IRONMAN 70.3 · Porec · 18 Oct 2026
How to train for IRONMAN 70.3 Poreč
The organiser sells the bike here as a smooth, fast and uninterrupted ride, perfect for first timers or a PR. On the numbers it earns the pitch. The roads are closed to traffic, 89.9 percent of the whole course is flat by distance, and across the three editions the organiser publishes, the air never got warmer than 22 C.
So people come to Istria to ride fast, and they ride the wrong part fast. The bike is an out and back, and the file cuts it into three unequal pieces. First 34 km of short rises inland from the coast. Then 45.8 km the engine reads as one flat segment. Then the drop back to the sea. The PR the organiser promises lives in the middle piece. Whether you get to use it is settled in the first one.
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 km0 m upCourse file
- Bike89.9 km676 m upCourse file
- Run20.9 km132 m upCourse file
You start in front of Hotel Parentium Plava laguna, beside restaurant Villa Romana, and swim point to point for 1900m, clockwise, inside the protected Plava Laguna cove. The file measures 1.9 km. The exit is in front of Hotel Molindrio Plava Laguna, and from there it is a run straight into transition at the parking Byblos.
The bike heads out through vineyards and olive groves and comes back the same way, 89.9 km on closed roads with 3 aid stations. The organiser gives the total elevation as 680 m and the file finds 676 m. Part of the route is a highway section you are not allowed to ride before the race, so the fastest road of the day is one you meet for the first time with a number on your back.
The run is a single loop along the Adriatic into the centre of Poreč, then back south towards Zelena resort and Funtana, with 7 aid stations and the finish line in Zelena resort. The organiser calls it rolling. The file finds 132 m of climbing.
Now the shape. Nearly every rise on the bike is packed into those first 34 km: ramps of roughly three to four and a half percent, none of them long, most of them followed by a false flat that keeps climbing gently after the ramp has ended. The steepest sustained one is 515 m at 4.5 percent from kilometre 8.7, and it takes 1.3 percent of the bike leg. From kilometre 33.7 the engine reads 45.8 km as a single flat segment on average, though the organiser's own word for the course is undulating. That segment holds 46 percent of the bike leg, the largest block of time in the race. The last ten kilometres fall back to the coast.
Course shape by distance
- Flat 90%
- Climbing 5%
- Descending 5%
The longest stretches
- Bike, climbing0.52 km1% of the bike
- Bike, flat45.8 km46% of the bike
- Run, flat11.4 km54% 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.
Aerobic endurance and muscular endurance, on every leg. The demand model scores them 85 and 82 on the bike and the run, and 85 and 80 in the water. Because the bike fills 53 percent of a Trained athlete's day, the seven largest demands in the cross-leg ranking are all bike demands, with threshold capacity at 70 and both durability scores at 66 behind the first two.
The score that belongs to Poreč is high-intensity capacity. It reads 55 on the bike against 43 on the run and 40 on the swim, and the difference is those first 34 km. Ask the engine for a session built from this bike file and it returns ten repeats of one minute climbing in Zone 5 straight into two minutes of false flat in Zone 4, with half a minute easy between. That is what the opening of the ride is: a short ramp, then a continuation that feels like flat and is not.
The swim has its own reading. Technical skill is its fourth demand at 67, well above the 41 it scores on the bike. A point to point course gives you one line to hold and no second lap on which to fix it.
Put the bands on it. A Trained athlete swims 38:09, rides 3:06:04 at 182 W and runs 1:59:28, for 5:53:41. The Competitive band finishes in 5:09:06 from 4.15 W/kg at 75 kg and 4:20 /km threshold pace, and holds 249 W on the bike. More of its bike advantage comes out of the first 34 km than out of the longer flat middle. Climbing is where a higher steady number pays best. It is not where a surge above that number pays.
Heat does not decide this race. The organiser promises mild temperatures and low humidity, and logged a high of 20 C in 2025. The cold end is more real. The low was 7 C in 2025, and the water was 19 C.
- Aerobic endurance85
- Muscular endurance80
- Threshold capacity70
- Technical skill67
- Aerobic durability65
- Threshold durability65
- Fueling resilience55
- High-intensity capacity40
- Anaerobic capacity25
- Strength / force20
- Environmental resilience15
- 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
Twelve dimensions get scored on both sides of the ledger. For the course they come from the organiser's files. For an athlete they come from thresholds and connected training history, and every score carries a note on what it was read from and how much weight it bears. Nymiva only counts something as a gap where Poreč asks for more than the athlete can show, and then weights each gap by the share of the day it occupies. Here that gives the bike more than half of the vote.
This page has no reader data behind it, so the season beside it starts from the plainest assumption: your gaps sit where the course demands most. On that footing it lays out 24 weeks with 5 developmental blocks and a two-week taper. Aerobic endurance leads the first block in all three sports. The second block splits by sport, threshold durability for the run, technical skill for the swim, aerobic durability for the bike. Threshold capacity leads the third block across the board, muscular endurance the fourth, and aerobic endurance comes back for the last one before the taper. A member's own season is built from their own numbers, and it will disagree with this one.
