Kristian Blummenfelt, an Olympic and Ironman world champion, has pushed the boundaries of human performance in endurance sports. A key element of his success, alongside rigorous training, is a carefully considered approach to nutrition. This article delves into the details of Blummenfelt’s training diet, examining the principles, strategies, and scientific understanding that underpin it.
The "Norwegian Method" and its Focus on Calories and Oxygen
When Bu started coaching with the Norwegian triathlon squad almost a decade ago, the demands were more binary. What would it take to become an Olympic triathlon champion? “As we progressed, I started asking myself: how far can we go?” Bu explains. What are fundamental limitations? It always comes back to calories and oxygen. While most of us view calories as food, Bu chooses the scientific definition: the amount of energy required to raise the temperature of 1 gram of water by 1 degree Celsius. The "Norwegian Method," known for lactate testing, controlled intensities, double session training days and high-volume training, emphasizes the importance of calories and oxygen. Olav Aleksander Bu, Blummenfelt's coach, challenges conventional wisdom about sustainable energy expenditure. Academic studies suggested that athletes would hit a ceiling of 2.5 times their basal metabolic rate (BMR) over extended periods. Bu disagreed, believing the human body was capable of much more. His focus is on exploring the boundaries of peak human performance.
The Science of Sustained Energy Expenditure
Research on endurance athletes in events like cycling Grand Tours has shown extreme levels of total energy expenditure. However, it was previously thought that sustained energy expenditure was capped at approximately 2.5 times the basal metabolic rate (BMR) over months. To investigate this, Bu’s team analyzed three years of Blummenfelt's training data (2020-2022) and data from two altitude training camps. The study, titled "Training volume and total energy expenditure of an Olympic and Ironman world champion: approaching the upper limits of human capabilities," was published in the Journal of Applied Physiology.
The study team needed to outline the parameters. A key variable in the concept of maximum sustainable energy expenditure is duration. How long is sustainable? If one minute, we can use VO2 max. Previous studies found that duration to be one week for cross-country skiers or three weeks for Grand Tour cyclists. Bu’s team looked at three years of training data from January 2020 to December 2022, along with two distinct altitude training camps from October 29 to November 8, 2021, and from January 26 to February 8, 2022.
The findings revealed that Blummenfelt's energy expenditure ranged from 7,019 to 8,506 calories per day. This far exceeded the perceived sustainable limit of approximately 5,000 calories per day (2.5 times a BMR of 2,000 calories per day). The annual training volumes for the years 2020-2022 were eye-watering at 1,480, 1,350 and 1,308 hours. This data suggests that Blummenfelt consistently surpassed the previously assumed metabolic ceiling for sustained total energy expenditure.
Read also: The Hoxsey Diet
Caloric Intake: Fueling the Machine
“We quickly understand it’s the sheer amount of calories that need to be put into the body that becomes a limitation,” Bu says. “There is also a misunderstanding that what we eat maintains the balance. Blummenfelt’s high energy expenditure highlights the critical role of caloric intake. Bu emphasizes that a limitation is the sheer number of calories needed to fuel such intense training. While calorie counting can be linked with weight loss, restriction, and a miserable relationship with food, Bu is coming at it from the other direction and bemoans a lack of easy-to-use technology that would help measure intake for performance, Currently, he believes, estimations can be wildly off the mark. He also bemoans a lack of easy-to-use technology that would help measure intake for performance. He envisions a future with better tools for nutrition, such as a "power meter for your food" that can accurately measure the mass and composition of food on a plate.
Bu isn't overly concerned that high carbohydrate consumption might be detrimental to long-term health. He notes that elite athletes typically have a more diverse microbiome than other people, which studies suggest is a sign of good health. “Neurologically, we can say that part of the system also needs calories to recover and I would rather say that trying to push peak human performance without staying with the fundamentals - calories - is more dangerous than trying to reach it when overly obsessing over kilograms.
