Interval Training – Science and Application part 1 with Paul Laursen | EP#128

Paul Laursen is adjunct professor and performance physiologist at AUT, he lead the Performance Physiology Team at High Performance Sport New Zealand for both the London and Rio Olympic cycles, and he coaches several elite triathletes. He is also the founder of HIIT Science together with colleague Martin Bucheit. In this two-part interview, we dive deep into all things interval training for triathletes.

• The three target systems and six types of intervals.
• What types of intervals are most beneficial for triathletes?
• How to use different variables (duration, intensity, rest, etc.) when planning your interval training.
• How to prescribe and measure interval workouts.
• Should you go to the well in interval training or not?
• Case study of Kyle Buckingham and the ketogenic diet. 

1:05 - 

• Paul is adjunct professor and performance physiologist at Auckland University of Technology.
• He led the performance physiology team at High Performance Sport New Zealand for both the London and Rio Olympic cycles. 
• Paul is a coach himself, coaching elite triathletes such as Kyle Buckingham. 
• He is currently writing a book with Martin Buchheit, titled 'The Science and Application of High Intensity Interval Training'.

3:23 -

• Interval training is a bit of a buzz term these days - the increase in interest over the last 5 years is clear. 
• Interval training has a lot of benefits in a global sense for any human.
• High intensity interval training is when you are exercising above your anaerobic threshold.
  • You're breathing quite hard, and there's a solid effort going into the workload.
• The key areas of benefit of high intensity interval training are:
  • Recruitment of fast twitch motor units.
    • We don't generally activate these in the modern world (e.g. sitting at a desk).
  • VO2max increase.
    • Exercise that targets maximal cardiac outputs will increase this, and we don't generally get it daily. 
    • Triathletes especially probably don't get this as much as prolonged, aerobic, fat burning exercise. 
  • Glycolytic system - the lactate burning one, and the neuromuscular system. 
• There's some general overall health benefits of high intensity training too. 
• The majority of triathlon training programmes that are obeying the principle of specificity tend to have a lot of base work and aerobic training. 
  • Interval training can give different ways of getting high muscle recruitment, high cardiac output, high VO2.
• Interval training allows you to get used to recruiting larger and larger motor units.
  • When you do this on a routine basis, you're getting the signals to become more fatigue resistant. 
  • You're giving them the signal to develop more mitochondria. 
    • Mitochondria are the power houses of the cells that facilitate aerobic respiration. 
    • They give us ATP aerobically with no byproducts. 
    • When you're looking at an elite athlete, they will have this system in large motor units dialled in and operating efficiently. 
• Interval training can be used by triathletes to get further down the line in performance.

9:28 -

• My background comes from a bit of a frustrated athletes perspective.
  • I got into exercise and sport at a young age, and into triathlon in my teens.
  • I tried to become a professional through my 20's, but failed at that. 
  • As a result, I went to try and learn more about it, and decided I wanted to make a career of it.
• I started looking into what exercise I could do that would give me the best bang for my buck. 
• I did my doctoral studies on a scholarship in Australia.
  • I spent a solid 3-4 years doing that. 
  • I did some work with the Australian Institute of Sport.
• On the other side of the world, Martin Buchheit was having similar questions from a team sport perspective. 
• We started with the true science.
  • We looked at how the body responds to different intensities and different formulas of intensities and durations. 
  • We formed a lot of experiments to collaboratively get at this question. 
• We mention a phrase in our book: there's more than one way to skin a cat. 
  • There's more than one way to skin a cat when it comes to training.
  • Meaning there's more than one way to get to an outcome. 
• We spent a lot of time together researching and publishing on the different ways you can skin a cat when it comes to interval training. 
• The popularity of interval training grew, and as a result the people high up in the journals contacted Martin and I. 
  • They asked us to form a review of the literature in a journal called Sports Medicine, a leading review journal. 
  • We put our heads together over 2-3 years to write the two-part paper. 
• After we published the paper it got a lot of interest and the publishers at human kinetics approached us.
  • They asked us to write a book on it.
  • We kept saying no and they kept coming back, and then finally the timing was right. 
  • I was working with the New Zealand Olympic programme, leading the physiology team in the Rio cycle. 
  • I came back to Canada and started to write the book with Martin, 
  • Martin was working as the lead of performance for Paris St Germain football club. 
• Our advantage is that we have a solid understanding of the academic/research side, alongside the way you can apply it to athletes. 
• The book is titled 'The Science and Application of High Intensity Interval Training'.
  • The application chapters are written by practitioners that are embedded in the worlds most popular sports that apply interval training. 
  • There is a disconnect in the academic realm with studies conducted in labs compared to what happens in the field. 
  • We're ultimately trying to bring the two worlds together.

