IRONMAN 70.3 · Zell am See · 29 Aug 2027
How to train for IRONMAN 70.3 Zell am See-Kaprun
The organiser labels this bike hilly and sells the race on its alpine climbing, and nobody who has ridden it will argue. So athletes come to Zell am See with a climber's preparation, a light bike and a head full of gradients. Then they meet the rest of the course.
Most of it is flat. By distance, 82.5 percent of the whole course reads as flat road. Most of the climbing on the bike sits in one block in the first half, framed by the Austrian Alps and over by kilometre 35. A Trained athlete's day of 6:06:26 is not settled on that block. It is settled by what the block leaves over for the long flat road home, and for a lakeshore half marathon that never tilts.
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.
- Swim1.9 km1 m upCourse file
- Bike89.4 km954 m upCourse file
- Run21.3 km113 m upCourse file
The swim is one lap of Lake Zell, 1.9 km from the Strandbad, in water the organiser logged at 21 C in 2025 and 23 C the year before. Transition is in the Alois Latini Stadium in Schüttdorf, right beside the swim start. You collect a blue bike bag on the way in and leave your wetsuit in it on the way out.
The bike is a single loop of 89.4 km with 954 m of climbing. The first 13 km are flat. A few short rises follow, and at kilometre 21 the road starts to climb and barely lets go until kilometre 35. First comes 3.4 km at 5.8 percent. Then a long drag of rises between 2 and 5 percent. Last, 2.56 km at 7.8 percent to the highest point of the day. The way down opens with 2.5 km at 10.5 percent. From kilometre 43 the road is flat again, give or take a handful of short bumps, all the way back to transition.
The run is one lap along the shore of Lake Zell, 21.3 km with 113 m of climbing, and the organiser calls it flat and fast. The file agrees. There is one rise of 232 m at 4.3 percent a little past kilometre 7, and nothing else worth the name.
Course shape by distance
- Flat 83%
- Climbing 10%
- Descending 7%
The longest stretches
- Bike, climbing2.56 km10% of the bike
- Run, flat7.42 km35% of the run
- Run, flat13.4 km63% 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.
Endurance first, and not the climbing kind. The demand model scores aerobic endurance at 85 and muscular endurance at 83 on the bike. Threshold capacity follows at 70, with aerobic durability and threshold durability level at 67. Strength and force, the quality people come here to build, scores 49. Because the bike fills 54 percent of a Trained athlete's day, the eight largest demands on the course are all bike demands. On the run the top two read 85 and 81, in the water 85 and 80.
That low strength score surprises people until they ride the climb. A 7.8 percent grade held for 2.56 km is not a test of force for a trained rider. It is a test of how much steady work they can still produce more than 30 km into the ride, and for a long time, which is muscular endurance by another name. In the engine's reference run that steepest stretch takes 9.6 percent of the bike leg. It feels like the whole race while you are on it. It is not.
Put the bands beside each other. A Trained athlete swims 38:12, rides 3:17:18 from an input of 3.03 W/kg at 75 kg and runs 2:00:56, for 6:06:26. The Competitive band, working from 4.15 W/kg at 75 kg and 4:20 /km threshold pace, rides 2:48:25 and runs 1:42:45 for 5:14:13. The climb is where the gap between them is easiest to see. Most of it is made elsewhere, on flat road and on the run.
Then there is the date. The organiser calls this a late-season race, and the next edition falls on 29 August 2027. The high reached 30 C in 2024 and only 21 C a year later, and the engine scores environmental resilience at 60 on every leg. Plan for the hot year. The cool one needs no plan.
- Aerobic endurance85
- Muscular endurance80
- Threshold capacity70
- Aerobic durability65
- Threshold durability65
- Environmental resilience60
- Technical skill60
- Fueling resilience55
- High-intensity capacity40
- Anaerobic capacity25
- Strength / force20
- Sprint power5
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 reads twelve dimensions off the course and the same twelve off the athlete. The course side comes from the organiser's file. The athlete side comes from thresholds and connected training history, and every score carries a note on where it came from and how far to trust it. Where the course asks for more than the athlete can show, there is a gap. Gaps are then weighted by how much of race day they govern, which at Zell means a bike gap weighs far more than a swim gap of the same size.
No reader stands behind this page, so the season below takes the plainest assumption on offer, that your gaps sit where Zell's demands are largest. On that assumption it lays out 24 weeks in 5 developmental blocks and a two-week taper. Aerobic endurance leads the opening block in all three sports. Durability leads the second, aerobic durability on the bike and in the water with threshold durability on the run. Threshold capacity takes the third block. Muscular endurance takes the fourth, and aerobic endurance returns to lead the fifth before the taper. Your own season is built from your own numbers and will depart from this one wherever they do.
Train the bike to protect the run
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.
