Showing posts with label Negative Split. Show all posts
Showing posts with label Negative Split. Show all posts

Thursday, 9 April 2015

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

 

Wednesday, 9 April 2014

Road Marathon Pacing - The Positive Split Pacing Strategy - My Final Comment

Hi,

Yes, back again, and this time I promise that it will be my last post to do with pacing for road marathons.  I know that this UltraStu blog is meant to be about trail running, however, the underlying principles that I will try to explain for the last time here for road marathons do translate to the trails, but to a lesser extent, as there isn't the same 'obsession' with finish times when running on the trails.

Still Some Confusion Over the Likely Disappointment in Adopting an Even Paced Strategy
Why bother writing one last comment about road marathon pacing you may ask.  Well it is because the standard accepted pacing strategy for road marathons, i.e. an even paced strategy or a negative split strategy, is totally the wrong approach for marathon runners, unless you are one of the World's very best.  And the fact that this coming weekend at the London Marathon, thousands of runners will experience disappointment at not achieving their target marathon finish time, and for many, not because they are not capable, but simply due to them following the totally wrong standard accepted pacing strategy for road marathons, with the false belief that they are capable of achieving an even split marathon!

As I stated in my marathon pacing calculator post last week, the topic of pacing tends to be vigorously discussed, and as expected, my post last week generated some quite animated responses.  But rather than directly respond to the comments that have been made during the last week, (which varied from containing some worthy points, to others being totally misguided or confused), I will simply attempt to clarify the confusion that is still evident.

Typical Road Marathon Goals
Lets start with: What is the purpose of running a marathon?  Well, simple really, the number one priority is to get to the finish line.  Apart from something catastrophic happening, pretty well nearly everybody with modest levels of fitness can finish a marathon.  However, it could take a long time, perhaps up to nine hours if one walked at around 3 miles per hour, i.e. 20 minute mile pace.

Although most runners have their number one aim to finish, I have yet to meet a marathon runner who hasn't started the marathon without a thought, a guess at the time they think they can achieve.  Many runners will then convert this possible time idea into a target marathon finish time.  To start with for novice marathon runners, the target finish time may be to break six hours, therefore involving a mixture of walking and running.  And then the next target is often to break the five hour barrier, which requires significantly higher levels of running.  The targets then get quicker, typically to break 4 hours 30 minutes, then the magical four hour mark.  As the finish time gets quicker, the target finish goal barriers tend to get closer, with the next target finish times tending to be 3:45, 3:30, 3:15 and then the 'holy grail' the even more magical sub three hour barrier.  Other finish times between three and four hours are often targeted such as 'good for age' race places for various marathons, e.g. London Marathon, or BM times, i.e. Boston Marathon qualifier times.  Once the sub three hour barrier is accomplished, the targets tend to get very narrow, e.g. 2:55, 2:50, 2:45 (which is the UK Athletics Male Championship qualifier time, then 2:40, 2:35, and finally, only reserved for the very best of male club runners, the sub two hour thirty minute barrier.

So as you can see from the above paragraph, pretty well every runner starting a marathon will have either some vague idea of a time they think they might be able to achieve, or for most runners, they will have a target marathon finishing time that they would like to achieve.  Hence why it is so important that these runners have some form of pacing strategy to help them achieve their target goal finishing time, and hence why I published last week a marathon pacing calculator that will help them pace the marathon and thus help them achieve their target time.

My Marathon Journey
Before I spend a little bit of time explaining in a little bit more detail just why the marathon pacing calculator will dramatically increase the likelihood of the runner achieving their target finish time, I will briefly provide a background of my marathon journey.  Although this section provides some context regarding the importance of different target finish time barriers, skipping this section won't affect your understanding of the marathon pace calculator and why the positive split pacing strategy is more successful.

I mentioned above that in terms of target marathon times, runners may progressively move down the marathon goal time barriers, from five hours, next four hours, then eventually three hours  For me, at the age of seventeen, I set the target immediately at breaking three hours, and I was successful with 2:56:51 in April 1980.  Yes, 34 years ago!


Breaking the Three Hour Barrier - 2:56:51 - April 1980 - Rotorua, NZ

Having achieved the sub three hour goal, I left marathons aside for a few year before returning in 1984, now as a twenty one year old, with the sub two hour thirty minutes barrier as the target finish time.  I'm not sure what happened to the 2:45, or even the 2:50 and 2:40 target times, but as a youngster I was always in a rush to get things done!  Did I achieve my goal time.  No!  Unfortunately I missed the 'super magical' sub 2:30 by a mere forty seconds.

