IRONMAN 70.3 · Cascais · 17 Oct 2026
How to train for IRONMAN 70.3 Portugal-Cascais
Most people choose Cascais for the postcard, and the organiser supplies plenty of it: a sunrise start in the bay, a lap of the Estoril Formula 1 circuit, a ride into Lisbon under the 25th of April Bridge. What the postcard leaves out is the order of events. The one serious climb on the bike arrives barely twenty minutes into the ride, on fresh legs, with the whole field around you. Almost everything after it is flat or gently rolling. Get that climb wrong and you carry it for the rest of the day.
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 km3 m upCourse file
- Bike90.1 km647 m upCourse file
- Run21 km in 2 laps150 m upCourse file
It starts at Ribeira Beach. The swim is one loop of 1.9 km around the protected bay of the village and out to the Fortaleza at Clube Naval, in water the organiser logged at 18 C in 2025 and 17 C in 2023. T1 sits on the Citadel Platform, 250 m from the swim exit, and the organiser warns that the first part of the way up is steep. It is also a long transition, and you can only mount at the exit.
The bike is a single loop of 90.1 km. It runs out along the Guincho road past Guincho Beach, then turns inland for Malveira and the Serra de Sintra by the Blue Lagoon, toward the Estoril circuit for its lap, and on to a turning point in Lisbon past the Tower of Belém and the Jerónimos Monastery. The file measures 647 m, and it puts nearly all the hard gradient in one place. After about 10 km of flat road the climbing starts: 2.3 km at 4 percent, a dip and two short ramps, then 914 m at 6.8 percent and a high point of 194 m at kilometre 19. From kilometre 26 on, the bike reads as flat stretches broken by short ramps, the longest a 17 km run of level road from kilometre 54.
The run is 2 laps, starting in Cascais and following the Guincho road along the coast toward Cabo Raso before returning to the heart of the town and the Marina de Cascais. It measures 21 km and 150 m of climbing. The rises are short enough that the engine reads the whole leg as level, but the organiser calls it challenging, especially on a windy day.
Course shape by distance
- Flat 87%
- Climbing 7%
- Descending 5%
The longest stretches
- Bike, climbing0.91 km3% of the bike
- Run, flat8.54 km40% of the run
- Run, flat11.8 km56% 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 scores 85 on every leg and muscular endurance 80 to 82, with threshold capacity at 70 in all three sports. The bike adds its own texture. High-intensity capacity reads 58 there against 40 on the swim and run, and strength and force and technical skill both read 47, which is what a climb at 6.8 percent and a coast road full of short ramps look like to the demand model. Environmental resilience reads 10. The organiser's highs run from 21 C in 2024 to 28 C in 2025. Warm at worst, never hot.
Ask the engine for a bike session from this file and it returns a dozen surges of three quarters of a minute, each followed by recovery, led by threshold durability. The picture is a rolling course where the effort has to be controlled over and over, not a mountain course.
The bands give it numbers. A Trained athlete swims 38:08, rides 3:06:05 at 182 W and runs 1:59:01, for 5:53:14. The Competitive band, from 4.15 W/kg at 75 kg and 4:20 /km threshold pace, finishes in 5:08:30, about 22 minutes quicker on the bike and 18 on the run. A good share of those bike minutes are made on the long flat stretches, where a higher sustained number pays every kilometre, rather than on the climb.
- Aerobic endurance85
- Muscular endurance80
- Threshold capacity70
- Aerobic durability65
- Technical skill65
- Threshold durability65
- Fueling resilience55
- High-intensity capacity40
- Anaerobic capacity25
- Strength / force20
- Environmental resilience10
- 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
The same twelve dimensions are scored twice in Nymiva. The course is read on them from its file and its setting. The athlete is read on them from thresholds and connected history, each with a note on its source and how far it can be trusted. A gap only counts where the course asks for more than the athlete has shown, and gaps are weighed by how much of the day they fill. On a course where the bike is 53 percent of a Trained athlete's race, bike gaps rise to the top of the list.
This page has no reader data, so its season makes the simplest guess about gaps: that they match the largest demands. From that it lays out 24 weeks in 5 developmental blocks and a two-week taper, with IRONMAN 70.3 Portugal-Cascais at the end. Aerobic endurance leads the first block in all three sports. Threshold durability leads the second on the bike and the run, while the swim works on aerobic durability. Threshold capacity takes the third block, muscular endurance the fourth, and aerobic endurance leads the last before the taper. A member's own season starts from their numbers and will depart from this one wherever those numbers say so.
