ReSUltS - The Reality Slowdown UltraStu Marathon Formula

Hi,

(To those of you that are a little bit short of time I have copied the link to the useful webpage that this blogpost is explaining immediately below.  The remainder of this blogpost helps to explain some rationale behind the webpage slowdown formula, but one can go straight to the webapage, and hopefully the data it provides will be reasonably clear.  If not come back to this blog post.)

How fast should I run at the start of the marathon?  This is where the following webpage is really useful.  http://rsusmf2.appspot.com/   Please note that this slowdown formula has been updated form the version one which I introduced on UltraStu April last year within the post A Helpful Marathon Pacing Calculator The two improvements are that version two of the slowdown formula takes into account the gender of the runner, as this seems to have a significant effect on the percentage slowdown for the same finishing time.  I have also removed those runners that in simple terms 'blow up', and therefore have a very high percentage slowdown. Further description on the formula are detailed below.

Back in May 2013 I wrote two blog posts on the fallacy of the negative split for road marathon running, which created 'a bit of a stir'.  Which was further 'stirred up' with two other posts during April last year:  A Helpful Marathon Pacing Calculator and Road Marathon Pacing - The Positive Split Pacing Strategy - My Final Comment   At the time I stated that those posts would be my final comment on the topic, however, with marathon season 'kicking off' with the Brighton and Worcester marathons this weekend, and then Manchester, London and others during the following two weeks, I felt that one final blogpost on the topic could be so beneficial to the thousands of runners who will be running a road marathon during the next few weeks.

By now with the bulk of the physical training completed, the focus of the preparation should be on the non-physical training.  By that I mean predominantly goal setting and visualisations.  In terms of goal setting many runners will have a target marathon finish time that they would like to achieve, so this can form one of your goals, i.e. a destination goal.  This is useful as having this target finish time goal can help you in providing a counter argument to the many messages you will get during the later stages of the marathon, strongly encouraging you to slow down.  In addition to a destination goal, it is also useful to establish some journey goals for you to evaluate along the way, just to check that you are on track, and running well.  These journey goals may be related to your emotions during the run.  Are you enjoying the experience, are you 'staying within the present moment', are your race focused. are you running at the ideal intensity, right on that threshold?  Yes, it is useful to establish some journey goals, and then include what you want to be achieving whilst running the event within your visualisations leading up to race day.  Anyway, enough about goal setting, lets get back to marathon pacing.

As mentioned above, many runners will have a target finish time that they would like to achieve.  The issue is, what pacing strategy is best to increase the likelihood of achieving ones target finish time.  Now as ideal as the even paced marathon pacing strategy sounds, and with the argument typically being that most of the World records are set with an even paced, or a negative split paced strategy, in reality around 93 - 95 percent of all marathon runners who finish the marathon quicker than four and a half hours run a positive split.  That is that they slow down during the second half of the marathon, so their second half marathon time from 13 - 26 miles, is slower than their first half marathon time from 0 - 13 miles.

Now, this post isn't going to repeat my discussions on why I think this positive paced strategy is the ideal strategy.  You can go to my two posts from May 2013 if you want to read my rationale for my stand: The Negative Split - The Realisation that An Accepted Running Concept is Actually Flawed!    and The Negative Split Fallacy - Part 2 - The Explanation!   No this post is amount the reality of actually running the marathon, not opinions, theories and speculation!

So, the situation is that around 93 - 95 percent of marathon runners finishing a road marathon quicker than four and a half hours slow down during the second half of the marathon.  At last year's London Marathon within the non-elite field.  I think it is best to disregard what the elite marathon runners do, as their characteristics are quite different to the non-elite, 2:30 - 4:30 marathon runner.  Interestingly though, at last year's London Marathon only two elite men (2/18 = 11.1%) and two elite women (2/14 = 14.3%) achieved a negative split, so not that dissimilar to the 10.0 and 16.0 percent of non-elite runners in the quickest time band (see below for time band explanation).  Mo Farah also achieved a positive split of 3.30%, which is also not that dissimilar from the 3.88% for the quickest non-elite mens time band.)

     Sorry, I got distracted there!  So, the situation is that around 93 - 95 percent of marathon runners finishing a road marathon quicker than four and a half hours slow down during the second half of the marathon.  As I was going to say, at last years London Marathon 93.3% of finishers quicker than 4:18 ran a positive split.  The overall number of women runners from the first 4000 women finishers (4:18:15) that negative or even split their half marathon times totalled 292, which corresponds to a percentage of 7.3%. The overall number of men runners from the first 12000 men finishers (4:18:10) that negative or even split their half marathon times totalled 782, which corresponds to a percentage of 6.5%, which is a slightly lower percentage than for women.

So for 93 - 95 percent of marathon runners the big question is "How much time should I expect to slow down during the second half of the marathon"?  The vast majority of marathon runners aiming for a target finish time need to have an idea of the amount of slowing down that is most likely to occur, as they need to take this amount of slowing down into consideration, so even with this slowing down, which I consider IS A REALITY, NOT, I WILL REPEAT NOT AN INDICATION OF POOR RUNNING OR POOR PACING,  so that they will still achieve their target finish time.

Now I am NOT advocating for road marathons to start as fast as you can, to gain as much time as possible ahead of the even paced schedule.  No, this would be unwise.  This would be as foolish as trying to run at a constant pace for 26 miles.  No, what I am suggesting is to look at the statistics on how much slowing down occurs within the marathon, and I have used the data from 4000 women runners, and 12000 men runners from the 2014 London Marathon as the database.  And to base the calculation of how much slowdown one can expect to occur, on the AVERAGE of what happened for these sixteen thousand runners.  So quite a good sample size!

In order for the resulting percentage slowdown formula to not be influenced by those runners that absolutely 'blew up', I removed the ‘mega slowdown’ runner, those that slowed down more than two standard deviations from the mean slowdown percentage.

Those of you that are particularly observant may have noticed for the quicker runners the percentage of runners that even split or negative split the marathon was greater the quicker the finish time, with the quickest time bands being 10.0% (men) and 16.0% (women).  Yes, there does appear to be a gender difference.  The percentage slowing down, (which is calculated as the time one slows during the second half marathon, divided by the first half marathon time, multiplied by 100), is therefore slightly less for the quicker finishers.  therefore to accommodate theses characteristics of the 16000 finishers, different slowdown percentage were established for different finish time bands and for men and women runners.  The following table displays the AVERAGE percentage slowdown values for each time band, for men and women runners.

Now having these percentages in a table is interesting, but what does it actually mean for the runner.  How fast should I run at the start of the marathon?  This is where the following webpage is really useful.  http://rsusmf2.appspot.com/ Please note that this slowdown formula has been updated form the version one which I introduced on UltraStu April last year within the post A Helpful Marathon Pacing Calculator As stated above the two improvements are that version two of the slowdown formula takes into account the gender of the runner, as this seems to have a significant effect on the percentage slowdown for the same finishing time.  I have also removed those runners that in simple terms 'blow up', and therefore have a very high percentage slowdown. Further description on the formula follows.  Opps, I also forgot the third improvement for version 2, in that the slowing down now doesn't start until the 16th mile, rather than the 14th mile.  I think this is more likely to be representative of what actually occurs.  As long as the runners have a realistic target finish time, maintaining a constant pace for 15 miles should be a problem.  It is during the last 11 miles when the effects of the previous miles run on the roads starts to have an impact and make the maintaining of the same constant pace a lot more difficult, hence the slowing down.

