Nutrition, Podcast, Science, Training

Nitrate loading, marathons, and endurance sports science with prof. Andy Jones | EP#187

 June 24, 2019

By  Mikael Eriksson

​Nitrate loading, marathons, and endurance sports science with prof. Andy Jones | EP#187

TTS187 - Nitrate loading, marathons, and endurance sports science with prof. Andy Jones

Professor Andy Jones is internationally recognized for his work in academia and applied sports science. He has authored more than 280 original research and review articles, worked with the two best marathoners in history (Eliud Kipchoge and Paula Radcliffe) and is perhaps best known for his pioneering work in the use of dietary nitrate (found in e.g. beetroot) and its impact on endurance performance.

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:

  • Nitrate loading: what are the benefits and what is the proper protocol for it?
  • Can nitrate loading be done with normal beetroot juice or beetroots, or are specific supplements preferable?
  • Will we see the 2-hour marathon milestone broken soon, and what advances in running should take place for it to happen?
  • Running and endurance performance in large part comes down to three parameters: aerobic capacity (VO2max), economy, and lactate threshold. How should we train to improve these parameters?
  • The Critical Power concept and how it stacks up to Maximum Lactate Steady State.

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About Andy Jones

4:15 -

  • I'm currently a Professor of Applied Physiology at the University of Exeter. 
  • My whole career has been about endurance exercise of one form or another, with a particular focus on distance running. 

    I got in to sport science in the first place because I was a pretty decent junior runner in the UK. 
  • Since then I've been obsessed by endurance exercise and the limitations and ways we can improved.
  • A lot of the research I have done has focused on the limitations on endurance performance.
  • A lot of the applied work with athletes has focused on trying to help the athletes achieve their goals. 

Improving physiological variables

5:40 -

  • The variables that are important for success in endurance generally, but running specifically, are VO2max, running economy and sustainable fraction of your VO2max - this is typically related to your lactate threshold.
  • Both ventilatory thresholds are important for different reasons - it depends on the type of event the athletes is training for - but both are important when prescribing training. 
  • It's important to track how these variables change over time.
  • If those variables are measured accurately, with insight and knowing the background science you can make predictions of what that athlete may be capable of over various distances. 
  • When it comes to improving these variables specifically there aren't key studies to guide this. 

    We have to use our experience to help develop this. 
  • VO2max is essentially related to maximal oxygen uptake, but it's the delivery of oxygen to the muscle that is the limiting factor. 

    Logically it would seem appropriate that to improve VO2max you'd need at least one session per week where you get close to maximal cardiac output/heart rate. 

    So whatever type of interval session will take you close to your maximal heart rate and keep you there for a few minutes will be relevant for developing that parameters. 

    This might be something like 16 x 400m, or 5 x 1000m - various sessions will get you the same result. 
  • With running economy there are both biomechanical and physiological factors that influence that. 

    Age and experience seem to be correlated with running economy - those who have been training longer have better economy. 

    For example, with Paula Radcliffe her running economy seemed to improve every year and correlated with her performance over that period of time. 
  • Being consistent, running reasonable mileage over many months and years is probably the best thing to do as your body adapts it's biomechanics and physiology to minimise fatigue and energy cost. 

    You find ways to move more efficiently. 
  • Finally you've got the lactate speed curve. 

    What you want to happen over the course of a training programme is for it to suppress and move to the right - shifting your lactate threshold to a higher speed. 
  • There are a variety of ways to do this:

    Having a high volume of aerobic training is one way, because if you increase your volume of mitochondria and efficiently use fats, the accumulation of lactate will be reduced. 

    Similarly, doing tempo or threshold sessions where you deliberately run for extended periods with lactate elevated seems to stimulate the ability to clear that lactate. 
  • A combination of things is essential - you need to do the long slow work, but also not neglect the tempo work where you're probably going to do most of your racing. 

Warm ups 

11:01 -

  • When it comes to warming up for very long duration endurance exercise it's less important.

    You have to be careful that you don't do too much in advance, especially if the conditions are warm as you risk overheating. 
  • Most of the research I've done in this area is for middle distance endurance events - 800m, 1500, possibly as far as 3-5km but not beyond that. 

