Cycling, Physiology, Podcast, Science

FTP, VO2max and VLaMax: what triathletes need to know with Sebastian Weber | EP#169

 February 18, 2019

By  Mikael Eriksson

​​FTP, VO2max and VLaMax: what triathletes need to know with Sebastian Weber | EP#169

Sebastian Weber is a sports scientist and highly successful coach, in both professional sports (having worked with athletes like Peter Sagan, Tony Martin, and André Greipel) and with age-group endurance athletes. He is also the co-founder of the physiological performance software INSCYD. One of the important factors for his success is his knowledge about exercise physiology and metabolism. Today, he shares this knowledge with us so that you too can benefit from it and become a faster triathlete.

Discuss this episode!

  • Let's discuss this episode and the topic in general. Post any comments or questions in the comments at the bottom of the shownotes. Join the discussion here!

In this Episode you'll learn about:

  • What is FTP (Functional Threshold Power), why does it even exist, and how can you train to improve it?
  • The only two variables that can be changed to improve FTP: VO2max (Aerobic Capacity) and VLaMax (glycolytic capacity)
  • Why you need to focus on changing VO2max and/or VLaMax, and NOT FTP itself, if you want to improve your FTP.
  • How to train to increase VO2max to increase FTP.
  • How to train to decrease VLaMax to increase FTP.
  • How VO2max and VLaMax determine your fat and carb oxidation at any intensity (including submaximal intensities).

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About Sebastian Weber 

0:50  -

Sebastian's background 

5:12 -

  • I am a sports scientist by training, I studied sports science and molecular human biology. 
  • I have been involved in performance assessment and coaching for almost 20 years. 
  • I started my own human performance lab and coaching business Steps in Germany, which eventually became one of the most successful coaching business down there. 
  • I also have a history of coaching in professional cycling. I've been the head coach and performance scientist on teams like HTC High Road Columbia, Katusha Cannondale etc.  
  • In the last 2-3 year I've moved away from that to coach some individual athletes.

    I have worked with triathletes too such as Cameron Wurf. 
  • These days I am mostly consulting and helping teams and organisations in different sports. 

    I do a lot in professional and Olympic swimming. 

Metabolic systems used in endurance sports

7:48 -

  • There are three metabolic systems that help a muscle produce energy. 

    By energy here, we mean the energy needed for locomotion. 
  • The three sources of this energy are:

    1) Breaking down creatine phosphate - this is a fast source of energy and only lasts a few seconds.

    2) Glycolysis (aka anaerobic system) - where you transfer glucose or carbohydrate into pyruvate or lactate.

    3) Aerobic metabolism - where you use oxygen to burn things - you burn the pyruvate or lactate to make fuel, or burn what comes out of the beta oxidation.
  • These are the only way energy or power is produced on the swim, bike or run. Power is provided by a composition of these three systems simultaneously. 
  • The shorter the duration and the high the intensity, the more you tend to use your glycolytic and creatine phosphate (anaerobic) systems. 
  • The longer you go and the lower the intensity, the more you are depending on your aerobic systems. 
  • However, how much you depend on one system or another can differ dramatically between athletes, even for the same efforts. 

    This isn't necessarily given by genetics, but it depends on the athlete's training. 
  • If you have a higher anaerobic capacity, you will use this system more. 

What is VO2max?

12:33 - 

  • VO2max = your maximum aerobic oxygen uptake. 
  • The oxygen uptake itself though is not something we are interested in. The question we are trying to answer is: how much power/ATP can you produce in your aerobic metabolism. 
  • You cannot easy take a sensor and stick it into the muscle and measure this power output directly.
  • However, the amount of aerobic energy production is proportional to the amount of oxygen consumption. 
  • This means your VO2max is nothing more than a marker for aerobic energy production.

    This is why you want to know it. You're not interested in oxygen uptake, you're interested in producing power, but it's proportional to it. 
  • If we had another easier way of assessing this, we probably would, but VO2max makes it accessible. 


