Podcast, Science and Physiology

Durability in endurance sports with Ed Maunder, PhD and Stephen Seiler, Phd | EP#295

 July 19, 2021

By  Mikael Eriksson


Durability can be defined as the time of onset and magnitude of deterioration of physiological performance parameters over time during prolonged exercise. Dr. Ed Maunder (Auckland University of Technology) and Dr. Stephen Seiler (University of Agder) join us to discuss their recent publication and the overall scientific knowledge on the topic of durability, as well as best practices for assessing and developing durability. 

In this Episode you'll learn about:

  • What is durability, why is it important, and what are the implications of it in racing and in training?
  • What do we know about durability and the mechanisms of it from the scientific literature?
  • How to assess and quantify durability in the lab or in the field?
  • How to train to develop and improve durability?
  • What is high-intensity repeatability and how does it relate to durability?
  • Practical recommendations for athletes and coaches 

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03:25 -

  • I am currently a lecturer at Auckland University of technology.

    I am originally from the UK but I moved to New Zealand to do my PhD.
  • My field of research is health and performance aspects of exercise.


04:25 -

  • Briefly I would define durability as an athlete’s resilience to withstand physical work during very long durations.

    We try to understand at what time and how much (the magnitude) an athlete is starting to deteriorate physiologically (like lactate threshold or HR at different paces/power output) during very long bouts of exercises.
  • Potential confounding factors that may impact durability is heat, hydration status and glycogen depletion.
  • A useful way of assessing or quantifying durability is by looking at HR decoupling (one must make sure to stay hydrated and on top of nutrition to be able to trust the yielded HR decoupling percentage).
  • Even within similar groups, like long distance triathletes, the durability within the group can vary very much.

Mechanisms of durability

12:30 -

  • It appears that fibre phenotype (more slow twitch muscle fibers is associated with greater durability), mitochondrion density (the more mitochondria, the more durability as well as training background (one need to train long sessions in order to achieve a high level of durability) are all connected to durability to some extent.

Improving durability


  • That is what I would like to find out with my research!

    However, I do believe that you need to expose your body for a certain stimuli in order to adapt to that, so doing long training sessions should be one rather certain way of improving durability.
  • (Michael) I have found (on an anecdotal basis), that high overall volume could have a positive development on durability.

High intensity repeatability

27:50 -

  • Conceptual, this is very similar to durability.

    It’s the athlete’s ability to repeatedly perform bouts of high intensity work over time.
  • The development of high intensity repeatability is probably both associated to aerobic and anaerobic capacity, you need a good aerobic capacity to recover from the high intensity bouts but in order to get a larger anaerobic capacity you need to stimulate the anaerobic system.

Practical applications

33:05 -

  • I do believe that it is important for coaches and athletes to start think about this concept, as it is very vital for certain sports (e.g. long distance triathlon).

    (Stephen Seiler)
  • My biggest tips to athletes and coaches is that they need to start embracing the fact that ”fresh FTP” or ”fresh VO2max power” is not something that you always need to strive for and trying to improve as you train.

    Probably, what kind of power you can put out after two, three or four hour could be much more relevant and hence, that is something you should care more about in your daily training.

    Basically, success is not only to improve your ”fresh 20mins power”.

    However, since there is yet no consensus on how to define durability, it is hard for coaches and athletes to try and target to improve.
  • Two interesting ”paths” in an attempt to quantify durability is through HR and changes in breathing patterns.

    HR (i.e. cardiac drift) is a very easy measurement and could be quite accurate as long as you control for confounding factors such as dehydration during the course of the session, however, I do believe we need to be more accurate than this.

    Changes in breathing patterns is a very interesting way of measuring and quantifying durability as the breathing more directly reflects the metabolic intramuscular environment.

Heat training

35:00 -

  • I did a study on heat training, which was HR controlled (i.e. both groups trained at the same HR % in hot and colder conditions respectively).

    The group that trained in the heat rode at lower power due to the heat stress but by the end of the study, they performed better at a 30mins time trial after 2h of constant load work.

    So it appears that training under heat stress yields additional physiological benefits.

Durability’s importance in triathlon

46:10 -

  • (Ed Maunder)

    I would argue that it is super important for endurance sports like triathlon!

    And I would say that it is equally important for amateurs and professional triathletes.
  • (Stephen Seiler)
  • I agree with Ed but would like to add that professional triathletes probably already are rather gifted in this regard and hence have less possibility to improve this matter compared to age group athletes.
  • I would also like to say that the way triathlon is developing towards a more ”stochastic” event (power and pace varies more) and this means that the demand for a high level of high intensity repeatability is greater.

Rapid fire questions (Ed)

52:20 -

  • What is your favorite book blog or resource related to endurance sport? I like everything that Alex Hutchinson comes out with, so I really enjoyed Endure.

    What is a personal habit that has helped you achieve success? I do daily ”to do lists”!

    How is somebody that you look up to and have inspired you? My father, he is extremely willing to think through a problem, which is something that I am trying to strive for myself.


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.

Please contact me if you have feedback on the podcast or want to make suggestions for improvement or send in a question for a Q&A episode.

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