    The work here was related to oxygen uptake kinetics. 
  • The idea there is that in addition to VO2max, submaximal VO2, VO2 at which the lactate threshold occurs, there is a fourth variable which is how rapidly can your oxygen uptake rise to meet the steady state requirement after the gun fires at the start of the race. 
  • If you're an 800-1500m runner, the first 45-60 seconds is a big fraction of the entire race duration. 

    If we can find a way to accelerate the risk in oxygen uptake to reach the steady state, then that ought to optimise performance. 

    We're assuming that the amount of anaerobic energy available is basically a constant, and therefore if we can generate more energy aerobically in that first phase by having faster VO2 kinetics it should be beneficial. 
  • We use the experience I and many others have had that when you run a set of intervals on the track (e.g. 12 x 400m), the second one often feels much easier. 

    This doesn't make a lot of inherent sense as you ought to be carrying some fatigue forward from the first one. 

    The reason seems to be that you're primed for the second and subsequent reps. 
  • We find that if you do a prior bout of high intensity exercise, your oxygen uptake rises faster at that second repetition. 

    This is a consequence of higher vasodilation so you're delivering more blood to the muscles. 

    Also the respiratory enzymes in the mitochondria within those muscles are primed to utilise the oxygen available to them. 
  • We did a few studies that demonstrated this was the case, and then began applying it back to athletes. 

    Most have adapted their warm ups accordingly. 
  • If you're a track runner the standard warm up is to do a couple of miles of running, a stretch, then 4 x 80m strides. 

    THere's been an inherent fear that doing more would mean you start the race with lactate in your legs and feeling a bit tired. 
  • If you take into account the research above, with the second rep being better than the first, introducing a longer fairly hard repetition around 20 minutes before the race seems to be beneficial. 
  • We've adapted athletes warm ups to include a 200-400m close to all out effort 10-20 minutes before the start of the race. 

    We were able to verify that performance over 800m was improved. 
  • This can be applicable particularly to competitive triathletes because the swim start is typically an all out effort to get into a good position. 

    Elite athletes often include something similar in their warm ups the morning before a race. 
  • The world cross country championships would be relevant for the same reasons as even though it's 7.5 miles, it's a sprint finish and it's a case of hanging on as long as you can. 

    If you're not in a reasonable position at the start you probably won't win so getting off the start quick is important. 
  • Similarly with cycling events, getting off the start can be really important. 


18:16 -

  • We've been interested in whether fast start pacing strategies can be beneficial. 
  • The pacing strategy that is optimal will depend on the race duration. 

    For a marathon, it seems that even paced is best, although interestingly Paula Radcliffe and Eliud Kipchoge both negative split when they set their respective world records. 
  • For shorter events we explored the possibility that starting (in the first 10 seconds or so) pretty much all out might enable a faster VO2 response. 

    The rationale is that when you start off at a very high intensity the phosphocreatine (PCR) in your muscle splits really quickly. 

    If you slow subsequently you can replenish some of that, but the fall in PCR is directly proportional to the ride in VO2 so you might be able to kick start the aerobic system to where it needs to be without incurring too much of an oxygen deficit. 

    There is a balance between going too hard and fast too soon and depleting your anaerobic energy store too much, and doing enough to stimulate oxygen uptake to rise more rapidly. 
  • We found that in some circumstances, when the exercise duration is less than 2-4 minutes, starting fast is probably a beneficial strategy. 
  • Our first studies manipulated the starting power getting them back to the same mean power and then assessing how long they could go for. 

    The idea was that if there was a physiological benefit in the first period that should translate to increase endurance capacity measured by improved time to exhaustion. 

    We found that this was true. 
  • We went on to do studies that looked at a fixed period of work for a certain duration and then a sprint to establish whether the fast start strategy had spared some of the anaerobic capacity that would then be available in the last phase. 

    There was decent evidence that this was true as well. 
  • If you start really fast for the first 10-15 seconds and settled into a steady pace, that would probably be more beneficial and less harmful than if you went all out for 60 seconds and then tried to settle into a pace. 

    The first 10-15 seconds is predominantly about the PCR system. 