Failing to Break the Two Hour Thirty Minute Barrier - 2:30:39 - June 1984 - Christchurch, NZ

Yes, those forty seconds were massively meaningful.  It meant the difference between massive joy and massive disappointment.  I was so disappointed at not achieving my goal that I moved not only away from marathon running, but running full stop, for the next eight years or so, and ventured into multisport (i.e. kayaking triathlons), road cycling, triathlon, and then Ironman triathlon.  It was only when preparing for the Ironman that I returned to the road marathon in 1992.

So you can see from above, how in some ways road marathons are quite different to trail marathons or ultras.  On the trails, the finish time isn't really that relevant as no two trails are the same.  But on the road, every marathon should be 26.2 miles, and although road routes will vary a bit in terms of undulations and exposure to wind, on the whole, road marathons tend to be over reasonably flattish courses, so direct comparison of marathon times are possible.  So the consequences of running just forty seconds, yes just forty seconds slower that I hoped for changed my entire endurance athlete experiences.  For the better or for the worse, I don't know.  But I do recall that at the time I was very disappointed.  Bizarre really, considering it was such a quick time, especially for a twenty one year old.  But as I have found, runners tend to be very 'hung up' about their race goals, and often will be very despondent over a time only slightly slower than their target time, even though in reality it is a great achievement.  But that is just the nature of many runners!

Therefore being just a few minutes slower than target finish time, or even just a few seconds slower, isn't what one wants. The majority of runners want to achieve their target finish time for the marathon.  Hopefully most people will agree with this statement!

So back to my marathon journey through the years.  Yes, in 1992, I was a full-on Ironman triathlete.  I had successfully qualified for the Hawaii Ironman at the end of the year, by finishing in 13th place overall at the very first 1992 Lanzarote Ironman, running the marathon portion of the Ironman in three hours and seven minutes.  Wanting to perform to my best at Hawaii, I placed more emphasis on my road running and entered the Scottish Amateur Athletics Association Marathon Championship in August 1992, which were being held in Elgin, near the top of Scotland.  I had been living in Aberdeen, Scotland for nearly a year, and so according to the AAA rules I was therefore eligible for the Championship, which was a pleasant surprise when I was awarded the bronze medal for finishing third in an official time of two hours thirty minutes, and this time sixteen seconds (2:30:16).  Yes, the super magical sub 2:30 barrier was still beyond me.  But now only by seventeen seconds,  Yes a measly seventeen seconds!


 

Again Failing to Break the Two Hour Thirty Minute Barrier - 2:30:16 - August 1992 - Elgin, Scotland

For the next few years I continue with Ironmans, triathlons and then duathlons, and it was in 1995, in preparation for the prestigious Zofingen Powerman Duathlon consisting of 13km run, 150km bike, and 30km run, that I ran the 1995 London Marathon. And yes finally in April 1995, fifteen years to the month since I broke the sub three hour barrier, and eleven years after being so close (40 seconds), I finally manage to go sub two hours 30 minutes with 2:29:34!


Finally Breaking the Two Hour Thirty Minute Barrier - 2:29:34 - April 1995 - London

Yes finally, I had made it.  Only by twenty six seconds, but those twenty six seconds were HUGE!  Yes, I recall at the time that upon finishing I was a bit disappointed with my finish time, as I had been running really well and was expecting to finish up to five minutes quicker.  But looking back now, whether I had run 2:28, 2:27 or even 2:25, these times in essence are all the same, simply sub 2:30.  Yes, these barrier goal times are important, hence why just a few seconds either way can be so meaningful.

Having achieved my long term marathon goal, there wasn't really anything else to achieve marathon wise.  I didn't believe I had what it took to be a sub 2:20 marathoner, so I again drifted away from the marathon.  Then in 2003, now as a forty year old, the prospect of running a quick marathon as a 'veteran' was appealing.  Unfortunately I didn't believe I could run sub 2:30 at the 'old' age of forty, so a 'soft' target time of sub 2:40 was my goal finish time.  And as you would expect, achieving the soft time that I had set was pretty easy, although, I did make tough work of it due to the lowered expectations, so I ended up struggling to a finish time of 2:39:12.


Slowing Down But Breaking the Two Hour Forty Minute Barrier - 2:39:12 - April 2003 - London

Following 2003, I finally 'let go' of the stopwatch and headed to the trails.  To date I have now raced thirty one trail marathons, and without the 'restriction' of the stopwatch, my running has gone from strength to strength.  From those thirty one trail marathons, I have won nineteen of them, finished second on eight occasions, finished in fourth place once, fifth place twice, and finally my most recent trail marathon last month, a disappointing DNF! 


