Podcast, Training

80/20 Triathlon (revisited) with Matt Fitzgerald | EP#152

 October 22, 2018

By  Mikael Eriksson

​80/20 Triathlon (revisited) with Matt Fitzgerald | EP#152

Research has shown that cyclists, runners, triathletes, and other endurance athletes improve the most when they consistently do 80 percent of their training at low intensity and the other 20 percent at a moderate to high intensity. Matt Fitzgerald, co-author of the new book "80/20 Triathlon" explains what 80/20 training is all about and answer commonly asked questions. 

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 Matt would put on a t-shirt if he had to distill 80/10 Triathlon down to a very short and concise slogan.
  • The proper planning and the proper execution of 80/20 training.
  • Is there "wiggle room" in the 80/20 percentages?
  • Should you apply 80/20 within each discipline or simply across all your training?
  • The most common mistake age-groupers make: not executing the easy training easy enough.
  • How are easy, moderate, and high intensity percentages calculated?
  • The difference between 80/20 training and polarised training.
  • What to do with the 20% of moderate to high intensity.

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About Matt Fitzgerald

0:45  -

  • Matt is a famous coach, author, endurance athlete and nutritionist. 
  • Matt co-wrote the book 80/20 Triathlon with David Warden, which was recently released. 

80/20 Triathlon 

5:53 -

  • The take home message of the book is slow down to get faster. 
  • The most common and costly mistake that endurance athletes make in their training is spending too much time at a moderate intensity instead of a low or high intensity. 

    Most endurance athletes spend more than half their time at moderate intensity. 
  • The 80/20 ratio refers to the idea that the most effective way to train is 80% of total time at low intensity, and 20% at moderate to high intensity. 
  • For 80/20 purposes the threshold that matters is the ventilatory threshold

    This is an intensity where you're breathing rate spikes; it's a big bump, after a linear increase. 

    You may not necessarily be conscious of this, but if you're breathing rate is measured it's mathematically significant.

    For the typical trained endurance athlete the border between low and moderate intensity is around 77-78% of maximum heart rate.
  • When you cross the ventilatory threshold, your brain begins to recruit more fast twitch muscle fibres, which makes the exercise significantly more stressful to the nervous system. 

    This means it will take longer to recover from. 
  • The original research behind 80/20 was from 2000 by Stephen Seiler, an American exercise physiologist, who looked at elite endurance athletes. 

    He found that across different disciplines, elite performers tend to follow the 80/20 balance. 

    Subsequent research has shown this distribution is more effective at increasing fitness than other ways of balancing intensity. 

Applying 80/20 for triathlon

10.40 -

  • There is likely a threshold for the minimum number of hours you should be training before applying 80/20, but it's quite low. 
  • One of the studies in recreational athletes (runners) who were running 45 minutes a day, benefitted more from 80/20 than a programme with more time spent at moderate intensity. 
  • The important thing is that you should intend to do most of your training at low intensity, and you should follow through on that intention. 
  • It's a big mistake than nearly every non-elite endurance athlete is making: either not having enough low intensity in the programme, or executing planned low intensity sessions at moderate intensity. 
  • In the book you can see the specific numbers in our calculated training plans, and they are very close to 80/20, but it doesn't need to be exact. 

Calculating the distributions

15:36 - 

  • There are different metrics that you can measure intensity with, e.g. power, pace, heart rate, perceived effort etc. 
  • For the actual planning, almost all of the high intensity work will necessarily occur in interval formats, where you passively or actively recover in between. 

    For calculation purposes, the entire interval block should be counted as time at high intensity. 

    This reflects the true physiological stressfulness of interval training. 
  • Low intensity workouts are generally basic aerobic sessions, warm ups and cool downs (but not interval recovery). 
  • Moderate intensity is usually done in medium size blocks - e.g. longer intervals, tempo or threshold efforts. 
  • It needs to be time based, not distance based. 

    If you typically measure your runs in kilometres, and you're planning a 20km run, you need to know how long that will take at low intensity for your calculations. 

    This makes swimming a little complex, but we explain this in the book. 

Measuring intensity 

18:49 - 

  • It's very useful to measure intensity as it helps you look for patterns (e.g. does an athlete improve more or less with a breakdown at a given intensity). 
  • A lot of the online tools that exist for logging your training allow you to see time in zones when you measure intensity. 

    This helps you track whether you're doing what you intend to do, and track your individual pattern. 
  • The 20% of time spent at moderate and high intensity will need to be balanced depending on what works for you. 

    This will likely be different if you are training for a sprint versus an Ironman. 