    If you go much longer than that you start to use anaerobic glycolysis to a greater extent and that might be more difficult to recover from. 

    This is where you'll start using carbohydrates and you have a limited supply of these. 

Breaking2 - improvements to be made

22:47 - 

  • I'm a believer, I think it will eventually happen! 
  • Breaking2 certainly contributed a large part to expediting that eventuality. 

    Kipchoge took more than 2.5 minutes of the existing world record which was amazing. 
  • I hope it can be Kipchoge, but he probably won't have too many more opportunities. 

    If it isn't him I don't know how long we'll have to wait for somebody like him to come along. 

    He's an absolutely incredible and special person and athlete, it's hard to think that there could be somebody better than him but there usually are as history shows. 
  • How quickly it will happen is a tougher question. 

    I think it could happen within 5 years, or it could take 15-20. I don't see it taking longer than that because Kipchoge has taken it within sight now. 
  • In terms of what can be done better, I think the Monza exprience was great and a lot of state of the art preparations were great. 

    Monza had the perfect track with sweeping bends and ideal surface. 
  • It was a little warmed than would be ideal, it was about 10-12 degrees C. 

    There's an argument that if the environment was 8-10 degrees that would have been more beneficial. 
  • Most endurance events are run in the evenings, with the marathon being an exception for logistical reasons. 

    Monza was run in the morning because it gave us the best environmental conditions. 

    If you could find a course that was equally fast but was cool in the evenings, such that as the race proceeded the environment got cooler, that may be of benefit. 
  • In Monza the idea was to go through half way slightly faster than 2 hour pace, (59:50). The idea was that psychologically you are slightly ahead of the game, and for the spectators it's nice to think it's still on! 

    On reflection, looking at how Kipchoge accelerated in the second half and last quarter in Berlin, arguably if you can hold your nerve and go through in 60:10/60:20 that might give you a better chance of breaking 2. 
  • We took the mile by mile pacing out of the hands of the runner, there was a lead car showing exactly where the runner needed to be to break 2 and they all ran to this pace.

    This gave no opportunity for pace to fluctuate - there may have been points where Eliud felt really good and would have preferred to go quicker, and equally occasions where he wanted to slow a little. 

    By going a little slower or faster you change your motor recruitment patterns and use your muscle fibres in slightly different ways which might minimise fatigue to a certain extent. 

    While even pace has a lot to be said for it, some of the stochastic fluctuations we see when runners run might be there for a good reason. 
  • Finally, sociologically the thing about Monza was that while there was a lot of support in the home straight it was pretty barren in the back straight and there was not a lot of encouragement. 

    I think all the athletes found that tough, so if you could motivate the athletes and cheer them on the entire way around it may improve things.
  • Regarding the women's side, it's fascinating that there hasn't been as much competition to beat Paula's record. 
  • In the last 5-10 years the mens record has really plummeted and the women's has not, and I'm not really sure why that was. 

    Paula was extremely talented and clearly was ahead of her time.
  • I think we are seeing a boom in East African female runners targeting the marathon now and that's likely to be where the next female world record marathon runner comes from. 

    Perhaps the opportunities for women runners from this part of the world haven't been as good as the mens to date. 
  • It's hard to say what has led to the plummeting of the male world record without being deeply connected to the runners involved.
  • When we visited Kenya and Ethiopia as part of the Breaking2 project it was amazing how relatively naive some of the athletes and coaches were when it came to training and nutrition. 

    That's changing, there are Western agents that are introducing some of these concepts which is definitely helping. 

    Some of the marathon runners are just not used to consuming fluid or carbohydrate during a race, or knowing how to manipulate their diet to support their training. 

    This is bound to contribute to improving marathon performance. 
  • When it comes to training, I think we can over complicate it so I don't want to say the methods we use in the UK are necessarily better than what they use in Africa. 

    I think the techniques they use there where they listen to their bodies more and know how to relax and recover by periodising their rest is useful. 

    There's not always a lot of sophistication in their training, it's just a lot of mileage in many cases - it's going back to what the runners in the UK were doing in the 50-70's. 