17:15 - 

  • VLaMax = the maximal lactate production rate. 
  • VLaMax is a marker for the maximal capacity for performance of your glycolytic system.
  • Every time you produce lactate in the glycolytic system, there's a production of ATP attached to that. 
  • If you have short term effort, e.g. 100m sprinter/50m freestyler in swimming, they will need to maximise their VLaMax because they need high glycolytic energy production. 
  • You will see tremendous differences in VLaMax for different types of athletes. 
  • It will also change a lot throughout the year depending on what training you're doing. 

    E.g. if you're training weights in the gym, you may see it rise. 

    Triathletes who come of their off-season having spend a lot of time weight training in the gym may have elevated VLaMax compared to their on season.

Tying VO2max and VLaMax into FTP

21:40 - 

  • FTP (functional threshold power) is the modern power training term for anaerobic threshold. 
  • It's the maximum intensity you can hold without accumulation of lactate, or the fatigue that goes along with that phenomenon. 
  • It's related to your 10km running speed or your 1-hour time trial performance. 
  • Your VO2max and your VLaMax determine approximately 97% of your FTP. 

    This is because your aerobic system defines how much lactate you can combust. Your glycolytic system determines how much lactate you produce. 

    These two combined determine what your FTP is.
  • If you want to increase your FTP, you are better off understanding what your VO2max and/or VLaMax are to decide which you need to work on. 
  • FTP is like how much money you have in your bank account. 

    This can occur by either earning more and spending more, or earning less and spending less. 
  • In endurance sport, people often train to change their FTP or prescribe training programmes without understanding the mechanics behind it. 
  • If you have a high VO2max it will lift up your FTP power.
  • If you have a high VLaMax it will decrease your FTP power.
  • For example, two 75kg athletes can both have an FTP of 300 watts.

    One athlete can have a VO2max of 65 and a VLaMax of 0.3/0.4.

    The other athlete can have a VO2max of 76 and a VLaMax of 0.7. 
  • If you don't know what is behind the FTP, you can't really establish a precise and focused training programme. 

    Decreasing VLaMax and increasing VO2max would require different training programmes. 

Substrate utilisation 

29:39 - 

  • As a triathlete you probably don't need to sprint, so you probably won't be that interested in your VLaMax. 

    However, the reason why you should care is because if your VLaMax is higher it means that you need a substrate to do that.

    The only substrate your body can use to produce lactate in glycolysis is glucose. 

    This means the higher your glycolytic system is trained (i.e. the higher your VLaMax), the higher your glucose utilisation is. 
  • This is also true in endurance conditions. So if you have a high VLaMax it means that your metabolism depends more on glucose and you burn more of this fuel and use less fat. 
  • If you had the same two athletes as above with the same FTP but different VO2max and VLaMax and they ride at the same pace, the athlete with the higher VLaMax will be oxidising more carbohydrate than the other. 
  • Glucose or pyruvate or lactate are primary fuels. Whenever your metabolism is producing a lot of energy and lactate, you are not burning fat. 
  • Let's say you do a hard interval session, and you do the intervals at the same power you do your long slow distance sessions. You assume you're burning a lot of fat.

    However, in the 6 minute recovery for intervals, you're not burning fat. You're doing it just to burn lactate. 
  • Whenever there is a lot of lactate production, you're not using fat. 
  • It's much easier for your muscles to use primary fuels, so whenever it's there your body will use that. 

    Whenever this system is highly developed, there is less fat burning, which is a performance limiting factor for a triathlete. 
  • If you are on a group ride and you sprint for two minutes, you will then have a lot of lactate leftover which will be used preferentially for fuel. 


36:18 - 

  • Percentage of FTP comes from percentage of lactate threshold. 

    It works in terms of a practical application. However, there is a systematic limitation because your FTP is not directly related to one single metabolic system. 
  • You can't say you're training at 60% of your VO2max because you can't identify which system you are specifically straining. 
  • In gym training, you base your intensity for squats on your one repetition maximum in squatting. You don't base it on your one rep maximum in the bench press because it's a different system. 

    This is the problem with basing your training on your FTP - it's not a clear link to just one metabolic system. 
  • When you train at a percentage of your FTP, you cannot understand how much stress you put on your aerobic system or your glycolytic system.
  • For example if you put 10 people on the same training programme based on % of FTP, 5 people will develop in one direction, and 5 in the other.

