Podcast, Science and Physiology, Training

Scientific Training for Endurance Athletes with Dr. Philip Skiba | EP#311

 November 8, 2021

By  Bernardo Gonçalves


Philip Skiba - That Triathlon Show

Dr. Philip Skiba is a medical doctor specialising in Sports Medicine, and also holds a PhD in exercise physiology. Dr. Skiba is also a highly-regarded endurance coach and endurance performance consultant. He has coached a number of Olympians and World Champion endurance athletes, including for example Joanna Zeiger in triathlon, and has been consulting on projects such as Nike's Breaking2 project.

In this Episode you'll learn about:

  • The new edition of Phil's much sought-after book: Scientific Training for Endurance Athletes
  • Understanding and training your physiology
  • The role of periodisation
  • The importance of specificity
  • When, why and how endurance athletes need to focus on power and speed development

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Philip Skiba's background

03:39 -

  • Professionally speaking, I live in Chicago, and I am the director of Sports Medicine for the AdvocateAurora Medical Group, one of the largest health systems in the United States. The more intriguing part of my job is the work I do with endurance athletes.
  • I have been coaching triathletes since the early 2000s. To help develop these athletes the best I could, I developed an intensive research program in the UK. I worked with Andy Jones. I completed my PhD in the Jones Laboratory at the University of Exeter and developed these tools and techniques to help athletes. (the British Triathletes for the 2012 Olympics)
  • Coming back to the USA, things snowballed. I had already coached a couple of world champions at this point. And I got hired by Nike to work on the Breaking 2 Project. Here, you use many of these mathematical tools to develop an evidence-based approach to how we can help athletes. (Lelisa Desisa, Eliud Kipchoge and Zersenay Tadese)
  • I created this network, and now, I am a doctor who qualifies in Sports Medicine. I coached many elite athletes who are world record holders and Olympians.

Books published by Philip Skiba

05:45 -

  • As a doctor and a scientist, my view on knowledge is there should not exist any secrets. We have done a tremendous amount of work in the last 200 years to understand how athletes' bodies work.
  • Instead of writing a thick book that no one might read, I wrote two short books around 200 pages long. These books give you the basic physiology everyone can understand. And they present the basic training techniques I know that work.
  • To support the knowledge, I give 100 or more references demonstrating that this works.
  • And no one was more surprised than me at how successful they were.
  • After the Breaking 2 Project, I focused on trying to combine the two books. But that took a bit longer than I was expecting. As science is developing, I constantly re-edited my ideas and thoughts on the new book.
  • It will be available by November or so.

Understanding the athlete's physiology

08:14 -

  • In the lab, you can do many things, and we can take a lot of good information. But the truth is you can do much of it without that kind of technology or incurring those expenses.
  • First, you can learn much only by training and observing what is going on with the body. The easiest way to look at it is to check the power/speed duration curve. Knowing this gives already much knowledge on yourself.
  • I have been successful because I analyse that power duration curve and apply it to the specific competition. You plot the demands of the competition and the athlete's profile and compare the two things. Therefore, you know understand how the athlete can perform better than others.
  • I would love to tell you it would be more complicated, but it is not. Thus, the first step is to look at what you have done to see what you will be capable of achieving.

Training based on the athlete's profile

10:10 -

  • If you look at swim coaches, they put the swimmer doing set at the target paces to perform well. (e.g., if you have a 400 m target pace, you start by doing 8x50 m at that pace and progress the distance over time - 4x100; 2x200)
  • With long events, it is a bit more complicated than that. The first step is to decide if your goal is reasonable or not. Using some of the impulse models I developed a few years ago, I figured out that to match Lance Armstrong on Alde D'Huez, I could train 96 hours per week. But training 96 hours per week is not possible.
  • It is here where coaches are helpful. They can access what you will be capable of doing. If you put me on the treadmill and I am in good shape, my Vo2Max is 44 mL/min.kg. (half of Kipchoge's Vo2Max)
  • There is no world where I could achieve that level. But suppose I could lose three or four kilos and could train four days a week. I might get that number to 48 and might take one minute out of my 5 km time. That is the goal, and to make incremental improvements towards something.
  • It all comes down to the training load. Before you can get to a higher level, you first need to manage a certain load level. And that is not easy to see from the inside.
  • I regularly have athletes who run a five-hour marathon and say they want to qualify for Boston. It is not reasonable we can take 1h30 out of your marathon time in the next six months. That is the challenge of athletes. (to understand what they are capable of doing)