    This still produced champions but we know there are other ways to go about that now. 
  • If you've got 100 talented Ethiopian runners and you give them a diet of 150 miles per week for a few years, there will be a few champions that emerge from that. 

    But there may be quite a few that are wasted as well who may have achieved more if their training was prescribed differently. 

Nitrate supplementation and endurance performance

33:42 - 

  • Organic nitrate is present in things like beetroot and green leafy salad vegetables (spinach, rocket, pak choi). 
  • There are bacteria in our mouths that use the nitrate for their own metabolism - we have a symbiotic relationship with these bacteria in our mouths and also our entire gastrointestinal tract. 

    The bacteria use the nitrate (NO3-) and produce nitrite (NO2-). 

    The nitrite gets into our bloodsteam, muscles and tissues, and you then only need a minor biochemical reaction to produce nitric oxide. 

    It's the nitric oxide that is important for the physiological effects we observe. 
  • Nitric oxide is the chemical that causes dilation of blood vessels, so we find that feeding people nitrate can reduce their blood pressure by a few mm of mercury within an hour. 

    This is because the nitric oxide is working on the blood vessels to cause dilation.

    There has been some suggestion that when you exercise you might be able to increase blood flow to your muscles as a consequence of that. 
  • Nitric oxide also works within muscle cells, potentially affecting the mitochondria to make them more efficient, and acting on the contractile elements of the muscle fibre as well so you can produce more force. 
  • Our original studies indicated that following dietary nitrate supplementation reduce the oxygen cost of exercising at a specific work rate. 

    In other words muscle efficiency had been improved. 
  • There have been more studies recently which suggest that even sprint performance and activities requiring high muscle power and speed are also benefited by this intervention. 
  • Lots of endurance athletes and team sport athletes have been using dietary nitrate supplementation or beetroot juice to augment their diet. 

    Many of them have found some benefit from it. 

    It may be a direct effect on running economy or exercise efficiency, or it may be an effect on blood flow, or muscle contractile function, or a combination of all of the above. 
  • It's a small improvement - you wouldn't expect a nutritional intervention to make more than 1-2% improvement - but that's the margins we see. 
  • Nitrate is now recognised as one of a few nutritional ergogenic aids that can genuinely be effective.

    The others being caffeine, creatine, sodium bicarbonate. All of which depend on the event the athlete is competing in. 

Conflicting evidence for nitrate supplementation

37:51 - 

  • For every study that you can find that is positive, with most of the nutritional ergogenic aids, you can probably find another that shows it doesn't work. 
  • The margins for improvements are so small, often less than 1%, that it's often within the measurement error of the tools in the lab. 
  • You also have variability day to day with athletes. 

    There's a placebo affect with interventions too - if the athlete thinks they feel better they may perform better. 
  • I think there's more to it than that- there are some legitimate mechanisms by which nitrate and caffeine might be beneficial to performance. 
  • Elite endurance athletes are likely to benefit less from nitrate supplementation than less trained individuals. 

    There was a study a few years ago that showed the benefit you might see the exercise economy and performance was closely correlated to VO2max. 

    The less fit you were, the more benefit you would get, and the more fit you are the less benefit you would get. 
  • This makes sense really, when you're an elite endurance athlete pretty much everything is already optimised. 

    It doesn't mean that nitrate isn't improving your performance by 0.1-0.2%, which is probably impossibly to detect statistically or measure, as it could change your performance time which may make the difference between 3rd or 4th. 
  • When we're interpreting sports nutrition evidence you have to bear that in mind, and individual case studies are important because they can show trial and error. 
  • We find responders and non-responders even among elite athletes. 

    Eliud Kipchoge for example is a big believer in beetroot juice and he's used it before every one of his last 8 or 9 marathons. 

    You can't say the beetroot juice has contributed to his performance as I'm pretty sure he'd have run similar times without it, but he believes it works and who knows, it may be worth 10 seconds to him. 

