Thursday, 3 April 2014

How to pace the perfect Marathon or Ultra-marathon

In search of Optimal Marathon and Ultramarathon Pacing.

The general rule for pacing that is preached by the best coaches and sports scientists is an even split or slightly negative is optimal, and this is prescribed for elite's and every day runners, but is this advice sound?  I'm not one to take things on face value, but as an inquisitive sort I've thought about the topic extensively and tried out things in my own racing.  The more I've looked into the topic the more convinced I have become that this approach is sound.  This view is based on analysis of what elite's use, and also my understanding of physiological demands that the runner is placing themselves under.

Previously I wrote about elite marathon pacing is my post  2013-London-Marathon-Elite demonstrate folly of Positive Split.  Another great discussion about elite marathon pacing can be found the Science of Sport website, relevant articles : Wilson Kipsang’s marathon world record: Pacing and splits, Geoffrey Mutai: 2:04:15, misses WRHaile Gebrselassie World Record 2007.  There is also a convenient thread for all their marathon analysis.  If you real all these bits of analysis it becomes clear optimum pacing for elites is even pacing, with big penalties paid for times when athletes surge or push on too hard at any one stage.

Another hint that even/negative pacing is provided in a quote from an Jez Brag in an interview published in Ultra Tales:

"Jez Bragg: From my experience the best way to find the ‘magic’ ultra running gears is to be patient, and start steadily. Even pacing, or ideally running negative splits, is the ideal approach to achieve this. By ‘magic’ gears I mean when you settle into a strong pace that feels effortless and like you can go on forever. It does happen; it is possible. That’s how the really special ultra running performances are achieved. The bottom line is that it’s very individual and it’s a case of finding out what works best for you."

Not only does Jez say even pacing is best, but this is exactly what he does - his course record on Devil O'Highlands is almost perfectly evenly paced. Last year I did some analysis Devil O'Highland splits, but alas been too rushed off my feet to write it, the short story of this analysis is Jez' course record stands out clearly as the strongest second half ever run on the route.  The pacing that female Devil O'Highlands record holder, Lucy Colquhoun, was also very close to even pacing.  This pattern is repeated in analysis I've done of the Highland Fling as well. Whether it's marathon world records or local ultra marathon records, the theme is consistent:

The best of the best run with very close to even pacing.

Muscle Fatigue and Muscle Damage

All marathoner will suffer fatigue and portion of this will be down to muscle damage.  Damaged muscles are less efficient so require more energy to generate the required forces, and also results in greater perceived effort level to maintain force output and pace.  Not only does this chime in with my own experience but studies have also shown how muscle damage accumulates through longer races, I guess it's one of items that is common sense and common experience.

I believe the amount of muscle damage and general muscle fatigue that we accumulate is directly related to pace that we have already run at for the preceding miles.  Running at 7:00 min/mile pace for 13 miles leaves the body with much greater muscle damage and glycogen depletion than running at 7:30 min/mile for 13 miles.  I do not believe the relationship to be linear, running 5% faster won't lead to 5% more muscle damage and glycogen depletion, but will lead to more than 5%.  Exactly how much I don't know, but I know for sure from my experience training and racing it's not linear, going a little bit faster can create a lot more damage.

In my articles from last year on the effect of fat vs glycogen utilization and  pacing strategies on glycogen utilization I touched upon the non-linear relationship between glycogen and intensity, one of the graphs that I included show how rapidly glycogen rises as intensity rises (this is based on study data of well trained athletes), I'll reproduce here so you can see how small increases in intensity have a big effect on how much fat and glycogen(carbs in the graph) you'll need:
My guess us that rate of glycogen depletion and muscle damage are correlated, although a causal link might not be direct.  The bottom line is the faster you run the faster you deplete glycogen and the faster your damage.  The fact that the relationship is non-liner it's likely we'll pay a dis-proportionate amount for going too fast over any particular section.  This is something that can been with the elite marathoners - an surge too early or too hard can blow a field apart and often kill the chances of the one pushing the surge.

Could a Positive split optimal?

Positive split has some advocates, even if they are far outnumbered by the those advocating event splits. In the British ultra-marathon scene Stuart Mills is one such advocate of positive splits with his "run as fast as your can for as far as your can" philosophy of pacing.  Could this approach be view be optimal?

A positive split strategy deliberately has the first run faster, but this does mean you are creating more more muscle damage and greater glycogen depletion in the first half of the race than an even or negative split strategy.  With more muscle damage you physically have to expend more energy per mile to cover the second half.  With greater glycogen depletion you also have to draw that greater energy contribution from your fat reserves, which in turn means greater oxygen load as well as greater perceived effort level to maintain pace.  Carrying a lower efficiency over the second half of the race will mean that the total energy requirement for a positive split will be greater than that of even or negative split.

Now Stuart's hypothesis is that in response to this muscle damage will enviably slow down and should plan for it.  Stuart's uses his own analysis of London marathon results that show the vast majority of runners including elites positive split, and my own analysis of ultra-marathon also support the observation most athletes positive split.  What Stuart then claims that this means positive split is optimal.  I can't figure out why he believes this to be sound conclusion.  To me it's akin to saying because on average the UK population is getting more overweight we should all therefore should aim to gain weight. To me all Stuart's analysis proves is that on average runners slow down in marathons, however, it simply isn't at all useful at telling us what is optimum - you have to use other types of analysis for this.

From a theoretical standpoint I can't see how running a positive split could be beneficial.  It requires more energy due to having to carry greater muscle damage through the second half of the race.  It requires you to run faster at the start of race before your body has fully warmed up and moved from anaerobic to aerobic metabolism wasting precious glycogen.  There is also a physiological price to pay - slowing down is demoralizing, as is being passed by runners who are looking stronger and fresher, you also have to carry yourself on fatigued legs that with every step eat into your soul and will to maintain the pace.  Going out fast and then hanging on is really tough mentally as well as physically.

Having followed Stuart's blog for a few years I do wonder if this last observation may be a key to understanding why he advocates a "Going out as fast as you can for as far as you can" - could it be this pacing approach makes you feel like you've run the absolute hardest and put in the most effort you could have at all points in the race.  It makes you feel that you put your all into all, you suffered for your performance so it must be the fastest you could have run.

This logic ignores the fact that such pacing causes greater muscle damage, dehydration and glycogen depletion and erodes your mental state, so while it might feel that you are running as fast as you can at any point in reality have to slow down more in the second half than you save in time by running fast in the first half.

Stuart's performance can be a bit hit and miss.  Some races he runs well and has won some huge races, but these all balanced with other races where things don't go right, or where it seems like after one third or half way he simply gives up racing completely.  Stuart often puts this less successful races down to lack of mental as much as physical preparation, but perhaps the pacing strategy is high risk and contributes to these days that don't go so well.  For these races that don't go well perhaps "Run as fast as your dare, or as far as you care" might be a more suitable signature.

I haven't yet seen a compelling argument why positive split might advantageous, and I've yet seen any good real world data to illustrate that it is appropriate for any one, let alone the average runner who is mostly likely to suffer serious muscle damage and fatigue from pushing pace early in long race.  I can't help feel a bit frustrated with Stuart.  He is massively talented runner that has so much potential, but for me I feel it rather squanders it on a less than rational pacing strategy.

What might be optimal pacing look like in practice?

So what should the runner do?  Even or slight negative split looks best from a theoretical standpoint (looking at muscle damage + glycogen depletion, heat stress and dehydration), and is backed by what pacing strategies that world top long distance athletes use when they run their best races.

In practice  one should run the first 15 minutes slower than your average pace to allow you muscles to warm up to temperature that it operates mostly efficiently at - start too fast an you are far more anaerobic and burn precious glycogen and increase muscle PH - which in turn leads to more fatigue and muscle damage.  Once past this easy start and your are fully warmed up you then steadily approach your average pace/intensity that you then aim to maintain for the majority of the race.  If the race has been run well then in the final miles it's then possible to pick up the pace a little and run a strong finish with what glycogen stores are remaining.

While I believe this to be an optimal strategy is hard to achieve and most runners aren't taught or practice pacing enough to do it.  Running the first few miles at slower than your target pace is especially hard as adrenalin is pumping and everyone else around is tearing off.  Adrenalin keeps hiding the true cost of the damage you are doing to your muscles and your prospects of running a good marathon - adrenalin prompts the the release glucose from your liver so you feel a buzz of energy, and reduces perception of pain and fatigue, which is great for a 10k, but not really what you want for a marathon.

For a marathon you need to make sure your glycogen stores in your liver don't empty too quickly, but are called upon steadily through the race.  If the body spots that liver glycogen levels are getting too low it actually creates the emotion of fatigue and slows us down, from their on it's a battle to stay focused and keep the adrenalin pumping because if you don't your body starts shutting down.  Once the adrenalin starts subsiding and the true state of damage and glycogen depletion is revealed it can be rather difficult to keep going.  I believe this is the wall that so many marathoners hit - it's not actually a hard limit of glycogen depletion but the central governor shutting things down as things have gone too far out of homo-stasis at too fast a rate.  These are the key reasons way it's so hard to run a marathon well.

How might an average runner achieve optimal pacing?

So how does an average runner run the optimal pace?  Being realistic, practice, and using tools.