Combining athlete's physiology and training

12:58 -

  • When we talk about the power/speed duration curve, we can reference W' or critical power in cycling. (the power where your values start to level out) You can look at these values as a battery. Every time you go above your "critical power", you drain your battery a little bit. And when you recover, you recharge the battery.
  • In the run, it is very similar by using D' (measured in meters). And you have critical speed, where the speed you can travel starts to level out. We know it is difficult to affect the battery. (Anaerobic capacity in a positive way)
  • Most training you do as an endurance athlete increases in critical speed/power and lower the size of W'/D'. It means the result of endurance training is a loss at high-end speed.
  • It is good if you are trying to be a triathlete but a challenge if you are a sprinter as a cyclist. You have to be fit aerobically to get to the end of the stage, but if you are too trained aerobically, you lose your sprint ability. It is not easy to make that balance.

Muscle typology and training load

15:12 -

  • It is an intriguing area of research because we do not have much work on it.
  • My experience has been on not attributing training based on muscle typology. Instead, I do it based on how the athlete listens to their body. I see many high-level endurance athletes overtrained. And I know their muscles are mainly slow twitch. But you must be careful when you interpret some muscle typology data.
  • There are challenges in biopsies. If you, do it deep in the muscle, you will get more slow-twitch muscle fibres. It also depends on the place where you do the measures.
  • It is hard to do exhaustive work in terms of this topic. Even on overtraining, we do not know much. We should question everyone who thinks that knows what is going on. There are too many different ideas on these topics.

Training considerations to improve certain aspects of physiology

17:51 -

  • There are two things to keep in mind. First, what is the best way to train your physiology? Second, what is the best way to train performance? Those answers are not the same thing.
  • My colleagues are doing incredible work, looking at the development of junior athletes. And what differentiates good junior athletes that develop into high-level professional athletes. What they find has to do with prior exercise.
  • If you take two people (one high-level junior and a professional), you will not find relevant differences in Vo2Max or critical power. We find that their ability to perform after an amount of workload is different between the junior and the professional.
  • It is not something we think about often. My threshold has gone up, but it does not guarantee performance. If you look at the way Kenyans train, they do their long runs at a progressive pace. They start very slow and increase speed as time passes. They do the work at the end of these runs. They go off at maybe 8:00 min/mile, but the last 5 km they are running at 4:30 min/mile.
  • They have already figured out that it is crucial to do the intensity at the end. For example, I prescribe long runs that are not that easy. They run easy for a while and do blocks close to their threshold at the end.
  • It is this combination of the coaching know-how and the science. And what my colleagues are doing points to that same thing.

Periodisation considerations for training

21:14 -

  • I wrote an article for a newspaper on how a periodisation is a tool used to avoid overtraining. And many have written a lot about this topic. But not much was evidence-based.
  • Part of this has to do with trial-and-error. But I tried to develop some rules about it.
  • The original work that addresses the topic was from Russia from the 50s. What they did was give a bubble sheet to the athletes. Or they trained slower or trained fast. And this became published as the best way to train athletes.
  • The western people do not earn about this anymore, so they started training everyone this way. That works if you are only doing short events. But it is not going to work if you are running a marathon.
  • The rule that subsequently became supported by people is that you have to go from general to specific. For a short race, it means going slow and then going fast.
  • For a longer race, the faster stuff is somewhere in the middle. And then, we maintain the intensity by increasing the duration of what we want to do. (e.g., run a successful marathon)
  • The most fundamental rule is going from general to specific. And second, you have to go short and fast before you can go long and fast.
  • If you look at the power duration curve over a long period, you see that curve rising first, and then the tail stretches longer.
  • Depending on the event that you will do, this is one good way to monitor your physiology.
  • Either you are going faster, or you are not. A power meter is a fun tool, but the real power is to answer basic questions about yourself. (Am I making more power or not?)
  • However, many coaches do not like this metric because it makes them accountable. And they are not getting faster because it is the coach's fault, not the athletes.

Adapting periodisation to sports like short distance triathlon

25:02 -

  • If you mathematically look at training, you can get one or two peaks per year. (Before the absolute performance in those events starts dropping)
  • And that is a real challenge if you look at those corporate races that require you to perform multiple times. At that point, success is only dependant on athlete selection. Is their baseline level of performance high enough? (They do not have to beat themselves too much to maintain the performance over those months)
  • There are many people I can train with one peak per year to perform at a professional level. But the difficulty is to find people who can maintain performance over a long period. That has less to do with the quality of the coach. And more with the genetic predisposition of the athlete.
  • The athletes must reflect on these points. Can I do a complete season, or have I got only one race in me?
  • That is something to consider. Trying to make a living as a professional triathlete is not easy. Many of the world champions I trained would earn if they were a manager in Starbucks.
  • You have to reflect on your goals in terms of the professionalisation of the sport. Or to be only an amateur healthy person.
  • One thing I mention in the book is some of the training Eluid Kipchoge and Paula Radcliffe did. I went through the training they revealed in public and analysed it to show how fast they trained.
  • Eluid Kipchoge can tolerate the training he does because he is Eluid. He and Paula do not become the best athletes in the world because they can sustain that training. When Paula was Junior World Champion, she was running less than 20 miles per week. She was already world-class without doing much.
  • Therefore, that is a person that could tolerate a considerable amount of training.

