Does anaerobic training damage aerobic fitness?

I am now well into the final phase of race-specific preparation for the Robin Hood half marathon in September.  I have added two sessions per week of moderately high intensity training, such as intervals or a tempo run, while making a slight reduction in over-all training volume relative to the base-building phase that was dominated by low intensity running.   My most recent sub-maximal tests show no improvement in beats/Km over the past month.  Perhaps this is a realistic indication that my fitness has peaked – though well below my target level.  However there is an alternative explanation.  This brings us back to a long-standing debate: does anaerobic training damage aerobic fitness?

There is at least one circumstance in which this is unequivocally true – the state of over-training which I will address in my next post, but at present, testing provides no evidence that I am over-trained.  I hope that the current apparent stasis in development of aerobic fitness is actually a sign of continuing improvement  in race fitness.  The explanation demands laying bare some of the misconceptions that surround the concept of anaerobic fitness.  But first it is necessary to review the much better understood concept of aerobic fitness

Aerobic fitness

Aerobic fitness is the capacity to fuel muscle contraction by means of the combustion of fuel – either glucose or fat – in the presence of oxygen, to produce carbon dioxide while transferring chemical energy  to create  high energy phosphate bonds in molecules of adenosine triphosphate (ATP), which in turn fuels muscle contraction.   The key steps of this process of oxidative metabolism occur in mitochondria within muscle cells, especially in slow twitch muscle fibres which are capable of generating a modest power output by repeated contraction over a period of hours, before they become fatigued.  The three major physiological adaptations that are required to establish aerobic fitness are increase in mitochondrial oxidative enzymes, increase in the density of capillaries delivering oxygenated blood to the muscle cells, and increased pumping capacity of the heart.  As was first clearly demonstrated by Arthur Lydiard , often described as the ‘father of jogging’ but also coach of Olympic champions including Peter Snell, gold medallist at 800m in Rome and at 800m and 1500m in Tokyo,  aerobic fitness can be established by a large volume of low intensity running.   However it should also be noted that at least some aspects of aerobic fitness, especially the development of mitochondrial oxidative enzymes, can also be enhanced by high intensity interval training, as clearly demonstrated by Martin Gibala and colleagues, at McMaster University in Ontario.

Anaerobic fitness

Anaerobc fitness is the capacity to fuel muscle contraction by metabolic processes that do not require oxygen.  There are two major anaerobic processes: glycolysis, which generates ATP from glucose in a manner that extracts only a small fraction of the energy available in glucose, by converting it to lactic acid; and the phosphocreatine system  which employs  the chemical energy contained in high energy phosphate bonds of phosphocreatine to generate ATP.   The phosphocreatine system can release energy very rapidly but the total capacity of the system is small, typically fuelling intense muscle contraction for a period of less than 10 seconds. Therefore this energy source is mainly of relevance to sprinting, and plays an almost negligible part in distance running.  However, the production of lactate from glucose via glycolysis plays a crucial, but ill-understood role, in distance running.

Anaerobic capacity

The term anaerobic capacity is used by different people in different ways.  Simon Green from University of Western Sydney wrote an interesting article discussing the various ways the term has been used, and the confusion that has arisen from this.  In a paper written in collaboration with his former mentor, Professor Brian Dawson from University of Western Australia, Green  offered the following definition: Anaerobic capacity is defined as the maximal amount of adenosine triphosphate resynthesized via anaerobic metabolism (by the whole organism) during a specific mode of short-duration maximal exercise.

I think that is a helpful definition though in my view it undervalues the important role of anaerobic metabolism in setting the limits on performance during events ranging from 800m to marathon.   At least for the distance runner, the capacity to sustain a minor contribution from anaerobic metabolism over a time scale of order of an hour or two, is important.  While the aerobic capacity produced by a large volume of low intensity running might be enough to transform a typical couch potato unable to run continuously for 5K into a 3 hour marathoner, I think it is likely that the ability to squeeze extra power from anaerobic metabolism makes a significant contribution to the difference between a 2:10 marathoner and a 2:05 marathoner, and indeed  allows recreational  athletes to perform at their best possible level across any distance from 800m to marathon.