15:36 - 

• This is probably the big twist that we try to do in the book.
  • We ask people to think more about the target they're trying to reach in terms of psychological adaptations. 
• We've broken these down into three basic physiological systems that we're trying to target. 
  • These are the systems I mentioned at the beginning. 
  • 1) Are we trying to enhance a systems ability to produce energy aerobically.
  • 2) Are we trying to enhance the glycolytic system - the anaerobic system. 
  • 3) Are we looking for various neuromuscular, mechanical or muscular skeletal type adaptations. 
    • E.g. recruitment principles or trying to lessen the impact of muscle damage. 
• If you take these three categories you can create 6 types of adaptations. 
  • Different forms of interval training target each system/
  • Type 1 is just the oxidative system.
  • Type 2 would be intervals that elicit and oxidative response but are also neuromuscularly demanding.
  • Type 3 would be an oxidative system targeting the anaerobic/glycolytic system.
  • Type 4 would involve hitting all physiological areas.
    • Oxidative, anaerobic and neuromuscular. 
  • Type 5 would be turning off the oxidative system and targetting the anaerobic and neuromuscular systems only.
    • You get enough rest and recovery between the intervals.
    • You turn off the oxidative system. 
    • These are associated with very high muscular recruitment levels. 
  • Type 6 would be a neuromuscular only type of response.
    • This isn't technically high intensity interval training, it's more speed and strength work. 
    • It's important that we have it in our model to appreciate the influence of neuromuscular stress. 
• This doesn't include the different formats of interval training. 
  • Start with physiological target responses that we're after when considering a program for athletes. 

23:00 - 

• The oxidative system is probably the most important to target.
• The neuromuscular/muscoskeletal system would be the next most important. 
  • Especially when considering the importance of it on the run. 
  • You need your neuromuscular stimulus right to withstand the heavy muscle damage of a triathlon run leg.
  • This also seems to be the most important stage, especially at the pointy end of competition. 
• The anaerobic system would be the last of importance but could still be useful at times. 
  • Especially in Olympic distance and draft legal races. 
  • It may also be important in the swim start for positioning. 

25:03 -

• We break it down into 12 various factors.
• To give you a level of the complexity we're dealing with:
  • If you run a factor analysis and throw 12 different variables in, it comes out to over a million different options.
  • This is why we see so many different ways of training that can lead to success.
  • However, the goal of our book was to try and get more specific. 
• I won't go into all 12 factors, but I'll explain the most important ones.
• Intensity of exercise is an important factor.
  • We're not taking about anything that's under your FTP or anaerobic threshold, only intensities above that. 
  • There's a long way to go from anaerobic threshold to all out max power (e.g. 1000 watts in cycling/12km an hour in running). 
• Paired with intensity is the duration of the exercise.
  • The higher the intensity, the shorter the duration you'll be able to withstand. 
  • This needs to always be factored in. 
  • Longer durations at higher intensity will have an effect on your physiology or your stress/strain.
  • This can be controlled by having appropriate bouts of recovery between interval bouts.
    • You can have passive or active recovery bouts. 
• Another factor down the road is the intensity and duration of recovery in the series.
  • You may have a number of different series of these intervals that you're prescribing. 

29:30 -

• We have our 6 physiological target types, the next process is understanding the main categorisation of interval formats.
  • These are placed into our programmes to hit those targets.
• Remember the intensity we're referring to is above your threshold. 
• The first category is long intervals.
  • These are interval bouts above threshold, longer than 2 minutes. 
  • No longer than about 5-6 minutes. 
  • These may also be referred to as VO2max intervals.
  • These give a type 3 or 4 target:
    • 3 = oxidative anaerobic.
    • 4 = oxidative, anaerobic and neuromuscular. 
  • If the intensity isn't crazy, you get a really nice type 3 response. 
  • If the intensity was high over 2 minutes, you can certainly get a neuromuscular target. 
  • ​It depends on the individual.​​​​​
• We always have to consider the context of the athlete.
  • The prescription that I give for an elite will be far different to someone just starting triathlon. 
  • My context is that I typically train very elite guys. 
• The next category is the short interval.
  • These are less used in triathlon training, but they're highly effective and versatile. 
  • The duration range is 10 seconds to 60 seconds. 
  • We can hit about every target type 1-4.
    • It can be oxidative only, which can be really useful.
    • If you can tick the aerobic engine along, but not elicit a sympathetic nervous response that you get with neuromuscular and glycolytic activations, you keep fatigue at bay. 
    • You keep your immune system functioning well but it's not overly stressful. 
  • The recovery time is important.
    • E.g. if you're going hard for 10 seconds, and then stopping for 10 seconds.
    • You get a complete restoration of myoglobin, and a result the oxygen is available for aerobic respiration in the next bout. 
    • Also it doesn't elicit the lactate system ultimately. 
  • If you manipulate your intervals down to 10 seconds (10 on/10 off) you can exercise at VO2max but maintain a manageable blood lactate level (4mmol).
  • This fascinated us when we first got into the area of interval training. 
  • Short intervals can be highly effective at gaining the aerobic stimulus and the recruitment without being overly stressful. 
• The next category is repeated sprint training.
  • This is more used in the team sport context.
  • It's all out activity - e.g. sprints over 3-7 seconds, and then a 20 second pause, and repeat.
  • It's used in team sports because they need to engage type 4 and 5 targets. 
  • Speed and the ability to repeat speed is important. 
  • These might be utilised in athletes lacking top speed in the run or swim.
• The final category is sprint interval training.
  • These are used even less in a triathlon training programme. 
  • These are when you're prolonging the all out maximal exercise. 
  • This would be 30-40 seconds or all out max, and then a very long recovery.
    • To fully recover the anaerobic and neuromuscular systems. 
    • The oxidative system isn't engaged too much. 
  • Solely type 5 targets. 
  • Similar to an 800m runner workout, or a sprinter workout. 
  • It's ultimately repeating a Wingate test. 

