Coaching, Podcast, Science and Physiology

Jason Boynton, PhD | EP#379

 February 27, 2023

By  Bernardo Gonçalves


Jason Boynton - That Triathlon Show

Jason Boynton, PhD, is a sports scientist and cycling coach with an interest in critical thinking and epistemology. In this interview, we dive deep into these topics and discuss how to improve our thinking about training, knowledge and evidence. 

In this episode you'll learn about:

  • Critical thinking, skepticism and falsifiability
  • Different levels of evidence
  • What does it mean to "train scientifically" or be "evidence driven"?
  • Pseudoscience, anecdotes, confirmation bias, logical fallacies and the placebo effect
  • Examples of how to apply these concepts in training, science, and the world of endurance sport

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Jason background

02:45 -

  • I am a sports scientist, exercise physiologist and cycling coach.
  • I'm also the co-host of the Cycling Performance Club podcast.  
  • I am a sports scientist, physiologist, and cycling coach, each equals cyclist engine builder, which is an easier way to express what I do than sports scientists doing research.  
  • I am primarily coaching and talking with other researchers through the podcast.
  • My PhD examined how environmental temperature affects high-intensity interval training in trained cyclists.
  • I have two extensive studies. One was a cross-sectional study, and another was a training study comparing intervals in two different temperatures waiting to get peer-reviewed.  

Finding truth in endurance sport

05:44 -

  • I came up with this back in 2014. So the science is a little dated. 
  • I've changed my opinion on some topics, but the overall message is important. 
  • We are missing an essential training component (what do we know and how do we know it?)
  • We should look deeply at these questions because we should ask why you prescribe or recommend something to somebody.
  • From my understanding, I've never gone through training like that when I went through my coaching certifications with USA Cycling.
  • You get courses in college around critical thinking. But it's important to frame our approach to training and developing athletes and making them perform better.
  • When people started watching, we looked back at things people did to improve their performance. (Smoking cigarettes before big climbs or drinking wine during the Tour de France)
  • Why would we think that we're any better? 
  • It's easy to have intellectual arrogance about ourselves because we're so modern. However, we're doing things now that we know wrong.
  • So how do we know if something is false, and how do we correct this? 
  • Imagine you were omniscient and could make every decision about your training correctly or if you got your cadence and nutrition perfect.
  • We would hit their ceiling of potential. 
  • But we're nowhere near that. So how do we get to the point where we approach that perfection and knowledge?

Critical thinking in training

11:40 -

  • Critical thinking is being as objective as possible in analyzing and evaluating situations.
  • The frameworks overlap because as soon as you're talking about critical thinking, the next thing you start talking about is scepticism.  
  • Scepticism is asking for a higher level of evidence for claims made. 
  • Those two things will work together.
  • Then two things I've added since is the idea of falsifiability (the idea that if there's a claim about something, we can prove it wrong in some way)
  • For example, what evidence would I need to see that HIIT doesn't work?
  • I can conceive situations where high-intensity interval training isn't necessary or beneficial.
  • I would drop high-intensity interval training in some situations, even though it's one of the most fundamental components of endurance training.  
  • I believe high-intensity interval training is a foundation, and I am asking myself what evidence I would accept that it isn't a foundation.  
  • It's an open door where I will accept new evidence that this isn't the case.

Example of something that would not be falsifiable

14:57 -

  • You could view HIIT as unfalsifiable if you didn't accept any evidence to the contrary. 
  • For example, ghosts - If you can't measure ghosts, that's not falsifiable because there's no evidence that can make you change your idea about it. 
  • Commentators often say, "it's down to who wants it the most".
  • That is something that you couldn't prove. 
  • Then it comes down to the importance of the claim. 
  • Endurance training is heavily physiological in its basis, meaning it will depend on factors.
  • In terms of falsifiability, these studies must be falsifiable.
  • We should design an excellent scientific study where the outcome is falsifiable (I have these beliefs, but I can conceive ways of evidence that would make me change my mind) 
  • To show the importance of falsifiability, think about the pre-flight checklist. 
  • Imagine you are on a small Caribbean island and approaching two pilots standing next to their aeroplanes and asking who is ready to go. 
  • The first pilot says, I'm ready to go and the second one says, I'll be ready to go as soon as I do a pre-flight checklist.
  • The first pilot did not do a pre-flight checklist. The plane has two wings, fuel in it, and it's ready to go.  
  • The other pilot is ready once he finishes his checklist.
  • That checklist is there because the claim is the aeroplane is ready to fly, and the checklist will try to falsify that claim.
  • If the first pilot is not willing to change his opinion, that could end badly at some point because he cannot question his reality.
  • If you are doing a training intervention or an approach, you should start breaking apart your intervention to figure out what is not working.