How is anaerobic capacity developed by training?  First we must consider the mechanisms by which anaerobic capacity might be increased:

One major mechanism is via hypertrophy of type 2 (fast twitch fibres) which are specialised for anaerobic metabolism  But other processes are important.  These include the ability to remove lactic acid, since the factor that limits anaerobic energy production is the accumulation of acidity.  (Lactic acid is a combination of lactate ions and hydrogen ions.  The hydrogen ions make it an acid.)  When acid levels in muscle become too high, muscle contraction ceases.    Removal of lactic acid is achieved by the Cori cycle, which regenerates glucose from lactate in the liver.   Furthermore, muscle, heart and even brain, can metabolise lactate directly to produce energy via conversion back to pyruvate which is an intermediate molecule on the pathway to the oxidative metabolism of glucose.   In the presence of oxygen, pyruvate undergoes oxidative metabolism in mitochondria generating ATP and fuelling intracelluar processes including muscle contraction.

A third mechanism by which anaerobic metabolism can be enhanced is by increasing the ability to tolerate acidosis.  This mechanism might operate via either an increased capacity of muscle to buffer acidity or an increase in tolerance of acidity mediated by the brain. Maybe this latter mechanism could simply be regarded as an increase in mental  toughness produced by anaerobic training, though I believe that the mechanism by which the brain regulates tolerance should not be dismissed merely as mental toughness. I believe that the regulation of tolerance plays a cardinal role in the over-training syndrome. But that is an issue I will defer to my next post.

In general, any form of exercise that involves rapid consumption of a large amount of energy will enhance anaerobic capacity.  For example explosive activities such as sprinting will promote the development of type 2 fibres.    In addition, activities that entail sustained exposure to moderate levels of lactate, such as intervals with short recovery or tempo running, would be expected to increase the body’s capacity to utilise and thereby dissipate the accumulated lactate.

Anaerobic metabolism during distance running

Because anaerobic metabolism provides a rapidly accessible but transient supply of energy, whereas aerobic metabolism provides a slow but sustainable supply, the proportion of total energy provided by anaerobic metabolism decreases with duration of activity.  For intense activity lasting about 90 seconds, the amount of energy provided by anaerobic metabolism is approximately equal to that provided by aerobic metabolism, but for longer events, aerobic metabolism is the dominant source.   However, for races over distances from 5km to marathon the pace is not far from lactate threshold – the level where lactate begins to accumulate remorselessly if exercise is sustained.  A 5K race is run a little above lactate threshold because modest accumulation of lactate can be tolerated for 15-20 minutes. In contrast, a marathon is run a little below lactate threshold, but nonetheless in a zone where lactate level is appreciably above resting level, though relatively stable because the rate of dissipation matches the rate of production.    Thus even in the marathon, a small portion of power is derived from anaerobic metabolism but perhaps even more importantly, the limit on marathon pace is determined by the ability to dissipate acidity.  Enhancement of this ability is crucial for maximal marathon performance.

What is the effect on anaerobic training on fitness for distance racing?

The black line in figure 1 is a schematic represention of the way in which lactate level might increases as pace increases, at the beginning of a training block.   As pace increases beyond a vaguely defined threshold known as the aerobic threshold, lactate level rises slightly, typically exceeding 2 mMol, but then remains nearly constant as pace increases up to the point where lactate begins to rise sharply – the lactate threshold.   Between the aerobic threshold and lactate threshold, a modest amount of anaerobic metabolism generates lactic acid but the level remains failry stable because the body is able to dissipate the lactic acid as fast as it is produced.  A crucial feature relevant to anaerobic metabolism during distance running is the fact that there is no sharply defined anaerobic threshold.  Anaerobic metabolism contributes a small but steadily increasing amount to total energy production as pace increases across the entire range.  As the runner approaches the lactate threshold, the upward trend of lactate level increases.  When the rate of production overwhelms the ability to dissipate the lactic acid, the concentration of lactate exhbits a marked upswing.

The green line represents the increase in lactate after a block of low intensity, high volume training (i.e. typcial aerobic training).  Mitochondrial enzymes and the density of capillaries around slow twitch fibres have increased, favouring aerobic metabolism. The decreased proportion of energy derived from anaerobic metabolism leads to a slower rise in lactate, so the lactate threshold occurs at a higher pace.  It would be expected that marathon performance would be improved because the runner could maintain a faster pace without remorseless accumulation of acidity.  Furthermore, since running at low intensity favours the metabolism of fat relative to glucose, this training would be expected to increase capacity to metabolise fat and hence, during the marathon, glucose would be conserved.  However, it should be noted that an athlete who has already enaged in extensive base-building prior to the beginning of the training block, there will be little scope for futher aerobic development and the rightward shift of the curve is likley to be curtailed.