39:55 - 

• Mid-pack half Ironman athlete:
  • You want to think about the principle of specificity. 
  • With 70.3 or Olympic distance athletes who spend 10 hours a week training, you would want a certain amount to be aerobic.
  • However you can get good bang for your buck with a low volume training plan to incorporate interval training activities. 
  • There's loads of options out there, including Trainer Road and Zwift. 
  • You might want to have some of these type 1 intervals (e.g. 10s on/10s off).
    • These may be just above VO2max intensity. 
    • This could be progressed to 30 seconds etc. 
  • Short intervals would be a great target. 
  • It would depend on the athlete, but a different format may be longer interval. 
    • 2-3 minute intervals, with a 2-3 minute recovery to fully recover.
  • The number of bouts will be important to consider.
    • The less fit you are the less you may be able to achieve without gaining too much stress in the body. 
  • For a typical 10 hour a week person, these would be good to do 2-3 times a week alongside your aerobic activities. 
  • It would depend on the individual whether you did interval sessions in every discipline. 
    • The fitter you are the more you can handle this.
    • One in each discipline would be more than enough in an individual that's just starting out. 
  • The modes of exercise in triathlon will have different physiological impacts. 
    • Running is the most stressful, then cycling and swimming is last. 
    • However again depends on the individual and their background in sports. 
  • This shows the importance of getting a good coach.
    • It can be worth its weight in gold. 

45:18 - 

• The discussion around polarised training is a really interesting topic. 
• I've seen athletes that are training up to 35 hours a week, and also weekend warriors who train 8-10 hours a week. 
  • We find the polarisation is really important for athletes in the high volume phase.
  • Usually above 20 hours a week is when it really starts to matter. 
    • You wouldn't want 30% of this time above your first ventilatory threshold. 
    • You don't want the majority of your training zone 3 or above. 
    • We generally see athletes trend towards overtraining. 
• In general, 80/20 polarisation theory works great for athletes training 20+ hours a week. 
  • It's great when the majority of this 20% is high intensity intervals. 
  • However for the majority of Ironman athletes, it might be in the high tempo zone for specificity for races. 
• This topic highlights how individual we all are.
  • I've been fortunate to train an elite professional who has won multiple Ironman's. 
  • He would be training 15 hours a week, but he would be incredibly high intensity interval training. 
  • He would be 50% high intensity, which is an outlier. 
• I also coach a hard working banking guy in Singapore who only has 7-10 hours training. 
  • He's a top age grouper in the world including at Kona. 
  • He has no time to train but when he's training it's all high intensity. 
• There's not a lot of rules that are absolute, we are all so individual.

52:40 - 

• Time in zone is a good place to start, and gives an insight into some of the polarisation.
  • You want to know heart rate and it's association with speed and power. 
• One of the most important things you can do as a coach or a self-coached athlete is make sure you have both your heart rate and speed power. 
• Using a system like Training Peaks or Garmin Connect you should be able to see your time in zone. 
• Intervals, or any type of exercise intensity, is prescribed by feel. 
  • It can be a zone feel - know what each zone feels like for you. 
  • It should be part of the educational process of the coach athlete.
  • If you get a prescription for an intensity and duration, you should know the ballpark of what that feels like. 
• Once you get this knowledge, you should be monitoring the associated power, speed and heart rate of those zones.
  • If you do this, it's enabling the body to adapt optimally. 
  • If you were prescribing absolute intensity, you don't know what the brain feels like doing. 
  • It's good to give a guideline, but if you're letting the athlete do the workout at the zone prescription, the brain will allow them to do a better workout if they're feeling good. 
  • Additionally, they're not overly stressed if for some reason they're not able to appropriately achieve that objective on that day. 

• The Science and Application of High Intensity Interval Training - book by Paul Laursen and Martin Bucheit
• The HIIT Science course by Paul Laursen and Martin Bucheit
• Video's from Martin Buchheit's presentation on interval training
• Triathlon Strength Training in 2018 - The Definitive Guide
• 80/20 Triathlon: Get Faster By Training Slower with David Warden | EP#121
• Threshold Confusion: Aerobic, Anaerobic, Lactate, Functional - Help! | EP#71

• On Twitter: @PaulBLaursen
• The HIIT Science Website
• On the Plews and Prof website, which is his website with Dan Plews. 

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Hi! I'm your host Mikael,

I am a full-time triathlon coach and an ambitious age-group triathlete. My goal is podium at the Finnish national championships within the next few years.

I first started the website Scientific Triathlon in autumn 2015 as a passion project to share my learnings with a larger triathlon audience. Later on, in early 2017 I started the podcast That Triathlon Show. 

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