Being realistic is really down to judging just what time you are likely to be able to achieve.  Marathon time calculators like the McMillan are based on what elite runners can do rather than average runners.  Average runners rarely have the aerobic, structural and metabolic resilience to be able to convert their 10k times to great marathon times like the elites.  This average lower reliance than the elites means you need to be more conservative about your time goals.

Practice is about running the target race pace regularly, getting a feel for the breathing, cadence and general feel for that pace.   As you approach your peak training and go into taper you need to speed more and more time at this pace to dial into it.  Dialing into the intensity/breathing is important is you need to run any hills at the same intensity and not judge them by pace.

Tools, here is something that may well be the crucial bit to helping elevate an inexperienced runner into a pacing god.  Heart Rate (HR) monitors are great for telling us just how hard our bodies are working.  While adrenalin may hide our actual effort level making fast pace seem easy and HR monitor will tell us exactly what is going on.  It's the face pace that does the damage so if the HR monitor values are high is indication that are likely incurring more damage than we are aware of.

HR monitors aren't flawless  - they can mis-read at times, and the thanks to natural HR drift the HR trace for optimal even pacing leads to a steady increase in HR from start to finish.  The mis-reading is typical down to poor/compromised contact, wetting a HR strap properly helps avoid this.  With the HR drift just what HR to aim for each stage is something that is likely to be personal, different runners experience different amounts of HR drift, and adrenalin can also elevate the HR for a given pace so if it goes up and down through the race what to aim for can change.

As a starting place one can use the HR guide suggested by the MARCO calculator:

From the Loch Katrine marathon that I ran 10 days ago I had a bash at using the MARCO HR guidelines. In a practice run 6 days before the marathon I ran a half marathon route on similar undulating terrain using the HR profile suggested by the MARCO calculator.  What I found is that my first mile was 15 seconds per mile too slow compared to the MARCO calculator, but in the second half on my run I had to run 30 seconds per mile faster than my planned pace.  This trail run told me that my starting HR needed to be higher and my HR drift was slower so I didn't need to target increasing my HR through the race at quite the same rate.

Race day is where it counts, does pacing by HR work?

Come Loch Katrine race day I used my HR monitor and the general principle of increasing HR through the race suggested by the MARCO calculator with tweaks based on my experience with my HR trail run, and also tweaking it on the day.  My aim for the day was to use the marathon as a training run so not push on too hard, and if possible set myself a PB with a target time of 3:30.

The Loch Katrine marathon is extremely hilly so each mile I either got ahead or behind my target average pace of 8min/mile, so I had to trust that pacing would even out.  I hit the turn around point in 1:45:09 which is far more luck than judgement to get that close, but getting so near to this just by using HR and tweaking it little bits each mile to how things were progressing is what got me in the right ballpark.  The tweaking I was doing was to lower my average HR I was targeting for each mile as my HR drift was less than I expected even compared to my half marathon trail run.

Thanks to less hills in the miles after the half marathon point by mule 16 I got ahead of my 8min/mile target without needing to up the intensity, but once I hit the hills between mile 17 and mile 22 my average speed dropped and I down a couple of minutes my the top, but as the downhill miles came I gradually got back on target.  All the while I was using my HR monitor to judge whether to slow down or speed up.

Once I got to mile 23 I was only just behind my target pace, and although it was only meant to be a training run I found myself picking up the pace, really just for fun.  My energy levels had been rock solid all through the race, my legs were quite fatigued from all the downhill miles but I overall I felt great so just pushed on.  The nearer I got to the finish the more I took the breaks off and ended up finishing the last mile in 6:10, and the last quarter at 5 min/mile pace.  Within the crazy finish I would have hit my target of 3:30 quite comfortably, but with the fun last few miles I did it in 3:26:50, nearly a 6 min PB on much hillier course than the Edinburgh marathon course where my previous PB of 3:32:26 was set.

Now I am capable of running a faster marathon, as I wasn't racing it, so I ran the first 23 mile at a slower pace than what I likely capable of.  Running such a big the negative split I did thanks the overly fast last mile isn't optimal in any way shape or form - this occurred because I was playing, not racing.  If I were to race a marathon I'd run the whole thing close to same intensity and pace.  I would certainly struggle more in the last few miles if I were racing simply because of the accumulated fatigue associated with running faster, but that's racing.  My target for sure would be even intensity and even splits.

When scaling up to ultra-marathon I have also found running by HR to be really beneficial.  In my three ultras last Autumn I raced them all far better than my previous ultra record had suggested likely.  One part of this improvement was changes in my diet to higher fat/modest carb diet so I have become better are burning fats and sparing carbs, but a big part of it is getting my pacing right - in my case by running to a constant HR. Targeting a constant HR lead me to run the first halves comfortable and then finish strong.  In my analysis of Devil O'Highland splits my own first half/second half pacing had a small positive split, but 0.7% different pacing than the winner, who just so happened to also run the strongest second half of all the people last year, and the closest to the pace that Jez and Lucy used.

Could it be coincidence that I paced in a very similar way to the best of the best or is it an indication that they run with an even pace and that running with a near constant HR is a good proxy for this intensity and pace?  Personally I can't think of more compelling indicator of just how effective pacing by HR can be.

Probabilistic pacing

Since even and negative splits are common mantra's for runners, me advocating the same really isn't novel.  My positive experience and advocacy of pacing by HR aren't unique either.  Before I wrap I'd like to put forward an idea/why of thinking about pacing that I haven't see discussed before - Probabilistic Pacing.

What is Probabilistic Pacing?  My idea is that we can view our race statistically, where each mile we run and how we run it effects the probability of achieving a particular goal be it time based, place based or just ability to finish.  What you do in each mile can improve your chances of succeeding in your goal or diminish it.   I believe we can simply view this as at high level of conscious thought - i.e if I push on too hard up this hill I increase the risk of cramp on the other side, or depleting my glycogen reserves too much, or to decide to hold back on descent to avoid going over an ankle, this high mental level of Probabilistic Pacing strategy could be partly thought as our Tactical brain.

I don't believe this idea of Probabilistic Pacing is just high level associated with conscious thought processes, I believe the Central Governor Theory suggest that at a sub-conscious level our brain/central nervous system is making calculations all the from external and internal factors to judge whether we are pushing our bodies too far out of homo-stasis as to be safe. If the Central Governor judges what we are doing as potentially damaging or dangerous then passes on it's assessment as the feeling as pain and fatigue to the conscious part of brain.  The further out of homo-stasis we get, or look likely to get, the stronger the Central Governor will dampen our ability to push on, hitting the wall/boning is likely more a manifestation of Central Governor taking charge than actual complete exhaustion.  Conversely if Central Governor judges what we are doing as safe it leaves us alone to run a good pace.

The high level tactical side to Probabilistic Pacing is really about us consciously setting a particular pace that will most likely get us to finish in one piece and at our goal pace/position, as well as working out what our body needs right now to maintain it's workload and also what we'll need next.  In an ultra-marathon this type of mental process has to include thoughts about navigation - do I need a check the map, is the route clear/familiar enough for me not need to check?  Do I need to eat now or later, do I need to drink?  Do I need to pick up some more clothing at the next check point?  Will I need my head touch?  In all these questions we are weighing up the probability that different help or hind our progress.

Probabilistic pacing relates to how fast or slow to run each section in that if we run faster we increase the probability that we'll deplete glycogen more, increase heat stress, sweat more, be able to digest less so absorb less calories and less fluid - running faster reduces can even reduce the probability of finishing at all.  If we run slower we help our bodies stay closer to the safe homo-stasis that it loves, and increase our chances finishing significantly.  However, if we want to achieve a personal best then we have to make a judgement and work out just how much risk are we willing to take with crashing and burning before the finish.

Now the Central Governor is also making these computations and if it decides to take control and cause massive fatigue then it doesn't matter how much me want to finish in certain time, if it feels that you are endangering yourself then it'll call a day and we can very rapidly feel massively fatigued and unwell. The Central Governor does like suddenly changes, non linear events are very hard to judge so it's natural for our safety systems to be conservative.  However, if we keep things smooth and linear our Central Governor is able to trust in what we are doing more and less likely to shut things down. An analogy that springs to mind is that boiling a frog, if you toss it into boiling water it'll jump out, while if you lay it cool water and let it slowly warm up it won't notice that things are getting hot.

Even pacing has the advantage that our bodies systems are steadily taxed and in way that is linear and predictable.  If the Central Governor sees that we are steadily depleting glycogen but at the rate we are burning it we will still have a safe amount left in our liver by the finish then it'll be happy and let us continue.  If we start fast or do a surge we inject a rapid and non-linear increase in rate of glycogen depletion, the heat stress on our bodies rapidly rises, our reserves of fluids get more rapidly depleted, again it's non linear, a modest increase in speed and we have to sweat much more, all of this is noticed and taken into account of by the Central Governor and makes it all more like to decide to create the fatigue that slows us down.

Listen to your heart

This probably all sounds rather complicated.  How are we supposed to use this in our next marathon or ultra marathon?  My advice is simple, listen to your heart.  I don't mean in the happy clappy, spiritual way, I mean quite literary, your heart is one of the best measures of physiological and physiological stress. The fantastic thing is we now have HR monitors that allow us to track ever beat.  We can now look down to our wrist and immediate now just how hard we are working.

With pacing by HR the absolutely simplest way is to run to constant HR.  Due to HR drift this will lead to your slowing through the race, but as long as you pick as sensible target HR this slowing shouldn't be too dramatic and just lead to a modest positive split, so it might not be optimal but it will be not far off.