    This is because the actual training of their aerobic and glycolytic systems will be completely different. 

Training to increase VO2max

40:28 - 

  • Everything has an impact on your VO2max! All training you do will use this system and will therefore have an impact on it. 
  • Whenever you workout or do endurance training, the longer the stimulus is applied to your aerobic system. 
  • You can just increase your training volume to increase your aerobic capacity and VO2max.
  • Also if you increase intensity, your VO2max will also go up.
  • There is no easy answer to the question of what you should focus on specifically.
  • Depending on your muscle fibre phenotype (slow twitch and fast twitch) you may react better to long slow distance training or high intensity interval training. 
  • The muscle fibre distribution is a little bit implied by the VLaMax. 

    We have coaches who actually use the VLaMax to make an informed decision on whether an athlete will benefit more on short high intense (fast twitch), or long slow distance training (slow twitch). 
  • Polarised training seems to favour development of your VO2max in a simplified manner. 

Training to decrease VLaMax

43:12 - 

  • It's more complicated in VLaMax. If you want to decrease it, the first answer is to avoid anything that increases it. 
  • For example, high intense gym training is a very good glycolytic stimulus, so you would not want to include this type of training if you are targeting a decrease in VLaMax. 
  • It's important to understand the principle of glycolysis. 

    The vast majority of glycolytic energy production is happening in the fast twitch fibres.

    The fast twitch fibres have a higher threshold for recruitment.

    If you're only going super easy (e.g. 40% of threshold), you are not recruiting those fibres. 

    If you're not recruiting the fibres, you are not expecting them to adapt.
  • Practically, this means you need to have a training intensity in the range of 80-90% of threshold (60-70% of VO2max). This is when you start using your fast twitch fibres. 
  • The sweet spot training, a little below threshold, trying to do endurance exercises at this intensity will help a lot with decreasing your VLaMax. 
  • You can also help this with nutrition. 

    If you're trying to lower lactate production and glucose consumption, you don't want to feed yourself a high glucose diet. 

    You would try to restrict the amount of carbohydrate you eat before these training sessions. 
  • If you do a year of training that lowers your VLaMax you might see a shift in muscle fibre distribution. 

    Therefore, the training you benefitted from that year may be different to what you would benefit from the next year. You may need to change the type of training to see the same improvements. 

Training to increase VLaMax


  • Avoid anything that decreases it! Avoid your mid-range intensity, low carb intake endurance exercise. 
  • Look at the Tour de France - the sprint on the Champ Elysees on the final day, the maximum power is usually decrease in all athletes because their glycolytic system is decreased. 

    This is because the three weeks of the Tour is the best recipe to decrease your VLaMax - you are never glycogen replenished, and you spend a lot of time riding mid-intensity, low RPM. Avoid this!!
  • Look towards polarised training that avoids mid-range. 

    Either have very low intensity endurance training, combined with high intense, high power, high speed gym training and sprint training. 
  • Make sure you are always glycogen replenished. 
  • Either don't use your fast twitch fibres, or use them in a high power, high glycolytic energy turnover sessions to trigger that system to increase its capacity. 

Nutrition considerations

53:39 - 

  • It's important to understand that 'not glycogen replenished' is different to 'glycogen depleted'. 

    Not being completely glycogen replenished is a small add on in terms of training stimulus to work on the VLaMax. 
  • There have been a lot of ideas around low carb training and carb-restricted training and its impact on the VO2max. 

    The truth is that on a molecular level, it works great, but on performance outcome the data is pretty weak, especially in amateur athletes. 
  • There's a lot of studies coming out from the Supernova project that there's no effect, even with periodised nutrition. 
  • This isn't to say it isn't working at all, but I would be super careful. When you look at the data on average it is not working. It only works in single athletes. 
  • It's important to understand that when you read about professional athletes doing a high fat diet, they don't care about average performance of an athlete. They care about improving performance of that one athlete. 
  • There are athletes that respond well to these nutrition changes, but if you want to go down this road I'd strongly recommend monitoring yourself regularly (VO2max, VLaMax, body composition etc). 
  • When I was coaching a professional bike team we were using these methods but only with single athletes. We would never have put all athletes on the same low carb diet. 
  • If the goal is performance improvement, maybe put more effort into how to train rather than the nutritional interventions. 