Figure 1: Schematic illustration of changes of the curve representing increase in lactate level from the baseline at the beginning of training block (black-line) produced by three types of training. The horizontal dashed line represent the lactate level tolerable for the duration of a marathon. Vertical lines represent marathon pace after various types of training  Green: low intensity high volume training shifts the curve rightwards, increasing marathon pace. However if there is near full aerobic aerobic development at baseline, the increase will be trivial. Red: sprints with full recovery produce hypertrophy of type 2 fibres, shifting the curve to the left thereby decreasing marathon pace though middle distance performance might be increased. Blue: intervals and tempo sessions lead to hypertrophy of type 2 fibres, increasing lactate at mid-aerobic paces, and also increase aerobic capacity, producing modest increase in marathon pace.

Figure 1: Schematic illustration of changes of the curve representing increase in lactate level with pace, from the baseline curve at the beginning of training block (black-line) produced by three types of training. The horizontal dashed line represents the lactate level tolerable for the duration of a marathon. Vertical lines represent marathon pace after various types of training
Green: low intensity high volume training shifts the curve rightwards, increasing marathon pace. However if there is near full aerobic development at baseline, the increase will be trivial.
Red: sprints with full recovery produce hypertrophy of type 2 fibres, shifting the curve to the left thereby decreasing marathon pace though middle distance performance might be increased.
Blue: intervals and tempo sessions lead to hypertrophy of type 2 fibres, increasing lactate at mid-aerobic paces, and also increase aerobic capacity, producing modest increase in marathon pace.

The red line represents the changes in lactate after a block of training consisting mainly of short, explosive bursts of activity separated by full recovery – typical of sprint training. From the point of view of energy production and utilization, the most important change will be hypertrophy of type 2b (anaerobic fast twitch) fibres. As these fibres have very limited capacity for aerobic metabolism, anaerobic metabolism will have increased relative to aerobic metabolism and the lactate threshold will be reached at a slower pace.  On the other hand, it is probable that the peak attainable level of lactate will have increased.   Because at least moderate elevation of lactate can be tolerated for periods of up to 15 minutes or so, it is quite likely that performance over middle distance events will have been enhanced by this block of training, but marathon performance is likely to have deteriorated. In this sense it might be claimed that the training block has impaired aerobic performance, though there had not necessarily been any intrinsic damage of the aerobic capacity itself.  Provided any conversion of slow twitch fibres to fast twitch fibres is negligible, the ability of muscle to metabolise fuel aerobically has not suffered sustained damage. In summary the athlete is likely to have enhanced fitness for middle distance events but impaired marathon performance.

What happens if the training block was focussed on tempo training or interval training during which effort epochs are separated by short recovery periods.  The likely effect is depicted by the blue line.   Some development of fast twitch fibres will occur.  These will be mainly aerobic fast twitch fibres (type 2a) which are capable of aerobic metabolism but derive a smaller proportion of energy form aerobic metabolism than slow twitch fibres.  Hence, production of lactate will be higher in the zone between aerobic threshold and the lactate threshold, than at the start of the block (black line.)  However, due to the sustained levels of lactate throughout the tempo sessions and interval sessions, capacity to handle lactate will be enhanced.   So the sharp upward turn of lactate level will be deferred to a faster pace.  The athlete is likely to be fitter for both middle distance and long distance racing, even up to marathon distance, than at the beginning of the training block.  However, he/she is unlikely to be as fit for a marathon as a runner who engaged in effective low intensity, high volume training, represented by the green line.

Does this mean that a marathon runner would be best advised to devote their training time to running at low intensity for as high a volume as time permits?   For a novice runner, preparing for their first marathon, I think that is the correct conclusion, though it should be noted that even high volume low intensity training can lead to over-training, as I will discuss in my next post, so there are limits on the optimum  volume.    However, for an experienced runner with a history of several years of regular training, the situation is different.  At the beginning of the pre-marathon training block, an experienced runner is likely to already have well developed capillary density around the slow twitch muscle fibres and mitochondrial oxidative enzymes.  Thus, the scope for the type of change depicted by the rightward shift from the black line to the green line in figure 1 is curtailed, and it is likely that a training strategy that includes a substantial amount of interval and/or tempo training is preferable, leading to an increase in type 2 fibres and also a small rightward shift of the lactate curve, thereby maximising race pace.