A refinement on just running against a constant HR is to factor in HR drift so that your pacing goes from a small positive split back to a even or slight negative split.  The MARCO online calculator can be used as a guide for marathons, but as I've found out the HR drift it assumes may not be appropriate for you.  Using your HR monitor in training and seeing how pace and HR drift are associated can give you an idea what is appropriate for yourself.

The nice thing about using HR as guide to pacing is that it works for ascents and descent telling you exactly how hard it's safe to push on up and hill or how fast you can safely run the descent.  It also tells you when heat stress is affecting you, if it's a hot day your pace for a given HR will be lower, but as we sweat more and use more glycogen when we are hot we can't race as fast when it's hot anyway so having the HR reading guide us to slowing down is exactly what we want.

If you are using your HR monitor as a guide during a race and find that you a feeling better than expected, or worse then your can up you target HR slightly to adjust things to speed up or slow down. I used this strategy when I did my three ultra's in the Autumn of 2013, each time I was hit with cramp I dialled by the intensity, reducing my target HR by 5 bpm till any further hints of cramping had subsided then I let the HR target rise back up.

One can also look at the average HR you set as a target in terms of probabilities - which brings us back to Probabilistic Pacing concept.  Targeting a higher average HR will lead to running faster, but increase the risk being unable to maintain the pace or worse failing completely, targeting a lower average HR will lead to slower time but much better chance of finishing.  Judging the right HR to use on the day is difficult, but if you've got a HR record of previous events then you can use the average HR as a basis. If you don't feel as strong as the previous race then it is probably sensible to target a lower HR and if you feel good in the second half up the HR value.  If you feel stronger then a higher average HR might be attainable, but... if you are fitting your HR for a given pace will be lower.   Through tracking average HR and drift from training and other events look for where you feel might be appropriate come race day.  Then on race day itself adjust as necessary for how you feel.

By using your heart as guide what you do is provide a nice stable physiological load on your body that enables your Central Governor to work with nice linear changes in your homo-stasis, it doesn't get any sudden shock and doesn't panic such as making like you feel like you've hit a wall.   By working so closely with your body it will allow you to achieve much more.

Listen to your heart and your body and mind will be strong.


  1. We have been waiting for quite some time for you to finally write this article!

    The HR based approach has clearly worked very well for you, but I do need to point out that runners like Jez or Lucy aren't likely to pace themselves via the HRM; they have the ability to run by feel and know how hard they can push their bodies. This is a superior way of pacing but needs a lot of experience. If you always pace yourself by the HRM you will probably not learn to listen to your body as much.

    I used to read Stu's blog a lot but eventually gave up, and it was his (mis?)usage of statistics that finally made me take him off my reading list. He does have a point though. Every now and then a fast start strategy does yield spectacular results that the same runner would not have achieved if he/she had paced him/herself more conservatively. The East Africans are notorious for pacing themselves in a highly optimistic way in marathons and while there are plenty of them fading badly in the last few miles of a marathon there are usually a few that achieve stunning breakthrough results.

    1. I agree Jez and Lucy are examples of athletes that have near perfected their ability to judge pace by feel. This is huge asset besides their stella aerobic fitness and structural resilience.

      What is impressive about using a HR monitor as guide is a middle of the pack, relatively in-experienced ultra-runner like me could pace close to how they paced. I took one of their great skills and copied by simply looking down at my watch to check against my target HR tell me when to push on or ease off. Being able to pace like pro without the skill and experience of pro is kinda neat, and surprisingly easy and liberating.

      I would advice against ignoring the body though, and discuss this in my article, although perhaps not in enough to make it clear. If you feel good and well capable of maintain a stronger pace then I'd suggest moving to a higher target HR, and conversely if you find that the pace associated with the target HR is too fast then to move the target HR downwards. This fine tuning on the fly requires one to be aware of how your body is doing.

      I would suggest this approach is much attuned and compatible with running by feel than attempting to run by splits that many runners attempt to use for marathons and ultras. When pacing by HR you are pacing by an internal measure not an external measure, it's hard to know how fast you HR is beating by feel, but a HR monitor feels this for you, it becomes a form of fine tuned super sense of how hard your body is working second by second.

      Particularly for an ultra marathoner I think running by feel for the first half of the race is exceptionally hard. It's so easy to push on too hard because the relaxed pace that ultra's are run at is so slow as it can feel easy to maintain for many hours. However, five or so ours even a relaxed pace can start to feel tough. One thing I've noticed consistently in marathon and ultra is that the vast majority of runners push on too hard up hills, again it's hard not to as the pace may feel pretty easy to maintain. It's only in the second half of the race does going out to fast start to bite.

      Pacing by HR takes the stress out of trying to judge pace, as long as your HR target is sensible you'll be able to run a good steady race all the way to the end. I've done exactly this is four race in row now. In only one of these race was I over taken after the initial miles had passed, the rest I just steady worked my way through the field and ended up in the top 15%.

    2. second half of my reply, as blogger couldn't handle such a long comment :-)

      Pacing by HR needn't by conservative like I did in the Loch Katrine Marathon - this was meant as just a training run. One can set a higher target HR range if you are feeling confident and want except the risk it might mean going out too fast and not being able to maintain this pace. This is touches on the Probabilistic Pacing concept, the higher the target HR the higher the risk, but the higher the average pace. If you always set a too conservative target HR then you'll never find out just how far you can push yourself.

      If you want to push the limits then setting a higher target HR than your usual average HR you usually can see can be tried, if you find out during the race that this was too optimistic then simply dial down the target HR. The earlier you spot and adjust the more likely you are to be able to avoid crashing and burning. It might be that a one has a second wind and at that point you can always dial the target HR back up.

      With the East African elite marathoners sometimes pacing rather optimistically, this mostly back fires like it did at the London marathon in 2013, but occasionally runners will find that on the day they can cope with pace and finish well. In the case of East African elite runners their numbers make for a very competitive environment with new runners keen to make their mark. Their are both big financial rewards and kudos associated with making that break through with an top performance so the rewards are probably well worth the risks of not quite pulling off the best marathon time you could on any marathon. If you throw enough talented athletes at races even occasionally you'll get this stand out performances. Pacing can also be erratic simply because of tactics, with surges done for the purpose of breaking competitors rather than trying to achieve an best possible marathon time.

      However, I wouldn't try and read too much into the unexpected performances. What the best of the best do in the races where they are trying to break the world record is almost certainly where we'll see the best template for optimal pacing - and this consistently is very near even splits as documented in the articles on the Science of Sport website that I linked to

    3. This comment has been removed by the author.

  2. That quote, saying, mantra, musing, thought, whatever it is at the end ("Listen to your heat and your body and mind will be strong.")

    What is this heat you listen to? Preapology -- I read things. I did enjoy the blog post. Thank you. John M.

    1. Oppps, a typo, heat -> heart ;-)

      I'm afraid I wrote the post in a bit too much of hurry and didn't properly proof read. I am blessed with an engineers problem solving mind, but rather struggle with the written word.

  3. Fascinating stuff. 100% agree that Stuart's statistics tell you what people have done, rather than what they perhaps should have done. This is also true for a lot of the calculators that you see based on actual race results. I'm also with you that the elite guys know how to do it right, and in general the further down the field you get the more positive the split. Someone (might even have been Stuart) published an analysis of the last Fling that Jez won, which showed that as a proportion of his overall time he had the slowest time to Drymen of anyone in the race. However there will always be one or two examples to go against the rule. My normal strategy is to run conservatively from the start, but taking the Fling as an example, of the 7 I've run I actually got my best time by going out faster than I would normally be happy with; I struggled over the last 10 miles and found it really hard, and because a big part of the game for me is enjoying the trip, I determined I wouldn't do it again. I told Stuart that at the finish, to which his reply was "Ah, but it got you the result, didn't it!" So I think going out fast sometimes works but it's a high risk strategy. I also think that one of the reasons that negative splits work generally is that you feel so much better over the second half of the race, so your head's in a much better place to deal with things that could potentially slow you down. I'm interested in the MARCO thing, never seen it before. Two questions (1) how do you think you could extrapolate marathon heart rate to ultras - experience will help but you have to have a starting point, and (2) I can see that managing effort by a constant heart rate will work for flat courses, or those with relatively short hills, but could you adapt it for hillier races? My experience is that you can possibly keep your HR down when going up a long hill (say 2000 - 3000 ft of climb) by going slower than you might otherwise choose, but on a long technical descent of a similar order it's almost impossible to keep your HR up because the ground dictates your speed.

    1. Hi Andy, I'll reply in three parts to fit in within the 4k characters limits.

      Part 1:

      The analysis of splits from last years Fling indicated that you ran a far stronger half vs first compared to the average runner, including runners who finished around the time. You didn't finish as strongly as the winner but then most weren't able to maintain achieve this, because it's really hard to do just by feel - it also requires everything to go right - training hydration, food, equipment, pacing, The fact that you found it hard in the second half is because you were running on average faster than you have ever done before on that route, if you are running to your limits it will hurt regardless of what pacing strategy you use. Curiously your perception was that you used a "Run as fast as you can for as far as you can", but the stats suggest that you didn't start out fast at all for what you were capable of - you finished strongly compared to most runners around you. To re-enforce that perceptions can play tricks on how we interpret results, you overtook John Kynaston in the second half of the race, and John reported that he aimed to go out steady and finish strong, and reported that he was really happy with how it went. So the reality of the splits on the day vs your perceptions of how you paced it and both the reversed, it's John who looked to have gone out faster and you more steadily.

