IRONMAN 70.3 · Cartagena · 29 Nov 2026
How to train for IRONMAN 70.3 Cartagena
The organiser lists the bike as flat and the run as flat, and promises high speeds on the road out of town. All of it is true, and none of it is what Cartagena asks about. This race is decided by the air around you. Athletes who train for a fast course arrive ready for the wrong one.
Read the weather the organiser publishes before you read the profile. The water sat at 29 C in each of the last three editions. The air peaked at 32 C in 2024 and 33 C the year before, and the low in 2024 never dropped under 26 C. Environmental resilience scores 90 on every leg, higher than aerobic endurance anywhere on the course, and a Trained athlete begins the run nearly four hours after the swim start.
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.
- Swim1.91 km11 m upCourse file
- Bike90.3 km545 m upCourse file
- Run21.2 km in 2 laps291 m upCourse file
The swim is one loop of the Bahía de las Ánimas, 1.9 km in water the organiser describes as calm and protected. Spectators can follow all of it from the Convention Center, from the boardwalks and marinas, or from on top of the walls. Transition is at Parque de la Marina.
The bike leaves from the Convention Center and the Clock Tower and heads for the Vía al Mar, the road that links Cartagena to Barranquilla. Beaches and mangroves line the way. It is one loop of 90.3 km. The first 22 km read as a single flat segment. A short drop follows, then another 14.6 km of flat road. Between kilometre 37 and kilometre 54 the road finally rolls: five climbs, the longest 924 m at 5.1 percent and the steepest 577 m at 5.5 percent, with descents as steep as 5.6 percent between them and the high point of the ride 77 m above the start. After that the last 36 km are flat again, broken only by three short rises of 3.2 to 4.2 percent.
The run is 2 laps through the Old City. It follows the west part of the city with the Caribbean Sea alongside, enters the walled city, and finishes in front of El Torre de Reloj. The file agrees with the organiser that it is flat. Its highest point sits 15 m above the start, each lap carries one short dip and climb at 4.4 percent, and the steepest reading on the whole run, 155 m at 5.2 percent, comes with 1.6 km to go.
Course shape by distance
- Flat 93%
- Climbing 4%
- Descending 3%
The longest stretches
- Bike, flat21.9 km24% of the bike
- Bike, flat14.6 km15% of the bike
- Bike, climbing0.58 km2% of the bike
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.
Heat comes first, on every leg. Because the bike fills 52 percent of a Trained athlete's day, heat on the bike is the heaviest demand on the whole course, and heat on the run comes seventh. Between them sit the pair every half-distance triathlon asks for. Aerobic endurance reads 85 on all three legs. Muscular endurance reads 82 on the bike and 83 on the run.
The rolling middle adds a little on top. High-intensity capacity scores 52 on the bike against 46 on the run. Strength and force reads 44 on the bike against 38 on foot. Modest numbers, and they should stay modest in your head. Seventeen kilometres of short climbs ask for the same power you held on the flat, not for a climber's legs. Fueling resilience reads 55 on the bike and the run alike, and on a day this warm the stomach is working under the same load as everything else.
Here is what that looks like in time. A Trained athlete swims 38:24, rides 3:04:14 at 182 W and runs 2:00:35, for 5:53:13. The Competitive band finishes in 5:08:40 from 4.15 W/kg at 75 kg and 4:20 /km threshold pace, about 21 minutes quicker on the bike and 18 on the run. The course has no climb that explains that gap. It comes from a higher number held steady for close to three hours in the heat, and legs that can still run afterwards.
- Environmental resilience90
- Aerobic endurance85
- Muscular endurance81
- Threshold capacity70
- Technical skill67
- Threshold durability66
- Aerobic durability65
- 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 the race and the athlete on the same twelve scales. The race side comes from the course file and the conditions the organiser records. The athlete side comes from thresholds and connected training history, and every score carries a note on its source and how far it can be trusted. A dimension counts as a gap only when Cartagena asks more than the athlete can show, and the gaps are ranked by the share of the day they fill. The bike is more than half of this day, so a bike gap outranks a swim gap of the same size.
There is no athlete behind this page, so the season on it cannot know anyone's gaps. It starts from the simplest assumption, that they sit where the demands are largest, and lays out 24 weeks in 5 developmental blocks closed by a two-week taper. Aerobic endurance leads the first block in all three sports. The second splits by sport: threshold durability on the run, technical skill in the water, aerobic durability on the bike. Threshold capacity leads the third block and muscular endurance the fourth, and aerobic endurance returns to lead the last one before the taper. A member's season is built from their own numbers and will choose its own order.