Specificity in the preparation of an athlete

28:58 -

  • The race-specific training comes as we get closer to the race. We had the Chicago marathon here. In the three weeks before the marathon, I always see many athletes show in my room with stress fractures. The reason is that all of them have been doing 20 miles long run for a month or two by then.
  • Their thinking is those sessions will help them get better. The point is you do not need to run 20 miles to know you can run 26 miles. And you do not need to do it repeatedly. Jack Daniels always says: "You do not want to leave your race in training."
  • You have to have something left in the tank. Overall, I perform these long efforts (race preparatory), where we fatigue you a bit before these efforts.
  • If you are an Ironman athlete, I make you do a 60-mile ride before. After that, we sit on race power for an hour. Can you hold that power with deviate for that time? If you can, it is a good sign.
  • What I reference is these types of workouts to estimate where you are in your race preparation. Training is not more complicated than that.
  • Athletes come to me telling me that despite improvements, the workouts are boring. They are right because either you can do the work, or you cannot. Preparing for a race is not about trying to do much improvisation like in a spin class. If you cannot do it, let's re-calibrate your goals.
  • The goal of those race-specific workouts is not to choose target intensities. It is to see if they can perform those efforts at the end. And all of this is about learning how to pace yourself.
  • Even more experienced athletes, when trying to plan the best race possible they have to listen to what their bodies tell them.
  • We might have a plan, but the weather conditions might be too hot, and therefore you have to adjust your goals at the moment. All athletes have to be willing, to be honest with themselves.
  • After 10 km, they must reflect if they can hold that pace. If the answer is no, you have to slow down. If you get to the last 10 km and you feel good, you can accelerate. Until then, you have to take it easy.
  • The athletes I see are the most successful are the ones with "coolest heads". Cat Morrison, a few years ago, was racing in Lanzarote. She had a mechanical problem in the middle of the bike length. It is hot, and Cat cannot fix it. She sits under a tree and waits for the service course car, and they repair the bike.
  • She has lost a lot of time, but she sits there eating and drinking without freaking out. After, she ran one of the fastest marathons she ever ran and won the race. Cat maintained like a "buddha state", where she focused on observing herself to get the best outcome possible.

Race specificity for longer distance events

35:01 -

  • The race-specific period is about the last eight to twelve weeks before the event. By that time, you hope to have enough training, and you can start to do some of these indicator workouts.
  • You do not need to do it all the time. Every few weeks you can try something like this. You do not want to do it often because there is a recovery cost associated with them. You do not want to beat yourself too much.
  • For shorter events, you can do more of those simulation workouts because the recovery cost is lower.
  • Every time I ask you to do a run after a long bike session beats you up. When doing shorter races is not like that. The athletes that excel are those that can recover a bit quicker.

Ways to quantify training stress

36:51 -

  • When you look at metrics like training stress score, you can treat that as a dose. (a medicine)
  • If I give you two aspirins, I will fix your headache, and if I give you three, I help with your hangover.
  • But if I give you ten, I will upset your stomach.
  • The more aspirins you take, the worse the outcome will be. The effects will be dependent on how fast the medicines will leave the body and how your body will react to them.
  • Exercise is the same thing. You cannot look only at the training stress you got from A. You want to look at it over time. And evaluate how long it takes for that to leave my body and its impacts.
  • There are software packages that can do that. (E.g., Golden Cheetah is for free)
  • Then, you can get an idea of how fitness and fatigue come and go from your body. Even without those tools, you should keep a complete log of how you feel after each workout. Using this information, you can start to have an idea of how your taper should be.
  • With the mathematical tools, you can get to where you need to be more quickly. I give some examples of world-class athletes that in the lab have similar numbers. Therefore, one assumption could be you could train them in the same way. When you analyse two athletes, you can find different mathematical responses to training. Thus, they cannot work in the same way.
  • For example, you can have an athlete that recovers fast from high-intensity workouts in a matter of days. And the other might take more than a week to recover.
  • You can plot these "affect curves", and they will show how long it takes you to recover from something too stressful. These curves are handy when dealing with team sports.
  • A swim coach might have many world-class athletes, but they must address each athlete individually. The reason is to get the best performance out of everyone because their fitness and fatigue curves vary.
  • It is about individualising the time constants because these are slightly different.
  • I had success because I built these models myself and strictly analysed every athlete. There are criticisms of these models, but in my experience, the pros outweigh the cons if people track how they train and perform. When you do those two things, the models are perfect.