How does this analysis match the recommendations of expert coaches?

Let us consider in turn the training strategies recommeded by six different coaching schools, ordered according to proportion of high intensity training.


Phil Maffetone recommends that the majority of training s done at easy paces where ‘easy’ is defined as slower than the pace required to produce the heart rate which he calls the Maximum Aerobic Function (MAF) heart rate.  MAF heart rate is defined as (180 – age) modified by some quasi-arbitrary adjustments allowing for experience and age.   At least for the novice non-elderly runner, the  MAF heart rate is likely to be comfortably below lactate threshold.  The analysis depicted in figure 1 suggests that Maffetone training is ideal for the novice.  For a more experienced athlete, the MAF heart rate is increased by 5 beats, and for an experienced elderly athlete, it is in fact increased by total of 15 beats per minute.   If I were to ignore a subtraction on account of my recent bout of arthritis, my MAF heart rate would be in a zone where I would expect to be generating appreciable lactic acid, so even training at the MAF heart rate is likley to produce some anaerobic development.


The late John ‘Hadd’ Walsh recommended a high volume of low intensity running at or below 75% of maximum heart rate, where lactate accumulation is slight, and in addition, one or two sub-lactate threshold runs of approximately an hour duration each week, during base-building.  The pace of the sub-lactate threshold runs is the maximum pace at which a steady heart rate can be maintained for an hour.  Such sessions would be expected  to produce substantial enhancement of capacity to handle lactate, and hence, increase anaerobic capacity.  Furthermore Hadd recommended a period of race specific training after base-building in which moderately intense session were introduced.  Thus Hadd training is likely to be suitable for a moderately  experienced athlete.  Nonetheless, I consider that an experienced athlete is unlikely to achieve their absolutely peak performance unless the base-building is followed by race-specific  training that is sufficiently intense to develop type 2a fibres.


Arthur Lydiard’s  base-building program was similar to that recommended  Hadd, and indeed probably provided  the foundation on which Hadd subsequently constructed his base-building program.   Lydiard  recommended a large volume of low intensity training, but prescribed sessions at one of three different effort levels.  A ‘quarter effort’ is a session that could easily be repeated again immediately.  A half-effort session could be repeated the next day while a three-quarter effort sessions requires at least a full day of recovery.    It is not certain how Lydiard’s three quarter effort session compares with Hadd’s sub-lactate threshold session, but from the available descriptions of the Waitakere hill run that Lydiard’s athletes performed on Sunday morning, I suspect that for  Lydiard’s elite athletes the three quarter effort session was more demanding than Hadd’s sub-lactate threshold session.  Lydiard’s stable of Olympic medal winners, over distances from 800m to marathon, demonstrates that his program was capable of producing world-beating performances, at least in the middle years of the last century.

Pfitzinger & Douglas

Pfitzinger and Douglas offer a range of marathon training plans, differing in weekly mileage but based on similar underlying physiological principles.  Their 18 week 50-70 mpw plan assumes that the athlete has already done a substantial amount of base-building. The plan itself is divided into four mesocycles.  The first mesocycle is focussed on building endurance by means of increasing total miles per week and increasing long run distance, mostly at a modest pace.  The second mesocycle places the emphasis on developing capacity to handle lactate, by adding a fairly demanding weekly lactate threshold session.  The third mesocycle prepares for running at marathon pace, while also including some faster sessions that are likely to promote the development of type 2a fibres.  The fourth is a three week taper.  This program is for experienced runners, and provides a fairly demanding combination of high volume at moderate intensity, lactate threshold development, and a modest amount of faster running.


The program developed by the Furman Institute entails only three running sessions per week: an intense interval session, a tempo session and a long run at a demanding pace.  In addition, the athlete is encouraged to do a substantial amount of cross training.  The Furman Institute has demonstrated that their program can lead to impressive performances, even by relatively inexperienced athletes.  I think that this program is perhaps the most efficient way to produce the shift from the black line to the blue in figure 1.   However to my taste, it is a rather brutal program.  Furthermore, adequate  cross training to augment aerobic conditioning is crucial.


The most successful distance coach of the modern era is Renato Canova, who coaches several of the leading Kenyan half marathon and marathoners.  He places much less emphasis on  low intensity running and greater emphasis on long tempo runs.  The key sessions in his marathon program are long runs at a pace very near to marathon pace.  However, Canova’s athletes almost certainly commence their training with well developed capillaries and mitochondrial enzymes, based on years of running to and from school in many instances.