As an aside, if I recall at the time last year there was some confusion expressed regarding my perhaps wrong assumption that the accepted view at the time was that an even paced strategy pace was the standard approach, which would result in most runners not achieving their target finish time if adopting this approach.  Now I think that probably more people realise that the even paced pacing strategy doesn't work, so hopefully this year there will be less confusion.

Unfortunately the webpage calculations aren't exactly correct, due to either some mystery formatting error or simply the effect of rounding error, which we now think is the likely cause of the error.  We, actually, in reality it is good friend Tim, who is the brains behind the webpage, who has been working hard on looking to solve the problem.  Anyway it is nearly working perfect.

Just to quickly summarise.  The way the webpage ReSUltS -  The Reality Slowdown UltraStu Marathon Formula works is that you select male or female, then enter your target finish time, then click calculate.  I mentioned above that the webpage isn't working exactly right, but If you look at the minute mile pace the formula produces, the half way and 5mile, 10 mile and 15mile split times are all correct.  But when the percentage slowdown linear increase occurs at mile 16, there is a big slowdown for mile 17 and then back to a linear increase in minute mile pace until the finish.  It appears that this big slowdown at mile 17 is where the slight error occurs.  In terms of the summary table on the right the pace column is for the last mile of that 5 mile split, NOT the average pace for the last 5 miles. 

However, although the webpage isn’t exactly working, the key information, e.g. the percentage slowing down, which allows you to calculate your half marathon split time is correct.  Also the idea that one should be able to run at a consistent pace for every mile up to 15 miles is also correct.  The last 11 miles around 93 - 95% of marathon runners slow down, how they slowdown will be quite varied, but a gradual linear increase every mile from 16 miles onwards seems a reasonable guess, which the slowdown formula adopts.  Remember slowing down after 15 miles doesn’t mean that you are running poorly, or that you did the first 15 miles too fast.  Slowing down is reality. The webpage does produce a different minute mile pace for each mile from 16 miles through to the finish, however, I would recommend that you simply use the minute mile pace generated for the first 15 miles, which takes into account the average slowdown for that time band, and then from mile 16 onwards, simply run by feel.  If feeling great then reduce the rate at which you slow down.  If not feeling so great, then allow a slightly greater rate of slowing down and hope that the 'difficult patch' will pass, and that you may be able to get back 'on track' a few miles later.


Hopefully the above explanation of this ReSUltS -  The Reality Slowdown UltraStu Marathon Formula webpage makes some sense, and for those of you are able to take on the fact that 93 - 95% of marathon runners slow down during the second half of a road marathon, I hope that you find this webpage useful.  To those of you that aren't aiming for a target finish time, or are aiming for an even paced strategy, well then this webpage probably isn't relevant for you, so apologies if you have read this blogpost down to here!

To all of you running a road marathon during the next few weeks, I wish you all the best.

I will sign off with a few relevant quotes which may help during those 'challenging' moments between 16 and 26 miles.

"The way we perform is the result of the way we see ourselves.  To alter our performance we need to alter or change ourselves and it is that changing that's difficult."  Gary Elliot, New Zealand Coach to awesome NZ marathon runner Alison Roe (1983)

“A large amount of what we achieve is governed by our mental state and how we see ourselves. (It is) a lot about opening the mind to what might be possible when we throw away the self imposed limitations of our mind.” Tom Williams from MarathonTalk (2011)

“Remaining positive really is one of the most precious faculties for any athlete.  That, and an ability to stay focused and disciplined.  Develop a mind bank of positive images and thoughts – family, friends, previous successes, favourite places, a big plate of chips.  You need to build it up as you would any collection, but soon you will have a range of thoughts to flick through when next your body and soul are screaming out for relief”.Chrissie Wellington, Four times World Ironman champion,  from her book titled "A Life Without Limits".

 
Enjoy the journey,

Stuart

 

The Negative Split - The Realisation that An Accepted Running Concept is Actually Flawed!

Hi,

Yes, a bold post title, but I feel that rather than delicately 'tip-toeing' around the subject, I perhaps need to be a bit more forceful in exposing the negative split myth, Why such an aggressive approach to this post? Well two reasons really: (i) in response to some challenging comments left on my blog "These aren't reasons that can be easily dismissed, I've loved to see you try to come up with some compelling reason why it's a good thing to go out hard and how this overcomes the well established reasons for an even split I mentioned above." So in response to challenging words like that, a changed response is obviously called for!


And (ii) listening to last weeks MarathonTalk, where even when Martin and Tom read out some data from the recent London Marathon, they failed to then explain to their audience what this data actually means, and even worse, throughout the show, as they have pretty well done in all of their MarathonTalk shows, they continued to 'celebrate' the negative spilt, as if achieving a negative split is a sign of a good performance. Whereas the data from the recent London Marathon clearly demonstrates that achieving a negative split more than likely represents a sign of a poor performance!

Now don't get me wrong. I really enjoy MarathonTalk, and what Martin and Tom have created in terms of the positive, supportive running community is absolutely fantastic. However, as mentioned in a previous post, way back in December 2011 when I first raised this 'negative split fallacy' with Martin and Tom, pretty well everything else on MarathonTalk is 'spot on', and is really excellent advice. It therefore does seem so strange that this one aspect, the over celebration of the negative split, is so in contrast to all of their other excellent messages.

So yes, tonight,s post may go against some people’s long help beliefs, but the main aim of the post is to challenge people to re-consider their ideas. Have they perhaps got it wrong? Is the commonly accepted concept that a negative split illustrates a good performance, actually wrong? We have seen it recently where commonly accepted concepts have been wrong. Best illustrated with the fallacy of the previous marathon hydration strategy message of "drink as much as possible, before you get thirsty" which was accepted wisdom for over twenty five years!!!

So, Tom from MarathonTalk, I am directing this blog post specifically to you in response to the comment that you left on my blog back in December 2011, "My money's still on the even / negative split but I'd be delighted to be proved wrong. My quote for the day... I'd rather know I was wrong than think I was right ;)"

Hopefully, the data from the recent London Marathon will “delight you” and prove that the even / negative split is wrong. That is my challenge tonight. I am hoping that this post will attract the attention of some new readers from the MarathonTalk community, so rather that asking new readers to my blog, to search around and read some of my previous posts, I am going to repeat myself a little, so apologies to those of you that have already read some of the following material.

My intention with this post was to first present the statistical data from the London Marathon, and discuss what this data actually means in terms of pacing strategy, and the possible application of using these findings to improve performance. I was then going to follow up with the scientific evidence to explain why the London Marathon data, that clearly illustrates that the negative split isn’t a sign of good performance, actually is the reality and not because over 95% of the entire marathon field ran poorly! However, as is typical with my UltraStu blog posts, simply presenting and explaining the statistics has taken longer than expected, and the post has already reached an ultra length. So unfortunately the scientific evidence to explain why, will have to wait until part two, which should be posted by the end of the week.

I will first start with the statistics mentioned on last weeks MarathonTalk. Tom reported that from the thirty four thousand MASSED START finishers there were a total of 5 even splits, and 1369 negative splits. This gives a negative split percentage of 4.0%. You will note that I have highlighted that this data is for the massed start, so does not include the elite field data. The reason that it is important to exclude the elite filed data from this analysis, is that what the elite runners do, often does not directly correspond to what non-elite runners do. This is obvious in terms of their minute mile rates and their finish times. But often what elite runners do in other aspects, example the quantity and intensity of training, the recovery resources available to them, and their pacing strategies, also differ significantly.