Macronutrient Balance and Food Choices
“We haven’t obsessed that it should be certain types of foods,” Bu adds. “But how can we still get a healthy balance? Bu emphasizes the importance of a healthy balance in the diet, but they haven't obsessed over specific food types. In previous interviews with Bu, there have been jokes about “food chambers” filled with candy, and he concedes that on some of the “most crazy training days” they might eat up to 5,000 calories in gels and drink mixes from nutrition partner Maurten. He acknowledges that on "crazy training days," athletes might consume up to 5,000 calories in gels and drink mixes from nutrition partners like Maurten. However, he stresses the long-term need for fiber to improve calorie uptake from the gut.
Bu cautions against blindly following dietary trends. “I won’t give a recommendation,” Bu shrugs. “But my feeling is that if we look at the Japanese for longevity, for example, and say we should eat like the Japanese, we are already heading in the wrong direction. They have been exposed to these foods their whole lives and have a highly specialized microbiome. He argues that simply adopting a diet known for longevity, like the Japanese diet, may not be suitable for everyone due to differences in microbiome composition and lifelong dietary exposure.
The Gut Microbiome and Nutrient Uptake
It’s why he has spent time analyzing Blummenfelt’s fecal samples - to find out whether he is getting the uptake from his food. Bu's analysis of Blummenfelt's fecal samples reveals his interest in understanding nutrient uptake. He believes an athlete who gains weight easier might be a safer bet because of a microbiome that facilitates better nutrient absorption. “If I have a choice of two athletes who run 1,500m at the same level of performance and one had to be more mindful about what he was eating because he gained weight easier, I would pick that guy,” Bu says. “Simply because that guy, seemingly for now, is a safer bet because he has a microbiome that makes him add more weight.
Read also: Walnut Keto Guide
Avoiding the "Watts per Kilogram" Trap
“For elite endurance athletes, a culture of watts per kilogram has made kilograms very important for performance, but that also becomes, subconsciously, a driver to start limiting how much food you’re taking into the body,” he explains. Bu cautions against the "watts per kilogram" mentality, which can lead athletes to restrict food intake to maintain a lower weight. He uses the example of bodybuilders, who prioritize calorie intake to promote muscle growth, to illustrate the importance of fueling performance. “As humans, we’re really poor at evaluating things that happen over a long time and how they contribute to growth. Bu uses the example of bodybuilders to further land his point. “No group in the world is more obsessed over bulking up and getting in more calories to promote muscle growth.
Volume and Caloric Intake: Finding the Right Balance
Of course, it’s not as simple as just increasing volume. Bu says Blummenfelt trained for approximately 1,406 hours in 2023 and then 1,311 in 2024, comparable with the years used in the study. But not all hours are equal. As such it is too crude to correlate Blummenfelt’s training regimen during the earlier years of the pandemic - less traveling and fewer non-training commitments - with improved conditioning compared to more recent years. Bu acknowledges that increasing training volume isn't simply about stuffing in as many calories as possible. It's about finding the right balance. “Enough” is the first answer. “There’s a rule of thumb when an athlete is developing that we should not increase the volume of their training by more than 20 percent from year to year,” he says. “If you do it quickly, you provide a lot more stimulus than you’re able to adapt to. But with some developing athletes, we brought up the volume by 100 percent over a year and they had a perfect response. He suggests a rule of thumb of not increasing training volume by more than 20 percent year-to-year to avoid overstressing the body. However, he notes that some athletes can tolerate much larger increases. Blummenfelt and Iden are adept at this, but their training volumes have reached levels where they have to be equally mindful of what they are consuming.
Practical Applications for Age-Group Athletes
While elite athletes like Blummenfelt operate under vastly different conditions than age-group athletes, there are still valuable lessons to be learned.
Prioritize the Basics
Amateurs (and pros, for that matter) should first focus on developing a foundation of health, repeatable training, and good sleep and nutrition. Before integrating technological devices, go through the following checklist: Ensure you have the time and resources required to use the tools appropriately. Do you have the necessary technical knowledge to properly apply the tools for their intended purpose, i.e., do you have a scientist or coach in your team? Finally, have you nailed the basics of endurance training, i.e., appropriate training prescription, proper sleep, nutrition, and realistic goals? A foundation of health, consistent training, adequate sleep, and proper nutrition are paramount.