The key lesson to be gleaned for figure 1 and supported by a brief review of the training programs recommended by experienced coaches is that the optimum training for an individual depends not only on the target race, but also on experience and fitness at the start of the training block.  At present, I am preparing for a half-marathon, which therefore tips the balance a little towards higher intensity sessions compared with marathon training.  But, I started this current training block with a less well developed aerobic system than I would have wished.   So it remains unclear whether or not I have been wise to move from a predominantly low intensity program to a program including tempo runs, intervals and progressive long runs.  However if my ability to handle lactate is improving, I might nonetheless be nearer to optimum race-fitness despite not yet having achieved maximal aerobic development.  I am aware it is a gamble, but I think that if I am to achieve the best half marathon of which I am capable this year, this is the preferred strategy.

Ewen jokingly claims to have found a bookie who is prepared to offer odds of a mansion in Forrest (the poshest suburb of Canberra) against Ewen’s garden shed on the outcome of my attempt to better my M60 HM best, achieved 6 years ago.  I think these odds are not unreasonable.  I have advised Ewen to make sure he removes his lawn-mower from the garden shed in advance, but I will certainly do my best to secure a mansion for him in Forrest , near to his favourite training runs around Lake Burley Griffin and not too far from Mount Ainslie.


21 Responses to “Does anaerobic training damage aerobic fitness?”

  1. Ewen Says:

    Thanks Canute. I have the utmost confidence in your ability to extract every last second of speed from the remaining training time. However, I have removed the lawn-mower from the garden shed, as you advised.

    It’s interesting about the arbitrary adjustments in the MAF calculation putting you into a lactic acid producing zone. I’m quite confident that my 129 HR calculation is highly aerobic, especially as I would race a half marathon (fairly aerobic event) at a HR of around 145 (even though, as you say, lactic acid clearing is needed in order to hold pace in the latter stages).

    Having been doing MAF training (with admittedly some short races included) since March (although I did have the break with the DVT), I feel my aerobic ability is still improving. Just yesterday I managed a 10k easy run at 687 h/beats per km, quite an improvement on a few weeks ago. When I was running weekly interval sessions in January (as well as short races), I believe these sessions were causing my aerobic fitness to decline. However, I think if I was able to cope with a larger volume of aerobic running, with perhaps one anaerobic session per week, this may not have been the case. Could it be that elite distance runners are able to cope better with regular anaerobic training because they are maintaining sufficient aerobic running whilst doing this training? What’s the ideal % of anaerobic training so that aerobic ability doesn’t decline? Perhaps elite runners are doing 3% by volume (?), so for myself on 65k per week, that would be 2k of anaerobic training?

    • canute1 Says:

      Thanks. I am pleased you have rescued the lawn mower.

      Your report of increasing fitness with Maffetone training is interesting and matches the reports of many other athletes who have done predominantly low intensity training. If in any doubt about whether to focus on high intensity training or low intensity training, the choice of low intensity is probably the safer choice in most circumstances. Nonetheless, I believe that the evidence does suggest that to reach one’s absolute best, it is necessary to focus on higher intensity training at some stage.

      Polarised training is probably best for most people. The question of the optimum proportions of high intensity and low intensity running is challenging. It almost certainly depends on prior experience. Numerous studies of HIT show that over a period of 6 to 8 weeks, in well trained athletes, High Intensity Interval Training accompanied by a substantial decrease in total training volume produces improvement in physiological markers of fitness without any evidence of loss of aerobic fitness, but also without improvement in race performance.

      However at least two studies in which the HIT was accompanied by a moderate amount of ’typical’ aerobic training, there were improvements in race performance. In the study by Esjfajnai and Lauresen (J Sci Med Sport. 2007;10(1):27-35. ) HIT twice per week together with 2×60 minutes of recovery running per week led to improved 3000m performance. In the study by Bangsbo and colleagues (J Appl Physiol. 2009; 107(6):1771-80) HIT consisting of six to twelve 30 sec sprints 3-4 times/wk , was accompanied by one 8Km ‘fast’ aerobic session and a 7Km easy aerobic session per week. This produced improvement in physiological markers (especially sodium-potassium pumping which I believe might be very important in fatigue resistance) and also improvement in 10K performance. Several of these runners (all with more than 5 years competitive experience and PB’s below 30 minutes -actually 38 min; see eidt note below) actually achieved new PBs after the HIT. This supports the proposal that HIT achieves the best results when accompanied by at a least moderate amount of lower intensity running. In these experienced athletes, about 8Km out of a total of 31 Km (i.e. a little more than 25%) was sprinting, 15Km was designated aerobic training and the remainder was warm-up or cool-down in the sprint sessions)