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.
- 01Environmental resilienceBike leg, 52% of the day90 × 52%47
- 02Aerobic enduranceBike leg, 52% of the day85 × 52%44
- 03Muscular enduranceBike leg, 52% of the day82 × 52%43
The bike takes 52% 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 Cartagena 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
8× 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, 7.8 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
- 85 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
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- 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 | 0:45:20 | 3:19:59 | 2:25:01 | 6:40:20 |
| Trained1:51 /100m critical swim speed · 3.03 W/kg at 75 kg · 5:06 /km threshold pace | 0:38:24 | 3:04:14 | 2:00:35 | 5:53:13 |
| Competitive1:36 /100m critical swim speed · 4.15 W/kg at 75 kg · 4:20 /km threshold pace | 0:33:13 | 2:42:59 | 1:42:28 | 5:08:40 |
| Elite1:26 /100m critical swim speed · 5.27 W/kg at 75 kg · 3:50 /km threshold pace | 0:29:45 | 2:28:51 | 1:30:38 | 4:39:14 |
Pacing plan
- 0 km0.1%30.3 km/h43:16
- 21.9 km-4.1%50.3 km/h0:17
- 22.1 km-0.1%31.3 km/h28:02
- 36.7 km3.5%16.5 km/h1:14
- 37.1 km0.8%26.9 km/h2:38
- 38.2 km3.3%17.1 km/h0:58
- 38.5 km0.9%26.5 km/h4:31
- 40.5 km-3.9%49.4 km/h1:15
24 more segments in the full plan.
- Run: reach 4:20 /km and this course gives back 44:33.
Where it is decided
On the second of the run's two laps. The bike writes the verdict first.
The two flat stretches at the start of the ride are the largest blocks of time in the race. The first 22 km take 24 percent of the bike leg for the reference athlete and the next 14.6 km another 15 percent. That is where the high speeds the organiser promises tempt you, and where you decide how much heat you carry into the rolling middle. Build this bike into a session and it comes back as eight hard efforts of 45 seconds in Zone 5, each with nearly eight minutes of easy riding after it. That is the honest shape of the leg. A handful of short questions in 17 km, each one answered at the power you rode on the flat, and nothing more.
Then the run. A Trained athlete covers it in 2:00:35 from an input of 5:06 /km threshold pace, and the first lap past the sea and into the walled city feels like a celebration because the crowd makes it one. The second lap has the same dip and climb at 4.4 percent, the same stones, and a body that has been in hot water or hot air since the start. The steepest ramp of the run arrives 1.6 km from El Torre de Reloj. A runner who paced the first lap for the second one passes people there.
Getting it wrong
Trusting the word flat. The organiser means it, and the first 37 km out along the coast are fast, but a flat road in heat still costs what you spend on it. Riders who time trial the Vía al Mar reach kilometre 37 hot, then treat each of the five climbs as a chance to make up time. The engine gives the steepest of them 1.8 percent of the bike leg. It is not worth a surge.
The swim is the second trap. The bay is calm, the water is 29 C, and nothing about it feels hard. A swimmer who pushes for two minutes here climbs onto the bike already warm, with more than four hours of heat still ahead.
The third is the Old City itself. Lap one through the walled city is the prettiest running most people will do all year, and they take it at the pace of the scenery. By the second pass the same streets are simply hot.
Conditions on the day
- 2025high 29 C, low 23 Cwater 29 C
- 2024high 32 C, low 26 Cwater 29 C
- 2023high 33 C, low 26 Cwater 29 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 Cartagena 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
- 5:53:13
- Of the day on the bike
- 52%
- Dimensions scored per leg
- 12
- Season runway shown
- 24 wk
Questions people ask
- How hot is IRONMAN 70.3 Cartagena?
- The organiser logged a high of 29 C in 2025, 32 C in 2024 and 33 C in 2023, with lows between 23 C and 26 C. The water in the Bahía de las Ánimas read 29 C in all three editions. Heat is the largest single demand on every leg of this course.
- Is the IRONMAN 70.3 Cartagena bike course flat?
- Mostly. The organiser lists it as flat and expects high speeds, and 93 percent of the whole course reads flat by distance. The real gradient sits between kilometre 37 and kilometre 54, where the steepest climb is 577 m at 5.5 percent.
- How many laps is the IRONMAN 70.3 Cartagena run?
- Two laps, 21 km in total, through the west part of the Old City with the Caribbean Sea alongside and then inside the walled city. The finish is in front of El Torre de Reloj. The highest point on the run file sits 15 m above its start.
- 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 season starts from their own numbers and can be longer.
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.