Nitrate loading prior to an event

40:57 - 

  • The evidence now is that you're much more likely to see beneficial effects if you've used nitrate for at least a few days, possibly a week, prior to an event rather than just acutely. 
  • You may want to do both - take nitrate once or twice a day for 4-7 days, and then also use it on the morning before a race. 
  • You might want to start the race with elevated nitrite levels in your blood and that would be the best way to do that. 
  • There have been some animal studies done recently which indicate that you might be able to boost your muscle storage of nitrate and nitrite if you have a starvation phase first. 

    It's a bit like carbohydrate loading, where you have a bleed out phase where you don't consume much, and then have a loading period to give a super compensation of muscle glycogen. 

    These animal studies found that if you deprive the mouse or rat of nitrate for a week, and then reintroduce it, the skeletal muscle acts like a sponge and really takes it up. 
  • The effects on exercise performance are yet to be established, but it indicates that skeletal muscle likes nitrate and it will soak it up more after a depletion. 

    This is good evidence that muscle function may be related in some way to nitrate. 
  • This may introduce human protocols for nitrate supplementation in the future - potentially looking at cycling nitrate consumption on and off. 

Beet It 

43:27 - 

  • I'm not formally associated with Beet It, but I do use their products in research because they guarantee the amount of nitrate in their products. 

    If you're doing a double blind experiment and want to introduce a specific quantity of nitrate they're very good for that. 

    Nitrate in food varies according to the time of year and other factors so it's hard to use this for studies. 
  • Beet It also have a nitrate depleted placebo drink so it's nice to be able to separate the effect of nitrate in that way. 
  • Even with beetroot juice and some supplements, unless they have a similarly strict quality control to Beet It, they may not have the amount of nitrate you think you are consuming. 

Nitrate performance benefits across different endurance events 

45:59 -

  • It keeps changing, when we first showed the improvement in exercise economy the focus was on endurance. 
  • We and others then did studies which indicated that multiple sprint and even one off sprint and power type activities seemed to benefit too. 
  • It could be something that is important across the board - different studies keep coming out that point to benefits in different areas. 
  • There's a recent study that shows it's more beneficial for shorter endurance than longer endurance, but then another showed the opposite so it's hard to pin point right now. 
  • If you're in any way deficient in an ability to produce nitric oxide then using that as a supplement is probably going to be beneficial for you. 

    Don't expect there to be big effects but it's very unlikely to do any harm so it's worth a try! 
  • If you don't use beetroot juice as a supplement, then as a lifestyle practice we all ought to follow the advice of the government in most countries and consume more green leafy vegetables and fruits. 

    These seem to be good for our cardiovascular and metabolic health in the long run, and so following that advice if nothing else will be likely good for your blood pressure, which will be cardio protective. 
  • Spirilising things like beetroot in salads can be a good way to get it in! 

Nutritional interventions outside of nitrates 

48:22 - 

  • I have done one or two studies looking at things other than nitrates, we did a study with sodium bicarbonate once, and we've done something on caffeine and creatine before. 
  • These are things that exercise physiologists/sports nutritionists tend to bump into occasionally and investigate! 
  • The one that has the best evidence is caffeine. 

    The balance of evidence is that caffeine is an ergogenic aid that most athletes can depend on. 

    Whether that's pre-exercise or even to spike beverages in longer exercises, or both, those are likely to be effects people can see. 

Andy's recent paper on critical power and maximum lactate steady state

50:09 - 

Related reading 

  • The purpose of the paper was to tackle the notion that the critical power or critical speed and maximal lactate steady state are the same thing. 

    They both point towards the same thing - giving an assessment of maximal metabolic steady state (what is the highest power output or running speed that you can go at where you're still in a physiological steady state). 
  • When you get above that maximal metabolic steady state you increasingly have to rely on anaerobic mechanisms of energy production and you'll get metabolites, a faster depletion of glycogen and you'll fatigue earlier. 
  • Both critical power and maximal lactate steady state are supposed to give some index of that maximal metabolic steady stead. 
  • For whatever reason its the maximal lactate steady state that has often been considered the gold standard for this, but I'm not sure why. 

    If you look at the definition, it's quite arbitrary: you get the athlete to do a series of trials and get a fingertip or earlobe blood lactate measurement every 5 minutes and you look at the difference between 10 minutes and 30 minutes. 