Intellectual honesty

21:16 -

  • It can be challenging for an athlete or a coach to look at something honestly if the outcome hurts them.
  • If you ask me about intervals and I present a level of evidence for intervals, I'm confident it works. A few years later, research showed that intervals might not be as effective, meaning my thinking was wrong. It will be beneficial for me to ignore that evidence.
  • However, that doesn't benefit my athletes.
  • So, ensure you're looking at things even if you must pull apart a big part of your practice. 
  • One unfortunate thing with journals is that we only publish studies presenting results.
  • Good editors are going to be pro-publishing of non-results. 
  • There is this pressure from the journals to keep their impact factor high and have people cite their research. (you're more likely to cite research that has positive results)
  • So, there's t a great incentive there. 

Levels of evidence and how to rank them

24:32 -

  • In terms of levels of evidence, different sources will give you slightly different ways to look at it.  
  • The take-home message is that there are higher and lower levels of certainties and better ways to understand things.
  • For example, some research methods or books say that tenacity is the lowest level of knowing (holding onto beliefs because they've always been accepted as facts).
  • The most annoying for an exercise physiologist and probably coaches nowadays is people saying their legs are burning from all that lactate.
  • However, we've known for 35-40 years, and that's not the case. Yet, ideas around lactate are still very persistent in the culture.
  • In my first exercise physiology course, even though I had already come out of an undergrad in physiology, they didn't talk about lactate, in the same way exercise physiologists talk about it. 
  • Things like that happen to people with science backgrounds all the time.


27:33 -

  • Intuition knows something based on your feeling.
  • Once you get to a point when you've been reading and studying something for a long time, you start to forget where you get your knowledge.
  • Those things could potentially become gut feelings, but at the same time, if I can't recall where I know something from, I have to be cautious.
  • It would be problematic to base all your beliefs on gut feelings. 
  • Getting that gut feeling from an expert is probably better than getting a gut feeling from someone that isn't an expert. 
  • Dunning-Kruger effect- When you don't know anything, you think you know more than you do.
  • Then you start learning more and realize how little you know. Once you learn much more, you get to that expert level, and your confidence increases again.  


31:05 -

  • You know something because you read it in a blog, heard it from a coach or a podcast. 
  • These are types of knowing through authority.
  • When you've set up the week for your athlete, what most athletes will perceive as being from Monday to Sunday is all the same level of evidence to them. It's an argument from authority.
  • Coach set this out, so it will work. 
  • However, you might see that as an argument from authority, but when I put those things in there, each one of those workouts has a different level of evidence attached to them.
  • If I put intervals for the week, I have a relatively high level of certainty about the effectiveness of the intervals I prescribe.
  • However, they race later in the week, and the day before that, I have a pre-race interval session set up for them.  
  • Therefore, I want my athletes to understand that my decision-making has different levels of certainty. If something needs to be fixed for them, athletes should tell me.
  • Behind the scenes, there are different levels of evidence, but the athlete is probably looking at that whole week with the same level of evidence as an argument from authority.  


34:15 -

  • If you get hot, you will perform worse in endurance performance.  
  • But if you look at a white kit versus a black kit, black absorbs more heat energy, and you could assume that the kit might warm up more and affect the thermoregulation of the athletes. 
  • If you choose between a white and a black kit, you might pick the white kit over the black kit just for a reasonable conclusion.
  • Simon Jones did some research in Sky, and there's not as big of a difference as you might think (actual science would go against the reason conclusion).
  • There's a lot of reasoning in coaching.
  • Our reason conclusions can be faulty if we lack science.
  • We should be aware that it is a reasonable conclusion, and it is lower on the level of evidence than having numerous scientific studies to base on our conclusions.  

