organiser calls this course fast and flat and recommends it to first-timers and to anyone chasing a personal best. Both groups come away surprised by how much it hurt. Flat does not mean easy. It means there is never a moment in the whole race when the road tells you to ease off, and never a moment when it tells you to push. You decide every watt yourself, from the gun in the harbour to the finish at the Stadsstrand.
A Trained reference athlete finishes in 2:43:52, and the demand model puts threshold capacity at 90 on the swim, on the bike and on the run. That is the whole story of Westfriesland in one number. The race was last held on 2026-06-21, and the organiser has not yet published the next date. The course it was raced on is set out below.
By Kian Briel, founder. Analysed by engine 1, updated
What is actually on the road
The organiser's own course files, drawn the way the Event Analyzer draws a member's race.
- Swim1.52 km0 m upCourse file
- Bike39.4 km34 m upCourse file
- Run10.1 km15 m upCourse file
In the old harbour of Hoorn, a town in the region the organiser places just north of Amsterdam, you swim one loop of 1.5 km. A short exit takes you onto a carpeted run to the single transition on the football pitch in Hollandia Park, where your swim kit goes into the blue bag and the bike is waiting on flat, short grass.
The bike is one loop of 39.4 km out of the centre of Hoorn into the countryside, through small towns and past windmills. The file measures 34 m of climbing across the whole ride. On a course like this that figure is noise. The engine reads the bike as a single flat segment from start to finish.
Back in Hollandia Park your helmet stays on until the bike is racked, then the red bag holds your run kit. The run covers 10.1 km through the historic centre, past monumental buildings and the docks, and finishes at the Stadsstrand. It climbs 15 m. The whole course, all three legs, reads as flat.
Course shape by distance
- Flat 100%
- Climbing 0%
- Descending 0%
The longest stretches
- Bike, flat39.4 km103% of the bike
- Run, flat10.1 km100% of the run
Each row is one unbroken stretch of the course that keeps the same shape the whole way. The number is how much of that leg you spend inside it, and it comes out the same whether you are fast or slow.
What this course asks of each leg
Twelve training dimensions scored for each leg against its own course, the way the Event Analyzer scores a member's race.
At Westfriesland threshold capacity scores 90 on every leg, and nothing else comes close. Aerobic endurance and high-intensity capacity follow at 70 on the bike and the run, muscular endurance at 60. Because the bike fills 44 percent of a Trained athlete's day, the bike's threshold demand ranks first on the course, the run's fourth.
The swim has a reading of its own. Technical skill scores 75 in the water, second only to threshold capacity there, against 36 on the bike and 50 on the run. Aerobic endurance in the swim reads 70. Technique counts for more in the water here than it does on either leg on land.
Put the bands beside those scores. A Trained athlete swims 29:30, rides 1:11:43 at 200 W and runs 52:39 from an input of 5:06 /km threshold pace. The Competitive band finishes in 2:23:49, riding 1:03:34 at 274 W and running 44:44. There is no climb on this course where that difference could be bought. It is bought watt by watt on flat road, and then again stride by stride along the docks.
The weather varies more than the terrain. The organiser logged a high of 29 C in 2025 and only 18 C the year before, with the harbour at 23 C and 19 C in those two years. Environmental resilience still scores 10 on every leg. Plan for either kind of day.
Feed the bike file to the engine and ask for one session shaped by it, and you get a single unbroken block in Zone 4 of about thirty-five minutes, with fifteen minutes to warm up and ten to spin down. No intervals, no recoveries. The course has no rhythm to copy, so the session has none either.
- Threshold capacity90
- Technical skill75
- Aerobic endurance70
- High-intensity capacity70
- Muscular endurance60
- Anaerobic capacity55
- Threshold durability45
- Aerobic durability35
- Fueling resilience20
- Sprint power20
- Strength / force15
- Environmental resilience10
Nymiva reads what you can already show, from your own data
Connect your training history and the Focus Lab scores the same twelve dimensions this course demands against where you sit today. The gap between the two is what you train.