      Edit 8 Aug 2013: I was careless is stating the 10K pace of the runners in the Bangsbo study was sub-30min; I meant to say sub 38 min – so they were moderatley good club runners, aged in their mid-thirties, but not sub-elites!

      In my own recent experience, last year, when I did a large amount of low intensity training I achieved remarkably low beats/Km (around 610-620 b/Km). Then after a small amount of sharpening up with drills and speed work, I ran a reasonably satisfactory HM, so that strategy was at least moderately successful. This year, I started from a lower base, but even after a larger volume of low intensity training than last year, the rate of improvement of aerobic fitness was less impressive than last year and appeared unlikely to get me to my more ambitious goal. So I have gambled on increasing the intensity of training.

  2. Ewen Says:

    Thanks Canute.
    The study by Bangsbo and colleagues is particularly interesting, especially as some of the sub-30 10k runners further improved their PBs. Presumably they’d come off ‘normal’ training mileage to do the study so would have had a good aerobic base. I think this is something I’d like to try towards the end of the next track season. The short races I’ve been doing have probably kept my legs in tune with the mechanical requirments of faster running (as well as having a small anaerobic component).
    By the way, although I removed the lawn mower, I left the whipper-snipper, such is my confidence in your ability to race a fast half marathon.

    • canute1 Says:

      I think the plan to try HIT after a thorough period of Maffetone training is very sensible. My current intention is to try regular Bangsbo style HIT after the HM to see if it can help me achieve a good 5K.

  3. Robert Osfield Says:

    Thanks for a great review of training methods. For your own goals I believe there are non running training elements that you could work on to help you achieve a great time.

    I believe my change in diet from relative high carb to moderate carb, and always training in a fasted state has helped with my bodies ability to metabolize fat. Better fat metabolism obviously helps with being an ultra marathoner, but I would also expect it’ll help with shorter distances as well as I’m sure it’s helping with my aerobic development and thus reducing my requirement for anaerobic. Even without extensive training in the last few month I have moved my aerobic development on – in effect I’m training my body day in day out thanks to the dietary changes.

    I have also started practising intermittent fasting (IF) which basically means that I skip breakfast on most days, eating lunch and dinner. Last week when tapering for the Devil I re-introduced eating porridge for breakfast to add some carbo-loading into my prep. What surprised me was that I felt more hungry and slightly low in blood in sugar come lunchtime, something that wasn’t happening when I skipped breakfast. The way I figure it rating carbs -> Insunline spike -> low fat metabolism and then low blood sugar.

    Given what happened during the week my breakfast at 3:30am before the race I stuck to scrambled eggs, salad and a drink of beetroot juice. The race started at 6am, no sugar low before it, and felt great throughout the race. Despite totally crap training ended up finishing in 21st in time of 7:17 which was hour faster than I expected. I totally nailed the race.

    How I did well in the race was far less down to running training and far more down to changes in diet and what I did on the day. Beetroot juice before the race, and a 200mg Caffine tablet at the half way point were important to performing well. Pacing using my HR monitor was also crucial – my splits percentages were within 1% of those this years and previous years winners. My food and drink plan went very smoothly as well.

    My head was also in a good place, while my training was far from ideal – effectively cramming training into the four weeks before the race and longest run of 15 miles, I wasn’t anxious about finishing or the discomfort likely in-store – I was 100% confident of finishing. I was nervous beforehand – couldn’t sleep the night before but I just didn’t worry, just enjoyed the nerves as part of the experience. I didn’t have a clue what time I’d finish it so had no real expectations, so my HR monitor was going to be my guide and whatever happened happened w.r.t speed, I’d just do my best to keep my body in equilibrium and not mess up food/drink/footing/navigation. I ended up running my the best ultra so far, it just went pretty well perfectly.

    I mention all this to help raise the idea that there are lots of other elements you can do in your life when not doing running training that can make a huge amount of difference. Get all of these other elements right and your training will go better and race day you could far exceed what you, or your training analysis might suggest.

