How Kristian Blummenfelt Trains (and What He Eats While Doing It)
The Norwegian method reached running through Jakob Ingebrigtsen. It reached triathlon through a small group in Bergen, of whom Kristian Blummenfelt is the most visible: Olympic champion in Tokyo, and since then a fixture at the front of long-course racing. The training principle is the same, controlled work at and just below threshold, governed by measurement rather than feel. What's different is the scale of the measuring, and the fuelling that makes the volume survivable.
Three sports, one lactate framework
Blummenfelt's training has been built around the same skeleton Ingebrigtsen uses: sessions clustered tightly around lactate threshold, held to a target window rather than run to exhaustion, often twice in a day, with a large easy base underneath. Reported threshold windows sit in the region of 2 to 4 mmol/L, with a handful of threshold sessions per week.
The complication is that he has to do it in three disciplines at once. Swim, bike and run each have their own threshold, their own mechanics and their own recovery cost, and the lactate meter is the common currency that lets one framework govern all three. Reported training volume sits somewhere around 30 to 35 hours a week across six or seven days, though the precise numbers come from secondary reporting rather than a published log, so treat them as indicative.
There is a real difference from the running version worth flagging. Ingebrigtsen's week pairs the double-threshold days with genuinely fast, VO2max-oriented work: threshold builds the base, the sharp stuff raises the ceiling. The long-course triathlon application leans further toward the aerobic end, because the event it targets lasts eight hours rather than three and a half minutes.
The measuring is the method
The Bergen group's signature is instrumentation: finger-prick lactate in the field, periodic lab testing, portable metabolic analysers, core body-temperature sensors, structured heat blocks, sauna protocols and repeated altitude camps. Their coach Olav Aleksander Bu has described the discipline behind it:
The strength of data comes exactly from what you say. You need to measure regularly all the time there, and it has to be done in a way that the athlete doesn't feel it as intrusive.
The second half of that sentence is the part most amateurs skip. Measurement that interrupts training stops happening within a fortnight.
Bu has also said something more useful for anyone who cannot afford a metabolic cart, which is that the tools are not the mechanism: he has suggested they could remove a lot of the technology and still arrive at roughly the same place. The data reduces uncertainty. It doesn't replace the training.
The VO2max number, and why to be sceptical
In January 2026, a reported VO2max of 101.1 ml/kg/min was published for Blummenfelt on social media and described as the highest ever recorded. It has not appeared in any peer-reviewed form, and several exercise scientists publicly questioned it, focusing on a respiratory exchange ratio of 0.93, well below the value normally expected at a genuine maximum, which points to either a test that ended early or a calibration problem.
None of that means he isn't an extraordinary aerobic athlete. It means the specific number is a claim, not a result. That's worth saying plainly, because it's the same story as Kilian Jornet's widely quoted VO2max: a striking figure travels much faster than the caveats attached to it.
The fuelling is the actually novel part
Where this group has genuinely shifted practice is nutrition. For years the accepted ceiling for carbohydrate absorption during exercise was around 60g per hour, later pushed to 90g using glucose and fructose together. The Norwegians treated absorption as trainable and went far past it.
Estimates reconstructed by journalists from the 2025 Ironman World Championship in Nice put Blummenfelt's intake at roughly 177g per hour on the bike and around 130g per hour on the run. Those are counts made from bottles and gels rather than laboratory measurements, and they describe one specific race on one specific day, so don't treat them as his standing numbers. Even heavily discounted, they are extraordinary.
The transferable principle is that your gut adapts to what you repeatedly ask of it, exactly like the rest of you. Most age-group athletes under-fuel long sessions, then blame their legs. Start from a sensible target and build toward it in training rather than experimenting on race day:
Target carbs
60g/h
Per hour of exercise
Total carbs
120g
Across your 2-hour session
Recommended carbohydrate by session length
| Under 1 hourWater is usually enough | 0 g/h |
| 1 to 2.5 hoursRecommendedSingle transportable carb (glucose) | 60 g/h |
| 2.5 hours or longerGlucose plus fructose, near a 2:1 mix | 90 g/h |
- Pair carbohydrate with fluid and sodium. Concentrated fuel without enough water sits in the gut and causes discomfort.
- Tolerating high carbohydrate rates is a trainable skill. Practice your race fueling in long sessions and build up gradually, never try a new high intake on race day.
- Above 60 g per hour, use a glucose-to-fructose mix near 2:1. Glucose alone saturates the gut transporter at about 60 g per hour.
- Hard efforts burn carbohydrate faster, so sit toward the top of each range.
A PDF of your personalized results, with a QR code to reopen them anytime.
Give it your session duration and intensity and it returns a grams-per-hour target and a session total. Use it as a starting point to practise with, not a number to leap to. If you're fuelling long efforts properly you should also be thinking about fluid, which is what our sweat rate calculator is for.
2026
He has had a strong season. He won 70.3 Geelong in March, then 70.3 Oceanside a week later with a course record, defended his Ironman Texas title in April, and in July made his Challenge Roth debut, finishing second in 7:26:24 behind Sam Laidlow, whose 7:21:04 is now the fastest time ever recorded over the full distance. Reporting suggests his focus for the rest of the year points toward the Ironman World Championship.
One caveat on the reporting: the exact shape of his coaching arrangement in 2026 is unclear, with some accounts describing the Bergen athletes managing more of their own day-to-day training while Bu consults, so I've written about the method rather than asserting who currently writes the plan.
What you can actually steal from it
- Control intensity, don't just survive it. The core idea is work held at a repeatable level near threshold, not sessions run until they hurt. You can approximate the cap with pace, power or the talk test.
- Train your gut on purpose. Build hourly carbohydrate intake gradually in training. It is one of the few genuinely large, cheap performance gains left for most amateurs.
- Heat adapts you too. A sauna or hot bath after training is the low-tech version of the heat blocks the pros run with core-temperature sensors.
- Measure something, consistently. A cheap number tracked for months beats an expensive number measured once.
- Discount the headline figures. VO2max claims and elite fuelling numbers are context-dependent and often unverified. The principle behind them usually survives; the number often doesn't.
More in this series: Jakob Ingebrigtsen, Eliud Kipchoge, Kilian Jornet, Marianne Vos, Demi Vollering, Tadej Pogačar and Jonas Vingegaard. The system itself is explained in the Norwegian method.
Sources
The structure of the Norwegian triathlon method, the lactate windows and Bu's comments on measurement are reported by TrainingPeaks and TrainingPeaks, with the measurement quote from Bu's appearance on The Peter Attia Drive. Heat-training practice is described by Science for Sport. The disputed VO2max figure and the scientific objections to it are covered by Sweat Science and 220 Triathlon. The reconstructed race-fuelling estimates are from Race Smart. His 2026 results are reported by Triathlete, TRI247 and TRI247. Training-volume figures come from secondary reporting and are given as approximate.
Cover photo by Rz98, CC BY-SA 4.0, via Wikimedia Commons.