An argument often used, in fact pretty well the only argument I have ever come across, in justifying that the negative split is the strategy that runners should use, i.e. that the negative split indicates a good performance, is that most of the marathon world records have been achieved on a negative split. Therefore, people often then conclude that because of this world record aspect, there is in fact no argument; the negative split must be the best approach for ALL runners! I state No! Why people believe that ALL runners can achieve the same as the elite runners, I do not know. We wouldn't expect an 'average' runner to train 100 - 150 miles per week, we wouldn't expect the 'average' runner to run at sub 2hour 10 pace, so why people think that a negative split is achievable by an 'average' runner, I just don't understand! But 1369 runners at the 2013 London Marathon, did achieve this negative split. Surely then, these runners achieved the best performances, and those that positive split, i.e. slowed down during the second half of the race, didn't perform so well.

Before I move on to explain what did actually happen within the massed start field. I will briefly provide the statistics for the men's and women's elite race. As mentioned above though, what the elite do, may not correspond to what the non-elite runner should do, as there are so many other factors that influence the elite race, their elite performances.

The London Marathon women's elite race was won with a negative split of 3:23, running 68:26, for a finish time of 2:20:15. The second placed women, also achieved a negative split of 2:06, but all of the other 15 elite women finishers positive split the race, with the largest positive split of 13:17 by the current Olympic champion, although she did get knocked down by a wheelchair racer! None of the entire men's elite field achieved a negative split. The winner ran a positive split of 2:52, and the largest positive split was 5:31 (8th place) and the smallest positive split was 0:19 (9th place).

One of the reasons that I state that we should perhaps not put too much focus on what the elite do, when comparing to the 'average' runners, is in relation to the perception of what is a long way! Looking at world records, as often pointed out, a negative split is typical for running distances of 5,000 metres, 10,000 metres and the marathon. However, for distances further than the marathon, e.g. 100km and 24 hour races, even the best in the world will positive split. Although I would like to provide evidence for all of my comments I state tonight, searching the literature to link the evidence takes time, and I do want to get some sleep tonight! So if there are some statements that I make, which I haven't provided any evidence link, please highlight by leaving a comment, and I will find the link and post it at a later date.

So even elite runners positive split a 100km. Just some quick data to illustrate this is from the recent UK 100km Championships that took place in Perth. The graph below clearly illustrates that all runners positive split the race. This positive split is also seen in all World and European 100km races, however, I haven't got to hand the data to confirm this, but I will try to search it out for those that aren't convinced.

The other interesting aspect in relation to being able to run an even pace/negative split, is that most good quality club runners are able to achieve an even pace for a 10km race, but not for the marathon.. So whereas for the elite runner the ability to hold an even pace seems to not be possible at a distance somewhere between a marathon and 100km. For the club runner, this even pace ability appears to stop somewhere between 10km and the marathon. Why the difference?

Well, I don't want to go into the role of familiarity, the impact of expectations on race performance just yet, but it does appear that perhaps ones perception of 'what is a long way', or simply the distances one has physically trained, may have an influence on the distance of the race, where the even pace is unable to be maintained. Elite marathon runners will typically cover the marathon distance in training, and typically cover weekly mileages of 125 - 150+ miles. Club runners are less likely to do these distances in training. Therefore perhaps this lack of familiarity with the distance contributes to the difference between elite and club level runners. Whatever the cause of the difference, I won't speculate any further now. But with only 4% of London Marathon finishers achieving an even pace / negative split, one cannot argue against the fact that on the whole, non-elite runners are NOT capable of running even paced for 26 miles!

Following on from this extremely low percentage of runners achieving a negative split, I thought it would be useful to see if the percentage of runners achieving the negative split varied throughout the field. Logically, due to the fact that those that run a positive split, are those runners that slow down the most during the second half of the race, one would expect that further down the field, there is an increase in runners that positive split. One would also expect the size of the positive split would increase, further down the field. The graphs below display the number of runners in each 1000 batch of finishers that achieved a negative split. What is really interesting here is that there appears to be a clearly distinctive finishing time, at 4 hours, where something interesting is happening.

Although a line of best fit has been added to the data above, the line seems to reasonably follow the data points for finish times slower than 4 hours, but not at all for faster finishing times.

It therefore appears from the graph above that the number of runners per 1000 band of finishers, is not at all influenced by the finishing time, up to the four hour mark.  The highest percentage of negative split runners was in fact at 10.6%, at a mid finish time of 3hours 28 minutes.  With the fastest 1000 finishers only having 8.4% of negative split runners.

For a finishing time slower than four hours there does appear to be a relationship, with there being a smaller percentage of negative split runners, the slower, the further down the field.
So, what does the above data tell us. Firstly, the key message is that a very low number of runners achieve a negative split. It was reported at 4.0% overall on Marathon Talk, and the table below shows how this percentage varies throughout the field for each 1000 band of finishers, for the first 25,000 finishers, i.e. up to the five hour, two minute mark..

Now I wouldn't want to upset any runners reading this post, but achieving a four hour marathon time is often a huge goal for many marathon runners, as running a sub four hour time is possibly seen as a time that indicates that one is a 'good' marathon runner. Yes, simply finishing a marathon is quite an achievement, but to finish in a time less than four hours requires substantially more preparation. Therefore the fact that there appears to be no relationship between finishing time and the percentage of runners achieving a negative split , up to a four hour finish time, warrants further attention.

To those that belief that running a negative split illustrates a good performance, perhaps they would expect there to be more negative split runners further up the field. And for me, who believes the contrary, i.e. for non-elite runners, achieving a negative split is actually a sign of a poor performance, as the negative split has only been achieved by the runner running so slowly during the first half of the race, that their overall time is slower than what they could have achieved. So surely one would expect more negative splits, the slower the finish time. But the data up to four hours, i.e. for 'good' marathon runners, the first 11,000 finishers, neither of these trends are shown. There is neither of these relationships!

I then had to really think, why there is a a lack of a relationship, either way? Why no clear relationship to indicate that a negative split is a good performance or a poor performance? In terms of my belief, surely those that run a negative split, have only achieved this because they have run the first half of the race so slowly, so the data should illustrate this. I then realised why no relationships are apparent within the data. Yes, those that negative split may have performed poorly, but they just simply move lower down the finishing place list. Throughout the field people will finish with a certain time due to many factors, so there is a massive spread of finish times. Within this spread of finish times, some runners will perform well in relation to their fitness, ability, belief, whatever else, and hence move further up the field, finish faster. Whereas some runners will perform poorly, i.e. finish slower. But the good or poor performances will not stand out within the results, they simply move upwards or downwards amongst the finish results. Hence it is not possible to observe any relationship between negative/positive splitting and finish time.

I then decided to look at the 'very good' runners within the field. Now looking at the first 500 finishers, so the top 1.5% of the field. The two graphs below display this data, first comparing positive split ranking,( i.e. those runners that slow down the most in the second half of the race, having a positive split rank of one), with finishing place. Then comparing the amount of time slowed down, i.e. the size of the positive split time, with the finishing time. Again, both ways of analysing the data failed to illustrate a relationship of any strength.

One interesting aspect did 'jump out at me' though.  That being, just how few negative splits there were in the very fastest of the runners.  The graph directly above doesn't show many dots to the left of the vertical, which are near the horizontal axis, i.e. with the quickest times.  So again back to the database, and this time looking at to see where abouts did the 84 negative split runners within the first 1000 finishers place.  So I split the first 1000 finishers into place bands of 100 runners, and 200 runners.  The data is in the table below.