The role of power and speed in endurance athletes

42:07 -

  • The power duration curve is high on one side (short efforts). And it gets flat on the other end.
  • It is hard to move one part of the curve without moving everything. (Especially on the endurance side)
  • First, you move the whole curve upwards when you are an amateur athlete. And as you get better and better, it starts to improve the longer duration side of the curve.
  • One way to increase critical power is by doing power-based training below or near the threshold. But you have to be willing to do that work. At some point, you cannot go any longer.
  • Therefore, you must look at another part. You might not have time to do a 6-hour ride if you have a life outside sport.
  • You have to think about power and speed because there is research on high-intensity sprint training being a potential stimulus for endurance performance markers.
  • I do not prescribe a lot of sprint interval training because it is not specific to what we are trying to accomplish in the long term.
  • It can have a place for people that are time limited. Generally, when I have athletes doing their hard sessions, they do two-minute intervals to start. (e.g., at their four-minute power)
  • Then, we can start those longer or manipulate them. In my experience, it does not take a lot of that training.
  • There is a push for this polarised training model, which I would be very cautious about it. When you look at the training of these successful athletes, they do a lot of work below critical power and near-critical power and above their first lactate threshold.
  • People call this the grey zone, but that is a powerful and necessary stimulus as well. In addition to that faster stuff, I make them work in this heavy-domain zone. These blocks are those we will do at the end of a long ride.
  • Remember, there is a measure of error around these parameters. One reason cyclists like FTP vs critical power is that they say they can hold FTP for longer. Therefore, it should be a better marker. However, that is not the case. If I tell you to ride at critical power, I do not know what power that is. It is a mathematical artefact, and if you are two watts above it, your physiological response is different if you are 2 W below it.
  • It means that training 5 to 10 W below the threshold, you might have a similar stimulus. You can do this instead of going too hard and blowing up too early.

Testing critical power

47:11 -

  • When doing time trial tests, it will depend on how hard you will go. For most athletes, doing three tests is enough. You can do more, but you have to know that you are not in a lab. Therefore, you have to go as hard as you can in the test duration.
  • I prefer to think about how many quality tests I can do to evaluate fitness.

High-intensity interval training

48:26 -

  • The glycolytic system is rarely a limiter. It responds to what you are trying to do. When you ride above the threshold, you have to use your glycolytic pathways to produce more lactate. And generally, that is not the limiter because if I make you sprint and do a biopsy on your muscle, I cannot drop your ATP count in the muscle. (even if you go all-out)
  • You are not burning glycogen enough to maintain that level. The idea of working the glycolytic pathway is not the goal of high-intensity training. When you ride hard, you train your neuromuscular system to fire quickly, with as many fibre units as possible and in synchronism. The more in synchronism they work, the higher the power output.
  • The metabolic systems are only meeting that demand. And even for top athletes, they are not limiting it.
  • Aerobic training is a different story. The performance will depend on how many mitochondria you have and how quickly they can produce energy aerobically. (before starting producing lactate)

Additional points on training

50:47 -

  • One thing I like to tell people is that everything has its place.
  • For a beginner athlete, any training will induce an increase in performance. However, their interest will depend on what you tell them to do.
  • Doing 30/30 sets can help you put some speed on athletes' legs and make them feel they are working a bit harder. But this will lead to a recovery cost.
  • It is this way we have to approach our training. Where can I put these power and speed blocks in the training plan?
  • That is why coaching is so crucial. If it were just about physiology, it would be easier to make champions. There is an art associated with this, and it is as fundamental as the scientific evidence.