- 01Aerobic enduranceBike leg, 54% of the day85 × 54%46
- 02Muscular enduranceBike leg, 54% of the day83 × 54%45
- 03Threshold capacityBike leg, 54% of the day70 × 54%38
The bike takes 54% of the Trained reference band’s day, so its demands carry the most race weight. What the bike leaves in the legs is what the run gets.
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 IRONMAN 70.3 Zell am See-Kaprun 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.
- 01Run muscular endurance, a practice block4 weeks
- 02Run aerobic endurance, a development block4 weeks
- 03Bike muscular endurance, a practice block4 weeks
- 04Bike aerobic endurance, 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 1Closes with a recovery week
- PriorityBike aerobic endurance
- PriorityRun aerobic endurance
- PrioritySwim aerobic endurance
- SupportBike muscular endurance
- SupportRun muscular endurance
- SupportSwim muscular endurance
- SupportBike threshold capacity
- SupportRun threshold capacity
- SupportSwim threshold capacity
- SupportBike aerobic durability
- SupportRun threshold durability
- SupportSwim aerobic durability
- Weeks 6 to 9Foundation 2Closes with a recovery week
- PriorityBike aerobic durability
- PriorityRun threshold durability
- PrioritySwim aerobic durability
- SupportBike aerobic endurance
- SupportRun aerobic endurance
- SupportSwim aerobic endurance
- SupportBike muscular endurance
- SupportRun muscular endurance
- SupportSwim muscular endurance
- SupportBike threshold capacity
- SupportRun threshold capacity
- SupportSwim threshold capacity
- Weeks 10 to 13Foundation 3Closes with a recovery week
- PriorityBike threshold capacity
- PriorityRun threshold capacity
- PrioritySwim threshold capacity
- SupportBike aerobic endurance
- SupportRun aerobic endurance
- SupportSwim aerobic endurance
- SupportBike muscular endurance
- SupportRun muscular endurance
- SupportSwim muscular endurance
- SupportBike aerobic durability
- SupportRun threshold durability
- SupportSwim aerobic durability
- Weeks 14 to 17Event shaping 1Closes with a recovery week
- PriorityBike muscular endurance
- PriorityRun muscular endurance
- PrioritySwim muscular endurance
- SupportBike aerobic endurance
- SupportRun aerobic endurance
- SupportSwim aerobic endurance
- SupportBike threshold capacity
- SupportRun threshold capacity
- SupportSwim threshold capacity
- SupportBike aerobic durability
- SupportRun threshold durability
- SupportSwim aerobic durability
- Weeks 18 to 21Event shaping 2Closes with a recovery week
- PriorityBike aerobic endurance
- PriorityRun aerobic endurance
- PrioritySwim aerobic endurance
- SupportBike muscular endurance
- SupportRun muscular endurance
- SupportSwim muscular endurance
- SupportBike threshold capacity
- SupportRun threshold capacity
- SupportSwim threshold capacity
- SupportBike aerobic durability
- SupportRun threshold durability
- SupportSwim aerobic durability
- Weeks 22 to 23PeakPeak
The taper. Load comes down toward the race, content stays specific.
- Week 24RaceRace
Race week.
Held at maintenance between blocks
- Runmuscular endurance, aerobic endurance, aerobic durability, threshold capacity, threshold durability
- Bikemuscular endurance, aerobic endurance, aerobic durability, threshold capacity, threshold durability
- Swimaerobic endurance, aerobic durability, threshold capacity, threshold durability, muscular endurance, technical skill
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 1 · Weeks 2 to 575 to 240 min
150 to 210 min at Zone 2
BikePower, Zone 2Trains aerobic capacity - Foundation 1 · Weeks 2 to 540 to 270 min
180 to 210 min at Zone 3, then 30 min at Zone 4
BikePower, Zone 3Trains aerobic capacity - Foundation 1 · Weeks 2 to 535 to 120 min
90 min at Zone 2
RunPace, Zone 2Trains aerobic capacity - Foundation 1 · Weeks 2 to 550 min
4 x 1.5 min at Zone 3, 6 min easy between
RunHeart rate, Zone 3Trains aerobic capacity - Foundation 1 · Weeks 2 to 545 to 51 min
4 x 8 min at Zone 2, 1 min easy between
SwimPace, Zone 2Trains aerobic capacity - Foundation 1 · Weeks 2 to 547 to 81 min
3 x 1000 m at Zone 3, 0.3 min easy between
SwimPace, Zone 3Trains aerobic capacity
12× rolling-course surges
0.8 min at Zone 5, then 0.8 min at Zone 5, then 0.8 min at Zone 5, then 0.8 min at Zone 5, then 0.8 min at Zone 5, then 0.8 min at Zone 5, then 0.8 min at Zone 5, then 0.8 min at Zone 5, then 0.8 min at Zone 5, then 0.8 min at Zone 5, then 0.8 min at Zone 5, then 0.8 min at Zone 5, 1.8 min easy between