57:53 - 

  • INSCYD is a software which launched 1.5 years ago.
  • It has been used in swimming and other professional sports. 
  • The method and knowledge behind it has been used for more than a decade in different swimming federations and professional cycling. 
  • It is a big algorithm engine which is made of basic fundamental physiology knowledge. 
  • It is a software which is debunking or showing you the composition of the performance of the athlete. 
  • It looks inside the body of the athlete to understand how energy is composed.

    How is your FTP composed (aerobic metabolism versus anaerobic metabolism)?

    How is your performance sub FTP composed - how much fat or carbohydrate do you burn? 
  • It looks at your running economy - how much energy do you have and how fast can you run with it? 
  • The software is able to tell you what you need to do to increase your performance. 

    E.g. should you work on body composition and losing weight? How much will this reduce your marathon time by?
  • Coaches for professional athletes and teams, but also amateur athletes are using the software to analyse the performance of their athlete. 

    It can then be used alongside training to monitor progress

Rapid fire questions

1:02:39 - 

  • What is your favourite book, blog or resource related to triathlon or endurance sports?
    • I don't have one really. I tend to look to other sports or field of research and try to learn from them. 
  • What is a personal habit that has helped you achieve success?
    • Honestly, endurance sports. Having been through training a lot of pushing my limits through the three disciplines has helped me build stamina, and a don't stop don't give up attitude. 
  • Who is somebody in endurance sports, or any field, that you admire and look up to? 
    • There have been several people I have a been happy to work with. 
    • From a business and work perspective - Bob Stapleton who was my manager at HTC.
    • I have people in the science world who I've learned a lot from too. 
    • From a coaching perspective, Dan Lorang. He was one of my interns 10 years ago and now he's a coach in triathlon and also cycling. I respect him for the skills he has and how he coaches people. 

Key takeaways

  • If you don't know your VO2max and your VLaMax you can make educated guesses to improve your performance but you can't know for sure. 

    It becomes easier one you know these for sure and you can have more confidence in your training. 
  • Personal example: My (Mikael) VLaMax was 0.30 which is perfect for triathlon. This means that if I want to improve I need to focus on my VO2max. 

    For me this means focusing on endurance training, and for quality sessions I do VO2max intervals. 

Links, resources and contact

Links and resources mentioned

    Connect with Sebastian Weber

    Connect with host Mikael Eriksson


    Hi! I'm your host Mikael,

    I am a full-time triathlon coach and an ambitious age-group triathlete. My goal is podium at the Finnish national championships within the next few years.

    I first started the website Scientific Triathlon in autumn 2015 as a passion project to share my learnings with a larger triathlon audience. Later on, in early 2017 I started the podcast That Triathlon Show. 

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    Let's discuss this episode and the topic in general. Post any comments or questions in the comments below. I'll be here to reply and take an active part in the conversation, so don't be shy! 

    Mikael Eriksson

    I am a full-time triathlon coach, founder of Scientific Triathlon, and host of the top-rated podcast That Triathlon Show. I am from Finland but live in Lisbon, Portugal.

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  • I found the comments about Power@fatmax as a proportion of FTP interesting. I’m guessing this might be another way of judging which knob needs adjusting to achieve your goals?

    • No, power @ FatMax doesn’t help you here as both FatMax power and the amount of fat oxidised at that power are directly influenced by both VO2max (higher is better for fat oxidation) and VLaMax (lower is better). You could have the same FatMax and fat oxidation by having a higher VO2max and higher VLaMax, or by having both of those be lower.

  • Thank’s for yet another very interesting episode!

    What does “high intense gym training” mean? The heigh weight low reps training perscribed for running or biking or does it mean “much to” intense lifting not resting enought between sets etc. (like tabata or HIT strengh training).