Now the data in the table directly above now tells the true story! As mentioned above, those runners that achieve a good performance, i.e. those that run quicker than what their 'ability' or 'fitness', or 'talent', or 'whatever' suggests they should achieve, simply move up into the higher placing band, and are therefore 'lost' within the data. Similarly those runners that run slower than what their form suggests, simply move down into a lower placing band, and again it is not possible to identify these poor performances. However, if you move to the very top placing band, because all of the poor performers who should have finished within the top band move down to the second band, and all of the good performers move up into the top band from the second band, the top band therefore represents the qualities of the good performers, and doesn't include the qualities of any poor performers, as they have moved down to the lower band. (There is no higher band from which poor performers will move down from.) Once we move down below the top band, then one would expect that the number of negative split runners within each band would again be similar, i.e. no relationship between the number of negative split runners and finish time/place.

So if we have the place bands set at 100 places, within the top band, i.e. that band that truly represents the characteristics of a good performance, i.e. running quicker than what would be expected, then we clearly see that the negative split runner does represent a poor performance, as there is only ONE negative split runner within the top 100 place band. This has occurred, as those runners that have run a negative split, have moved out of this top band, down to the next band, as expected when achieving a poor performance. There is no longer the standard 8.4% of runners (the average for the first 100 finishers) being a negative split runner within the top band, It has dropped to only ONE percent! Hopefully, the above two paragraphs make sense. It is quite a hard concept to explain, but hopefully it is semi clear.

Having now identified that running a negative split is an indication of a poor performance, is it possible to identify how much slower have these negative split runners ran, by starting out too slowly? Asking the following question may help. How much slower does the negative split runner have to run their first half of the race in order to achieve a negative split. This answer can possibly be answered by looking at runners of similar finishing times, in this instance, for runners at the very top end of the field. How much of a positive split time, do these good performing runners on average slow down during the second half. This average positive split slow down time, would then be a close approximation of how much slower the negative split runners must have ran their first half in order to achieve an even/negative split. The average positive split time for the first 100 positive split finishes is 3 minutes 46 seconds. And for the first 916 positive split runners within the first 1000 finishes, they slowed down on average 4 minutes and 57 seconds, which for their average half marathon time of 1:21:12, corresponds to a slowing down of 6.1% of the half marathon time.

This percentage represents the average slowing down of the best performing 2.9% of the field. It is an average, some slowed down more, some slowed down less. Actually to get the true slowdown average of the best 1000 runners in the massed start field, one should also include the influence of the 84 negative split runners that sped up. Their average negative split was 1 minute 23 seconds, which in relation to their average half marathon time of 1:25:17, results in an average speed up of 1.6%. So overall the average slowdown for the first 1000 finishers is 4 minutes and 26 seconds, which in relation to the average half marathon time of 1:21:33, corresponds to a percentage slowdown of 5.4%.

This percentage slowdown value is actually quite an interesting figure. However, I mentioned above that perhaps the amount of positive split may vary across the field, hence why one should look at the value of slowdown of runners in a similar finish time to oneself. The fact that the percentage slowdown is only 5.1% for the first 100 finishers, in comparison to 5.4% being the average for the first 1000 finishers suggests that perhaps not only the actual amount of slowdown time will vary through the field, but there may also be some variation in the percentage slowdown throughout the field.

I therefore split the first 11000 finishers, those that finished under 4 hours, into bands of 1000 runners, which equated to typically a finish time band of around five minutes, except towards the top end of the field. To account for the wider finish time band near the front, I split the first 1000 place band into 0 – 100, 101 – 500, and 501 – 1000 place bands. This analysis produced some interesting results, which are displayed in the following table.

 

As indicated within the table above, it does appear that only at the very top end of the field is the percentage slowdown affected by finishing time. For runners finishing in a time between 3:17 and 4:00, the percentage slow down appears pretty consistent, and averages 9.9%. At the very top of the field whether finishing in the top 100, or between 101 – 500 there is a slow down percentage of 5.1%. This percentage slowdown therefore appears to represent the very least amount of time that the very best runners, i.e. the top 1.5% of the field., will slow down during the second half of the race. For finishing times, between 2:49 and 3:17 the slowdown percentage progressing rises up from 5.1% to 9.9%. I have identified three intermediate bands within the table. I guess with further analysis more bands could be added, but I will leave it at three bands, which therefore results in a total of five slowdown percentage bands. I haven’t carried out the analysis for finish times greater than 4 hours. However, I think the best proposal is that runners who plan to finish in a time slower that 4 hours should aim to maintain a slowdown percentage of 9.9%, i.e. the same percentage as for those runners between 3:17 and 4:00. With a slower planned finishing time even with the runner aiming for the same slowdown percentage, it would actually result in an increased slowdown amount of time, as their half marathon split time will be longer.

These average slowdown percentages are therefore very useful. In the future, hopefully now realising that trying to run an even pace for the entire 26 miles is not the strategy to use, resulting in a slower performance than one is capable of, it is quite easy to calculate what runner's half marathon split time should be in order to achieve a certain finishing time.

For example if a runner wants to run a 2:36 marathon time, they would simply divide this time (156 minutes) by 2.051. This represents a slow down of 5.1% on their half marathon time. So to obtain a 2:36 marathon finish time, with the average percentage slowdown, the half marathon split would be 76:04 (76.06 minutes), and then running the second half in a time of 79:56, results in the time of 2:36:00. So running a positive split of 3:52.

Interestingly, last month I was giving some pacing strategy advice to a friend that was wanting to achieve a PB at the London Marathon. His current PB was 2:38, but I felt that he could achieve a time of 2:36 if he adopted a positive split strategy. This predicted possible time was based on his recent half marathon race time, and also him getting wiser, gaining more experience as a runner over the last year. However, I hadn't carried out the detailed analysis of previous London Marathon data like I have recently carried out and illustrated above. I therefore went with my 'gut feeling', in terms of what positive split he should try to achieve, based on my 35 years of endurance running. I proposed to him that he should aim to go through half way in a time of 76:30 and then positive split by 3 minutes, i.e. 79:30 for the second half, resulting in a finish time of 2:36:00. Knowing what I know now, I would have realised that only positive splitting by three minutes (3.9%), compared to the average positive split of 5.1%, for that region of the field, is a bit ambitious. Based on his recent half marathon performances, running a time of half marathon split of 76:04 would have been most likely a wee bit beyond him. So in reality a finish time of 2:36:00 was really a wee bit beyond him. Applying a 5.1% slowdown to a 76:30 half marathon split results in an 80:24 second half time, so a total finish time of 2:36:54 was more likely for a 76:30 half marathon split that was decided upon.

What did he run? He went through half way in a time of 76:47 (76.78 minutes), a little slower (17 secs) than planned. With an average slowdown percentage of 5.1%, he should, following the 76:47 split time, therefore run the second half in a time of 80:42 (80.70 minutes), so a predicted slowing of 3 mins 55 secs, resulting in an overall predicted finish time of 2:37:29. What time did he run? He ran the second half in a time of 80:20, and finished in 2:37:07, so 22 seconds quicker than the average slowdown prediction. But still 13 seconds slower than the predicted finish time of 2:36:54, if he had ran 76:30 for the first half. Whereas in the past he would have considered running a positive split of 3:33 as a poor performance, having been 'brainwashed' with the myth that an even split is what one should achieve. He was therefore able to truly celebrate his good performance, as in the second half of the race he run 22 seconds quicker than expected.

