Walking the Aid Stations: Does a Run-Walk Strategy Cost You Time in an Ironman Marathon?

In the closing stages of the 2026 IRONMAN World Championship in Kona, the men's race turned on walking. Magnus Ditlev led onto the run but began slowing badly and was reported walking before Vincent Luis passed him to take the lead. In the women's race, defending champion Solveig Løvseth went down twice in the final kilometre and Taylor Knibb passed her to win. Professionals walking because they have no choice left is one thing. For most age-groupers, walking is something they will do at some point in an Ironman marathon, whether they plan to or not.

The question this article tries to answer is narrower and more useful: if you walk on purpose, in short planned breaks, does it cost you time? And how does that change when the run comes after a 3.8 km swim and a 180 km ride?

What the run-walk trial found

The best evidence comes from a single randomised trial by Hottenrott and colleagues, published in the Journal of Science and Medicine in Sport in 2016. They recruited 42 non-elite marathon runners (22 men and 20 women) and randomly allocated them to two strategies for the same marathon:

• Run/walk: running with planned walking breaks.
• Run only: running the whole distance.

The headline result:

• Finish times were not significantly different. The run/walk group averaged 4:14:25 and the run-only group 4:07:40. That gap of a little under seven minutes was not statistically significant (p = 0.377). With 21 people per group, a real difference of that size could exist, but the trial couldn't show one.
• Cardiac stress was similar. Blood markers of cardiac stress (BNP, CK-MB and myoglobin) rose in both groups after the race and returned to baseline within four days. Only two runners showed raised troponin. Walking didn't reduce these markers.
• Muscles felt better. The run/walk group reported less muscle pain and fatigue after the race (p = 0.006).

The authors' conclusion was modest. Run/walk didn't reduce the load on the heart, but runners finished in similar times with less muscular discomfort.

This is a small trial in recreational runners finishing in around four hours. It's the right population for many age-group triathletes, though not for the fastest. And it was a stand-alone marathon, not the third leg of an Ironman.

Why an Ironman marathon is a different problem

An Ironman run starts with your legs already damaged, your glycogen already partly spent, and often in the hottest part of the day. Three things make planned walking potentially more useful there than in a stand-alone marathon, and one thing makes it riskier.

1. Fuelling happens at aid stations

Most of your carbohydrate on the run comes from aid stations. Drinking from a cup or opening a gel while running at race pace is hard, and much of it ends up on your shirt.

In a study of 221 athletes by Pfeiffer and colleagues, carbohydrate intake at Ironman Hawaii averaged 62 ± 26 g per hour and at Ironman Germany 71 ± 25 g per hour across the whole race, but individual intakes ranged from 6 to 136 g per hour. Higher total carbohydrate intake was associated with faster finishing times in both Ironman races, although it was also linked to more nausea and flatulence. That's an association, not proof that eating more made people faster, but it fits with what fuelling research shows in controlled studies.

Inference, not finding: if a few seconds of walking at each aid station is what lets you actually get your planned carbohydrate in, the walk may pay for itself later in the run. Nobody has tested this directly in an Ironman.

2. Late-race collapse is common and expensive

Large datasets of recreational marathoners show how often the late stages of a marathon go wrong. In an analysis of more than four million race records, Barry Smyth defined "hitting the wall" as slowing by at least 25% for at least 5 km after the 20 km mark. By that definition, 28% of men and 17% of women hit the wall.

A second analysis by Smyth and colleagues, of 82,303 recreational marathoners, compared heart rate with running speed throughout the race. In the third of runners whose heart rate drifted most relative to pace, the drift began on average around 19 km. Those runners raced at a lower average percentage of their estimated critical speed than the most durable third (82% vs 88%), yet still finished more slowly.

Neither study looked at walking. But both show that the second half of a marathon is where most time is lost, and that the cost of a collapse is far larger than a few seconds of walking. TriForward's article "Why the Ironman Marathon Falls Apart After 25 km" looks at this in more detail.

3. Muscle damage accumulates

The run/walk group in the Hottenrott trial reported less muscle pain and fatigue. After a long ride, your quads and calves are already fatigued before the run begins. Inference: a strategy that reduces muscular discomfort in fresh marathoners is at least plausible as a way to protect the legs in the third leg of an Ironman. It's an extrapolation, and should be read as one.

The risk: stopping is easier than starting

The downside is psychological as much as physical. Every walk break is a moment where you have to choose to run again. Late in an Ironman, that choice gets harder. A rule that is vague ("I'll walk when I need to") tends to expand. A rule that is specific ("walk from the first table to the last table, then run") is easier to keep.

Planned walking vs forced walking

It helps to separate two very different things that look the same from the side of the road.

Planned walking starts early, often at the first aid station, while you still feel fine. The breaks are short and predictable, and they have a job: drinking, fuelling, cooling with ice or sponges, and resetting your form.

Forced walking starts when you can't keep running. It usually appears in the second half, gets longer as the race goes on, and is a symptom rather than a strategy. The cause is almost always earlier: a bike pace that was too high, too little carbohydrate, heat, dehydration, or a run pace that started too fast.

Ditlev's walk in Kona was the second kind. It began when he was already struggling, after leading into T2. The trial evidence says nothing about forced walking. It only tells you that planned walking, done from the start, didn't cost the recreational runners in that study any significant time.

The arithmetic of a short walk

How much time does walking actually cost? The following is arithmetic, not a study result, so treat it as an estimate.

Suppose your Ironman run pace is 6:00 per km (10 km/h, about 2.8 m/s), and you walk for 20 seconds at each aid station at about 6 km/h (1.7 m/s).

• In 20 seconds of running you'd cover about 56 m.
• In 20 seconds of walking you cover about 33 m.
• The difference is about 23 m, which takes roughly 8 seconds to make up at your running pace.