- MeasuredFrom your thresholds and testsThreshold power, threshold pace, critical swim speed and field tests you have done. The dimensions they can carry are scored directly.
- EstimatedFrom your training historyConnected activities are read for what they prove: long efforts, late-session fade, repeated hard work, fueling on long days. Each score says how it was read.
- ProxyFrom a stand-in, and named as oneWhere only an indirect signal exists, the score carries the proxy it came from and a lower confidence, never a number dressed as a measurement.
- UnmeasuredHonestly blankA dimension nothing in your data can answer stays unmeasured. It is never a zero, and the plan does not pretend to know it.
Every dimension ends in one word
- Develop the course asks more than you can show
- Maintain close enough to hold at the minimum dose
- Covered nothing to build here
- Unmeasured the course needs it, your data cannot say yet
Nymiva scores twelve dimensions on the course, from its files, and the same twelve on the athlete, from thresholds and connected training history, each score marked with what it rests on. Where the course asks more than the athlete can show, that is a gap. Gaps are weighted by how much of the day they fill, so a bike gap here counts for more than a swim gap of the same size.
No reader's data sits behind this page, so its season takes the plainest assumption, that gaps line up with the biggest demands, and lays out 16 weeks with 3 developmental blocks. Threshold capacity leads the first block in all three sports. In the second, aerobic endurance leads the swim while muscular endurance leads the bike and the run. In the third, technical skill leads in the water and aerobic endurance on land, and a two-week taper follows. Your own season is drawn from your numbers and will choose its own order.
What this course asks for first
Which demands matter most across the whole race. A leg's demand counts for as much of the day as that leg takes, so a score of 85 on the bike outweighs the same score on the swim.
- 01Threshold capacityBike leg, 44% of the day90 × 44%39
- 02Aerobic enduranceBike leg, 44% of the day70 × 44%31
- 03High-intensity capacityBike leg, 44% of the day70 × 44%31
Which demand gets a block, and when
The engine freezes one lead focus per sport on every developmental block, holds the rest at maintenance, and verifies before it reprioritises.
An illustration, not your plan. This page has none of your data, so the season below is the engine’s answer to one stated assumption: that your gaps line up with what 5150 Westfriesland demands. Your own season is built from your history, your thresholds, the days you can train and the races you have entered, and it will differ from this in its priorities, its sessions and its load.
- 01Swim threshold capacity, a development block3 weeks
- 02Run threshold capacity, a development block3 weeks
- 03Bike threshold capacity, a development block4 weeks
In the order the allocator places them, general first, most race-like last.
- Week 1PrepPrep
A lead-in week. It develops nothing by design.
- Weeks 2 to 5Foundation 2Closes with a recovery week
- PriorityBike threshold capacity
- PriorityRun threshold capacity
- PrioritySwim threshold capacity
- SupportSwim technical skill
- SupportBike aerobic endurance
- SupportRun aerobic endurance
- SupportSwim aerobic endurance
- SupportBike muscular endurance
- SupportRun muscular endurance
- Weeks 6 to 9Event shaping 1Closes with a recovery week
- PrioritySwim aerobic endurance
- PriorityBike muscular endurance
- PriorityRun muscular endurance
- SupportBike threshold capacity
- SupportRun threshold capacity
- SupportSwim threshold capacity
- SupportSwim technical skill
- SupportBike aerobic endurance
- SupportBike high-intensity capacity
- SupportRun aerobic endurance
- SupportRun high-intensity capacity
- SupportSwim high-intensity capacity
- Weeks 10 to 13Event shaping 2Closes with a recovery week
- PrioritySwim technical skill
- PriorityBike aerobic endurance
- PriorityRun aerobic endurance
- SupportBike threshold capacity
- SupportRun threshold capacity
- SupportSwim threshold capacity
- SupportBike high-intensity capacity
- SupportRun high-intensity capacity
- SupportSwim aerobic endurance
- SupportSwim high-intensity capacity
- SupportBike muscular endurance
- SupportRun muscular endurance
- Weeks 14 to 15PeakPeak
The taper. Load comes down toward the race, content stays specific.
- Week 16RaceRace
Race week.