Coaching and Support
The endurance journey is tough without perspective, expertise, and support. The Norwegians lean heavily on their coach for guidance, as should you. Coaches should rely on athlete education and empowerment. Only you know how you feel, and should have the know-how to adapt training if needs be. Adult athletes do not need a dictator for a coach. There should be flexibility and independence built into your training plan, and the opportunity to push back if need be. A coach can provide guidance, expertise, and support, while empowering athletes to understand and adapt their training.
Read also: Weight Loss with Low-FODMAP
Recovery Strategies
Perhaps the most talked about part of the Rich Roll podcast with the Norwegians was their claim that they don’t use “traditional” recovery methods such as massage or ice baths. This information is especially applicable for you type-A amateurs insistent on chasing the next best recovery hack. Gustav and Kristian (and me) instead highlight the critical importance of plenty of calories and sleep. Recovery is critical, and the Norwegians prioritize calories and sleep over traditional methods like massage or ice baths.
Some additional actionable recovery tools are: Power naps between sessions. Refueling after every workout. And adequate hydration. Additional recovery tools include power naps, refueling after workouts, and adequate hydration.
Long-Term Planning and Patience
Long-term planning and patience for development over time. A passion for the process - the Norwegians seem to truly enjoy training, as should you. High coachability and the appropriate approach steeped in education, empowerment, and collaboration. Support and accountability - a shared journey is better. A healthy relationship with failure. Long-term planning, patience, a passion for the process, coachability, support, and a healthy relationship with failure are all crucial for success.
The Future of Performance Optimization
In terms of looking for peak human performance in 2025, Blummenfelt and Iden will be focusing their efforts on the Ironman Pro Series, while Bu will take on more of a hands-off mentorship role as well as bringing his wisdom to Norwegian UCI ProTeam Uno-X Mobility as head coach. “The role I had with Kristian and Gustav was extraordinary, you won’t find any other coach who is stupid enough to travel with their athletes for 200 days a year,” he says. “I’m now in a role that looks more like what a lot of coaches do where they are overseeing the program. Looking ahead, Blummenfelt and Iden will focus on the Ironman Pro Series, while Bu will transition to a mentorship role and head coach for Norwegian UCI ProTeam Uno-X Mobility.
“I can’t travel more than 200 days a year and barely see my family for year after year,” he concludes. “What makes me cry is not the victories of the races, but realizing how fortunate we are that we have the families and people behind us who put so much into it for us to be able to do what we do. He acknowledges the sacrifices made by his family and support system.
Training Methodology: Key Elements of the Norwegian Method
To give you a flavour of what this training looks like here’s Ingebrigtsens’ typical training and is well known and commonly shared: A strong focus on anaerobic threshold training and development Typical base week training of 2 x threshold morning and evening twice a week, hill work x 1 with a combination of slightly over 180 km of weekly volume (where the threshold work type varies from morning to evening - one with somewhat shorter and one with a bit longer intervals with a variation of intensity around the anaerobic threshold, see above) threshold training split into intervals instead of continuous sessions high altitude training winter and summer the threshold work in the lower range touching in to their anaerobic threshold Focused lactate meter-controlled sessions in winter and summer. The Norwegian training system incorporates several key elements:
Anaerobic Threshold Training
A strong emphasis on anaerobic threshold training and development, often involving two threshold sessions per day.
Interval Training
Threshold training is split into intervals rather than continuous sessions.
High-Altitude Training
Regular high-altitude training camps in both winter and summer.
Lactate Monitoring
Focused lactate meter-controlled sessions to guide training intensity.