Length of a high-intensity training block

52:38 -

  • One point from my PhD was a study on if our model worked (W' model). Our hypothesis was treating W' (anaerobic capacity) as a battery. So, we trained some athletes to evaluate if this was the case. (study the point where they would get tired)
  • It turned out that it worked well. But one way we tried to break the model was doing first a couple of short efforts and then a long set until exhaustion. We wanted to see if the model predicted when the athlete would get tired.
  • After two weeks of training, people increased their Vo2Max by 10 % and their critical power by 15 %. A small amount of this work (but incredibly hard) induced a substantial increase in their numbers.
  • You can move things around in a short period if you do something like that. And some athletes were talented. (critical power above 300 W)
  • Nevertheless, I was one of the subjects in the study. My numbers did not move at all, and I suffered a lot. It is crucial to remember that what works for the group might not work for the individual. I have a poor response to high-intense training. Even training considerably, I cannot see an improvement in my numbers. Therefore, you have to consider each individual differently.
  • If I trained myself as I train my athletes, I would never get any better.
  • The athletes in the study did three high-intensity workouts per week. The interval portion would vary from 20 to one-minute intervals.
  • The results in the study might result from how frequently we did those workouts over a short period. But you might get the same response if you did one of those per week for six weeks.
  • The way we conducted the study is not the right way to train people. But it shows that intensity can move numbers around.

Additional topics address in the book


  • I cover some more practical things. In particular, I cover hydration and nutrition. When you are doing long events, success will not come from training but from the execution of nutrition and hydration.
  • When you see in marathons people falling off at mile 20 is because they burnt their glycogen stores. Those are nutrition errors as well as pacing errors.
  • There has been some research done on this topic. Athletes need 1 to 1.5 g/CHO per minute of exercise. It is the best way to maintain the glycogen stores and put off fatigue.
  • One other point I cover is supplements. We have seen athletes taken from the Olympics due to adverse analytic findings. In one case, the runner used the excuse she ate a burrito from uncastrated pigs (absurd). Now, they changed the claim to supplement contamination.
  • What we know is there have been extensive studies on supplements. We know that almost none of them work, and the ones that work have something illegal.
  • How is it possible we find steroids on creatine supplements? Why are the steroids on the creatine factory? You are doing supplements for weight loss, and you find stimulants in them.
  • The contamination of supplements is probably on purpose.
  • At the amateur level, they do not test that often. But there is a health risk associated with supplements. For elite athletes, they might not get benefits anyway. Risking your career and reputation by supplementing is absurd, so do not take them.
  • All the products you need to perform, you can buy at the supermarket. Caffeine and carbohydrates will help your performance. High nitrate vegetables will help you as well.

The general take on vitamin supplements

59:59 -

  • The problem is we do not know if the supplements are trustworthy. In the USA, there is no law to say what information supplements need to provide. And they can put something they do not list on the ingredients.
  • I often tell people that the best vitamin supplements are the urine from athletes. Everyone is taking these things, thinking it is going to help.
  • If you are eating a healthy diet, you do not need vitamins. If you feel you want to take a general multi-vitamin, do it. (if you think you need it)
  • Once you go outside those lines, you are taking a risk.
  • I cannot tell how many kids I had, and they take supplements contaminated with steroids.
  • Anything more than a multi-vitamin is more likely to do more harm than good.

General questions

1:01:40 -

What would you tell yourself ten years ago if you could?

I would tell myself to enforce more rest on my athletes. You do not get better by training but by recovering. I have seen some athletes with catastrophic results as a doctor. (overtrained) Several years ago, I tested a top runner who had numbers like Paula Radcliffe. And after seven or eight stress fractures, she retired from running before finishing college. I would spend more time reinforcing the importance of rest.

What is one thing within coaching or training you are now learning/curious about or fascinated by and why?

I am working on a couple of different studies, and we are refining the mathematics of the W' model. And we are looking for correlations between those models and physiology. It is good we developed these models, but mathematics is not secure in reality.

Rapid fire questions

What is your favourite book, blog or resource?

Running: Biomechanics and Exercise Physiology in Practice by Frans Bosch HBO BSc

It has through much information for strength and conditioning.

What is an important habit that benefited athletically, professionally or personally?

It is about being lazy. To make improvements, you have to have time to think. There is a reason why a person like Albert Einstein only published some scientific articles in his lifetime. If you look at the people who make the most impact are those that took the time to think deeply about something. None of us will be a genius, but we can all benefit from taking time to think clearly. I reduced my coaching services to a third of the athletes I would coach in the beginning. The reason is why I want to think carefully. When you do it, I think you can make better decisions. When I was working with Nike, I could not work with anyone else. That allowed me to work with a small group of people. And it made my interaction and my level as a coach increase dramatically.

Who is someone you have looked up to or who has inspired you?

The group at Jones Laboratory at the University of Exeter (UK) are the ones I looked up to even today. We tried to work on things that could help regular athletes. What was inspiring was that they were one team. I work with doctors all the time, and I know how hard to work with them. But in Exeter, it was not like that. Everyone was giving a hand if needed. What Andy and I brought to the Breaking 2 Project was focusing on moving the project forward.


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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