    • canute1 Says:


      Congratulations on your great performance in the Devil.

      I agree that consideration of aerobic and anaerobic capacity alone is simplistic, and that many other physiological processes (including what are normally regarded as psychological processes) matter.

      Your experience with diet is intriguing. Certainly the evidence for benefit from beetroot and also caffeine is quite strong, though in relation to caffeine, I am concerned about the question of how one should define unacceptable strategies for enhancing performance. For the time being I think it is sensible to accept the arbitrary rules of the IAAF. I am inclined to think that things that can be described as part of a nutritious diet are OK even if taken in atypical but ‘reasonable’ quantities. Beetroot juice is nutritious, but caffeine is primarily a stimulant. However because it is so widely used, IAAF is unlikely to ban it, though I personally would not take tablets as I would regard the primary goal of caffeine tablets to be stimulation. The effects of intermittent fasting and also of adjusting ratio of carbohydrate to fat are intriguing. It is likely that your pacing strategy also played a large a part in your success. In contrast to the HM where avoiding lactate accumulation is crucial, in an ultra, fuel conservation is crucial, and keeping in the zone where ratio of fat to glucose utilzation favours fat almost certainly helped that.

      But other factors also come into play. I also believe that the benefits of HIT are not only achieved by improved aerobic enzymes and capacity to handle lactate. I think that the role of HIT in optimizing ion transport is also important.

  4. Robert Osfield Says:

    When reviewing my logs after my Devil O’Highlands for indications of how I achieved a better performance than I had anticipated from training logs/general feel I believe a big factor is that my HR drift is now much lower than in previous years.

    What I effectively see from my logs is my HR beats per mile at short distance is similar to last year for running for one hour, but my HR beats per mile for two hour or longer runs doesn’t increase as much as it did last year. The effect is that for really long runs such as ultras I’m now able to maintain pace better for a given HR. My guess is that is an indication that I’m burning more fat now, right from the start of a run. This could well go some way to explaining my stronger than expected ultra performance.

    My training has been far worse than last year due to a series of injuries – except for January and February my mileage is way down, and have done far less long runs as well. To me it looks likely changes in diet must have had a strong positive influence on my fat utilization despite the reduced training.

    Another aspect that my experience is worth noting is that using short distance HR/pace measurements is not sufficient to get an accurate measurement of likely performance. Testing at short distance then testing again after a long period of exercise is important. I would suggest adding some extra tests to your own testing regime to get a better overall picture of fitness.

    • canute1 Says:

      Thanks for that comment. I agree that ability to minimise increase in beats/Km over a long period is a key index of fitness for long races. For several years I have assessed beats per Km over 2 Km of similar terrain in the early and late stages of a long run ( see for example In my long run this morning, I was pleased to note that after achieving equilibrium over the first three Km, beats per Km remained remarkably consistent at around 690 b/Km throughout the remainder of my run. Unfortunately, despite being consistent over the duration of the run, the actual value was much higher than in Jan 2010 (638 b/Km in the early stages and 645 b/Km near the end). So my aerobic capacity is still poor compared with 2010, but my endurance for up to 2 hours at modest paces is now quite good. I attribute this to a relatively large volume of low intensity running during base building this year. Nonetheless, I am concerned about my inability to maintain target HM pace. Perhaps I would be better advised to enter an ultra rather than a HM in September. (Though, I am not seriously tempted by the prospect of an ultra simply because I still get very tired after more than 2 hours of running.)

      The question of whether diet was a key factor for your great performance in the Devil is intriguing. I suspect that the crucial factor that allowed you to minimise the increase in beats/Km was the ability to avoid recruiting type 2 fibres. In part this was due to your deliberate strategy of keeping HR low, but this strategy would not have worked unless your type 1 fibres were capable of sustaining the work load. Since type 1 fibres are well adapted to use fat whereas type 2 fibres use glucose, you were almost certainly burning a favourable ratio of fat to glucose. It is plausible that your diet played a role in encouraging the preferential recruitment of type 1 fibres.

  5. Robert Osfield Says:

    Hi Canute, less than a week to go to the Robin Hood Marathon so I can only presume that you are now enjoying taper. How has the things gone in the final month?