Volume and Intensity for Blummenfelt
For Kristian Blummenfelt the volume of training could look like this based on Strava data: Monday Cycling 60km + Running 20km + Swimming 2km Tuesday Running 10km + Swimming 2km Wednesday Cycling 60km + Running 20km Thursday Cycling 60km + Swimming 2km Friday Cycling 60km + Running 20km + Swimming 2km Saturday Running 10km + Swimming 2km Sunday Cycling 60km Based on Strava stats which also showed that most of his cycling sessions were outdoors. This is not exact but shows the volume of training he did in 2020. Blummenfelt's training volume includes significant cycling, running, and swimming distances.
Lactate Threshold and Training Zones
Lactate Threshold 2 (LT2) is the second point at which the lactate curve kicks up; this is the point at which the body can no longer keep up with (and clear) the amount of lactate that the muscle is producing. The Norwegian training model has athletes controlling their intensity by monitoring their lactate levels, with a large portion of their running volume done at an easy pace (or zone 1). The majority of their interval training is done at an intensity that is just below their lactate threshold (zone 2), and a very small amount of their training is done at zone 3 (high intensity). The Norwegian training model prioritizes training at or below the lactate threshold, with most volume in Zone 1 (easy pace) and Zone 2 (just below lactate threshold).
Practical Approaches to Lactate Threshold Training
Most people don’t have a lactate tester, so you have a couple of options. When I was training in the UK my old University was offering lactate testing in the Sports lab for a reasonable price, so I underwent a very hard evening of testing and got my result based on a series of blood tests. Ideally you should do this for running, cycling, and swimming but if you had to choose one, I would complete the running test. The alternative to work out you running threshold is: Warm up with 5 mins in Z1, then 5 mins in Z2 then do 20 mins in the upper part of Z3 and finish with 5 mins in Z2 then 5 mins in Z1. Take your average pace for the 20 mins section and multiply by 0.95 to get an estimate of your current threshold. For the bike if you can’t do a lab-based test then you can use Functional Threshold Power (FTP) which most triathletes are used to completing on Zwift, Wahoo etc. Your maximum effort for 1 hour is commonly the same as your lactate threshold. Dr. Andy Coggan realized this, so he came up with the FTP concept and simplified things for everyone. If you don’t have a power meter you can do a Heart Rate based similar test. Details of these test can be found in this Blog. Of course, these methods will only give you either data valid on that day or an approximation of your lactate threshold. But you can do these tests periodically to reset your targets for each session. It’s not going to be blood, sweat and tears - but no blood, plenty of sweat and hopefully no tears! You can estimate your lactate threshold through lab tests or field tests like a 20-minute time trial.
Double Threshold Sessions
According to Bakken’s paper, one of the biggest differences between the Norwegian training model and other training models is the inclusion of days when the athlete does not one, but two threshold workouts. Of course, the concept of doubling (especially for triathletes with Brick sessions for example) is not new. In fact, it is a very commonplace practice for most elite runners. In most cases, though, the athlete will do one workout and one recovery run in the same day, not two hard workouts. Doing two hard sessions a day may sound daunting, but these are not all out maximum effort sessions but two threshold sessions. When these workouts are run at the correct intensity you won’t feel too fatigued so you could theoretically do another threshold session a few hours later. This allows the Norwegians to do a greater volume of work than they could if they tried to do one big session. But for age group athletes time may not allow for two threshold sessions a day so one good quality threshold session should be enough to gain the adaptations you need. A key feature of the Norwegian model is the inclusion of double threshold workouts on the same day, allowing for a greater volume of work.
Low-Intensity Endurance Sessions
In the Norwegian modal a large portion of their running volume is done at and easy pace (zone 1) and interval training is done at just below lactate threshold (Zone 2) and a small amount of high intensity in Zone 3. This is good news for age group triathletes as doing the majority of your sessions in Zone 1 will help prevent injuries. But you must be disciplined in this regard and not venture to much out of Zones 1 or 2. Practically speaking if you have a plan that has 80% of your training at lower intensity and 20% for example, at high intensity you could adapt this to 80% in Zone 1 and 20% or less at Threshold.