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
- 53 min
- Trains threshold durability
- Supports muscular endurance
- Supports high intensity capacity
24 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
- 17
- 18
- 19
- 20
- 21
- 22
- 23
- 24
- 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 | 0:45:05 | 3:40:30 | 2:25:26 | 7:01:01 |
| Trained1:51 /100m critical swim speed · 3.03 W/kg at 75 kg · 5:06 /km threshold pace | 0:38:12 | 3:17:18 | 2:00:56 | 6:06:26 |
| Competitive1:36 /100m critical swim speed · 4.15 W/kg at 75 kg · 4:20 /km threshold pace | 0:33:03 | 2:48:25 | 1:42:45 | 5:14:13 |
| Elite1:26 /100m critical swim speed · 5.27 W/kg at 75 kg · 3:50 /km threshold pace | 0:29:36 | 2:33:49 | 1:30:54 | 4:44:19 |
Pacing plan
- 0 km-0.1%31.3 km/h25:10
- 13.1 km-4.7%52.9 km/h0:12
- 13.3 km0.1%30.3 km/h2:30
- 14.6 km3.9%15.4 km/h2:07
- 15.1 km0.5%28.4 km/h2:15
- 16.2 km-3.9%49.4 km/h0:41
- 16.7 km-1.6%38.7 km/h1:14
- 17.5 km-3.4%47.2 km/h0:27
51 more segments in the full plan.
- Run: reach 4:20 /km and this course gives back 52:13.
Where it is decided
On the flat road home, after the descent, when the race goes quiet.
Everyone reaches the top at kilometre 35 having worked. The 2.5 km at 10.5 percent that follows gives them a few minutes to feel recovered. Then the gradient runs out. From kilometre 43 to transition it is flat road, more than 40 km of it, the longest stretch of the day and the one nobody trains for because nobody talks about it. A Trained rider holds 182 W there, the same number as on the climb. A rider who climbed above plan finds that the flat asks for exactly that number and that it has gone.
The run reads the bill aloud. The engine splits the lakeshore into two flat stretches either side of the single rise. The first 7.4 km carry 35 percent of the run leg. The last 13.4 km carry 63 percent, the largest single block of the run. A runner working from 5:06 /km threshold pace covers the whole lap in 2:00:56, and whether that holds was decided back on the flat road home, long before the run began.
Getting it wrong
It starts with the training. Riders read the word hilly and spend the spring on hill repeats. They arrive with strength Zell barely scores, 49 on the bike and behind eight other dimensions, and short of the steady endurance it asks for everywhere else.
The second mistake is the first 13 km. Flat road out of Schüttdorf, fresh legs, a full field around you. Riders treat it as free speed before the climb and start the 3.4 km at 5.8 percent already above their number. There is no descent on this course long enough to pay that back.
The third is the lakeshore run. It is flat, the organiser calls it fast, and after a hard bike people run the first 7.4 km at the pace they trained for in cooler weeks. In 2024 the day reached 30 C. Run to the day you have, not the one on the course page.
Conditions on the day
- 2026high 25 C, low 15 C
- 2025high 21 C, low 16 Cwater 21 C
- 2024high 30 C, low 16 Cwater 23 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 aerobic endurance moves from your baseline to a stated target by the end of Foundation 1
- 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 IRONMAN 70.3 Zell am See-Kaprun 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
- 6:06:26
- Of the day on the bike
- 54%
- Dimensions scored per leg
- 12
- Season runway shown
- 24 wk
Questions people ask
- How hilly is the IRONMAN 70.3 Zell am See-Kaprun bike course?
- The organiser calls it hilly, and the file they publish measures 954 m of climbing on one 90.1 km loop. Most of it sits between kilometre 21 and kilometre 35, finishing with 2.56 km at 7.8 percent. After the descent the road is flat back to transition.
- What water temperature should I expect in Lake Zell?
- The organiser logged 21 C in 2025 and 23 C in 2024, and publishes no water reading for 2026. The wetsuit decision is not on the organiser's course page, so check it in race week.
- Is the IRONMAN 70.3 Zell am See-Kaprun run course flat?
- Yes. The organiser describes one flat, fast lap along the shore of Lake Zell, and their file measures 113 m of climbing over 21.1 km. The only rise worth the name is 232 m at 4.3 percent, a little past kilometre 7.
- How hot is race day in Zell am See?
- It changes a lot from year to year. The organiser logged a high of 30 C in 2024, 21 C in 2025 and 25 C in 2026. The next edition is on 29 August 2027.
Course data from the organiser’s published files, analysed 24 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.