Podcast, Training

Interval Training – Science and Application part 2 with Paul Laursen | EP#129

 May 24, 2018

By  Mikael Eriksson

Interval Training - Science and Application part 2 with Paul Laursen | EP#129

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.

Discuss this episode!

  • Let's discuss this episode and the topic in general. Post any comments or questions in the comments at the bottom of the shownotes. Join the discussion here!

In this Episode you'll learn about:

  • 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. 

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Structuring interval workouts

2:59 - 

  • For example, take a track workout:
    • You can do 10x400 with some recovery.
    • Or you could do 4x1000.
    • How do you decide which will be more effective? 
  • This goes back to the short interval versus long interval, and it will depend on the intensity you do the intervals. 
    • The 400m repeats is closer to short intervals.
    • If you have appropriate recovery, it could be a less stressful workout than 4x1000.
    • If you bring them down to 300m with appropriate recovery, it would be a lessened neuromuscular and anaerobic/glycolytic.
  • For the 4x1000 you are prolonging intensity, and this would be more like type 4 target.
    • These are almost like VO2max intervals.
  • It may help having both types of workout in a week.
    • As opposed to two workouts of the 4x1000m. 
  • Another pair of workouts could be:
    • 3x1 mile, and 6x800m which are around the same distance.
    • Similar types of workouts but different length intervals. 
  • It's important to always go back to the athlete. 
  • There is a philosophy that the more time you spend at your VO2max the more able you are to make that adaptation. 
    • The problem is that this is too stressful in some individuals.
  • Using longer intervals may work great with some individuals, but it might be overly stressful for another. 
  • The name of the game for any athlete is training consistency.
  • We really want to nail as many sessions as we can. 
    • We're then enabling the frequency of the stimulus in the cells in the body to be consistent. 
  • If a person is ready for longer intervals, that's great.
    • But if they're just starting out, they may not be able to manage the more high stress workouts. 

How hard to work during intervals

9:00 -

  • You don't want to be empty at the end, you always want to leave feeling you could do more.
  • If it feels too stressful, it probably is.
  • Again it's subject to individual differences.
    • There's some individuals that are very resilient.
    • However there are some who may feel they're thriving on it, but you could be either causing an injury or ruining your next day. 
  • Being able to do your training the next day is one of the key factors that will elicit adaptations in the long run.
  • The people I coach are very motivated, and would go to the well every time if I prescribed it. 
    • I've found that if this happens I help to create an injury in them. 
    • For me, always coming away feeling like you could have done one more if needed, is the best level.
  • There's a chapter about this in the book written by Phil Maffetone about health and interval training. 
  • We have to remember that high intensity interval training is a stress.
    • It's a good stress if used the right way.
    • But if we go to the max of ability, it's a heavy stress on the body. 
    • Couple this with other stressors in people's lives and it's probably the main reason for overtraining syndrome. 

Recovery from interval workouts 

14:20 -

  • One of the main ways you can recover is ensuring you have one interval left in you. 
  • You might want to consider incorporating short interval work in your prescriptions. 
    • If you're breaking intervals into shorter bout durations at high intensity, and separating with appropriate gaps, it's generally less stressful. 
    • This is a way to still achieve high intensity in a session but not have it be as excessive and off putting as long interval work. 
  • The other thing you can do is have a period of sub-maximal recovery.
    • For example 6 to 8 times 30 on/30 off. 
      • Separate each 30 on/30 off with 5-10 minutes easy spinning or light jogging. 
    • This keeps stress a little more at bay but you still get a great stimulus. 

Modality of interval training 

16:28 - 

  • We don't know a lot about different modalities based on the research. 
    • (i.e. is is better to train on a treadmill or on the road etc)
  • Personally I like to switch things around a lot from a coaching stand point.
  • Talking running specifically:
    • I like to manipulate my intervals so a few are off-road, some on the track etc.
  • A big mistake I've made on the track is not reminding athletes to turn the other way.
    • Consequently they've developed ITB syndrome because they've going round the track only in one direction. 
  • I try and programme intervals based on the race coming up. 
    • Have them course specific where possible. 
  • Having some hills in there as well can help. 
    • Hill repeats are fantastic.
    • Again we don't prescribe this as a speed, it's done on feel. 
    • E.g. Have athletes complete a short interval but on a hill. 
    • It's a great way to build leg strength. 
  • One French research study looked at hill repeats compared to track workouts.
    • They found track workouts were significantly better in terms of time at intensity.
  • I tend to see benefits from variety of the stimulus.
    • This may be more from a mental standpoint. 
    • The athletes I coach seem to like things changing up from time to time.  