Polarized vs. Pyramidal Training
In an episode of the Physical Performance Show, Bu said that this shift resulted in a change to the programming model for Blummenfelt and his training partners: “From the Olympics, where it was more or less threshold-oriented, it has maybe become more base or pyramidal-oriented…as you go down in intensity, you get more and more volume.” He also noted that while a training week can be polarized, this is not the pattern that the team typically follows. The concept of training intensity distribution (TID) is defined as the amount of time that the athlete spends in different zones of training intensity during exercise. Usually, TID is calculated by using three training zones: zone 1 (Z1), below the first threshold; zone 2 (Z2), between the first and the second threshold; zone 3 (Z3), above the second threshold. The intensity distribution known as polarized training is defined as having the highest percentage of time spent in Z1, a smaller, but relatively high percentage in Z3, and only a small portion of training in Z2 (i.e., Z1 > Z3 > Z2). On the other hand, pyramidal TID is characterized by accumulating a higher percentage of training time in Z2 and less in Z3, but, as in the case of the polarized model, the highest percentage of training is spent in Z1 (i.e., Z1 > Z2 > Z3). Several experimental studies have shown the potential benefits of both polarized and pyramidal TID compared to other TID models for endurance sports. A recent review on this topic showed that these two models appear to be the most effective for boosting endurance performance in middle‐ and long‐distance runners. In practical terms you can find both polarised and pyramidal style plans on platforms like TrainingPeaks and Final Surge so you can choose which type of training will suit you best and the time you have to train. A professional athlete has the "luxury" of lots of time to train so pyramidal can work for them. For a busy time crunched triathlete a polarised 80/20 style plan may be easier to fit into a working week. You could also deploy either approach situationally. If for example you missed the podium in a race because you got beat during the mad sprint to the finish, perhaps a polarized approach with a bit more time spent in zone three would be beneficial. Or if you posted a couple of DNFs in longer events, then perhaps your baseline endurance and moderate intensity output maybe lacking, and could benefit from going back to the zone one, two, and three spread of pyramidal training. Training intensity distribution can be polarized (high volume in Zone 1, smaller volume in Zone 3) or pyramidal (high volume in Zone 1, moderate volume in Zone 2).
Advanced Monitoring Technologies
Three things Ole Aleksander Bu (Kristian’s coach) points out as essential for his massive success are calorimetry and indirect calorimetry, the Moxy Oxygen Monitor and aerodynamics. Calorimetry: The measurement of energy consumption in humans, where we distinguish between direct and indirect calorimetry. In direct calorimetry, energy consumption is calculated by measuring the heat the person emits, while in indirect calorimetry, energy consumption is calculated by measuring the amount of oxygen consumed and the amount of carbon dioxide produced - especially during training. The measurements tell how much protein, fat and carbohydrates have been used as an energy source, and thus how high the energy consumption has been. Moxy: An oxygen monitor that measures and provides insight into oxygen levels in muscles. The oxygen level in muscles can change based on altitude and climate. Moxy kits start from €749. Core Temperature: The Norwegians changed from a suppository sensor to a non-invasive sensor from CORE which you could use either on a chest or arm strap €259 per sensor. I will leave it up to you if you think this is important for your training. When exercising your core body temperature rises and as this rises, your performance (power) goes down. Monitoring your core body temperature will give you the knowledge and insights to improve your performance Aerodynamics: The study of the movement of air and the forces bodies are exposed to when they move through air or when air flows around them. Alongside the Supersapiens sensor, moxy sensor and core temperature sensor Kristian also wears a heart rate monitor and Styd running footpod. An easy first step is to calculate your Basal Metabolic Rate (BMR) and from there your c… Bu emphasizes the importance of calorimetry, the Moxy oxygen monitor, and aerodynamics.
Calorimetry: Measures energy consumption by measuring heat emitted (direct) or oxygen consumed and carbon dioxide produced (indirect).
Moxy: Monitors oxygen levels in muscles.
Core Temperature: Monitoring core body temperature can provide insights into performance.
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