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, 53% of the day85 × 53%45
- 02Muscular enduranceBike leg, 53% of the day82 × 53%43
- 03Threshold capacityBike leg, 53% of the day70 × 53%37
The bike takes 53% 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 Poreč 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
- SupportRun threshold durability
- SupportSwim technical skill
- SupportBike aerobic durability
- Weeks 6 to 9Foundation 2Closes with a recovery week
- PriorityRun threshold durability
- PrioritySwim technical skill
- PriorityBike 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
- SupportRun threshold durability
- SupportSwim technical skill
- SupportBike 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
- SupportRun threshold durability
- SupportSwim technical skill
- SupportBike 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
- SupportRun threshold durability
- SupportSwim technical skill
- SupportBike 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
10× climb-to-false-flat repeats
1 min at Zone 5, then 2 min at Zone 4, then 1 min at Zone 5, then 2 min at Zone 4, then 1 min at Zone 5, then 2 min at Zone 4, then 1 min at Zone 5, then 2 min at Zone 4, then 1 min at Zone 5, then 2 min at Zone 4, then 1 min at Zone 5, then 2 min at Zone 4, then 1 min at Zone 5, then 2 min at Zone 4, then 1 min at Zone 5, then 2 min at Zone 4, then 1 min at Zone 5, then 2 min at Zone 4, then 1 min at Zone 5, then 2 min at Zone 4, 0.5 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
- 60 min
- Trains muscular endurance
- Supports strength force
- Supports anaerobic capacity
- Supports threshold durability
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 | 0:45:01 | 3:21:58 | 2:23:41 | 6:40:40 |
| Trained1:51 /100m critical swim speed · 3.03 W/kg at 75 kg · 5:06 /km threshold pace | 0:38:09 | 3:06:04 | 1:59:28 | 5:53:41 |
| Competitive1:36 /100m critical swim speed · 4.15 W/kg at 75 kg · 4:20 /km threshold pace | 0:32:59 | 2:44:36 | 1:41:31 | 5:09:06 |
| Elite1:26 /100m critical swim speed · 5.27 W/kg at 75 kg · 3:50 /km threshold pace | 0:29:33 | 2:30:19 | 1:29:48 | 4:39:40 |
Pacing plan
- 0 km0.2%29.8 km/h0:57
- 0.47 km4.4%14.2 km/h0:58
- 0.7 km0%30.8 km/h0:20
- 0.87 km-3.4%47.2 km/h0:20
- 1.14 km1.1%25.5 km/h2:06
- 2.03 km3.2%17.4 km/h1:04
- 2.34 km2.1%21.3 km/h0:56
- 2.67 km3.9%15.4 km/h0:54
35 more segments in the full plan.
- Run: reach 4:20 /km and this course gives back 44:35.
Where it is decided
Before kilometre 34, by what you decline to spend.
None of the rises is big. The steepest takes 1.3 percent of the bike leg, which means a surge on any one of them is too cheap to register. The trap is the false flat after each ramp. The road still climbs, the legs are still at climbing effort, and nothing in the view tells you to ease off. Ten of those and a rider who planned 182 W has ridden the opening at something else entirely, whatever the average says at the turn.
Then comes the payoff the organiser advertises. The 45.8 km from kilometre 33.7 are 46 percent of the bike leg, and a steady rider banks the day there. A rider who spent the rises rides the fastest road on the course slower than they should, and they cannot get it back on the descent to the coast, which is short.
The run settles the account. A Trained athlete covers it in 1:59:28 from an input of 5:06 /km threshold pace. The first 11.4 km read as flat and fill 54 percent of the run leg. What comes after is rolling, and the final kilometre rises to the finish in Zelena resort.
Getting it wrong
The first mistake is saved for the road nobody has seen. You cannot ride the highway section before race day, so the fastest stretch arrives unrehearsed, on fresh-feeling legs, and riders treat it as a place to make up time at more than their planned power. It is the right place to be fast. It is the wrong place to be heroic.
The second is the start of the bike. It leaves the coast and starts climbing inside the first kilometre. Riding the first rises at the effort of the riders around you sets the power for the whole ride.
The third is the run's flat opening. Eleven flat kilometres along the Adriatic feel like the easy half, and they get run at the pace the drop back to the coast suggested. The rises wait for you after that, and the last of them is between you and the finish line in Zelena resort.
Conditions on the day
- 2025high 20 C, low 7 Cwater 19 C
- 2024high 22 C, low 17 Cwater 19 C
- 2023high 15 C, low 7 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 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 Poreč 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
- 5:53:41
- Of the day on the bike
- 53%
- Dimensions scored per leg
- 12
- Season runway shown
- 24 wk
Questions people ask
- How hilly is the IRONMAN 70.3 Poreč bike course?
- The organiser calls it an undulating out and back with no major climbs and a total elevation of 680 meters, and the file measures 676 m. Almost all of the rises sit in the first 34 km. The steepest sustained one is 515 m at 4.5 percent, and it takes 1.3 percent of the bike leg.
- What water temperature should I expect in the Plava Laguna cove?
- The organiser logged 19 C in 2025 and in 2024, and 22 C in 2023. The swim is a point to point 1900m course, swum clockwise inside a protected cove. The wetsuit decision is not on the organiser's course page, so check it in race week.
- Is the IRONMAN 70.3 Poreč run course flat?
- The organiser calls it rolling, with 130m of total elevation. The file reads the first 11.4 km as one flat segment and puts the short rises after it, the last of them inside the final kilometre to the finish line in Zelena resort.
- How many aid stations are there on the course?
- The organiser lists 3 aid stations on the 90 km bike and 7 aid stations on the one-loop run. Start times and cut-offs are not on the course page, so read the athlete guide for those.
Course data from the organiser’s published files, analysed 23 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 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.