Case Study: Kyle Buckingham 

20:46 - 

  • Kyle Buckingham, one of the athletes I coach, recently won Ironman South Africa.
  • It was a career highlight from my standpoint. 
  • It's been an absolute pleasure to coach Kyle, and I feel blessed that our paths crossed. 
  • He's right in the prime time to reap the benefits of the work that he's done now. 
  • Kyle is a student of the sport which makes him so enjoyable to coach. 
  • I met Kyle after Kona and at that time his GI system was really letting him down in races.
    • He was getting carbohydrate intolerance. 
    • Those who do Ironman will know how the gut can really take us out of the game sometimes. 
  • Kyle wasn't aware of the LCHF benefits. 
    • It's not for everyone, but Kyle benefitted from that. 
    • He was able to throw away the 90g/hour carb amounts and was able to bring it down to a more manageable 60g/hour.
    • He was then able to run free a bit more. 
  • We didn't get a before and after measure of his metabolism, but I've seen enough of athletes in the labs to know what happens. 
  • The main litmus test is that Kyle can do an 8-hour ride fasted and on water. 
    • He'll do 210 watts on an 8-hour ride, which not a lot of people can do. 
    • You can only do that if your fat oxidation is super max. 
  • He did full keto to start, and was actually a doubter at the start. 
    • After about 5-6 weeks he realised the value, and hasn't turned back. 
  • After we got the baseline fat oxidation level high, we lost sight of the top end. 
    • We then brought interval training back in to work on that.
  • To bring interval training and LCHF together, we did a lot of work on the periodisation of macro nutrients.
    • Now it's more carbohydrates during the high intensity sessions, and LCHF elsewhere.
  • Nutrition, as with intervals, depends on the context of the person. 
    • Periodisation and individualisation are so important.
  • Try things out for yourself and see what works for you. 
    • Try not to fall into fads, but don't be afraid to give something a try.
    • If you try something, give it some time. 
  • With Kyle, he gave LCHF enough time to give it a good chance. 
    • It took him 4-6 to get to a decent level. 
    • The real litmus test is to try your long run fasted and see how long you can go without feeling hungry.
      • The longer you can go means you know you're on to something. 
      • Kyle is the extreme end and he's got that up to 8 hours. 

Rapid fire questions

29:49 -

  • What is your favourite book, blog or resource related to triathlon or endurance sports?
  • What's a personal habit that has helped you achieve success?
    • Routine is a big one.
    • Doing my best to practice what I preach.
    • Trying to prioritise the things that I know will help facilitate my health, like my nutrition, sleep, exercise and time with family and friends. 
  • What do you wish you have known or wish you had done differently at some point in your career?
    • I went to the well too often on my training, and I wish I'd had a coach that guided me better and told me not to do that. 
    • I got injured too much and I got overtrained too much. It would have been nice to see if I had more in my that I was able to get too on a performance level.

Key Takeaways

  • Don't go completely to the well each time you do interval workouts, finish with 1-2 intervals left in you. 
  • A summary of the types of interval training:
    • Three different systems:
      • Aerobic/oxidative
      • Anaerobic/glycolytic
      • Neuromuscular/muscoskeletal. 
    • Six different types of intervals:
      • Type 1 - Focusing on aerobic.
      • Type 2 - Aerobic plus neuromuscular.
      • Type 3 - Aerobic plus anaerobic.
      • Type 4 - Aerobic, anaerobic and neuromuscular. 
      • Type 5 - Peripheral aerobic plus anaerobic system. 
      • Type 6 - Neuromuscular only.
  • Short intervals may be under-utilised in triathlon.
    • They can create great stimuli for what you're targeting and cause less stress.
    • By knowing the different types of intervals and playing around with the variable, you can better design your interval training. 
      • You can be specific with what you're targeting without causing undue stress.

Links, resources and contact

Links and resources mentioned

Connect with Paul Laursen

Connect with host Mikael Eriksson


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  • Hi Mikael! Hello from Montreal, Canada! I enjoy listening to your podcasts on my commute to-from work.

    Paul Laursen mentioned 12 variables to build a workout. He quotes a few of them: intensity, interval duration, duration, rest intensity, … What are the others?

    I am not familiar with peripheral aerobic workout. What would be an example of it?

    Thanks again for your show. I especially love to read your show notes after listening to the podcast to make sure I did not miss anything.

    • Hi Hugues,

      I’ve asked Paul to provide a list of the 12 variables, I’ll post back here when I get it.

      As for peripheral aerobic workouts, these focus on targeting the oxidative system components in the actual muscles, rather than the heart and lungs. So for example, oxidative enzymes, mitochondria, capillary density, etc. In reality, all intervals do a bit of both (peripheral and central adaptations), but I believe what Paul refers to hear is intervals at speed/power outputs above the speed/power at VO2max. At VO2max, we’re already stressing our central system maximally (depending on the duration of the interval – it may take some time to rev it up) and for our bodies to produce outputs higher than those associated with VO2max, we place an increased stimulus on the peripheral systems.

      So an example would be 1-minute intervals at 130% FTP with 1-minute recoveries. VO2max would be around 115-120% FTP typically.

      Finally, thank you so much for the great feedback! 🙂

      • Awesome! Thank you very much for the comprehensive answer. It is not easy to vulgarize this knowledge for the common of mortals. That’s what I like with your show; we understand the science stuff without having done a degree in science of sports.

        • Here are the variables, quoting Paul directly:

          “Not yet published, but to come out in the book: These include the
          1) work bout intensity,
          2) duration of the work bout,
          3) recovery period intensity
          4) recovery period duration,
          5) number of intervals or series duration,
          6) number of interval bout series and
          7) their between-series recovery duration and
          8) intensity. The variables of 1 through 8 accounts for the
          9) total work performed. Additionally, other factors that play a large role on the physiological outcome of an HIT session are the
          10) exercise mode and ground surface for run-based HIT,
          11) environment (heat and altitude), and
          12) an athlete’s nutrition practice. “

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