      From my experience with running by to an average HR in my 3 ultra's last Autumn each one of them I finished more strongly than almost all runners around me (only one runner overtook me after the quarter way point in 3 ultra's.) I ran with close as even intensity as could, but I was racing, my target average HR wasn't conservative. For each of these three ultras I was racing hard enough that muscle fatigue was a serious enough issue that I had deal with cramp in each of these ultras. If I had chosen a more conservative target HR then I have little doubt that I would have avoided the cramp issues, but I was racing them, even if it looked like for the first half I was taking it easy. While I had to deal with cramp and muscle fatigue during the last quarter of each race my energy levels and determination were undiminished, I was clear headed, focused and enjoyed the races - they were tough in the later stages for sure, but it was only tough for relatively short period of the race. This is the way racing should be - it should be about getting over the line in the fastest time you can, or the highest place you can.

      If I had set too high a target HR then it's very likely that in each of my ultra's I would have had more severe cramp, greater heat stress, greater fluid loss, lower absorption of food and water I drank, greater glycogen depletion and greater muscle damage. You can use mental determination to override some of the distress that all these factors force upon you but it's very likely I would have been over-whelmed and had to walk in much of the final parts of my ultras - like many of those around me.

    2. Part 2:

      Choosing the right target HR is really about just how hard you want to race and what risks of failure you are willing to accept. Setting a conservation target HR will no tax your system unduely and it should be easy and enjoyable to complete the whole race, and overly optimistic target HR will over tax your system and you will fail to maintain your pace, somewhere in between is the perfect target HR on doing your best time on the day. This fastest time target will still require tolerance of a bit of discomfort at the end - racing is all about leaving it all out on the course, finishing fresh ain't racing.

      With your own goals this year to be more of tourist rather than a race so you can enjoy your races more then this suggest a nice conservative target HR. In my Loch Katrine marathon I ran conservatively for most of the race with a HR around 10bpm's lower than I had raced marathons at previously. I am fitter now so this still meant that I was well within reach of a PB, and that just what I got myself, even with my crazy last mile I still finished fresh enough that I got told that I clearly wasn't trying hard enough... Even the last crazy mile I was enjoying myself, there wasn't ever any struggle to maintain pace, even finishing at 5 min/mile pace felt paradoxically effortless.

      If you know what average HR you required for previous races similar to your target race then using this as guide would be sensible. If you want to run it easier then lower the target below this, if you want to race harder and are will to take the risk of blowing up then nudge it higher a bit. Also during a race you can adjust the target depending on how you feel.

      W.r.t a similar tool as the online MARCO calculator but for ultra, this is something I'm not planning to write, but I guess long term I probably capable of doing something similar (I'm a programmer for a living these days even if I am still an engineer at heart), I don't know of anyone developing such a calculator. One of things need would be more real-world data.

      I am planning a following up blog entry on what target HR's might be sensible to use for ultras of different lengths, but haven't yet collated enough data. What I might do is do an initial blog entry with a small sample of runners then use this as a call for more data. The more data we have the more we'll be able to guide the fine tuning of what HR's to aim for during races.

      On the topic of what to do about HR when ascending and descending long hills during ultras, I agree with your that it possible to keep the HR down by taking it easy on ascent, but on steep technical descents it's sometimes impossible to run hard enough to maintain the same HR. I touched on this issue in my article above, my guidance would be to run as swiftly as you can do comfortably and relaxed manner without risking injury or excessive muscle damage. One does still need to keep an eye on the HR as sometimes once you get past a really technical bit just relaxing and letting gravity pull you downhill fast can require such a rapid leg turnover that your HR can rise quite quickly.

    3. Part 3:

      With races with lots of steep ascents/descents it will be impossible to keep the HR within a small target range, the ascents you'll push the upper end and the descents you'll push the lower end of the range, you can't avoid this, but I believe it's still beneficial to avoid significant spikes away for the average HR, going 10 bpm for a half hour climb will do far more damage to your prospects of finishing well than descending a bit slower than necessary with 10 bpm lower than your average. With such races you should have a target average HR, and have a hard upper limit to what you'll allow you HR, while if you are below the target HR then you can be easy going about it as long as it's for a short period - if it's a bit low then it probably a sign that your should probably chivvy things along a little more. With these up down races I believe a slightly lower target HR is probably sensible.

      The reason why I caution about letting the HR go too high is that the costs of doing so are exponential, so the further away from you target HR the bigger the cost in muscle damage, heat stress, slowing digestion and glycogen depletion.

      Another area where we'll need to adapt the target HR principle of pacing would be in very long ultras where you are running part of the race during the night. Because of Circadian rhythms our bodies aren't present for a great deal of activity during dark hours, as well as just the extra technical challenges of running in the dark. What this means for optimal pacing I'm not sure yet - I have yet to explore this area in my own running yet, come the WHRW this summer I should have a bit more personal experience to shed light on it. Thoughts from others experienced with night time running would be useful.

      Weather conditions are also likely to affect optimal pacing - getting quickly in and out of unpleasant conditions on a summit can be crucial so allowing for a higher HR in this zone may well be sensible. Also in cold/exposed sectors one may need to push on to just keep warm as getting too cold can have a manage effect on ability to move efficiently.

    4. Hi Robert, many thanks for the comprehensive reply. A lot of food for thought. As an (ex) engineer, I always find it fascinating when we try to work out just what is happening in any system. Keep the posts coming!

  4. I agree that minimising muscle damage is crucial is marathons and ultras. If damage rises increasingly rapidly with increasing pace, the least damage will accumulate with even pacing. You then advocate maintaining constant HR though you also point out that maintaining constant HR is likely to result in a positive split. This suggests that ideally you should let HR rise a little as the race proceeds. Furthermore I strongly agree that you should be prepared to adjust HR according to feel because HR is not always a good measure of the relevant stress.

    I have an additional concern: muscle damage is often greater on the descent, so allowing pace to increase to maintain HR on descents is likely to increase muscle damage. I think it is sensible to let HR rise a little on the ascents (but certainly do not attempt to maintain constant pace), and on the descent take care to minimize perceptible jarring rather than adjust according to HR. Maybe the degree of caution required on the descent depends on skill (and shoe characteristics).

    1. Hi Cantue,

      Thanks for your comment. I agree that pacing to a constant HR will lead to slowing through a race. As I discuss in the post I believe the ideal HR to aim for will be one that takes into account HR drift so that pace remains more even. The MARCO online calculator that I linked to uses an assumption of HR drift through a marathon to arrive at a negative split pacing plan, as I mentioned for me this actually leads to me having to speed up too much, so I need need to account for less HR drift and this is what I used during the Loch Katrine marathon - I adjusted for the drift I saw on the day to keep a roughly even split.

      For my ultra's last year I used a constant HR as a target. On the really steep ascents I actually exceeded it a bit, and when I exceeded it too much I really paid for it getting cramp shortly after. When cramp hit I really struggled to maintain the HR target but when it subsided I was able to get back to around my target. In the last parts of the race I run increasingly by feel - running as hard I could so would allow my HR to rise about the target when I felt capable to maintaining that pace.

      As for descents, as I discussed in the post and in my reply to Andy Col it's very hard to maintain enough speed to match a target HR so you just have to run and smoothly and as swiftly as you can safely do. As you say hammering a descent too hard will lead to excessive muscle damage and lead to greater slowly later in the race. What I have noticed is that in last years ultra's I generally ran ascents slower and descents faster those around me. One thing that helps with the descents is practising them, and luckily for me I have plenty of mountains around my home so can develop the skill and muscle resilience to do it without undue muscle damage accumulation.

  5. Wow!...In depth and interesting read Robert....I can’t help feeling sorry for any runners new to the sport who happen to stumble across these various debates though..God help them!..Reading Stuarts articles too are a similar statistical bewildering experience. In that very spirit I will keep this short and sweet....Two things stand out to me..One ..If a positive split really is the way to go, then super talented athletes who run exceptional half marathons should in theory do fantastic marathon times?..Then do what they do best and then simply slowed down.Their blistering speed in the first 13miles should finish the rest of the field off...But that just doesn't seem to be the case...So here I agree with you Rob, in that the evidence just isn't sufficient enough to prove positive splits are the primary PB achiever for the majority of runners - whatever the level....Granted - we may not put 100% effort into the first half but looking at my own races Its a mixed bag of splits with almost identical times..Pbs with a negative and some with a positive....Two: If what the majority do demonstrates the correct way to do things why aren’t most runners using HR at a guide..I can tell you why..Because it isn't as simple as you make out ...I’ve asked many runners if they use HR gadgets to monitor their pace and the usual answer is that it’s too complicated and can distract from the moment - even when they do own a HR monitor watch..If what I hear from much better runners than myself is true (70% of running is mental) then the debates about splits are worth much less than we all make out…..The numerous other variables and factors such as training , diet, shoe choice , genes, cadence, will power, weather, quality of training and even personal pain threshold limitations, probably have more to do with our finish times than precise pace as far as I’m concerned….But role on the discussions.

    1. Thanks for the comment Peter. I agree the technical side to pacing can get a bit esoteric for most runners, let alone new ones trying to fathom what they should do themselves.