My First Ever Trail Marathon Did Not Finish (DNF) - 00:00:00 - March 2014 - Steyning

Please note that I have made reference to some of my successes I have achieved with regards to marathon running, not to 'blow my own trumpet', a saying that my mother would always criticise people for, but I guess partly in response to a comment left on last week's blog post that suggested that my performances have been "hit and miss" and that I have performed poorly due to poor pacing strategies! "To me your race success has been really hit and miss over the last few years. .... Personally I think a big part of the problem is your pacing strategy" Well I don't think in any of these thirty one marathon races (excluding the DNF due to injury) that I  had a "problem", as I didn't perform poorly.  Sure, in some races I didn't achieve the 'perfect performance', but to try to discredit the positive split pacing strategy, by classifying my performances as poor, I find a bit bizarre.  Especially with the criticism coming from a 3:30 marathoner who has "nailed" all of his recent races!  "How do I know.... well in all of my races in the last 9 months- four races, three ultras and one marathon I nailed them all, in the only two race that I had done before I did big PB's."

So, as my personal marathon journey above illustrates, I have had quite a long association with the marathon.  For the majority of my marathons, there has been joy and satisfaction, but intermingled in relation to road marathons, there has been disappointment, at times deep disappointment, which looking at it now seems rather pointless.  What do a few seconds matter?  Yes, I know to the 'outsider' a few seconds mean nothing, but to the road marathon runner, those few seconds can be very meaningful, and hence why with my marathon pace calculator, I am trying to help potentially thousands of marathon runners this weekend at London to avoid this disappointment of not achieving their target finish time, which may be missed by just a few seconds, and for many simply due to trying to adopt a a flawed even paced strategy!  That is my motivation, and why I am hopefully not wasting my time, trying to clarify the confusion that exists out there!  So please forward the following link to the Marathon Pace Calculator website to people you know running at London on Sunday. http://rsusmf.appspot.com/


The Marathon Pace Calculator
So lets look in detail at my marathon pace calculator.  The calculator was based on the data of the first twenty five thousand finishers at last year's London Marathon.  Yes, 25,000 runners finished before five hours and two minutes, so I did not include the data from runners slower than five hours and two minutes.  The blog post from May last year described the process in detail, but to summarise, I analysed the data of these 25,000 finishers in blocks of one thousand runners, except at the very top end of the field I analysed the data in blocks of one hundred runners.  I looked at the number of runners per thousand or hundred block that ran an even or negative split, and then looked at the average percentage slowdown that occurred for each block of runners.  It is this average slowdown percentage that is used within the marathon pace calculator to calculate the percentage slowdown.  Which is then used to give the most important information required by the marathon runner, being:  What pace should I go out at, should I run at during the first part of the marathon?  And also, what time should I aim to run through half way in?

Now if you follow the standard pacing advise that an even paced marathon strategy is best, then the answers to these two key questions are easy.  Simple, your time at half way is simply half of your target marathon finish time, and the pace to start at, is the same pace you aim to run for every one of all of the twenty six miles, which is simply your target marathon finish time, divided by 26.2 miles.  Straight forward really. No need for a marathon pace calculator.  Simple!

UNFORTUNATELY IT IS NOT THAT SIMPLE.  IF RUNNERS TAKE THIS EVEN SPLIT APPROACH THEN THEY HAVE A NINETY FIVE PERCENT LIKELIHOOD OF NOT ACHIEVING THEIR TARGET MARATHON FINISH TIME. I will repeat, they have a 95% likelihood of NOT achieving their target marathon finish time!!!  It is as simple as that!  That is the data from the first 25,000 runners from last year's London Marathon.

Those of you may recall that last week I stated that they had a 96% likelihood of NOT achieving their target time, why now reduced to 95%.  Well the 96% refers to the entire field of 35,000 runners, having just re-checked my data.  When looking at only the first 25,000 finishers, i.e. quicker than 5:02, it becomes 95%.  Yes, only FIVE PERCENT, yes I will repeat!  Only 5% of these runners managed to run an even paced or negative split run.  That is they managed to run the second half of the marathon at the same pace or quicker that their first half of the marathon.  Now bearing in mind, if the runner has adopted the even paced strategy, they will pass through half way in exactly half of their target marathon finish time.  With 95% of the runners, running the second half of the marathon SLOWER, then this means that 95% of runners MUST THEREFORE NOT HAVE ACHIEVED THEIR TARGET MARATHON FINISH TIME!