Looking at the above one can quite clearly see the potential of this analysis. Runners can now calculate what pace they should go out at, i.e. what time they should pass halfway in, based on what finish time they are planning, specifically up to the four hour finish time. Please note that for runners that finish slower than four hours, I haven’t extended the above analysis as I feel that basing what one should aim to achieve on what the average of these 4 hours plus runners achieve, i.e. on the average slowdown of these runners, probably isn't ideal. As for these runners, their more substantial slowing down is likely to be a result of less than ideal preparation, and therefore capable of changing if the preparation had been better. This level of slowdown is therefore not as a consequence of the actual reality that for a non-elite runner, one MUST slow down. As mentioned above, I think that for runners planning to finish in more that four hours, they should plan for a slowdown percentage of 9.9%, which is quite different to the typically message given out, especially by MarathonTalk, in that one should aim for an even paced marathon, so a slowdown percentage of 0.0%!

As the statistics have clearly shown above, slowing down during the second half of the marathon is a reality. It is NOT an indication of a poor performance. Yes, if a runner slowed down by a percentage substantially more than the average slowdown percentage, for their finishing time, then this would be a poor performance. If a runner was hoping to finish in a time of 4 hours, applying the MarathonTalk strategy of running an even pace, they would then plan to go through halfway in 2 hours. With a 9.9% slowdown percentage, they would typically slowdown 11 minutes 53 seconds, so typically not achieving what they felt they were capable of. Not because they ran poorly. No, because they were given the wrong advice, and started out far too slow!
In order to achieve a 4 hour finishing time, the runner needs to divide 4 hours by 2.099, NOT by 2.000 as suggested by Marathon Talk. Dividing 4 hours by 2.099 generates the half marathon split time of 1:54:20. Slowing down during the second half by 9.9% (on 114.34 minutes) results in the second half marathon being run in a time of 2:05:40, so a positive split, i.e. slowing down of 11 minutes and 20 secs. Producing a finish marathon time of 4:00:00. Achieving what the runner set out to achieve.

As you can see, taking on board the data from the thousands of runners that successfully completed the 2013 London Marathon, and not implying that a massive 96% of them have performed poorly because that didn't run an even paced race, one is able to provide a realistic pacing strategy, which doesn't actually vary that much from the even split pacing strategy. But the difference is sufficient enough for many many runners to not achieve their goal, simply as a consequence of listening to poor pacing strategy advice. In the 4 hour marathon example above, if the runner simply went out at a half marathon pace of only 5 minutes 40 seconds quicker, based on the data from thousands of runners, the likelihood of achieving their goal is massively enhanced. Running the first half marathon split 5 minutes 40 seconds quicker, means running the first 13 miles at 8:43 second minute mile pace and then slowing for the second half of the race to an average minute mile pace of 9:35. This pacing strategy which takes into account the typical slowing down percentage of 9.9% , which is in contrast to maintaining a 9:09 minute mile pace for the entire 26 miles!

Remember this slowing down is a reality, which I will hopefully be able to show why it happens with some scientific evidence within my next blog post.

As illustrated with two examples above, the application of this slowdown percentage is really exciting. The potential benefits of this percentage slowdown is huge! Marathon runners by applying the percentage relevant for their finishing position within the field, will then know how much time they should expect to slow down, rather than trying to achieve an even pace or even worse, a negative split result!

Just one last useful bit of information before finally finishing part one of this negative split myth post. With regards to the pacing strategy, the intention is that runners should be able to run at a pretty consistent even pace for the first 13 miles. However, for the 14th mile, they shouldn't instantly slow their pace to the average minute mile pace they are scheduled to run for the last 13 miles. What tends to happen is that the slowing down begins to start not too far after half way. One could calculate an accelerated rate of slowing down, where the slowdown starts of slowly for the first few miles after 13 miles, and then the slow increase accelerates, however, for ease of application, and which probably isn't too far of what happens, one should apply a linear increase in the slowing sown for the second half of the race. The best way to illustrate this linear increase in slowing down is for the 4 hour marathon example above.

The first half is run in 1:54:20 which is 8:43 minute mile pace. The second half marathon is planned to be run at an average of 9:35 minute mile pace, so an average slow down of 52 seconds per mile. This minute mile pace should then be divided by 6.5. This value, in this example 8 secs, is then the amount the running pace slows per minute mile, every mile.

The split times for mile 14 would then be 8:51, mile 15 = 8:59, mile16=9:07, mile17=9:15, mile18=9:23, mile19=9:31, mile20=9:39, mile21=9:47, mile22=9:55, mile23=10:03, mile24=10:11, mile25=10:19, mile26=10:27. Running each mile 8 seconds slower from half way will result in running the second half at an average minute mile pace 52 seconds slower. So just with this 4 hour marathon finishing time example, where the average percentage slowdown of 9.9% has been applied, hopefully it is easy to see the benefits. When one gets absolutely shattered during the last few miles, instead on having to maintain the same pace, that was achieved during the first few miles when the runner was totally fresh. Remember this is what is proposed with the even pace strategy! (Whoever thought that this is a good approach to take, really needs to reconsider!) With an application of the 9.9% average slowdown percentage, for the last mile one is able to slow down to a 10:27 minute mile, and still achieve the 4 hour marathon goal, simply by running just that little bit faster over the first half marathon, when feeling fresh and easy. Why not run that 26 seconds per mile faster during the first half when feeling great!

Finally lets apply the same formulae to our 2:36:54 marathon example runner from above. Going through the half marathon split in a time of 76:30 is a minute mile pace of 5:50. The slowing for the second half split time of 80:24, this being the 5.1% slowdown percentage, is a minute mile pace of 6:08. The minute mile pace therefore slows by 18 seconds per mile. Divide this 18seconds by 6.5 gives a minute mile pace slowing adjustment of 2.75 seconds. The easiest approach in this situation is to round the the mile splits up or down, so rather than the following mile pace for each mile from mile 14miles=5:52.75, 5:55.50, 5:58.25, 6:01.00, 6:03.75, 6:06.50, 6:09.25, 6:12.00, 6:14.75, 6:17.50, 6:20.25, 6:23.00, 6:25.75, simply round up or down so you would then get the following mile splits from mile 14=5:53, 5:55, 5:58, 6:01, 6:04, 6:07, 6:09, 6:12, 6:15, 6:17, 6:20, 6:23, 6:26 Resulting in the required average minute mile pace of 6:08 for the second half. I guess a little bit ‘fiddly’, but I would suggest worth the effort, as at least the runner would then have realistic mile splits to aim for, rather than trying to achieve the constant running pace approach which is 96% guaranteed to fail!

I will sign off tonight with two quotes. Firstly a repeat of the quote from Tom from Marathon Talk:

“My money's still on the even / negative split but I'd be delighted to be proved wrong. My quote for the day... I'd rather know I was wrong than think I was right ;)" Tom Williams, 2011.

And the second quote from the example 2:36:54 marathon runner, who listened to the wisdom of a positive split pacing strategy, and had the humility to accept that in the past his views on the even paced strategy may perhaps have been wrong, so he took a gamble and changed his pacing strategy.

“I was delighted when I came round on to the Mall and saw the time (a PB). I think that undoubtedly your (positive split) strategy paid off and thank you so much for taking the time to advise me. It is a challenge to go in to a race with a mindset that assumes slowing down, which seems on the face of it to be a negative thing. But in reality I think that acknowledging the slow down and embracing the fact that it will require extra effort to minimise the decrease in pace is actually very positive.” Simon, 2013

Keep an eye out for part two, where the science behind why slowing down in a marathon is a reality will be explained.