      W.r.t majority not using HR monitors as guide even they own one, I think you are right - most currently won't even be thinking about it or if they thought about wouldn't have the knowledge or patience to try it. While pacing by HR is not yet widespread and may never be, but I believe that anything new will take time to evolve and to spread so not being widespread or well understood right now isn't likely to be reflection of what value it may hold going forward.

      What is clear to me is that very few runners are able to pace well just by feel, and the further we run the fewer are able to do it well. I believe part of the problem is that our ultra race pace or marathon pace is so far below our lactate threshold that we get little direct feedback on just how hard the pace will be to maintain for many hours. 9 min/mile can be trivial to maintain for half marathon for many runners, it can feel effortless, but maintaining 9 min/mile for a double marathon is only achievable by a small percentage of athletes. In the first half marathon of a double marathon ultra running 9 or 10 minute miles can feel equally easily, but 9 min/mile will not be maintainable for most athletes so will slow.

      This is where pacing by HR can be valuable, it can provide a concrete measure of just how hard we are working, and can pick out differences in pace that seem largely irrelevant to most runners. However, these pacing errors can lead to much more muscle damage, glycogen depletion etc. than is ideal, so runners typically end up with too much of stress deficit to really make the most out of there race.

      W.r.t 70% of running being mental, while a common theme, I don't believe this to be the case. Personally I don't see a distinction between the elements of our body and processes that are typically classically assigned as mental and physical. I believe it more helpful to see our whole mind and body integrated within on system, there isn't one dominant element within the system. As much determination I could ever muster I will never beat Usain Bolt in a sprint or Kenenisa Bekele in a 10k. However, there is a good chance that I might beat Usain at an Ultra, even if he has was really determined and trained hard for it - genetically I'm a slow twitch dominant so am slow but have good endurance.

      What I do believe is to be a good distance runner the whole system requires needs to be well balanced and co-herent, we need to have the mental will to push ourselves through exhaustion to be able to make the most of what of what the physical elements of our body can deliver. Being lazy kinda equates to safety when it comes to ultra endurance, as being slower or dropping out is almost certainly more healthy for our bodies than pushing on further and faster. You can't go any faster than your muscle and energy reserves can take you, but with commitment and determination you can get nearer to getting near to 100% of the physical potential you have.

  6. Nice blog Robert and interesting comments too. One of the key points in pacing and one often missed completely (eg Stuart Mills) is the role of effort levels - which of course should steadily increase as the race progresses and muscle damage and fatigue rise. Increasing effort can counteract the slowing caused by rising fatigue. It's a case of even pace, but very uneven effort levels. I don't see why non-elites can't improve their effort levels in the later stages too? I also agree that the objective HR measure can help in controlling early pace and effort in marathons and ultras although this is less effective in undualting trail races.

    1. Thanks for comment William. I totally agree with your points, all except the last bit - I have found pacing by HR really important when running undulating trail races as running and even walking ascents too hard is very easy. What I've seen in the first half of ultra's that almost everybody streams past me on ascents only for me to catch them back on the descents. As the ultra's progress their pace on ascents drops to a point that I over take on the ascents as well as the flats and descents.

      Stuart Mills has discussed effort levels quite extensively in other posts he's made on his blog, in fact he has a model that attempts to mix various aspects of physiological and psychological stress and effort. However, Stuart consistently pushes the idea that you should run fast while it feels easy, but oddly ignores the fact that doing this accumulates more stress early the race that you will pay for later. As far as I can tell Stuart feels that slowing is inevitable so rather than try to pace to mitigate this just go fast while it's easy and then slow down when it starts feeling tougher. I find it difficult to understand why he ignores the cost of this early pace, it seems blind to things that don't fit with his pacing model.

      However, like you I don't believe slowing is inevitable, and as you say ordinary runners just like elite's are capable of running even splits by increasing the effort level through the race. The crux to achieving a constant pace is actually much more about going out easy enough in the first half than the requiring super human effort levels in the second half. If you go out too fast then it doesn't matter how much you really want to place well or reach a certain time it won't be safe for your body so it'll simply not let you.

      I have another post planned on "Why we slow down and what to do about it", I'll would like to expand a little beyond just pacing. Just new to find a few hours to pen all my ideas down...

  7. Interesting post Robert but I'm not sure how relevant it is to trail ultramarathons particularly 100k+ .( you dont qualify what type of ultras you are talking about) I'll leave the debate about a positive or negative split being better for a marathon to you and Millsy ;-) But for a long trail ultra - there would be few if any negative splits. Hard to assess on a looped course but on out and back course eg Leadville everyone was slower by a significant amount on the back section.

    Yes someone like Jez has a strong second half but he isnt running faster than the first half , just faster than many others. When I did UTMB I was 600th and something after 70k and finished 74th - not because I ran the second half faster than the first , I just ran in faster than a lot of other people

    Your theory that slowing done isnt inevitable would mean that every elite 100mile trail runner has got it wrong.

    Also dont agree that HR is a good measure of pace in the longer trail events - heart rate on almost everyone drifts down not up (as happens in a marathon) - too many variations in heart rate in a 100mile race for it to be any more than a ballpark guideline. Developing internal RPE far better means of determining pace

    If you are talking about shorter 50mile or less ultras on runnable terrain ( as opposed to something in the alps with 6000m of vert in it) then your theories have more merit

    Thoroughly enjoyed the read though - great food for thought

    1. HI Andy,

      Thanks for comment. I haven't yet run a 100 mile ultra so can't provide anything more than projections for this. I agree that even the best of the elite's don't do negative splits in most ultras. However, in recent ultra track records even splits have been used and achieved. I believe even effort level is probably the gold standard to go by rather than splits as the terrain in most ultras is just too uneven to use conventional splits - this is where using a HR monitor has an advantage.

      Your observation about declining HR reading through a big race suggests that Adrenalin may be elevating the initial HR, and that fatigue later in the race is limiting the available power, slowing the runner so the load on the heart is lower so you see a further drop. However, fatigue is directly related to the effort level that the runner has put in so far in a race, the harder he/she runs the first half the more fatigue and more slow down they will see. Slow down is not inevitable if one paces correctly. Most runners including elite's probably pace poorly and go out way too fast, with much of the slow down being a direct consequence of going out too fast.

      In my follow up post on splits for the Highland Fling I discuss the splits of the winners, the winners very consistently have run the strongest second half so I used this as a basis for "Good day" splits % where everything goes well and you are able to run strongly through to the end. Last weekend I ran the Fling and paced primarily by heart rate and actually finished stronger in the second half than the "Good day" splits.

      My first half/second half ratio was 4th fastest of all the runners this year, 99.3% of runners ran a proportionally slower second half. My pace in the last 3 flatter miles was very similar to my pace in the first 12 (also relatively flat). I ran a PB by over an hour so I wasn't hanging around or leaving anything out on the course. What I did was run my own race, listening via my HR monitor to what my body had to say about effort level. Ignoring the pacing of others around, and ignoring ego and adrenalin takes discipline and patience.

      Whether I can map this success with using HR monitor for pacing to my West Highland Way Race I can't yet say.

      As for developing internal RPE (Rating of Perceived Exertion) for pacing, the problem with this adrenalin and mental state can cause such large deviations in perception of pain that the RPE value can go all over the place. At the start of race RPE for an appropriate pace can be so lower than one easily goes out too fast. I believe almost all ultra runners fail to run conservatively enough in the first halves of races, I also believe that most runners feel like they are running conservatively enough at the start. This mismatch shows the difficultly in getting a proper assessment of Exertion level that one is at and can maintain is the clear pointer than RPE isn't an easy or reliable way to gauge the appropriate pace.


  8. Hi Robert - thanks for the reply. A couple of points to follow up

    Totally agree about running your own race , ignoring others around you and leaving the ego aside

    But re heart rate I still dont think its the gold standard to measure effort by. I know in my training that a level of 170 is bloody hard work to get to and will only reach it in hard hill efforts or 1 mile reps but when fully tapered and fresh I can hold 170 for a half marathon. Same thing happens at lower paces. So If I run my race by heart rate I'd have to adjust Heart rate for the lack of fatigue in my legs, also have to adjust it for weather, time of day as they will also affect heart rate- . It all gets a bit too much like guess work. I find by really listening to your body RPE is a better way to determine pace ( I'm not the only one Matt Fitzgerald in his latest book agrees and there has been some research that RPE is better way to determine pace as well - I'll dig it up)
    Agreed most people dont develop an accurate RPE but I think thats due to the fact they spend too much time looking at pacing calculators and garmins and not listening to their body. If you take the time to listen to your body and learn how to interpret the signals you can account for adrenalin and mental state ( which also affect heart rate so the same argument applies to heart rate)

    Yes most runners think the pace at the start is conservative when it isnt but that comes down to experience - knowing the pace yto start off at the still allows you to run strong in the later stages of the race

    Yes fatigue is related to the effort level put in during the race so far but for a 100mile trail race the chances of running faster in the last half or even getting close to even splitting when you've already run 50 miles is very small and I'd suggest not the fastest way to run the race. It maybe a good strategy for shorter races but for 100mile trail races I think the pace you;d have to run at in the first half to give yourself a chance to neg split or even split would be so slow that you wouldn't run anywhere near your potential . Yes most people go off to fast and to have a good race you want to be feeling strong in the last half but you wont be running faster. When I ran UTMB - no-one could stay with me over the last 30-40 miles - passing hundreds of people but I wasn't running as fast as I was in the first half.

