Nutrition, Podcast

Nutrition for endurance and ultra-endurance athletes with Trent Stellingwerff, PhD | EP#265

 December 21, 2020

By  Mikael Eriksson


Trent Stellingwerff, PhD, is the Director of Performance Solutions at the Canadian Sport Institute Pacific in Victoria, Canada. His primary research focuses are in the field of nutrition and physiology interactions, as well as in environmental (heat and altitude) physiology. In this interview, we discuss the current best practices from and applied and scientific perspective in endurance and ultra-endurance sports.

In this Episode you'll learn about:

  • The importance of nutrition, and the simplicity of doing it well enough
  • Periodised nutrition and the "train-low" paradigm (training with low muscle glycogen levels)
  • Specific advice for ultra-endurance athletes (athletes doing events lasting longer than 4 hours)
  • Relative Energy Deficiency in Sport (RED-S)
  • Trent's top nutrition advice as an applied practitioner to endurance athletes

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05:15 -

  • My name is Trent Stellingworth and I live in Victoria, Canada, and I am one of the performance directors at the Canadian Pacific Sports Institute, which primarily works with the Olympic and Paralympic teams.

    Primarily (but not exclusively) I am engaged in endurance sports.
  • I am also an adjunct at the local University, and has an extensive background within academia.

    My research over the years has foremost been related to nutritional aspects of sports and performance, even though I have conducted studies unrelated to this topic as well.

    My take on the importance of nutrition for sports performance is that it is fairly easy to get to 90-95 % of the potential gains that nutrition can give an athlete, it is about doing the basics (3-4 healthy meals/day + some snacks related to training) and you’re practically there.
  • In my youth, I was also an athlete myself focusing on middle distance running.

Top nutrition advice to athletes

13:30 -

  • Try and eat regularly (every 4-6h).
  • Spread out the calories evenly over the day.
  • Focus on refueling well after every session (0-3h after each session).
  • In the race situation, make sure to have a really diligent nutrition and hydration plan.

Periodized Nutrition

16:30 -

  • This is a really broad subject and covers many fundamentally different time perspectives and types of nutrition (creatinine charging, low carb training, etc.).

    In many ways, it is extremely intuitive, like you need to take in more calories in times when you train more.
  • In endurance sports, one much debated way of periodized nutrition is the low glycogen availability training.

    There are many, many factors to consider in regards to training with a low carbohydrate stores.

    Athletes engaged in non-weight bearing sports such as cycling and swimming, where the biomechanical load normally does not pose an issue for the total volume of training that can be conducted, these athletes typically train between 25-30h per week and hence one will automatically come across periods where the glycogen stores are fairly empty during the week, and for these athletes, one does usually not need to undertake specific nutritional interventions.

    For runners, who maximally can only run maybe 12h per week (due to the risk for injury), however, nutritional interventions can be a really powerful tool to utilize to simulate for instance that last 10km in a marathon.

    There are also potential risks involved in practicing low glycogen availability training, new research suggests that it may be associated with increased bone break down, consequently leading to a greater risk for stress fractures.

    On the other hand, there are plenty of research on a molecular level that suggests that some of the most important signaling pathways that enhances mitochondrial biogenesis, fat oxidation rate (basically processes that favors an endurance muscular phenotype) etc. are massively up-regulated when training with low glycogen stores.

    Conversely, one has not been able to reproduce these research results on a macro level, i.e. translated into performance, where one instead has seen decreased performance in the low glycogen availability training groups.

    However, in my opinion, the design of these studies could have not been ideal and representative of how one would implement low carb training, and therefore I still think that there are some potential benefits to be had from this approach when implemented correctly.
  • From an amateur perspective, I think that a periodized (around once a week) approach to training with low glycogen stores can be quite beneficial, since most amateurs don’t have the time time to train large volumes so that they automatically sometimes end up in a low glycogen state (then creating this state by nutritional interventions could yield a rather powerful stimuli).
  • In relation to this, I would also like to raise a red flag for RED-S (relative energy deficiency in sport), which basically is when the energy intake is not matching the energy output (also highly related to over training).

    One will be at a higher risk of acquiring this when doing these types of nutritional interventions.

    Moreover, it is important to stress that the workouts conducted in a low glycogen state should not in any circumstances be high intensity workouts.

Periodizing iron supplements

47:50 -

  • Iron is obviously a very important subject for endurance performance, because of it’s vital role in the hemoglobin molecule.
  • Some knew knowledge within the iron metabolism research has raised some interesting questions on how and when to best take iron supplements.

    The uptake and utilization of iron is dependent on many different factors, including time of the day, state of inflammation in the body etc., and it seems like the best way to take iron supplements is to take a large dose early in the morning (rather than spreading out the same amount of iron over the day).

    Additionally, iron uptake also seems to be related to energy deficiency, new research suggests that a low energy state may inhibit the uptake of iron.

    I’m estimating that 60-70 % of female elite athletes and 40-50 % of male athletes do take iron supplements during the majority part of the year.

Nutrition for ultra-endurance athletes (events > 4h)

58:00 -

  • My day-to-day advice wouldn’t change from the tips I gave earlier.
  • In terms of race nutrition, it maybe very obvious but the longer the event (and hence the lower the intensity), the more options you have (during 3-4 days events one can eat plenty of regular food).
  • If one individual is competing in ultra-endurance events that lasts between 10-15h or more (hence relatively low intensity of the event), and at the same time is having recurring issues with GI-distress from taking in a lot of carbohydrates during racing, implementing a keto diet could be a viable option.

Handling GI-distress

01:03:20 -

  • Some research has indicated that fodmap (short chains of carbohydrates that are slightly more difficult for the the stomach to digest and absorb), can be a cause of GI-distress, and for those having these issues, it is recommended to reduce the intake of fodmpas in the weeks leading up to a race.
  • In regards to how ”trainable” the gut is in terms of being able to take up carbohydrates and fluids, there are both scientific evidence of that this is trainable as well as I myself have empirical experience of that this is possible from practical contexts, so that is definitely one aspect not to ignore.

Rapid fire questions

01:13:15 -

  • What is your favorite book, blog or resource related to endurance sport? Alex Hutchinsons blog at Outdoor Magaizine’s website and his book ”Endure”.
  • What is a personal habit that has helped you achieve success? Staying discipline and diligent in terms of keeping my emails and work folders very well organized.
  • Who is somebody that you look up to or have inspired you? I have so many people that I look up to but if I was forced to pick one person I would say my old Phd advisor Lawrence Spreat, who is both an extraordinary scientist but also has a unique ability to balance family and work life.


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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