Scientific method

36:31 -

  • The scientific method is a structured way of finding the truth, and it is the best because it works.
  • An excellent example is science-based medicine; its outcomes have greatly benefited. This is something that a well-funded field is already applying and using correctly.
  • Many people need to understand how you apply science. Even within scientific studies, not all scientific studies are at the same level of evidence.
  • A well-done meta-analysis will be better than a training study with no control. 
  • For example, you will never know what's going on within an athlete's muscle in the Tour de France in the middle of that event because you would need a muscle biopsy.
  • When you take that muscle biopsy, that person's race is over.
  • There are well-made studies that will not be considered as high a piece of evidence as others.
  • The tricky thing is to remember these issues and understand where you got your information.
  • It would help if you had the argument and references to understand that you must change your mind about something.
  • Some people are super secure about things like polarised training on Twitter. And then you look at scientists who are still debating it. (Mark Burnley and Jones vs Carl Foster and Seiler)
  • The takeaway from that was that it was an excellent exchange, but I question whether the sources of Seiler and Foster were good or not. 
  • If you end training in that way and it works for you, more power to you.
  • One significant similarity between them is a large amount of volume at a low intensity.

What does it mean to train in science?

45:47 -

  • It is common within coaching to say this is science-based.
  • Imagine that you could read every scientific paper about training and physiology. (omniscient type of being)
  • Even if you could read all of the papers out there and retain them, you still would need more time to make every single decision in your training of you and your athletes based on science. 
  • At some points, you will have to reason a conclusion about something. 
  • So there's no way always to make every single decision based solely on some research available. 
  • But on the other side, imagine a coach that doesn't read any science.
  • At some point, this person will accidentally stumble into something science-based. (increase volume or tell their athlete to eat more carbs)
  •  If even the most science-based person can't make all their decisions on science, we have to ask what science-based is.
  • If you're the athlete, you'd ask the coach precisely what makes them science-based.
  • There are examples of great coaches who have achieved excellent results that would not be science-based.
  • I would put value in thinking about the performance outcome, trying to reverse engineer things based on experimental data and empirical observations,
  • You can hop into all these papers and read them all. But if you don't have an excellent epistemological framework and philosophy, it could be harmful consequences. 
  • A lot of the learning was learning facts. But these days, you need critical thinking skills and how to acquire information and be sceptical, those sorts of things. 
  • It's like trying to train an athlete and having no care or concept of how physiology works.


55:13 -

  • Pseudoscience is something that looks like science but is not falsifiable. One example is Freud's arguments about things that are not falsifiable because they're anything depending on how you put it. 
  • Alternative medicine studies show the benefits of something like acupuncture.
  • Pseudoscience, colloquially, would be taking a very mechanistic study (evaluating what happens at a cellular level) and extrapolating a specific type of training. 

Applying science

58:46 -

  • Imagine you do a study where you have an exercise bout (high-intensity intervals), take a blood draw, and look at mRNA and that mRNA (coding a protein that improves endurance performance). 
  • It's a different level of knowing the outcome of overdoing an intervention with improving 20-km time trial performance.
  • Many people use VO2max time-to-exhaustion as a proxy for how beneficial the interval bout will be.
  • Now, that's problematic because only a few intervention studies have compared two different times at or near VO2max.
  • There are more reviews around time at or near VO2 max than intervention studies on time at or near VO2max. 
  • Most people need to remember all the nuances in those reviews.
  • But if you have a critical interval study with a high time at or near VO2max benefit, it could be better if I saw this in an actual training study. 
  • Some of the Tabata-style intervals are a good example. 
  • First, researchers developed an acute study, followed by a training study with the same intervals. 
  • There are many problems around that because there is no universal control for an interval study. Is the acute study useless because it's not a training study? No, it can still inform your practice. You have to understand it's not a training or an intervention study. (it's lower on the tier, where you are less sure of it)
  • Realizing that you have less evidence for it than a whole body of research means you can drop and put something else in because you don't have enough to back it up for them.
  • The problem is if all you have is molecular studies, and you're saying this intervention is better because it benefits VO2max more than another approach, it becomes problematic because you're taking lower forms of evidence to make a case against this whole body of research.
  • Now, if we ran many studies ten years later, we might find out that they are correct. But they just don't have the evidence to back up their claim.