    The trick is to run the first half at a pace that allows you to still run the second half well and not resort to a shuffle

    1. Hi Andy,

      I haven't found pacing by heart rate difficult, I have also found accounting for race day HR rather than training HR is relatively straight forward. I do find I need to account for adrenalin on the day, but previous race data equalises this out.

      I am planning a follow up article on average HR for different distance races. So far I have data for Thomas Bubendorfer, John Kynaston and myself. If yourself or others have average HR data for races of different distances it'd be great to have as much data as I can to base my analysis. My email is robert.osfield at gmail dot com.

      How well using even effort level for a long ultra will work is something I an only speculate on. Not only do you have to pace conservatively enough in the first half to enable you to maintain the pace, but you also have to do everything else right - drinking and eating, navigation, maintaining a consistent positive mental attitude etc, get any of these things wrong and you'd be off your schedule. However, I still think from a mental and physiological standpoint even effort level is probably the strategy that makes it most likely that you'll be able to maintain a good effort level through to the end.

      I did an article last year on pacing and carbohydrate needs and found that even pacing resulted in the lowest carbohydrate needs, but the curve of how much extra carbohydrate you need starts off quite flat around even splits and only really steepens up as you go significantly away from an even split. From this analysis I suspect that small deviations from even split will have little impact on overall performance, while the bigger the deviation the higher the risk that you'd struggle to produce a good performance.

      From the sound of your own pacing it's now even effort level, but far closer than most ultra runners achieve. There may be opportunities to improve your pacing further, or perhaps you are is good enough already. It would be worth having a look at how your HR changes through a race to see if there are areas of peaks and troughs that you could even off - the micro pacing (minute to minute) is just if not more important than the macro pacing (hour to hour).

      In the Fling I believe I probably ran pretty close to optimal pacing, but there were still legs that I felt that I didn't complete as fast as I should have - Rowardenan to Beinglas I was slowed by bit of cramp and queued up behind other runners that were slowing badly on the narrrow technical sections. My micro pacing wasn't always ideal, some of the ascents I ran too hard - mainly when chatting with others and getting carried along, while even more so some of the descents I ran too hard too - my peak HR was on the descent from Conic hill as I charged down enjoying myself. While the final descents down the hills above Crainlarch I ran slower than I could/should have because of bruised toe. I also wonder if the last leg I could have run more aggressively, I was holding back a little as not to risk cramping up - I knew a good time was in the bag as long as I didn't screw up, all I had to do was finish strong and get home safely.

      Looking forward to the West Highland Way Race, I believe that ideal splits would probably be to look at my splits from the Fling this year, and the Devil O'Highlands last August and then slow them down by 20% to give me something that would roughly approximate to even effort level. Both races I averaged a HR of 154 and finished strongly. Whether it'll work out well is down to far more than just picking good splits or a good target average HR, but this is what I'll prepare for and give it my best shot.

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  10. When you say you cannot see why Stu would argue for a positive split just because so many people run one and liken it to saying people should become overweight just because thats what the rest of the population do you are forgetting one thing. The VAST majority of these runners were not looking for a positive split, as Stus article makes clear, most runners, even those very high level ones who are running in the top few percentile (outside of the elites) will have been aiming for even or negative splits and then simply failed to achieve them. Making it an ACCIDENTAL positive split as a pose to a strategic choice that they have trained for and refined.

    If this is the case it makes perfect sense that someone like Stu would come to the conclusion that perhaps the negatve and even strategies are simply not ideal for the majority of runners and in using them the vast majority of runners will not run to THEIR optimum performance on the day (I say that with emphasis as we are talking about non world class runners for the most part, runners who have to be considered as a separate case to elite runners). The problem is these strategies working to give you the best possible result hinge on the fact that you actually DO manage to achieve a second half speed up or you DO actually manage to even pace. if you dont you have effectively just winged it and gotten a random result....sometimes one close to your target and sometimes not. So there an awful lot of people failing and subsequently winging it which at any level of sport, elite to novice, is not a good scenario.

    If so many people positive split anyways even when they are trying to do the exact opposite then to say 'ok, regardless of the strategy you employed you run a positive split so lets accept and refine that so that it works the best it can for you' is not a nonsensical conclusion.

    The problem with a lot of the debate on this is with a negative or even split we can never know what those running with the strategy and succeeding with it (again non elite Im talking about here) would or could have ultimately run and vicd versa for the positive split....its all just theorising and using the evidence of what worked for others. And this is kind of funny given in ultra running more then any other form of running there appears to be so many unique routes to success. Even at the elite level the differences in mileage, vertical, use or non use of speedwork, terrain trained on etc etc is actually quite staggering. What this shows us is different things ARE working for different athletes and there is no one answer the the training question.

    I think that this is a lesson we need to perhaps relearn in so much as each strategy will work for some and not for others. My ultimate position would be there is NO gold standard just a lot of unique individual cases (and a lot of people following the crowd therefore making certain choices more popular). The bottom line in sports however should always be the position that what works best for one athlete will not necessarily be what works best for the next and we must find for OURSELVES what works best for us. Of course, that doesn't help promote debate but what I'm trying to say is we always as athletes should be choosing and promoting experimentation because this is the only way to ever truly know what works for us and our own unique physiology. Experimentation gives real feedback, real evidence and it gives us it in the most person specific way. This is the only way anyone will ever find what works best for themselves, that is, through trial and error.

    1. Thanks for the comment Michael.

      I agree there is individual differences between us all and what is optimum for one may not be optimum for another.

      However, my expectations is that the optimum pacing for all runners is likely to be pretty similar, far more similar than the range of pacing strategies we see out in races. My reason for believing this to be the case is down to fact that we all effected by similar physiological and mental stresses when running - we all suffer muscle fatigue, well all suffer glycogen depletion, we all suffer dehydration, we all suffer mental fatigue and the consequence of going out too fast is the same for us all - we all suffer more and slow down more as consequence.

      Big positive splits aren't at all inevitable, but are a direct consequence of runners going out too fast for their fitness level or not eating/drinking appropriately. The further we run the more difficult it is to judge the appropriate pace as the average pace in marathons or longer is typically at an easy pace that feels effortless in the first few miles of the race. Some runners are very good a judging pace and go run a very evenly split race without a garmin or HR monitor, but most (99% of runners looking at this years Fling) don't have this fine skill. For all these runners, myself included using a HR monitor to guide pace is a great proxy for that fine judgement of pace.

      I suspect that pacing by HR during training and racing may be a good way to help train that fine judgement of pace and it could be that we an dispense with the tech assistance once we tune in more to appropriate pacing.

      W.r.t experimenting ourselves what works best, I agree with this, but humans aren't always as objective at accessing things, for instance Stuart Mils is convinced that his "Run as fast as you can while you can" is ideal and advocates that we all follow his example, but it's clear from his track record of races in the last few years that his approach is prone to a large number of failed races where he slows dramatically in the second half and produces a poor result. For me the rational response to this high failure would be to directly question the "Run as fast as you can while you can", but so far Stu has stuck with his approach. I believe most runners will struggle to be objective enough as you have to fight human nature - we all feel safer with things that are familiar.

      Contrast this with my own approach of using HR monitor to guide pace, aiming for a close to an even split as I can achieve, since I've adopted this approach last summer I've ran 5 ultras and marathon and every single one I've come pretty close to running the perfect race, achieving results right at the upper end of my expectations. If the approach wasn't sound then I'd be seeing hit/miss races.

      Is pacing by HR optimal or me? Very likely not, but I believe given all the physiological and mental demands it probably is close enough to be considered a pretty effective proxy - it gets you in the right ballpark of what is likely to be optimal.

      Is pacing by HR optimal for others? Probably same story as I've found, unlikely to be absolutely optimal but certainly good enough to help runners get good results.

    2. Continued from my last comment...

      It would be great if we could create a big study to test this all out, but I haven't ever seen a similar study, and funding for such a study isn't likely to be hard to secure. If I were to do such a study I'd get runners to use different HR profiles, some with increase HR (negative split), some with even HR (what I use), some with decreasing HR (Stuart Mils style) but with the same average HR. You'd want to do series of runs where all the runners get to try different HR profiles out. One could look at race times and also the mental and physiological markers to see the effect of each pacing strategy.

      As a thought experiment look at how these mental and physiological markers develop for each of these HR profiles. The positive split HR for sure will lead to the highest overall physical and mental fatigue as you develop this fatigue much earlier and have to carry it with your for the rest of the run. For even and negative splits you delay the onset of fatigue to much further into the race.

      If you look at photo's of my in this years Highland Fling (53 miles) and West Highland Way Races (95 miles) you'll see that I was looking and running much faster and more comfortable than almost everyone else around me. Most runners had faces etched with pain associated with hours of pushing against fatigue. Finishing faster and in less discomfort and achieving results right at the upper of your capabilities isn't too good to be true, pacing by HR works.

  11. Thanks Robert,

    I think when it comes to the human body its way to easy to simplify things right down to the biological and physiological. But history has shown us that within this the body dimply does not respond the way one would assume if we were to only look at things through that one lens.

    So we could say yes the body responds in a particular way and as such ideas about what works in a race and in training should be transferable from one person to the next BUT it simply isn't always the case. Within a seemingly simple system we as runners take a million and one different roads to achieve the same end result...a better performance, a better level of running etc etc.