    You say “sweet spot training, a little below threshold will help decreasing your VLaMax”. Does this mean that zone 4 and 5 training will give the opposite effect and therefore should be avoided (if let’s say the aim is to lower the VLaMax).

    I guess that the VLaMax differs between diciplines? Let’s say you have a high biking VLaMax. Could you at the same time have a low running VLaMax? And will having different targets for the bike and run training give conflicting effects. Let’s say you’re doing a lot of zone 3 on the bike to lower the VLaMax and at the same time you’re doing a lot of zone 4 on the run to work on the VO2max.

    Finally. You never hear about any sweet spot run training? If having a high running VLaMax. I guess that the high zone 3 is the way to go?

    Thank’s again, Mikael!

    • In a different INSCYD webinar by Lotto-Visma cycling team coach, he said the following for *improving* VLAmax:

      * short all out intervals (beginning of the training session)
      – 20s to 30s (almost) all out, complete recovery
      – follow by very low intensity ride to maintain aerobic capacity
      * strength training
      – 8-12 reps submaximal (60-70% of 1RM): speed of movement all out
      * no low carb training
      * no torque training (no low cadence)
      * basic endurance intensity
      – lower volume training weeks (15-18 hours)

    • Hi Rickard,

      About gym training, to my knowledge explosive lifting is one of the best drivers of increasing VLaMax in this context. I don’t think that a pure high weight low rep protocol is a strong driver/stimulus for increasing VLaMax when done correctly, but perhaps if recovery between sets is too short it may become one. Tabata and HIIT strength training though most likely (depends on the exact protocol) are very glycolytic and therefore strong drivers for VLaMax on the other hand, same thing with typical crossfit workouts.

      I think in fact that Z4 work can be combined quite well either with sweet spot training (to lower VLaMax) or with VO2max training to increase VO2max, but mind you, this is based on anecdotal evidence and personal observations. But I definitely do not think that it has opposite effects to Z5 work. The question is, is it “ideal”, and that’s I guess where personal experimentation is the best way to get an answer. If the objective is to lower VLaMax you might focus more on lower Z4 work with longer interval durations, and if the goal is VO2max improvements you might want to focus on high Z4 work, so interval durations will naturally be shorter. Also, in the former case, combining the Z4 work with low cadence work makes sense, but not in the latter case.

      Yes, VLaMax differs between disciplines. There is likely a correlation between biking and running, as both sports rely on leg muscles. But a correlation doesn’t mean they are the same and that training prescription will be the same. I don’t really think that there will be conflicting effects if you do different type of work in the two disciplines, but sure, in an ideal work I try to program similar type of training simultaneously in both cycling and running. At least in terms of VO2max, since some of the adaptations are so central (e.g. stroke volume) there is a strong crossover effect there, that improvements in one discipline will have a positive impact on the other. And, if you do one VO2max workout in each discipline, you do two total VO2max workouts per week and therefore the stimulus gets stronger, so it may be a case of 1 + 1 = 3, as both disciplines may benefit.

      No, the term Sweet Spot isn’t used in running, but really, sweet spot is only an invention that’s made it’s way into the cycling vernacular because power meters allow us to be so granular with intensity. That doesn’t mean that that level of granularity is necessarily needed. In running we talk about things like tempo runs and cruise intervals and threshold intervals, and all of them overlap with SS training.

      • Thanks Mikael for a very detailed and clear answer. It had Joel Filliol class all over it:) This made many of my thoughts more clear.

        If you need ideas for future pod-episodes maybe you can do one about zone 4 training and how to structure it in different ways. When to train below or above the anaerobic treshold (or spot on). The so-called Y-zone that Matt Fitzgerald believes should be avoided and the the high zone 4 that Steven Sieler found to be very effective etc.

        • That’s a great idea for a podcast. I might use it in a future Q&A. Although, I should warn you that the answer to that question will be very much anecdotal.