    You can answer these questions through trial and error, and monitoring your intensity can help you fine tune your planning. 
  • It can be helpful to check back once you've completed the session, and compare what you did with the intensity range you set out to do. 

    You can often overlay these in training logs such as training peaks, which makes it easy to visualise this. 
  • There are calculators on 80/20endurance.com which help with mapping your training.

    Everything relies on baseline testing, so the website details calibration tests or recent race results (for running) which can be used to establish current fitness level.

    You put this result into our online calculator to establish your zones. 

Time frame for 80/20 

23:05 - 

  • Having the 80/20 ratio weekly is probably the best.

    Applying it daily, or to every session, will be too complicated and too granular. 
  • At some times you may need to be doing more or less, but generally trying to stick to 80/20 on a weekly basis if you're training in 7 day cycles. 

Distribution across the three disciplines


  • In my previous book 80/20 running I found that runners tended to get injured, so may do swimming or cycling to build their fitness. 

    For those athletes who were competing in running, the overall balance of combined training should be 80/20. 
  • However, for triathletes it's a little different because you're competing in every distance you train in. 

    Therefore, if you find you get the most performance gain with the 80/20 approach, you should be applying it to each individual discipline. 
  • A case study was done with an Olympic level triathlete, and her training was tracked over a full year. 

    When everything was combined, the intensity balance was very close to 80/20, and each individual discipline was also very close to to 80/20, which proved successful. 

Polarised training


  • There are some people who feel you should avoid moderate intensity all together, or minimise it. This leads to the polarised training concept.

    For this concept, all of your training is either low or high intensity, and little to none is spent at moderate training. 
  • To get the most out of a polarised approach, you would still want to spend a lot more time at low than at high intensity. 
  • Mikael's example: Norwegian triathlon team actually avoid high intensity, but do follow something close to an 80/20 plan with low and moderate intensity. 
  • As a coach, I take a pragmatic approach because I can't wait for the scientists to figure everything out! 

    What makes sense to me is that the distribution within the 20%, which encompasses moderate and high intensity, should depend on the distances you compete at. 

    If you're a pool swimmer doing 100-400m races, most of your 20% should be spent at high intensity. 

    Whereas if you're an Ironman distance competitor, most of the 20% should be moderate intensity. 
  • When you're training upwards of 20 hours a week, you can't do the full 20% at high intensity! 
  • Your training can and should evolve. It becomes more race specific as time goes by. 

Recent research in this area

33:04 - 

  • More recently, Stephen Seiler and others have turned their attention to periodisation. 

    They're conducting studies where everyone is generally training the same, but they differ in their sequencing of types of training. 

    For example, everyone trains the same amount and same intensity distribution, but some athletes do an A phase then B phase, while the other athletes do the opposite. 
  • This is a more granular question, looking at how to sequence phases of training to get the best results. 

80/20 triathlon book

35:19 - 

  • The book contains complete training plans, which are organised by degree of difficulty and competitive race distance.

    However, there is also an entire chapter which shows you how to create your own training plan step-by-step. This chapter is valuable to read, even if you intend follow a pre-created plan. 

    It will help you buy in to what you are doing, and help you problem-solve difficulties that may arise during training.
  • The strength and conditioning section is another really useful section, and underscores how important this is as part of a training plan. 

Listener questions

37:57 - 

  • Dan from facebook: Do sweet spot sessions on the bike, or criss cross interval variations, fall into the 'grey area' and should they be avoided? I can see how an 80/20 approach works with very time restricted training.
    • Moderate intensity doesn't need to be avoided, just minimised to fit within the 20% bucket. 
    • Just make sure that you intend to do most of your training at low intensity, and you actually follow through with this. The biggest mistake is not doing 70/30 instead of 80/20, it's doing 45/55. 
    • If 65/35 works for you, it's still a lot closer to 80/20 than what most people are doing. 
  • Tim from facebook: It would be good to know if there's any guidance on how to pick power targets within the zones? For example, if I'm writing a workout that calls for a zone 3 interval, should I pick a low, middle or upper end target, or should we be working in ranges and how do we define these?
    • My approach is to tailor your specific effort to the specific format of the workout. 
    • For example, zone 5 (highest in our system). You can do 20 second intervals in zone 5, or 90 second intervals. It wouldn't be my intention as a coach for you to do the 20 second intervals at the same power as the 90 second intervals. 

      The shorter the intervals are within the same zone, the higher you should aim within the zone. 

      The total number of intervals will also effect this as you're basically pacing. 
    • This is where the usefulness of the gadgets reach their limit - you are a conscious human athlete and you have some responsibility to use your capacity to think and feel to pace your workouts appropriately. 
    • You should understand how hard you should go. 
    • E.g. You go to the track and run 10x400m in zone 5. The idea is to finish the session having done roughly equal splits for each interval. You want to finish the workout feeling tired, but not completely exhausted. 