    I think a simple look at the various training methods of elite ultra runners is the perfect example of this. Be that someone like William Sichel the amazing 24hour and multi day runner who is known for running with a weighted best and doing a lot of cross training, runners like Anthony Kupricka and Timothy Olsen running 100-200 miles a week compared to runners like Stu Mills running 30-40 miles. There are those who run nearly all there training miles at slow pace but then blast out record breaking times for 100k.... there are runners that train in altitude but then there are those who don't, those who run lots of hills and others who are barely hitting a few hundred feet a run. What this shows us, if anything, is that the body is not a one size fits all machine. Conventional wisdom simply doesn't always work when it comes to the human body, it has been proven time and time again. If it was as simple as going on basic physiology then runners would simply testing their lactate threshold, v02 max and economy etc and then working to improve these specific elements as this would be a sure fire way to success given it is the readily accepted formulae for running performance...the reason they don't however is because we realise there are simply too many OTHER elements at play in performance. Elements that are unique to the individual and often seem to follow no real scientific reasoning but for whatever reason work for that athlete and they seem to thrive of it.

  12. Contd from above.....

    Most top level athletes learn this over time. Elite athletes especially, indeed, it is often intrinsic to there achievement of elite status...they have learned what works best for them to a high degree and exploited that with time and effort. Those who dont are often the guys who end up bombing there careers because they end up doing the wrong things for them. Many a runner has killed off there career for following a high mileage approach for example, where others runners where thriving off of it. Same approach, two hugely different outcomes.

    Sure, we can always argue the unprovable, such as arguing there IS in fact an optimum approach amongst elites for training and all these guys are just not following it but simply because they are genetically gifted they get away with sub optimum training but this doesnt add up. If it did there would be, amongst all the routines adopted, be those that were training closer to an optimum way and those that are far away from it so the results would repeatedly reflect that....but when we look amongst the field of elites this is often not the case. There are plenty of runners who regularly race one another and are always shifting positions, sometimes placing higher then the other elites and sometimes placing lower.

    One thing we know is that different things seem to work for different people and sometimes these things range from a little bit different to outright bizarre. And often these approaches would be considered to be completely non transferable, we recognise that it worked for one person but could be downright crazy for another person to attempt. Someone like runnijg legend Emil Zatopek for example, who would run 20 x 200m followed by 40 x 400m and finished off with, another 20 x 200m!

    There are so many examples of those who did what felt right and found a route to success unique to themselves. Things often merely stumbled across in the course of training by accident that they found 'felt' right and appeared to work, no science, just trial and error.

    1. Bringing this back to pacing, finally, you say that there is a simple formulae for fatigue and a slowdown but much like everything else to do with the human body this will not translate into a one size fits all approach. The body doesnt work like that and as Carl Jung said 'the shoe that fits one man, pinches another'. If HR training works for you then its great that you have found something that works for you. For others however that approach could be a nightmare, the constant checking etc could drive another runner insane and really take the enjoyment away....and that been so no matter how good an approach on paper for this person it would be an absolute terrible one as they would cease to enjoy the running. This applies to every pacing all comes down to you and what you like. Finding this out is the fun is the art of running and fitness in general, finding YOUR path and listening to YOUT body and mind, sometimes even in the face of contradictory evidence or opinons.

    2. I agree there is lots of variation in the way that elites have train and gain success. This can be partly down to individual genetic variations but it's also largely down to culture that surrounds and influences runners and coaches. It's all quite noise, but if you tear down the stimulus and response of different training methods there are lots of overlaps - doing two different things can achieve the same end.

      W.r.t pacing, it's not necessarily so varied as the various physiological and mental parameters that influence our ability to keep running at a good pace are similar enough in that they all have the same trends - the further we run and the faster we run the more we fatigue. The rate of fatigue may change for different parameters and for different runners but it's always follows the same path. The slow of the trends changes for different parameters but they all slope downwards, whether it's glycogen reserves, heat, or running economy. If one just isolate one parameter then even or negative splits almost always is the best way to manage that parameter for best overall performance from that parameter. It's only for very short races that such as 800m and shorter where positive splits become and advantage, everything else above even or negative splits are best.

      What really changes between runners is how quickly different runners fatigue and how they respond to going out too fast. Some runners completely crash on going out too fast, others can get away with it and just ease off once fatigue hits. My guess is runners like Stuart Mills are lucky enough to recover quickly after going out too fast and the penalty is not so high as for others. However, just because the penalty for going out to fast might be less for some runners the penalty is still there, it's still more efficient for them to run an even or negative split - none of us can escape all the physiology of what happens when we run.

      As for pacing by HR, once you get used to do it, you don't have to check your HR monitor too often, as long a your know your are in the zone and get the feel for what running in the zone is like you can relax. Hitting a hill I'd usually check my HR a couple of times to make sure I'm working at the right level, and when descending I might check occasionally, but if the terrain is not changing in gradient you really don't need to check it too often.

      By pacing by HR you can actually relax more because splits become largely irrelevant, your HR is a far more objective measure of your level of intensity than any subjective "feel" that you might be able to develop. Many runners "feel" that they are going out easy enough but still end up crashing and burning in the second half of race. It really is very hard to race by "feel" and pace well, only few runners are capable of doing it.

      Frankly the find YOUR path and listening to YOUR body and mind is arm waving none-sense that is meaningless advice for would by ultra-runners. Almost everyone in an marathon and ultra-marathon tries to pace well and fails, we have to look at why this is happening and come up with advice and strategies to help them turn there racing around. Pacing by HR is an objective and reliable tool that works very well - it has the capability of transforming those who currently to pace well to runners that can reliable run great races.

      Waving your arms around saying listen to your body and mind hasn't worked, it's time to move on to what can work.

  13. Its not a case of just listening to your body its a case of learning what works for you as an individual. There are many ways to get to Rome and your suggestion is as good or bad as the next man....until it works for me it has zero validity, period. Same as a positive split, a negative split or an even split and that is the same for every other runner out there. Anyone can follow blindly such and such an approach but if someone cares enough about there performance and about there running they would be well advised to try a number of different approaches and see what works and feels right for themselves be that HR training, low mileage high intensity, high mileage, negative split, even split etc etc. It costs nothing and certainly has the potential to open new doors performance wise, I think the biggest mistake an athlete and a human being in general can make is to follow what others tell them and not question the norm or commonly held beliefs. If that was how everyone trained a thousand and one athletes would never have gone on to greatness given that history is FILLED with athletes who have done amazing things DESPITE the general consensus as to what is the right way to train and not because of it. If a coach ever tells you his way is THE way id advise you get yourself another coach. On the other hand there are also countless athletes who have and will forever remain unknown because they were average again, despite following the consensus.

    There is no right or wrong per se, only a right or wrong for you as an individual. Who would you rather decide that however, you yourself through trial and error and a constant learning, knowledge seeking approach..,,or a guy you have never met, who has never run a mile beside you let alone in your shoes? Anyone that has been around sports a long time will know that trends and supposedly 'new' thinking comes and go's and comes back again. Speed work, high intensity, lsd, heart rate training and each time you will get a bandwagon of people espousing this way as the best way.....and of course there will be elements to each particular way that are in fact beneficial. What I suggest is that no one approach is correct and never ever will be, this has been proven a million times over and even a casual observer to sporting achievement or performance can bear witness to this....instead what I think EVERY athlete could benefit from is the same simple message, adopt what is useful and disregard what isn't.....the only way anyone can figure out what is useful however is to experiment, to learn, to try and fail...or succeed and then try again.

    1. It's clear you more influenced by the "idea" of indivuality rather than anything else. I fear that you are dismissing approaches that may help your own running simply because it doesn't fit with your own philosophy.

      Might I suggest you actually give pacing by heart rate a try rsether dismissing off hand, you never know you might just find it's works as well.

  14. I dont dismiss it Robert I think I might be misunderstood, the only thing I dismiss is a non self tested approach as I have said, that is all that will ever pay dividends to the individual.

    I fear from some of your responses you might be missing perhaps the most fundamental message. It is science is flawed. Take our understanding of lactic acid for example... For 70 plus years it was considered the enemy, the cause of muscle fatigue....yet recently we have come to understand lactic acid has a fundamental and oftentimes beneficial role to play as a fuel for working muscles.

    Did this huge error stop coaches and athletes from achieving success? Of course not, coaches have long since devised programs that have seen huge payoffs in their athletes. You would be surprised how many of these where actually done in the 'arms waving about in the air' manner you suggested training by trial and error was.

    In fact, Author Lydiard...a mythical like figure in the world of running renowned for his training of elite world marathoners came up with his system how? trial and error on himself.

    Science is only ever a guide, the real utilisation of theory and knowledge comes at the specific, individualised level...that is, the trying and experimentation on oneself. This is what the very best coaches of the past 100 years have understood and advocated and it goes beyond the simple this approach is better then the other. It is a basic message of what works for you works for you and what doesn't...doesn't....even if it works for the other 95%!

    In the words of past ultra running great Tim Osler,

    ''Science is wonderful (as a mathematician, I am one of her servants myself), but she has her limitations. Frankly, I believe running is far too complicated for successful technical analysis at this time. It is the runners themselves, through their direct empirical findings, who will point the way for the professional physiologist and rarely, very rarely, that the physiologist will provide practical knowledge of use to the competing athlete. In the words of the great mathematician and engineer Oliver Heaviside, “One does not need to understand the physiology of digestion in order to enjoy a good meal.”