All the best with your next marathon,

Stuart

A Liitle Bit More on Pacing

Hi, and Happy New Year.

Tonight’s post will be a short post, just tying up a few issues to do with pacing during endurance events. Within my last post I focused solely on a physiological rationale for not adopting a negative split strategy, but as I have tried to explain, performance during endurance events is not determined directly by physiology but is to do with managing Race Focus Energy (RFE), so tonight’s post will hopefully provide the complete answer to the ideal pacing strategy.

One thing that has been highlighted by many, including Brett who left a comment to my last post, is that most world records, especially for track distance races, come of an even split (or a slight negative split) pacing strategy. Simply in terms of physiology I think the reason for this is that for track distance races the races are too short for cardiac drift to occur, hence an even paced strategy does correspond to an even physiological demand. But for marathons, both the men’s and women’s world records were set with a negative split.  So why is this so?

Looking at my RFE fatigue model above, where physiological demand, (which could be concluded as being represented by rating of perceived exertion, RPE), is a core component. There is not a direct link from RPE to RFE. Although running a negative split could be the wrong strategy in terms of there being a progressive increase in RPE as the race progresses, the positivity one receives by not slowing down, and as you overtake other runners is likely to result in a downward swing of the RPE-RFE arrow, and therefore could result in a constant rate of RFE usage. The key here is the thoroughness of the race preparation. If you have considered the demands of the race, and prepared for a negative split (even paced) race strategy, then hopefully you have the confidence to run slowler than what you are capable of during the first half, and to not allow negativity to develop as you are further down the field than you would expect to finish. Then with the expectation that during the second half of the race you will overtake the 95.7% of the field who slow down, the positivity will hopefully counteract the increased physiological demand.

Then why is it that I don’t recommend this approach to endurance racing. I guess the main reason is that to develop this confidence to remain positive during the slowly run first half of the race is very difficult. A human trait appears to be to easily react negatively to situations whilst racing. As mentioned in my previous post, there are so many factors that can swing the RPE-RFE arrow upwards. The elite runners who adopt a negative split strategy succeed not only because of their superior physical abilities, but also due to their superior TOTAL preparation abilities. They have the ‘mental skills’, the belief, to remain positive throughout the duration of the race. Based on my experiences during 30+ years of endurance racing, I have found it extremely hard to keep the negativity ‘at bay’, hence why I adopt the positive split pacing strategy, and to quite an extreme.

My 'extreme' positive split strategy is to start at a fast pace, quicker than I am capable of maintaining for the duration of the race, i.e. “Run as fast as you can, while you can”. I am then further up the field and ahead of runners who would expect to finish ahead of me. There are two advantages of this. Firstly, if the preparation by the other runners hasn’t been thorough, then there is the likelihood that they may start to develop negative thoughts due to being behind. But the biggest advantage is the positivity I receive as a result of running fast and being up the field. I am usually on an absolute high, receiving loads of positive energy from marshals, feed station volunteers, spectators and from within. And with this positivity, although I am working at a physiologically high level, the RPE-RFE arrow is rotated down and the RFE usage is therefore lower than what would be typical for such a fast running pace. My performance at the IAU World Trail Championships in Connemara, Ireland back in July is a clear illustration of this positivity reducing the RFE usage rate, and therefore enabling me to perform so much better than what physiologically I should have been able to perform at. Starting the race fast, and actually leading the World Champs for a short period, with a helicopter buzzing above, and a camera crew on a quad bike with a camera jammed close to my face (see the video of the race on the following link: http://www.youtube.com/watch?v=LLUVVBUMALU) had such a massive swing of the RPE-RFE arrow, that I felt amazingly positive for the entire 7+ hours of the race, and everything felt so much easier than usual!

Again in terms of adopting a positive split strategy the key is the thoroughness of the preparation, the completeness of the visualisations. Although, it could be interpreted as being negative visualising slowing down during the second half of the race, in my situation it is a reality due to the quick pace I start at. Therefore knowing that a slowing down of pace has nothing to do with me performing poorly, this prevents the negativity from developing. Brett made a very valid point with his comment “How many times have you read that when people start positive splitting and slowing down they lost all motivation and shut 'er down?” And that is the real problem with trying to achieve a negative split, or an even paced strategy. Many runners may not be aware of cardiac drift, and that to maintain a constant pace throughout a marathon requires a massively disproportionate demand in terms of both physiological intensity and Race Focus Energy. Therefore when they are ‘required’ to slow down, yes the negativity often takes over, and then it is all ‘downhill’ from there!
So to conclude, as with most issues to do with endurance running there is not one ‘golden rule’, there is not one ‘solution to fit all’. The key to success is being aware of the different approaches and having an understanding of the underlying factors that influence performance. This is where the Race Focus Energy Fatigue Model is so beneficial, as it helps to clarify the many, many factors that contribute to race performance. It is with an increased understanding of endurance running that I look forward to another great year of running in 2012. I wish you well for the upcoming year of running, May you achieve success, by achieving the goals you set yourself. Time to sign off with a quote I have signed off before with, but I feel is quite appropriate for this post.

"In order to address what training (preparation) is appropriate, one must first consider what limits performance!" Stuart Mills, 2010.

Hope to see you at a race or two in 2012,

Stuart

Thoughts on Pacing Strategy for Endurance Running Races - The Negative Split

Hi

Tonight’s post, as the title indicates, is about Pacing Strategy, and specifically, does a negative split improve performance? Part of my Dorset Trail Marathon race report last week included a bit of a ‘rant’ about how I felt that the negative split resulted in slower finishing times, not quicker as suggested by many, including Martin and Tom from MarathonTalk. Well following my post it was pleasing to know that both Martin and Tom read my race report with them both leaving a comment on the blog. I especially liked Tom’s quote "I'd rather know I was wrong than think I was right". So it got me questioning what is it that makes me think that I am right, that makes me believe that the negative split is the wrong strategy? So hopefully tonight I will provide some material to confirm my beliefs, but I guess the real purpose, as with most of my blog posts, is to encourage you the reader, to question your approach to running, to consider alternative approaches, even if they are not in agreement with the accepted norm, and at first impressions appear a ‘bit too far out of the box’!

The starting point is first to confirm what causes fatigue during endurance running performance. As mentioned in previous posts, fatigue in the past used to be considered to be due to peripheral fatigue, for marathons, typically due to glycogen/carbohydrate depletion. With the availability of carbohydrate gels, fatigue in marathons now seldom occurs due to low blood glucose levels, as evidenced by the frequent sight from the 1980s of jelly legged runners stumbling towards the finish line of the London Marathon, now a very rare occurrence. The latest research, initiated by Professor Tim Noakes, highlights the importance of the brain (The Central Governor) and more specifically the integral role of RPE (Rating of Perceived Exertion). While doing physical activity, the runner rates their perception of exertion, i.e. their feeling of how heavy and strenuous the exercise feels, combining all sensations and feelings of physical stress, effort, and fatigue. This rating, typically known as the Borg Scale 6-20, (as there is also an alternative 1 – 10 scale) ranges from 6 (no exertion at all) up to 20 (maximal exertion), has been shown within the scientific research to be a stronger predictor of fatigue than any physiological measurements. The latest fatigue models within the scientific literature therefore propose that fatigue within endurance events occur once a maximal RPE is reached. Therefore during the marathon one should have a strategy that prevents one’s RPE from reaching maximum levels prior to the finish line.