1:03:58 -

  • Anecdotes aren't data.
  • If you wear your lucky socks and win a race, it doesn't necessarily mean those socks make you win races. 
  • However, our experiences have a lot of weight on us.
  • We all think scientifically, but an anecdote, if an anecdote stands out within our practice, we're all susceptible to that.
  • If you've got your anecdote that whatever intervention works, you can't be critical of that training intervention.
  • The other issue is confirmation bias. (motivated reasoning and pattern-seeking).
  • These are all things that we do. So you have to be careful about that. 
  • People say coaches are ahead of the science.
  • It's also a confirmation bias because it's only remembering the instances where the coaches got it right. 
  • There's no recollection of when the coach's practice was wrong. 
  • How do you know you're ahead of the science if you haven't done a science experiment to show that you're ahead of the science? 
  • So you can only say you're ahead of the science with the experiment happening.
  • After the experiment happens, coaches say they have been doing this for an extended period, and scientists have only now caught up.
  • If I'm sitting here saying we should try to be training with science, we're not trying to be dogmatic. We're trying to push for better practice.
  • Coaching and science should be mutualism. 
  • Scientists should ask the coaches and practitioners what they think works and then develop experiments to help the practice and determine whether it works.
  • And then, on the other side, scientists aren't the fastest thing in the world. But World Tour cycling teams are doing that.
  • Coaching generates a lot of hypotheses that science can test, some of which will be proven right, and some will be proven wrong. 
  • Some coaches use more of the proven hypotheses that may be correct than those that are proven wrong.
  • For example, now there's a reasonable amount of scientific evidence that the whole low carb high-fat thing isn't necessarily great for endurance performance. 
  • But we and we had had coaches have been using that before science started investigating it in the endurance sports context.
  • You get one triathlete that does well at Ironman, and they become like the pinnacle of what to do, and everyone forgets that all the other athletes that won before them didn't do that.  
  • It's new, and we connect with it, but we need to look at all the observational data we had before.
  • It's a different level of evidence. 
  • People are looking for the performance edge, so they want to get the latest bit, and we have the least amount of evidence and research. 
  • About that new thing to understand how to apply it. 
  • It is a constant battle between the new thing (performance advantage) and the determination to understand things. 
  • Some initial paper says beetroot juice will improve. 
  • Your performance, but when you look at that study, it was all done with fit college students.
  • There's the placebo effect of spending your money on something, and then obviously, they're going to work because you spent the money on it.
  • Suppose I've got these recovery boots, which are a placebo effect. Do I perform better because I've added the booties and the other placebo supplement? 
  • Everything has a cost. You have to lay it within what the athlete will do. 
  • Evidence shows that if you do all-out efforts, l(6x3min and the power output decays over time), you would have more time at or near VO2max. 
  • There's evidence to say that that is better than doing your intervals paced to try to get the highest average across them all. 
  • My athletes will do the one that's maximally paced effort. Best average because, in the context of the athlete, it is miserable and unsustainable over time with the athlete.
  • Logical fallacies get in the way as well. For example, I did this and saw a benefit afterwards; this is the only thing that explains it. 
  • There is also the intervention ad populum. Everyone does this, so that I will do it too. 
  • For example, high torque sessions are an excellent example of this. 
  • Do something because everyone else or what's within the culture seems to be doing it.
  • I wasn't brought up through a junior program. I eventually was on a Devo team but not young. 
  • By the time I got a coach, I had already had a hard science degree.
  • The initial process in some fields will start to heighten our critical thinking faculties,
  • When my coach prescribed things to me, I wondered if he knew this worked and what evidence he had for this.
  • I got this path of going into exercise physiology because of questioning the thought process behind it: how certain is he that this will even work for me?
  • I have a tiny library of workouts, which I haven't used in a long time because many things out there don't have evidence.