    1. I very well know the limits of current scientific sports science, if you had followed my own blog and contributions to others you'll know that I have am constantly striving for a better understanding and not follow anything blindly. This is a trait shared by good scientists around the world. The fact that science invalidates old ideas is proof that the scientific method is sound not that it is flawed.

      The change in understanding of lactate over the last ten years is a good example of how science keeps advancing forward as better tools and theory allow us to dig deeper and reveal what is happening around us more clearly. You cease to be scientist if you for a second pause and think that we now know everything there is to know.

      My own use of HR monitor for paces comes from my own reflection on the physiology of running which suggests even or negative splits are best, and actually doing the experiments with using a HR monitor for pacing in training and racing. I have done the real-world experiments and refined my approach to the extents that it's now pretty reliable.

      It works well enough that it'd be wrong to hoard this approach to myself, sharing it has the potential to not only help others with their running, but also gather more real-world experience so we can refine the approach further and make it easier for a wider range of runners to benefit from.

      The approach is very much based on personal experimentation and individualization, perhaps you should re-read the post and my subsequent ones on racing. The approach to using HR monitors for pacing doesn't stop at this post, it's a method that I expect to evolve over the years, but we have to start somewhere. I also believe that once a runner has mastered good pacing from using a HR monitor for a while they are likely to be able to pace better without the HR monitor as they know better the rhythm of their own body and how it responds to conditions on race day.

  15. and just in closing. If a study came out tomorrow, one that radically departed from what many had come to accept as common knowledge such as with lactic acid....and this study said HR monitoring was absolutely the wrong way to race and it was now proven to be bar strategy. Would you, someone who has claimed to utilise it time and again and lays testament to its benefits then denounce it? Would this study be cause enough for you to completely reinterpret tour results?

    You would be a fool if you did.

    I think you have lost sight of the bigger picture when it comes to running and sports in general. I think if you spent some time learning your running history you would be very surprised just how little science and physiological understandings have influenced running. You would see that what I am discussing is not MY thoughts, it is actually what running is underpinned by, it is the well known 'secret' that elite coaches and runners have been utilising for the past century, science and common opinion or knowledge can and will only ever play catch up to these very real examples.

    HR monitoring is a prime example of this actually, having only come into use in the past few years what the hell where all these athletes doing prior?! How did these records shift and break? There are records still standing today with which athletes never saw any HR feedback at all! Will wearing a HR monitor and using it to race now allow runners to smash these records that have been so longstanding....I doubt that. And thats not to say HR tracing isn't going to be useful for some...just like negative/ positive or even splits or any other training/ racing input are but to claim this to be transferable to everyone is ignorant of pretty much the entire history of the sport.....When push comes to shove, it is and always has been the seemingly 'arms waving in the air' approach that has typically being behind the success of an individual elite athlete...not a single specific method. There is nothing special or unique about this approach however, it is simple doing what athletes have always done, finding what works best for them and then refining this continually over years and decades or until a new, better way is found.

    1. You don't seem to tire of kicking tyres do you.

      You written lots of words but really added nothing to do the debate about what might be optimal pacing, weaknesses or strengths of pacing approach I've proposed. All you've said is we are all individuals, we need to experiment for ourselves and the science can't be trusted. This isn't a big picture it's just arm waving platitudes.

      If a study came out tomorrow that provide a better guide to pacing ultramarathons then for sure I'd read and digest it and adapt my own approach to take advantage of the new insights - then try it out in the real-world and if it worked well I'd stick with it. If it didn't work well I return to the study and see if they've missed something - a flaw in the study or a limit to it's applicability, or my application of that new approach - I would set about refining my own understanding and approach.

      This isn't foolish, it's very much the scientific approach. It's the approach that took me to the point of coming up with a reliable method for using HR for pacing and I'd hope as we learn more about human condition and running, and as technology improves we can refine approaches.

      Right now pacing by HR works well when applied appropriately, it's not perfect, but so far I've found it to be a surprisingly good method at replicating the type of pacing that top elites like Jez Brag and Lucy Colquhoun have used when setting course records. Neither Jez or Lucy used HR monitors but they are hugely skilled and talents runners, but the sad fact it is almost everyone in the field doesn't share those skills - the experiment for yourself simply doesn't work for the vast majority of runners, much as they might try and run like Jez or Lucy they can't. This is where pacing by HR can help, it can turn someone who currently lacks the skill to pace well into someone that reliable pace and race well.

      I believe there a range of reasons why most runners struggle to pace as well the best of the elites, part of it is that we don't have the experience coaches to work closely with, partly is down to running and racing far less, partly it's down to simply don't having the right balance of skills to be able to refine pacing, partly it's down to non elite's not being able to sustain that short distance pace as well as the elites. There are lots of reasons beyond this. Looking at stas for marathon and ultra marathon races it's clear that pacing is hard to do well, only a very small minority (I'd guess around couple of % of a field) can pace well just by feel - often even the elites blow up and get it badly wrong. It's abundantly clear that most runners need more help to get pacing right.

      With this post I'm doing my bit to help fix this problem.

      What I don't quite understand why my proposal of pacing by HR has seemed to offend you enough that you've spent may words trying to belittle this effort and "educate" others to think like you. If you want to write about your own philosophy of pacing then go start a blog, share your own personal race insights - if you have something positive to contribute then I'd sure be interested in hearing.

      As things stand the only thing I've learnt from your comments is that some people will have already made their mind up and aren't receptive to learning something new, and suggesting anything new will be shouted down just because it's not their accepted dogma.

  16. I think if you actually read what I have written properly instead of becoming 'ultra' defensive you would a) see that I haven't once tried to belittle yours or anybody else's approach, mu opinions on HR are the same opinions I have every training modality! and b) much of what you just said fell very much in line with what I was actually advocating! Learning from science, studies and evidence and trying it out for oneself!....the only difference seems to be that you are unable to look past the limited scope of yourself and what works for you as a pose to accepting that there are many approaches and some, however different or unpopular will work for others, given each of us has unique strengths, weaknesses and abilities.

    I can see that you perhaps do not like discussion that gives alternative views then your own so I will leave my input to that. Discussion is not a battle to win or lose but I feel you may have interpreted my views as that and rather exploring middle ground to learn something. Good luck with your running and your future training.

    1. I've read everything you've written. Almost none of it is actually about pacing. It would seem you don't really haven't anything to contribute on the actual topic of pacing save for generic platitudes that don't help anyone. Colour me unimpressed. I haven't read a single insight from what you've written that moves the debate forward.

      As for not entertaining debate, well I'm happy for debate. However, one sentence you dismiss the science, then the next you advocate the method of testing things - which is roughly what science is about, next you say I don't have the big picture, then I'm in line with what you are advocating. Next you saying I can't see beyond my own limited viewpoint.

      You are often offensive in what you write, but claim not to be belittling. That's not debate. Of course I'll get fed up with the pointless tyre kicking and push back. You have convinced me that your not likely to contribute positively to any discussion. You comments have been of the poorest quality in term of politeness and lacking in insight of anyone I've had comment on my blogs.

      It's time to start your own blog. Put up records of your own training and racing. Let's see what you can achieve with your "greater" wisdom and insight. I just hope you'll be a bit more coherent and polite than you've been here so far.

  17. Hi Robert, I've read your article with interest. I'm doing Loch Katrine marathon this year and have been worried about pacing on such an up and down course. I tried a half marathon the other day using the Marco marathon pacer you mention over a fairly hilly course and found it worked well (very strange how much I walked a lot at the start then found myself going much quicker on the downs later on). I'm not aiming for anything as quick as you but after 13 miles I was only 2 minutes out of the target time at the end of the run. So, however strange it felt HR pacing worked well. One thing I did find hard was meeting the target heart rate on the long downs. I wasn't able to get my heart rate high enough as I didn't seem to have the leg speed to go quicker without thinking I might be working too hard so early on. Is this something you have ever came across? I would be worried about going too quickly and trashing my legs. Any insight or help would be greatly received.

    Many thanks, Paul

    1. HI Paul.

      The steep descents in parts of the Loch Katrine Marathon can make sticking within a HR range more difficult as it can require going well below 7 min mile pace, I'm sure several of the descents I ran at below 6 min/mile pace compared to an average nearer 8 min/mile pace. The best thing you can do is practice doing descents as relaxed as you possible can and let gravity accelerate you and try to remain well balanced, comfortable and smooth.

      Once you have the basic leg speed and comfort at running fast downhill you needn't worry too much about HR, just occasionally check it to make sure you aren't going overly fast. If you are under your target HR zone I wouldn't worry about it, if you are a long way under it's possible a sign to give yourself a kick up the back-side.

      Running the descents fast will put quite a shock load on the quads so if you aren't well conditioned to handle descents then you will find the later stages of the race very uncomfortable and unable to run them smoothly and efficiently. Wasting precious energy by limping down a descent isn't good either. You want to avoid this by spending time in training to condition the quads, if you do then you'll find yourself able to run all the descents strongly right to the finish and this is a lot of fun so well worth it.

      The best way to condition the quads is to do lots of descents in training. The bigger the descent the better, so a walk up and then run down the likes of Ben Ledi/Ben Lomond is excellent for conditions. If you can't fit in a single big descent like this in training, spreading the ascent/descent through the week will work effectively too. If most of your training is on the flat then seek out hills where you can.

      Best of luck next month.