Although I accept that RPE is the core component that contributes to fatigue during endurance events, the concept that maximal RPE must occur in order for fatigue to take place, in my experiences doesn’t seem to ‘fit’. During the latter stages of ultra races and marathons, I am not really working at a very high intensity, so I am therefore not experiencing maximal levels of physical stress, although there are high levels of effort, although this is what would typically be classified as mental effort. If one takes on board a ‘fuller/wider’ interpretation of RPE, more than the physical stress/fatigue, then I suppose the maximal RPE concept contributing to fatigue can apply. However, I prefer the introduction of a new theoretical measure known as RFE (Race Focus Energy). Where RFE is a measure of the mental effort, the concentration, the race focus required in order to keep running at a fast pace, i.e. a race pace. RFE is largely determined by RPE, however, the relationship between the two is not directly linked, with many aspects, specifically positivity and negativity, being able to alter the link between the two, i.e. swing the arrow up or down. The RFE Fatigue model also ‘fits in nicely’ with most marathon runner’s experiences, i.e. that towards the end of the race, they run out of energy. Remember, this is no longer carbohydrate / biochemical energy, but more likely Race Focus Energy, or simply mental energy.

Therefore to improve performance during an endurance event such as a marathon, one either has to ensure RPE doesn’t reach maximal levels, or alternatively adopting the RFE Fatigue Model, ensure one does not empty their RFE tank prior to the finish line. At first I will disregard the impact of positivity/negativity and simply look at RFE as being directly determined by RPE. Then if I aren’t too fatigued I will attempt to introduce where positivity and negativity fits in.

The key idea behind an equal paced marathon running strategy is for the “power output” as Tom describes it, to remain even throughout the entire race. With even power output on a flat course translating to even running pace, i.e. constant minute per mile rate, and subsequently equal half marathon split times. The only problem with this idea is that an even pace throughout a marathon does not mean you are running at an even physiological intensity. Due to a number of physiological aspects that occur as the duration of the race increases, such as dehydration, muscles gradually fatiguing, and possible changes in fuel utilisation towards an increase in fat burning (which requires more oxygen for the same ATP generation), there is an increase in the physiological load for the same power output / running pace, which is known as cardiac drift. Runners will be well aware of this if they race with a heart rate monitor, as they will observe a gradual increase in heart rate throughout the race, with the increase being greater during the latter stages of the race, even if they maintain a constant running pace.

Runners who don’t use a heart rate monitor will also be well aware of this phenomenon when reflecting on how ‘hard’ the race was, as their Rating of Perceived Exertion (RPE) increases as the duration of the race progresses when running at a constant pace. Typically, if adopting a constant pace strategy, their RPE would be low at the start of the race, maybe around 11(Light) – 13 (Somewhat Hard), and then progressively increases up towards 17(Very Hard) – 19 (Extremely Hard) during the latter stages of the race. An increase in RPE therefore results in an increased usage rate of RFE.  The figure below is taken from Parry et al., 2011.  An article on perceived exertion among Ironman triathletes, within November's edition of BJSM.  The figure clearly shows how the RPE increases during the marathon (of an Ironman), even though the actual running pace decreases as the marathon progresses. (The decrease in running speed is not clearly illustrated by the poor scale on the axis, up to 30 km/hr!) It looks like the pace has dropped from around 10.1 km/hr (5:56 per km) down to around 8.8 km/hr (6:49 per km).  Therefore to maintain an even running pace throughout the entire marathon would require an even larger rise in RPE than illustrated within the figure below.

I guess the ‘million dollar’ question is, “Is this progressive increase in intensity, from light at the start, up to hard at the end, really the best pacing strategy?” If we look at the strategy to reduce the likelihood of emptying one’s RFE tank, then one would conclude that starting at an easy pace, where the RFE usage is low at the start, would lessen the chance of running out of RFE before the end of the race. However, due to running at a lower intensity, this means you are actually running slower than what you could have run at. The theory behind the even power output is that because you have taken the first half easy, i.e. with minimal Race Focus Energy, then you are more likely to be able to maintain the same running pace during the second half of the race, as your RFE tank will be substantially fuller than if you had started with a higher intensity, at a higher usage of RFE.

The even power output strategy therefore looks good. However, what happens during the second half of the race? Remember an even power output strategy (even running pace on a flat course) means you have run at a slower pace than you could have achieved, so you have time to make up in order to cross the finish line in a quicker time. What it gets down to is how much extra RFE will you consume during the second half of the race in order to maintain the same running pace, over and above the amount you would have consumed, if you had started running initially at a higher intensity, therefore at a quicker running pace, and therefore having the ‘luxury’ of being able to reduce your pace during the second half, and hence use less RFE? As just highlighted, the benefit of starting at a quicker pace is that you are able to keep the RFE usage, (or the RPE value), the same during the second half of the race, as you have ‘time up your sleeve’ so therefore able to allow the pace to drop gradually to equally match the gradual increase in physiological load as a result of cardiac drift.

The confusion often arises because it is assumed that starting at a quicker pace, i.e. quicker than what you are capable of maintaining for the entire duration of the race, means that you are working at a higher physiological intensity, higher than what you could maintain for the entire duration of the race. This assumption is incorrect. By starting at a quicker pace, you are actually keeping the physiological loading, the intensity, the RPE, and most importantly the RFE at a more even value! It is attempting to run at an even pace, with an even power output, that results in large variations in physiological loading, RPE and RFE. It is typically assumed for most variables that an even constant value is more efficient than fluctuations or a wide range of values. So YES adopting an even strategy is the answer, but not an even running pace, or an even power output strategy, but a strategy that results in an even physiological intensity, and an even usage of Race Focus Energy!,

Looking at the example of a runner adopting an even power output strategy, means the runner has taken it easy at the start, running slower than one could quite easily have run at, as there is no fatigue, heart rate is therefore the lowest it will be throughout the entire race before cardiac drift, and their RPE will also be at the lowest, as this continuously rises during the race, as clearly illustrate in the figure above. However, will they actually be able to translate having a fuller tank of RFE leading into the second half of the race into actually maintaining the same even running pace? Before answering this question, there is one aspect that I haven’t mentioned yet: muscle fatigue / muscle damage. The muscular force required from your lower limbs to run is typically in the region of around 20% of one’s maximal force value that they can generate. Now during endurance running, as muscles gradually fatigue, the decline in the muscle force that is able to be generated actually plateaus, at a level of around 30 - 40% decrease. So even at the end of ultra races, the muscles are still able to generate 60 - 70% of their maximal force, which you can see is significantly more than the 20% that is needed to run. So the muscle fatiguing aren’t actually the limiting factor. They simply cause the running to be less efficient, hence the drift upwards in heart rate, RPE and therefore increased RFE usage, at the same running pace.