List of workouts Jason has

1:23:52 -

  • I have classic high-intensity interval training, some Tabata-style ones, and the rest is the things that are in the heavy and moderate domain. 
  • I haven't prescribed over-unders in years. They seem weird to me to do that. 
  • I don't do a lot of cadence workouts.
  • Threshold and tempo are handy for people with day jobs to get a lot of training stress in two hours.
  • The isocapnic response between the two ventilatory thresholds has somewhere to start a hypothesis because there's something physiologically unique there. 
  • Some research shows different molecular markers that occur after exercising in different domains. 
  • We're at least starting to understand that.
  • People argue about the minor details about something when there are so many cascades that could show that not to be correct.
  •  Most people will try to emulate a rule as opposed to throwing the rule out the window and trying to disprove it. 
  • What would tell you if something didn't work or not is if you didn't do it. And people might be afraid to do that because we might have a year where the athlete can't sprint as well because he didn't do his stop drills or didn't do this intervention. 
  • But at the same time, you have people chasing after a bunch of workouts and interventions that don't work as well as you think they do. 
  • Much of my process comes from understanding what evidence there is for everything and when I will limit its use.
  •  Certain things are old, but I would use them in certain situations. 
  • So, it does not have to be super science-based if it helps them get through the trainer season.

Examples of interventions that Jason does not use

1:34:13 -

  • High torque intervals - some people are promoting, and I asked them if there was any more literature on the topic. 
  • The person promoting it had a particular intervention or workout they were prescribing.
  • And the response was an acute study. One of Peter Leo's new studies showed torque's importance among pro cyclists.
  • One of the big points was that they were saying it was fundamental, and you would need a higher level of evidence if you call something fundamental. 
  • High-intensity interval training is fundamental because we have a lot of evidence and papers to show that.
  • You could probably say that with volume – high volume, low-intensity training. We have a lot of evidence for that, and I think we have a lot of evidence for carbohydrate ingestion. 
  • One of the responses is it causes a complicated cascade.
  • Every training intervention has a complicated cascade and is arguably hard to isolate. 
  • I'm not saying we shouldn't do it. Do it if you feel it has benefits. 
  • If you did training any other training intervention with evidence and you didn't see an increase in power, wouldn't you assume that that also increased torque?
  • I could see how it would be a missing stimulant.
  • But let's do some real training studies before we have a definite conclusion.
  • Cooling base layers on hot days is funny to me. 
  • We've been putting on more layers of clothing to stay warm and taking off layers to stay cool, but the modern cyclist is now putting on layers to stay cool. 
  • And many people have spent their money because it feels good for them. 
  • The other one is this idea of the technological black boxes that are becoming more prevalent.
  • For example, the Garmin watch is spitting out your VO2 max interval.
  • If you don't believe that value, you don't see any value in that number.
  • But the problem is when we have technology specifically marketed to coaches to work with athletes. 
  • However, Garmin will give you suggestions. 
  • And that's entirely based on the black box.
  • You have things like the Whoop and similar devices that take a bunch of scores and try to put them together into some sort of composite score, and then they give you advice for what you should or shouldn't do that day.
  • Those things attempt to give actionable advice, but there's no transparency in how it's done and no evidence that it works.
  • I wouldn't have any issue if someone bought that watch.
  • The problem is for self-coached athletes. If they follow Garmin, I think there are better ways to do it. 

Rapid fire questions

1:45:50 -

What's your favourite book or resource related to endurance sports

Read papers. 

And what's an important habit you have benefited from athletically, professionally or personally?  

Riding my bike, of course.

Who is somebody that you look up to that has inspired you? 

Mostly my academic mentors.
I also look to Deion Sanders, Teun Van Erp, Peter Leo or James Spragg


Bernardo Gonçalves

Bernardo is a Portuguese elite cyclist and co-founder of SpeedEdge Performance, a company focused on optimising cycling and triathlon performance. He writes the shownotes for That Triathlon Show, and also produces social media content for each new episode.

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