Podcast, Running, Science

Running biomechanics, economy, and training load with Izzy Moore, PhD | EP#241

 July 6, 2020

By  Mikael Eriksson


In this Episode you'll learn about:

  • Running biomechanics, self-optimisation, and gait analysis
  • Wearables and running biomechanics metrics
  • Running economy: what factors impact it, and how can you improve it?
  • Injury risk and prevention
  • Footwear, and the impact on biomechanics, economy, and injury risk
  • Training load quantification

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04:00 - 

  • I am doctor and phd in biomechanics specializing in understanding the biomechanics, running economy and moving patterns in running.

Performance aspects of running biomechanics

05:25 -

  • One of the first studies that I carried out, which also came to kick start my phd was a study where we looked at female runners over a period of time of consistent run training.

    These women were not told specifically to change anything intentionally in their running technique, but after the intervention period, we could still see significant improvement in running economy and running efficacy in these individuals.

    We could see quite clearly that the running economy improved in the same way as their fitness increased.

    The intervention period of the study was 10 weeks and the subjects were completely untrained females.

    In terms of results, the average improvements in running economy of the subjects in the study were around 7 %, which is regarded as an extremely big improvement.

    Looking at the kinetics of these women, we also could see that their movement pattern by the end of the study was much more similar the kind of movement pattern that is typically associated with a good running technique.

    This big of an improvement can basically only been seen in untrained individuals, in trained athletes, these major kind of improvements is never seen.
  • In terms of performance translations of improvements in running economy, a good rule of thumb is that an 8 % improvement in running economy tends to yield a 5-6 % improvement in actual running time.

Barefoot running

22:50 -

  • In another study we compared barefoot running compared to cushioned shoes as well as mid foot shoes.

    What we could see in this study was that people who run barefoot express a better running economy compared to both types of shoes.

    The movement pattern also changed in a quite substantial way when running barefoot.
  • The metabolic benefits of running barefoot seems to go away when the shoes way 220grams or less, then the data shows that you are getting the same benefits as running without shoes at all.

    If one takes the Nike Vaporfly for instance, these are both light and have a great cushioning, which offers an increased return energy as well as giving the metabolic advantages as running barefoot, therefore offering the ”best out of two worlds”.
  • One could also discuss the eventual effects on injury risk by running barefoot, which by alternating barefoot running with ”regular running” could actually decrease the injury risk.

    However, the injury risk could also be diminished by switching running shoes every 2 weeks or so to make sure that the muscular skeletal system is not being overloaded in the exact same way all the time.

    Studies on this suggest that the injury risk could be reduced by 10-20 % just by regularly alternating shoes in training.

Intentionally changing running patterns/movements

30:35 -

  • In another study we investigated what kind of cues (external or internal) are best in order to initiate a change in running movement patterns and as a consequence also running economy.

    However, we could not see any differences in what type of cues are the best strategy to change running movement patterns
  • Furthermore, we could also see that only the athletes who are being rather far away from the ”mathematical optimum” of running economy were the ones who could see some gains in trying to deliberately change their running economy.

    More experienced runners who already showed a rather good running economy and efficacy did not improve their running economy by external or internal cues.

    However, other studies suggest that a high running volume over a very long time (several years) lead to slow but steady improvement in running economy.

    This effect is even stronger in unexperienced athletes.

Gait analyses

40:00 -

  • In my opinion, the benefits from doing gait analyses are for most people quite slim.

    Many of the people carrying out the analyses are really knowledgable people and have a firm knowledge and understanding of biomechanics.

    However, how to implement this knowledge to consumers in a constructive way and without ”over coaching” is really difficult and on this level, I see many of these professionals making mistakes.

    For the most part, just continue to encourage a high running consistency and volume is enough.

    Changing too much could also result in injury.

    Another aspect to it is that novice runners, who has not yet paved in a moving pattern have a higher chance of benefiting from such an analysis.

Running dynamic metrics

46:00 -

  • Unfortunately, the data of many of the new running devices such as running power meters etc. have not been validated scientifically, which makes them a bit hard to trust.

    On the other hand, as long as the metrics are consistent, for you as an individual it does not matter that much if they are correct or not.
  • However, most of these data, such as for instance contact time, I would not know exactly what to do with these metrics
  • Cadence can, however, be a quite good metrics to keep track on.

Injury prevention 

52:00 -

  • For injury prone runners, their biomechanics can play a big role in the development of frequent injuries.

    These athletes could highly benefit from trying to deliberately change their running movement pattern, and the science say that working with internal cues are the most effective way of initiating such changes.

    Examples of interventions possible to carry out is to increase or decrease cadence, increase ground contact time, changing the hip angle etc.

    In order to successfully change running mechanics it is important to give the athletes short and straightforward instructions on how they should change their gait.
  • In a couple of ongoing studies, I hav tried to relate workload, chronic and acute, to injury risk.

    However, there are some major issues on how to define chronic and acute workload as well as workload itself, which makes it really difficult to do science on this subject.

    With this said, I would like to emphasize that I do think that workload plays an important role for injury risk, it is just that we do not really know how to address that scientifically yet.

Final advice

1:05:45 -

  • I would like to advice people not to try and change their biomechanics for performances reasons, instead do it as a part of rehabilitation from an injury or to prevent injury.

Rapid fire questions

1:08:20 -

  • What is your favorite book, blog or resource related to running, endurance sports or anything that we have basically discussed here? Biomechanics of Distance Running by Pete Cavanagh, which is a real classic from the 90s.
  • What is your favorite of gear or equipment? My iPod.
  • What is a personal habit that has helped you achieve success? It is nice to be important, but it is more important to be nice!


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.

If you are a long-time listener and appreciate the value the podcast brings, please consider taking a couple of minutes for leaving a rating and review on iTunes/Apple Podcasts, or wherever else you can think of leaving a rating and review.

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