The problem during marathon / ultra running is actually the muscle damage, the increased pain the runner feels as the race progresses, on each and every foot strike. This pain is usually worse on the down hills where the muscles are contracting eccentrically (i.e. the muscle lengthens as it contracts) and also during road racing, where there isn’t the same ‘give’ in the road as there is on the trails. So during the latter periods of endurance races, such as a marathon, although the runner that started at an easy pace has more RFE in the tank, the usage rate is now magnified immensely simply due to the pain from the muscle damage. If you reflect back to your last marathon or ultra race, how much mental focus did it take to keep moving at a reasonable pace when your legs were ‘screaming’ for you to stop? There was most likely increased RFE usage simply due to the muscle damage pain! Yes, if your experiences were similar to my typical experience in an ultra race, then it probably took significantly higher levels of RFE to maintain the same pace. Not due to a lack of physiological fitness such as VO2 max, or lactate threshold, but simply due to the muscle damage that is unavoidable in endurance racing. One could suggest that the muscle damage would be more if the runner runs the first half of the race at a faster pace, however, the muscle damage is much more time/duration dependent rather than pace dependent, especially when running on the trails, where the running pace effect on muscle damage is even much smaller. It isn’t just muscle damage that can cause the RFE usage to significantly increase during the latter stages of the race. Other factors such as blisters, cramps, dehydration, overheating, stomach/digestion issues etc, can all increase significantly the amount of Race Focus Energy that is required in order to maintain the same running pace.

Hopefully it is becoming clearer in terms of ‘where I am coming from’! Slowing down during the second half of a marathon isn’t solely determined by the pace the runner runs the first half in. Yes, it does play a part, as a quicker pace will have used up more RFE, but during the second half of the race, there are so many other factors that can significantly increase the RFE usage rate, which far exceeds any ‘savings’ achieved by running at an easy pace during the first half. Those runners that are able to maintain an even paced marathon, or even a negative split, in some ways are achieving it, perhaps one could say by as much a little bit of luck, as opposed to their physical preparation (which plays an important role – but another post), or more specific to this post, as opposed to their conservative running pace in the first half. The easy running pace during the first half I believe plays only a little part in everything seeming to ‘fall into place’, i.e. that they didn’t cramp, didn’t get dehydrated, didn’t get blisters, didn’t get overly painful muscle damage etc., and with the easy running pace during the first half I would suggest most likely does not have such a large affect, that it was worth ‘wasting’ the opportunity to run faster while they could, before these multitude of potential problems possibly arise during the second half. Hence my philosophy; “Run as fast as you can, WHILE you can!” Before the muscle damage, dehydration, etc. massively increases the rate of RFE usage!

Although I haven’t even touched on the role of positivity and negativity above, (another post), now is a good time to look at some actual race data. Is this ability to run an even running pace in a marathon, or even better, to run a negative split, actually an indication of a good performance, of being a better runner? Is it a quality of better runners, such as one may associate a high VO2 max or lactate threshold as a quality of better runners? And secondly, how many runners actually achieve this so called ‘great running performance’ to achieve a negative split. If you achieved it, would you therefore be within the ‘quality’ runners that make up say 10% of all runners, or is this quality performance not that distinctive, and in fact you are just one of say 20% of all runners. Still an aspiration to aspire to, to be within the ‘best’ 20% of the field, as remember, the negative split is portrayed as THE achievement!

To help answer these questions I looked at the results from this year’s Virgin London Marathon. Perhaps as one would expect, based on the status the negative split has, both the male and female winners ran negative splits. So therefore why have I wasted all of this time typing up this blog post, attempting to get you to consider that the negative split isn’t what it is made out to be? But let’s look a little deeper at the results. How many of the other 99 runners in the top 100 in the massed start race also achieved a negative split? Remember these runners are the very best, at the very front of a field of over 35,000 finishers. Surely then one would expect around half of the top 100, or at least a third! No, only seven other runners in the top 100 finishers ran a negative split. This ‘strange’ result could however be because at the front of the race many of the runners went out with the pace makers at nearly world record pace, in the hope of hanging in there to the finish, they therefore were never going to achieve a negative split. So if I look at how many within the next 100 places from 101 – 200 achieved a negative split, this would give perhaps a more true representation of the frequency of the negative split occurring. These runners from 101 – 200 are still top quality runners, and in relation to the overall field, very, very fast runners, with an average finish time of 2 hours 39 minutes. The results show that there were only 6 negative split runners from the 100.

If you look at the following graph, that shows the number of runners that negative split from samples of 100 runners at different time gaps for the first 10,000 finishers, then you will see that there is ABSOLUTELY no relationship at all between the finish time of the runners and the percentage that achieve a negative split. If running a negative split was a quality of being a good runner, of a good performance, then surely one would expect that further towards the front of the field there would be a higher percentage? With a correlation of pretty well zero, one shouldn’t need any more evidence that the negative split is NOT something to aim for, NOT something that indicates that you performed well!

Another key statistic is the percentage of runners within the first 10,000 finishers that actually achieve it, being only 5.8%. With this evidence it therefore still amazes me that there seems to be the message ‘out there’ that the negative split is something all runners should aim for. If we look at a 10% sample, in batches of 100 runners, spread throughout the 23,600 runners that finished within 5 hours at London, then the percentage that achieve a negative split drops even lower to only 4.3% of finishers!  The following graph also show how the positive split slowing down time increases as the finishing time increases.

A really issue that needs attention is in terms of the potential effect this low percentage of negative splits may have on the marathon finishers, when 95.7% of them do not achieve probably the number one goal that is drummed into them apart from finishing! Remember the message ‘out there’ that the negative split indicates that you ran well, probably even more important than your actual finishing time. So 95.7% of runners are potentially disappointed because they didn’t achieve one of their goals. So if they do another marathon, which hopefully they will still want to, even after the disappointment of not negative splitting, then what do you think their likely race strategy will be for their next marathon? Well I would suspect that they would likely run the first half of the next marathon at an even slower, easier pace, as they possibly would have concluded that the reason that they didn’t achieve the negative split is that they started off too fast, and therefore that is why they ran out of energy. Which they may associate as running out of carbohydrate energy, as it is reasonably well known within the running community that the higher the physiological intensity, the greater the usage of carbohydrate. But remember that is the old model of endurance fatigue, before gels were available. Carbohydrate depletion is no longer the cause of fatigue in marathon runners.

As I have mentioned above, fatigue is more likely a consequence of RPE, or specifically getting close to emptying the tank of Race Focus Energy. As many runners are not aware of the latest fatigue research which is based on the Central Governor, i.e. the brain, it is probable that most runners are likely to conclude that their running pace being too fast at the start was probably the cause of their fatigue! And as I have highlighted above, the rate of RFE usage during the second half of a marathon is determined by much, much more than one’s running pace during the first half of the race. So starting their subsequent marathon at an even slower running pace, doesn’t guarantee that they will achieve this much wanted negative split goal, as demonstrated by only 4.3% of runners finishing in less than 5 hours achieving it.

Well, time to take a breathe! Phew, I think I have definitely got this negative split ‘dislike’ off my chest!

I think now is an appropriate time to call it a night. Hopefully those of you that have reached this far, have found something worthwhile within this blog, once you manage to navigate past the occasional frustration that may be evident within my writing. Please feel free to leave me a comment, explaining where I have gone astray, where I have got it wrong. I’m not saying that my ideas must be right, probably on most occasions, the majority of you would conclude that my ideas are a bit ‘far-fetched’, however, with regards to pacing strategy, hopefully I have at least got you questioning that maybe it is the negative split concept that this time is too ‘far-fetched’!

I will sign off with a quote from Tom Williams from MarathonTalk, which was within the comment he left on last week’s race report post:

“A large amount of what we achieve is governed by our mental state and how we see ourselves. (It is) a lot about opening the mind to what might be possible when we throw away the self imposed limitations of our mind.” Tom Williams, 2011.

All the best with the formulation of your pacing strategy for your next race. Remember, whatever strategy you adopt, you must have total belief that it is the right strategy that works for you.

Stuart