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 Portugal-Cascais 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 threshold durability
- SupportRun threshold durability
- SupportSwim aerobic durability
- Weeks 6 to 9Foundation 2Closes with a recovery week
- PriorityBike threshold 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 threshold 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 threshold 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 threshold 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, 6 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
- 100 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 | 0:45:00 | 3:25:23 | 2:23:08 | 6:43:31 |
| Trained1:51 /100m critical swim speed · 3.03 W/kg at 75 kg · 5:06 /km threshold pace | 0:38:08 | 3:06:05 | 1:59:01 | 5:53:14 |
| Competitive1:36 /100m critical swim speed · 4.15 W/kg at 75 kg · 4:20 /km threshold pace | 0:32:58 | 2:44:25 | 1:41:07 | 5:08:30 |
| Elite1:26 /100m critical swim speed · 5.27 W/kg at 75 kg · 3:50 /km threshold pace | 0:29:32 | 2:30:10 | 1:29:27 | 4:39:09 |
Pacing plan
- 0 km0.1%30.3 km/h19:02
- 9.61 km3.7%15.9 km/h3:43
- 10.6 km1.1%25.5 km/h0:26
- 10.8 km4%15.1 km/h9:16
- 13.1 km1.8%22.5 km/h2:54
- 14.2 km-4.8%53.3 km/h0:40
- 14.8 km3.4%16.8 km/h0:51
- 15 km2.4%20.1 km/h0:45
50 more segments in the full plan.
- Run: reach 4:20 /km and this course gives back 44:44.
Where it is decided
On the climb into the Serra de Sintra, in the first hour of the ride.
The steepest ramp takes only 3.3 percent of the bike leg, which is the trap. It is short, it is early, and it comes after a flat run out along the coast where everyone has been riding fresh. The field is still bunched, the gradient invites a standing effort, and the high point at 194 m is close enough to feel reachable at any power. A Trained athlete who climbs it at the 182 W they plan to ride all day loses a little time to the rider who goes harder. That rider then spends the next 70 km of flat road and short ramps paying it back, including the 17 km level stretch that takes more of the leg than any other.
The run shows whose account is in credit. The first of its two long level stretches takes 40 percent of the run leg, the second 56 percent. Out along the Guincho road toward Cabo Raso, with wind if the day brings any, the runner who respected the climb holds pace and the one who did not starts to count kilometres.
Getting it wrong
The transition catches people first. T1 is 250 m from the water, uphill at the start and on two levels, and the organiser says the crowd makes you fly into it. Flying into T1 costs heart rate you will want back on the first climb twenty minutes later.
The second mistake is the lap of the Estoril Formula 1 circuit. The organiser bills it as unlike any other IRONMAN event and promises it will boost your power, and riders treat it as a time trial. It is a small part of a long loop. Ride it at your number and enjoy the view.
The third is the run's second loop. The crowd at the Marina de Cascais is loud on every pass, and if the wind is behind you on the coast road out to Cabo Raso, it is in your face on the way back. Pace the outward half so you still have the return.
Conditions on the day
- 2025high 28 C, low 15 Cwater 18 C
- 2024high 21 C, low 15 Cwater 18 C
- 2023high 22 C, low 19 Cwater 17 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 Portugal-Cascais 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
- 5:53:14
- 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 Portugal-Cascais bike course?
- Rolling, with one real climb. The single 90 km loop measures 647 m of climbing, and most of the serious gradient comes in the first 26 km, on the way up toward Malveira and the Serra de Sintra. The steepest sustained ramp is 914 m at 6.8 percent, and the high point is 194 m at kilometre 19.
- What is the water temperature at Ribeira Beach?
- The organiser logged 18 C in 2025 and 2024 and 17 C in 2023, and says the bay sits between 17 C and 19 C in October. The wetsuit decision is not on the course page, so check it in race week.
- Is the IRONMAN 70.3 Portugal-Cascais run course flat?
- The organiser calls it rolling. It is two loops from Cascais out along the Guincho road toward Cabo Raso and back, and the file measures 150 m of climbing, all of it in rises too short to break the leg into climbs. The organiser warns it is challenging on a windy day.
- How long is the season on this page?
- The illustrative season runs 24 weeks, with five developmental blocks and a two-week taper. It is built from the course alone. A member's own season starts from their numbers and can be longer.
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.