    If the increase in lactate is more than 1mmol, that's considered above maximal lactate steady state, and if it's below 1mmol it's deemed to be below. 

    I couldn't find anything in the literature to support that definition. 
  • In contrast, if you establish the critical power or critical speed, you find that if you exercise people just below it (95% of confidence interval), they are able to achieve a steady state.

    This is not just for lactate but for VO2 and ventilation, neuromuscular fatigue and muscle metabolic variables as well.
  • If you exercise them just above their critical power then everything goes haywire. 

    When you're above your critical power we have this other peramater from the power duration relationship called WPrime for cycle, or DPrime for running or swimming. 

    These two things combined can tell you how long a person will be able to sustain a particular work rate or speed above that critical threshold. 
  • To my mind it didn't seem sensible that when people did a comparison of maximal lactate steady state and critical power, when there was a difference (and often their was, with critical power being a bit higher), they would then assume the latter was the gold standard and would use that to criticise the critical power concept. 
  • In the article I tried to reverse that thinking, and defend critical power against that criticism. 
  • To my mind, the hyperbolic power duration relationship is a fundamental property of human bioenergetics. 

    You see it in animals, and it's something about the mechanical performance of a human. 

    I think it has a stronger theoretical application that the maximal lactate steady state. 
  • The paper basically goes into the two concepts in some depth and argues that you shouldn't consider them to be interchangeable.

    Because of the way the maximal lactate steady state is defined it will inevitably be below the critical power, and will tend to underestimate the true maximal metabolic steady state too. 
  • To determine critical power, if you've got a runner and in the last couple of weeks they've run their best time at 800m, 1500m and 3000m, I can put those into an equation.

    We know the distance they run and the time it took them so you have a speed time relationship. 

    That will be curvilinear and where it levels off to the right hand side of that graph, that gives you their critical speed. 
  • Similarly I could bring someone into the lab and put them on a cyclergometer, give them a high power output and get them to last for as long as they could. 

    For example, 400 watts and they last for 2 minutes 10 seconds.

    On another occasion I'll bring them in and exercise them at 350 watts, and maybe they go for 3.5 minutes. 

    Then I bring them in at 320 watts and they might go for 7-8 minutes. 

    The same thing is true, I plot power against duration. You can either plot the curve or linearise the relationship, and you can determine the critical power and the curvature constant. which is notionally an anaerobic component of the energetics. 

Practical applications of critical power

56:05 - 

  • If you do an incremental type exercise test there are two thresholds - the first lactate or ventilatory threshold, and the second lactate threshold. 
  • If you exercise below the first lactate threshold you're in the moderate domain. 
  • Once you get beyond your first threshold but below your second threshold, you're in the heavy domain in VO2 kinetics terminology, or the steady domain. 
  • That second lactate threshold is pretty close to critical power or critical speed, and not far off the maximal lactate steady state. 

    If you want to do threshold or tempo training, that's the one you want to go at. 
  • Once you get beyond that you're in the severe domain, and if you exercise even at a fixed power output or speed in that domain you're going to hit your VO2max and you'll fatigue relatively quickly. 

    This is where you tend to do your interval training.
  • If you're evaluating a runner or endurance athlete in the lab, knowing where those two thresholds are in terms of speed and heart rate, as well as the maximum, you can start to prescribe training sessions which should have specific physiological effects. 
  • If these sessions are repeated often enough over a period of time, they should result in specific physiological adaptations. 
  • The critical power and second lactate threshold is useful because it determines speeds which could be deemed to be challenging but sustainable for long periods, from those that aren't sustainable for longer than approximately 20 minutes. 

    Those three domains, separated by those thresholds give you very discrete physiological responses.
  • Below the first lactate threshold your lactate won't rise above baseline, you'll feel really comfortable. 
  • If you're in the zone between those two thresholds your lactate will be elevated but it will stabilise after 5-15 minutes and you'll be able to go for a while and get a good quality aerobic training stimulus. 
  • Above that second threshold, which I think is best defined by critical power, homeostasis is lost. 

    This isn't necessarily a bad thing, it won't be sustainable for the long term but can be still beneficial. 
  • Having the second component of the hyperbolic power time relationship - the WPrime - is also useful as well. 