    • canute1 Says:

      Yes, the RH marathon and half-marathon will be on Sunday so I am now tapering. Unfortunately, although the sub-maximal tests have indicated continual small improvements in aerobic capacity throughout the preparation, I am even less fit than last year. Maybe this is largely due to aging, as I feel more clunky with each passing year – mainly due to aches in joints and bones rather than muscles. On the positive side, my body has coped with a larger volume of training this year, despite the missed training due to arthritis early in the year. Maybe this will be reflected in greater endurance on race day, but even more important, it suggests that next year I might be able to cope with a enough to training to prepare for a reasonable marathon.

      • Robert Osfield Says:

        My HR recordings prior to the Devil didn’t suggest that I was capable of the time I did. Afterwards I had to recalibrate how much heart rate drift I experience during long runs so that subsequent ultra’s I’ll be able to better estimate performance.
        I mention this as there is chance you might see something similar – better performance on race day than your training suggests.

        A factor that helped me on race day, and what I’d recommend you do to get the best out of your performance is to take 200ml+ of beetroot juice each day for the last few days before the race, then just before the race take a 200mg caffeine tablet. I know the you’ve expressed the feeling that caffeine is a stimulant rather than a nutrient so not desirable, but I’m pretty sure it’s effective so if you want to reach your goal then giving yourself a bit of boost might make all the difference.

        For a half marathon you probably don’t need to worry about running by HR, as lactate threshold and experience should be a sufficient guide to getting the pace right. With an ultra you are running so far below lactate threshold that it’s very difficult to know whether you are going to fast or too slow by feel, so having a quantitative measure of effort level is useful guide.

        Good luck on race day.

    • canute1 Says:


      Thanks for those comments. I certainly hope that beats/Km at race pace will improve during the taper as a result of the reduction in training stress. That is what I experienced last year, though unfortunately I start for a worse state prior to taper this year.

      Nonetheless, I maintain modest optimism that I can achieve a time near to last year’s time, on account of better endurance this year. I think that lack of endurance rather than basic aerobic capacity was the ultimate limiting factor last year. If endurance is better, I can perhaps afford to start a little more agressively – though my legs are a bit more fragile this year so I will be careful.

      I will look into beetroot juice. At this stage I need to establish what effect it has on my gut. In the past I have not suffered gut problems during a race, but this year my gut has been a little temperamental during training. I remain ambivalent about both caffeine and anti-inflammatories, because they can scarcely be regarded as nutritional, though I accept that this judgement is a little arbitrary.

      But overall, I am drawing inspiration from your performance is the Devil.

      • Robert Osfield Says:

        I view caffeine as a stimulant that looks to act much like the hormone adrenaline. There seems to be diverging views as to whether caffeine actually stimulates adrenaline release – no doubt you’ll have a much better understanding on it’s effect on your body than I.

        I’m planning on doing a 10k race this weekend, after 6 months of my average pace being slower around 9 min/mile I’m going to attempt to run near 6:30 pace for 40 and a bit minutes. Yehaaa!!! Today I did a tempo run, partly out of deluded hope that I might be able to spur some improvements in ability to buffer lactate, but mainly to tune my muscle tension and brain for race pace.

        I have using this race pace training runs in the last week before a race and feel they are quite useful. What inspired this was some recent taper studies that suggests that when tapering it most effective to drop the mileage very substantially in the last week (down to 30% or less) and with it cut almost all the easy runs, but retain a few miles at race pace. Steve Magness also write about muscle tuning for race day on his blog

        When doing ultra’s my last training runs are also a race pace, but these of course at a very easy pace indeed. Quite different from taper studies which look at shorter distance but I believe the principle carries across – for an ultra you want to detune muscle tension, for a 10k or half you want to tune up muscle tensions.

        For yourself it’d mean put in an three or four run, starting easy to warm up but finishing at race pace for the last couple of miles.

    • canute1 Says:

      As I see it, the purpose of the taper is maximising recovery from heavy training while maintaining fluency at race pace. I therefore agree with cutting volume drastically and focussing on race pace. In fact, after a long period of training mainly at slower than race pace, I think that a few relaxed stride-outs (eg 6x80m) somewhat faster than race pace helps get the limbs moving freely. So this week I have cut training volume down to 30% of my recent average. I will have two rest days, and on the days that I run, I will warm up; do some relaxed strides faster than race pace, followed by 1Km at race pace. If done three times in the week, I hope this will be enough to establish the rhythm of race pace with minimal stress on the body.
      I have started beet juice today – cautiously to test for any adverse effects.
      Good luck with your 10K.

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