      You're going to blow the workout the first time you do it if you're a novice athlete! Pacing takes experience. 
    • The structure and the zones don't do the whole job for you, execution requires pacing and reliance on perception of effort. 

Rapid fire questions

44:15 - 

  • What is your favourite book, blog or resource related to endurance sports or triathlon?
    • For running, I love Greg McMillan's running calculator from mcmillanrunning.com.
    • It's a very useful website for digging deeper to set pace targets for all different types of workouts, and performance equivalent calculations. 
  • What do you wish you had known or done differently at some point during your career?
    • A long list of things! I wish I'd taken more time to know what I was talking about before I'd started talking. I'm proud of 80/20 triathlon, but I wish I hadn't written my earlier books. 
  • Who is somebody in endurance sports that you look up to and admire?
    • I'm a fanboy of top athletes. I'm a big fan of Lionel Sanders right now, he has a great story, he's a gritty guy and he deserves the success he's having. 

Key takeaway

  • There is nothing magic in the numbers, but you should plan to do a large majority of your training at an easy intensity, and then follow through with that

Links, resources and contact

Links and resources mentioned

    Connect with Matt Fitzgerald

    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! 

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    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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  • Hi,

    About the 80/20 distribution and way to do it. If I understood correctly Matt calculates time in zone and that distribution should fall close to 80/20 (low intensity vs intermediate and high). In recent Flo cycling podcast Seiler said that the original idea was to do 80% of sessions as low intensity and 20% as high intensity. He continued by saying that if you count time in zone the distribution should be close to 90/10 because 80/20 would burn out most of the athletes. What do you think about this 80/20 vs 90/10, should one count sessions or time in zone and what the distribution should be?

    • Yes, I’ve also heard Seiler say that on the Flo podcast and others My personal opinion is what we said in the interview already:

      -For age-groupers I would go with using the duration concept rather than the number of sessions, because the number of sessions is low enough that you might not even get in one hard workout per discipline per week if you use the number of sessions approach.

      -With the duration-approach, my *personal* opinion is that 90/10 is not enough intensity for the majority of age-groupers. I see in my coaching that 80/20 works for some, but some (particularly more advanced age-groupers) do best with more intensity, e.g. ~70/30.

      -It’s key that the intensity that is prescribed at low intensity is actually executed at low intensity.

      -Personally, in my latest race build (IRONMAN 70.3 Cascais), my duration distributions were (low – moderate – high)
      Week 1 (recovery from previous race, easier week): 80 – 15 – 5
      Week 2 (build): 75 – 20 – 5
      Week 3 (build): 66 – 28 – 6
      Week 4 (taper): 84 – 12 – 4

      I ended up winning my age-group in a time of 4:20 so I do think this worked well, even if my average low-intensity percentage was only 70% if we discount the taper week and the fact that I had a race before that I needed to recover from. I will have more and better data from future races to compare this to.

      -Of course, these are only my opinions, and yes, it does go against Seiler’s research to an extent. The key for me isn’t the intensity distribution itself, but rather, that the easy workouts are done easy enough and that you are performing in your hard workouts.

  • Thank you for the interesting podcast.
    In the podcase matt mentioned that when you exersice above LT there is a recrutment of fast muscle fiber and increased fatigue.
    I would like to learn more about it, can matt specify a reference on the topic ?

  • Sorry to be a bit late to comment on this.
    What Seiler’s research shows is that elite endurance athletes completing HIGH VOLUMES of training have a training intensity mix with the so-called polarized, 80 (below vt1)-20(above vt2) distribution. This is actually not a choice, but is pretty much obligative to avoid nutritional fatigue. Shifting the mix upwards would place greater demands on glycogen stores that could not be replenished.
    In my opinion, this says very little about the optimal training intensity mix for athletes completing lower training volumes. Indeed we have seen examples of elite athletes following the opposite ends of high and low volume training regimens, whilst producing near-identical performances (e.g. Bannister vs Elliott, Coe vs Ovett).
    What is not understood is the relative contribution of the 80%low intensity and 20% high intensity to race performance in Seiler’s studies, and therefore which components should be prioritised in low volume training regimens in triathlon

    • Hi Dave,

      Yes, I 100% agree with you.

      Note that the episodes report on the interpretations/opinions of my interviewees, I don’t necessarily agree with everything myself, but I think it’s important for anybody to hear and try to understand different perspectives. That way we can continue to learn and grow as athletes and coaches.

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