    When that depletes to 0 this is when you'll become exhausted, so you can prescribe individualised interval training sessions where you can predict in advance how much of that WPrime is going to be utilised during each rep, and how much will have recovered in the recovery interval. 
  • One of many possible examples would be someone with a higher WPrime would be able to do longer duration intervals above critical power, and repeat those.

    Whereas somebody with a low WPrime may be better doing short intervals, possibly trying to get the same total duration of work but splicing it into shorter segments. 
  • Having some measure of the second threshold, which is at a higher intensity than most people imagine, is useful. 
  • Maximal lactate steady state can be useful as an anchor point, but my preference is for critical power. 
  • Critical power can be defined to a single watt, so it may go up and down by a few watts each day. 

    The beauty of it is that it separates domains where the physiology is different, so you can't really answer how long you can go at it. 

    You can go for a long period below it, and you wouldn't go for long higher than it, but how long you can go at it is a moot point. 
  • If your critical power was 280 and you did a TT at 270, I'd be confident you'd be below your critical power and I'd expect you to be able to do 40 minutes plus there. 

Near infrared spectroscopy (NIRS)

1:01:54 -  

  • Consumer devices of this kind are definitely improving. 
  • I know of some unpublished data that is pretty impressive showing they seem to track critical power quite well, and the oxygen saturation measures respond in ways you'd expect following various interventions. 
  • I wasn't a believer that this stuff could be miniturised and consumerised but I'm becoming more confident that eventually it might be. 
  • I don't think it's quite there yet but it might be in the not too distant future. 

Upcoming research

1:03:10 - 

  • We are currently looking at how you can predict performance based on critical power assessed in advance of the event itself. 
  • We are also looking at how critical power changes over time as you do an endurance performance. 

    Clearly as you fatigue, these variables that we think are of importance such as VO2max, economy, efficiency etc, are almost certainly not going to be the same at the end of the event as the start. 

    However, nobody has really tracked the extent to which they deteriorate. 
  • You can measure VO2max, lactate threshold and running economy in a couple of runners, and you might predict they'd be capable of the same performance time and yet they're not. 

    I suspect it's because the deterioration of those variables differs quite considerably from one athlete to the next. 
  • We've been doing some studies to track how these change over time, and specifically how critical power and WPrime changes, and whether there is anything we can do to modify the extent to which they deteriorate. 
  • We've got a paper coming out on that soon, it's the fourth in a series of studies where the first author was Eda Clarke, a PhD student of mine. 

Rapid fire questions


  • What is your favourite book, blog or resource related to endurance sports?
  • What is a personal habit that has helped you achieve success?
    • Resilience. I used to be a decent runner, and I think if you apply the discipline you need as a runner, and the motivation you have, to your science I think you can go a long way. 
  • Who is somebody in endurance sports or science academia that you look up to?
    • The marathon runners we've mentioned today. I've been blessed to cross paths with Paula Radcliffe and Eliud Kipchoge, which has been an amazing opportunity. 

Mikael's practical example of nitrate loading

  • This was before my race in Lisbon, where I swam, biked and ran faster than I ever have before, coming in third age grouper of the day. 
  • There is a great article by Alex Hutchinson on his sweat science blog that links to new research showing that after 4 days of nitrate loading, blood nitrate and nitrite started to max out. 

    The takeaway was that you may not need to load for more than 4 days, so this is the approach that I took. 
  • Two shots per day of Beet It for four days before the race. Each shot contains 400mg of nitrate, which is the amount used in research typically. 
  • I also took one shot the morning of the race, roughly three hours before. 

    In the study they actually took two shots on race day so I may have missed out a little! 
  • From what I read about nitrate loading and what was discussed in this episode, it's important to ensure you get the right amount of nitrate which isn't easy with beetroots, or beetroot juice from a grocery store. 

    There is so much variance in how much nitrate is available in whatever beetroot based product you're using. 
  • Beet it quality controls their supplement so they can guarantee 400mg of nitrate in each shot, and this is why it's used in research. 
  • I have no affiliation with them but I really like the product! 

Links, resources and contact

Links and resources mentioned

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    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.

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