Held at maintenance between blocks
- Swimthreshold capacity, aerobic endurance, high-intensity capacity, muscular endurance, technical skill
- Runthreshold capacity, aerobic endurance, high-intensity capacity, muscular endurance
- Bikethreshold capacity, aerobic endurance, high-intensity capacity, muscular endurance
Touches scheduled by each capability’s own decay, at a fraction of its development dose, so earlier work is still there on race day.
The sessions the blocks are built from
One entry per kind of work the block trains, at the intensity that work is meant to be done at. Where the same work runs at several lengths, the entry shows the span it grows across rather than one entry per length.
- Foundation 2 · Weeks 2 to 553 to 167 min
4 x 10 min at Zone 4, then 20 min at Zone 4, then 10 x 0.2 min at Zone 7, then 30 min at Zone 3, 5 min easy between
BikePower, Zone 4Trains threshold capacity - Foundation 2 · Weeks 2 to 576 to 135 min
5 x 1 min at Zone 1, then 2 x 20 min at Zone 4, then 45 min at Zone 3, 1 min easy between
BikePower, Zone 1Trains threshold capacity - Foundation 2 · Weeks 2 to 552 to 62 min
3 x 8 min at Zone 4, 3 min easy between
RunPace, Zone 4Trains threshold capacity - Foundation 2 · Weeks 2 to 560 min
3 x 8 min at Zone 3, then 3 x 7 min at Zone 4
RunPace, Zone 3Trains threshold capacity - Foundation 2 · Weeks 2 to 532 to 44 min
12 x 100 m at Zone 4, 0.3 min easy between
SwimPace, Zone 4Trains threshold capacity - Foundation 2 · Weeks 2 to 546 to 59 min
10 x 200 m at Zone 3, 0.3 min easy between
SwimPace, Zone 3Trains threshold capacity
Sustained course race pressure
35.5 min at Zone 4
Compiled by the deterministic course compiler from the organiser’s file: the course’s one repeatable requirement, rehearsed at a dose the progression allows.
- Bike
- 61 min
- Trains threshold durability
- Supports aerobic durability
16 weeks, laid out backwards from race day
The shortest runway Nymiva builds for this event type, with its blocks, recovery weeks, taper and race week in place.
- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 9
- 10
- 11
- 12
- 13
- 14
- 15
- 16
- Prep
- Foundation
- Event shaping
- Peak
- Race
- Recovery week
Your own season carries these same phases on your own dates, with the load solved from your fitness and the days you can train, and it changes when your data does.
What each level does on the day
Reference finish times per peer band, the pacing plan the model holds each band to, and where the day is decided.
| Band | Swim | Bike | Run | Finish |
|---|---|---|---|---|
| Recreational2:11 /100m critical swim speed · 2.47 W/kg at 75 kg · 6:08 /km threshold pace | 0:34:49 | 1:17:43 | 1:03:19 | 3:05:51 |
| Trained1:51 /100m critical swim speed · 3.03 W/kg at 75 kg · 5:06 /km threshold pace | 0:29:30 | 1:11:43 | 0:52:39 | 2:43:52 |
| Competitive1:36 /100m critical swim speed · 4.15 W/kg at 75 kg · 4:20 /km threshold pace | 0:25:31 | 1:03:34 | 0:44:44 | 2:23:49 |
| Elite1:26 /100m critical swim speed · 5.27 W/kg at 75 kg · 3:50 /km threshold pace | 0:22:51 | 0:58:07 | 0:39:34 | 2:10:32 |
Pacing plan
- 0 km0%32 km/h1:14:00
- Run: reach 4:20 /km and this course gives back 20:03.
Where it is decided
In the opening kilometres of the bike.
You leave Hollandia Park with the swim still in your arms, the town behind you and the road perfectly flat ahead. Nothing slows you. The engine reads the bike as one flat segment, so the only pacing on this course is the pacing you bring. A Trained rider needs 200 W for 1:11:43. Ride the opening kilometres a few watts over that and it feels like nothing at all. There is no hill waiting to make you pay, and no descent to recover on either. You pay on the run instead.