So each 20-second walk costs about 8 seconds of race time. Over 25 aid stations, that's about 3 to 4 minutes, on a run that might take around four and a quarter hours.

Now compare that with the cost of hitting the wall. Using Smyth's definition of slowing by at least 25% for at least 5 km, a 6:00/km runner who slows to 7:30/km for the last 10 km loses 15 minutes. If walking the aid stations makes that kind of collapse even somewhat less likely, the arithmetic favours it. Whether it does is exactly what hasn't been tested in Ironman racing.

When walking feels harder than running

There's a quirk of human movement that matters for slower Ironman runners. In a treadmill study by Hreljac (1993), 20 young adults (10 men and 10 women) naturally switched from walking to running at an average of 2.06 m/s, about 7.4 km/h. Walking at that speed felt harder than running at the same speed: perceived exertion was 13.5 for walking versus 10.0 for running.

Inference: if your late-race "running" pace has dropped to around 8:00 per km or slower, a brisk walk and a shuffle can be very close in speed. Some athletes find that a controlled run-walk keeps them moving faster than a continuous shuffle that feels terrible. Others find any walking hard to restart from. The only way to know which you are is to try it in training.

Walking, heat and cooling

Kona is a reminder that many Ironman runs happen in heat and humidity, and that changes what an aid station is for. Besides fuel and fluid, it's where you get ice, cold sponges and water to pour over your head and neck. Those are hard to use well at running pace. You drop half the ice, the sponge misses, and you're through the station before you've done what you came for.

Inference: on a hot day, a short planned walk turns an aid station into a cooling stop as well as a fuelling stop. TriForward's article "Humid, Not Just Hot" covers the evidence on cooling during a race and why humidity limits how much sweating can cool you. The trial evidence on run-walk didn't measure temperature, so this is reasoning from what aid stations offer, not a tested effect.

The same logic applies in reverse on a cool day. If you don't need to cool and you can fuel well on the move, the case for walking is weaker, and the arithmetic cost of each break matters more.

What we don't know

• No Ironman trial exists. Every number in this article comes from stand-alone marathons, lab studies or observational Ironman data.
• Faster athletes weren't studied. The trial's runners averaged around four hours for a fresh marathon. A walk break is proportionally more expensive for a 3:15 Ironman marathoner.
• The best ratio is unknown. The trial tested one run/walk pattern. Nobody has compared different walk lengths or frequencies in a triathlon.
• Women and men may differ. Men were more likely to hit the wall in Smyth's data, and decoupled more in the 82,303-runner study. The run/walk trial was too small to compare sexes.

How to use walking on purpose

If you want to use a run-walk strategy in your next Ironman, these steps follow from the evidence above. They're reasoned practice, not tested prescriptions.

1. Decide your rule before race day. For example: walk each aid station from the first table to the last, take what you planned, then run. Write it down.
2. Start from the first aid station. Planned walking only works if it starts while you still feel good.
3. Give every walk a job. Fuel, drink to thirst, cool with ice or sponges, and check your form. Then go.
4. Keep walks short and brisk. Swing your arms and walk with purpose. A long, slow wander becomes hard to restart from.
5. Rehearse it. Practise the routine in long runs and long bricks, including restarting on tired legs and taking gels or drinks while walking.
6. Pace the bike for the run. No walking plan rescues a run that starts after an over-paced ride. See TriForward's "Smooth Beats Surgy" on how bike power variability affects run splits.
7. Know the difference between a plan and a warning. If you need to walk between aid stations far earlier than expected, slow everything down and prioritise fuel, fluid and cooling, rather than trying to force your way back to goal pace.

Common mistakes

• Walking only when you're already in trouble. That's forced walking, and the trial evidence doesn't apply to it.
• No restart point. "I'll start running again in a minute" turns into five. Pick a landmark.
• Using walks to drink far beyond thirst. Extra cups at every station over four or five hours can add up. More fluid isn't always better.
• Never practising. Restarting a run on tired legs is a skill. Your first attempt shouldn't be at kilometre 30 of an Ironman.
• Treating walking as failure. Plenty of age-groupers who walk every aid station run faster overall than those who try to run every step and collapse.

References

• Hottenrott K, Ludyga S, Schulze S, Gronwald T, Jäger FS. Does a run/walk strategy decrease cardiac stress during a marathon in non-elite runners? Journal of Science and Medicine in Sport, 2016;19(1):64–68. doi:10.1016/j.jsams.2014.11.010
• Pfeiffer B, Stellingwerff T, Hodgson AB, Randell R, Pöttgen K, Res P, Jeukendrup AE. Nutritional intake and gastrointestinal problems during competitive endurance events. Medicine & Science in Sports & Exercise, 2012;44(2):344–351. doi:10.1249/MSS.0b013e31822dc809
• Smyth B. How recreational marathon runners hit the wall: a large-scale data analysis of late-race pacing collapse in the marathon. PLoS ONE, 2021;16(5):e0251513. doi:10.1371/journal.pone.0251513
• Smyth B, Maunder E, Meyler S, Hunter B, Muniz-Pumares D. Decoupling of internal and external workload during a marathon: an analysis of durability in 82,303 recreational runners. Sports Medicine, 2022;52(9):2283–2295. doi:10.1007/s40279-022-01680-5
• Hreljac A. Preferred and energetically optimal gait transition speeds in human locomotion. Medicine & Science in Sports & Exercise, 1993;25(10):1158–1162. doi:10.1249/00005768-199310000-00012
• TRI247. IRONMAN Kona 2026 as it happened as Knibb and Luis crowned champions (live race report), 10 October 2026. tri247.com