  • Just to clarify my second question; Sebastian says that you don’t want to prescribe training that stimulates different targets. For me, I have been thinking about zone 3 and 4 work as very similar; that it will be raising the FTP from below, the first is not as effective but you can maintain it for longer time etc. So it’s easy to Think that you could bunch the two together in a block, while it would be better to put the zone 5 work in another block. But, if I understand correctly, is it so that zone 3 mostly will trigger lowering the VLaMax while zone 4 mostly will raise he VO2max and is the most effective way not putting them together in the same training block?

    • See my previous response. I think in my personal experience Z4 work can be used in both ways. But that doesn’t mean you have to use it of course, doing a block where the intensity is completely focused on Z5 may be just as good or better if you can handle it. Individuality is key here.

  • I may have missed it, but there was no discussion about how
    one might measure VLamax. There is a Wingate test
    (and a variation of it such as 15s all out sprint) of course. However, in one of the INSCYD webinar Dan Lorang (whom Sebastian mentions) said that measuring VLamax is very difficult and that they (Team Bora) rely on software to calculate VLamax.

    You can of course devise your own test that will show you whether your Lamax (NOT Vlamax) is increasing or decreasing during your season. Jan Olbrecht describes a simple protocol for swimming in his book “The Science of Swimming”.

    It would be good to hear what Sebastian’s suggested protocol for
    measuring VLamax is for both running and cycling.

    • Hi Ivan,
      One could measure VLaMax with a 15-s sprint, by taking lactate samples before and following that sprint and doing some calculations.

      Or one can do a critical power test and analyse the results with the INSCYD software. That’s the testing Dan Lorang refers to. And since Sebastian is the founder of INSCYD, I think it’s pretty clear that that’s what he would recommend 🙂 Not only do you learn about VLaMax, but also VO2max, anaerobic threshold, fat and carbohydrate combustion at various intensities, and much more, so you would get much more information than from just a lactate test designed to calculate VLaMax that way. See more at the page I linked to.

      I’m not sure, but I don’t think that LaMax is a good proxy at all for VLaMax. Since the former is lactate concentration and the latter is production rate. Theoretically, you could have a really high production rate but still not be able to have a high concentration of lactate in your blood. It’s depending on training status and many other factors. So while LaMax is also useful to know, I would not use it to infer anything about VLaMax or the training objectives discussed in this context.

  • Thanks for all information you share with us.

    Decrease VlMax with z3 or low Z4 , (20min to 40min ) right? but how you organized in polarized training,? thinking of z3/z4 its the zones you want to avoid .

    And you have ideas for decrease VlMax with running , or you think biking is enough for change across disciplines.?

    last question (sorry) , you think Olympic and sprinters, want a greater VLMax (higher than 0,3 ) than half/ironman athletes?

  • That was one of the best and most interesting podcasts I’ve heard here so far, thanks for bringing this subject to the discussion Mikael.
    Just a thought, if I divide my FTP by my power at Vo2Max, this ratio could not indicate which knob should I be switching?
    Explaining better, if the ratio is higher than 88% would indicate my VlatMax is already pretty low and I should work on increasing my Vo2Max if I want to improve.
    If it’s lower than 88% I should work on decreasing VlatMax instead and this would lift my FTP closer to my Vo2Max power.
    Considering that 88% is a desirable ratio, of course (not sure about that, read this is in a book).
    Best regards,

  • Hi Mikael,

    That was another great podcast and definitely got me thinking about things differently. One thing that jumped into my mind while listing to Sebastian talk about ways to lower VLaMax, and how you want to avoid highly anaerobic work was the different types of HIIT interval training discussed by Paul Laursen. Type 1 and Type 2 HIIT training are meant to be mainly oxidative, with Type 2 also having some neuromuscular components. Given that these two types minimize the anaerobic aspect, would you think they would be a type of VO2 max workout you could do, to increase your VO2 while also working on decreasing your VLaMax.

    I had this thought as I would guess most age group athletes would be looking to both decrease VLaMax and increase VO2 at the same time. Based on my understanding, it would seem that having one sweetspot workout and one type 1 HIIT workout would a week would help to both increase VO2 max and decrease VLaMax. I may also be missing something and have this totally wrong so would be really interested to hear your thoughts.

    Thanks for all the great podcasts.


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