The run is where it shows. 10.1 km of flat road through the old centre, 52:39 for a Trained runner, and every second of it at a pace the bike has already decided. Riders who held their number through the countryside run past the docks at the speed they trained for. Riders who did not are still running, just slower, and the Stadsstrand is further away than it looks.
Getting it wrong
Trouble starts with the word flat. Athletes read it and train for comfort, long easy rides with nothing hard in them, and arrive with no experience of holding threshold for an hour on end. Threshold capacity scores 90 on every leg of this course. Train for that.
A second error sits in the harbour. The swim is short and the exit is quick, then comes a carpeted run to transition, and it is easy to sprint that stretch and the first minutes on the bike together. Keep the run to transition steady and let your breathing settle before you ask anything of the bike.
The third is the hot year. The organiser's own record runs from 18 C to 29 C, and a pace set on cool training days does not transfer to the warm end of that range. Check the forecast in race week and set the run pace against it, not against your best training day.
Conditions on the day
- 2025high 29 C, low 17 Cwater 23 C
- 2024high 18 C, low 13 Cwater 19 C
- 2023high 22 C, low 14 Cwater 22 C
From the organiser’s own records. Not a forecast.
Every session is a claim, every block is a test
A plan is not a calendar. Each key session states what it trains and how that is checked, and each block ends with a public verdict before the next one is chosen.
What a block promises
Bike threshold capacity moves from your baseline to a stated target by the end of Foundation 2
- The baseline is your measured score when the block starts. The target is the score the model predicts for it.
- Verified at the block’s recovery week, by a field test or a refresh of the supply read from your history.
- Confidence rises by agreement between independent signals, never by one metric crossing a line.
- A block that misses its target is a public miss. The next block is chosen from what was proven, not from what was planned.
- 01Stimulus achievedThe work landed in the zone the session named, for the dose it named.
- 02Partially achievedSome of the work landed. The session banks what it can prove.
- 03Not achievedThe load may have been there. The stimulus was not, so nothing is banked.
- 04Data insufficientNo usable stream. The session is neither credited nor blamed.
- Session verified
- Progression banked
- Block verified
- Priority reassessed
- Plan adapted
Your numbers, this course
Analyze 5150 Westfriesland against my fitness
The same simulation and the same Focus Lab read, on your thresholds instead of a band’s. Three numbers give a finish estimate and a partial read. A connected history gives the whole table.
The first 14 days are free.
- Trained band finish
- 2:43:52
- Of the day on the bike
- 44%
- Dimensions scored per leg
- 12
- Season runway shown
- 16 wk
Questions people ask
- How flat is the 5150 Westfriesland course?
- As flat as a triathlon gets. The bike file measures 39.4 km with 34 m of climbing and the run 10.1 km with 15 m, and the engine reads every metre of the course as flat. The organiser sells it as fast and flat, ideal for first-timers and personal bests.
- Where is the 5150 Westfriesland swim?
- In the old harbour of Hoorn, one loop of 1.5 km. A short exit leads to a carpeted run to the single transition on the football pitch in Hollandia Park. The organiser logged the water at 23 C in 2025, 19 C in 2024 and 22 C in 2023.
- What is the 5150 Westfriesland run like?
- One run of 10 km through the historic centre of Hoorn, past monumental buildings and the docks, finishing at the Stadsstrand close to the old centre. It climbs 15 m in total.
- When is the next 5150 Westfriesland?
- The organiser has not yet published the next date. The course and the training it asks for are on this page, and the season shown runs 16 weeks with three developmental blocks before a two-week taper.
Course data from the organiser’s published files, analysed 25 Sept 2026 by engine 1, demand model 4. Reference times are simulated for a peer band at a stated reference athlete and are not a prediction for anyone. Nothing on this page is medical advice.
IRONMAN® and IRONMAN 70.3® are registered trademarks, and 5150 is a trademark, of World Triathlon Corporation. Nymiva is an independent training platform and is not affiliated with, sponsored by or endorsed by World Triathlon Corporation. Course data is read from the organiser’s public course pages for the purpose of describing the event.