Now I don't know how I can make this above point much clearer.  It is not me mis-using the statistics as accused by Thomas in a comment left on the linked blogpost "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." The above is the correct interpretation of the data from last year's London Marathon.  If anyone is able to explain to me how I have got the above conclusion (That 95% of runners MUST THEREFORE NOT HAVE ACHIEVED THEIR TARGET MARATHON FINISH TIME) wrong then please leave a comment. below on this post.

Some people may suggest that running a positive split strategy, i.e. running the first half of the marathon quicker than the second half of the marathon will result in the first half being run far too quickly, and the runner will 'blow up'!  Now I don't want to get into a discussion here what 'blowing up' means, but if one simply looks at the data from the 2013 London Marathon, if runners don't adopt a positive split strategy then it is near guaranteed, well 95% certain, that they won't achieve their target finish time, as 95% of them will slow down during the second half of the marathon.  Considering that the even paced strategy is so widely recommended in pretty well all publicity mediums, such as magazines and podcasts, then even with this being the standard pacing message, 95% of runners quicker than five hours are still not managing to run an even paced marathon.

Now you may argue, that if the runner runs the first half of the marathon even quicker, then more runners will slow down during the second half of the marathon.  And yes, that is exactly what should happen.  Slowing down during the second half of the marathon is a reality, as demonstrated by the fact that 95% of the runners do slow down.  It is quite simple really.  Accept that slowing down during the second half of the marathon occurs, so take this slowing down into account when planning your pacing strategy, so one is still able to achieve their target marathon finishing time, even though they have slowed down.  If runners plan their pacing strategy, wishing, hoping, expecting not to slow down, so hoping that they are the one in twenty runners that don't slow down, then yes, they have a one in twenty chance of achieving their target marathon finishing time.  But odds of one in twenty don't sound too appealing to me!


The Under-Trained / Inexperienced / Foolish Argument
A frequent counter argument to the presentation of this very low percentage of runners that are actually able to run a marathon with an even split between their first and second half marathon split times, is that just because this is what occurs it doesn't mean that this is the best or the most efficient strategy.  Comments like the following are often left:

"How many runners are under-trained for the marathon, yet you happily include their stats? How many runners make *obvious* pacing or executional mistakes, yet you include their stats too?"

"Huge numbers of people running a big city marathon are inexperienced, and you can put money on them going off too quickly. Foolish, but predictably foolish."

So lets maybe restrict the data analysis to the first 11,000 runners that ran quicker than four hours.  Yes, there are more runners that do achieve an even paced or negative split, but this percentage is only increased up to eight percent for the quicker runners able to finish under four hours.  So even with the percentage of quicker runners being able to run an even split strategy only increasing up to 8%, there is still a massive 92% likelihood of failing to achieve the target marathon finishing time.  So to conclude; Adopting a pacing strategy that only has an eight percent (8%) likelihood of succeeding doesn't really seem to be the "best or most efficient" strategy.  Rather it seems a pretty poor strategy to adopt!

Okay maybe these sub four hour runners are simply under-trained, inexperienced and foolish.  So simple, lets move to the very top end of the massed start field.  So we are ignoring the elite start, as remember what the elite are able to achieve has absolutely no relevance to the non-elite runners.  (Note: Please refer to the bottom of this post for an explanation into why what elite marathon runners are able to achieve is not relevant to the non-elite runners.)  So if we look in detail at the first one hundred massed start finishers, so those runners that finished quicker than 2:36:53, then surely these runners would obviously demonstrate the even paced / negative split pacing strategy works.  What would you expect from these very best non-elite runners, maybe 80% of them achieving an even paced / negative split pacing strategy?  Or maybe these very best runners, which one surely couldn't argue as being under-trained, inexperienced or foolish, that maybe 90% of them would achieve an even paced / negative split pacing strategy, thus finally providing indisputable evidence that the even paced / negative split pacing strategy is the best, the most efficient pacing strategy.

So what percentage of these very best non-elite, well-trained, experienced and not foolish runners achieve an even paced / negative split pacing strategy?  The ANSWER, JUST ONE RUNNER.  I will repeat, yes JUST ONE RUNNER, therefore just ONE PERCENT of the very best non-elite runners achieved an even paced / negative split pacing strategy!  Does anyone really need any further evidence that running an even paced / negative split pacing strategy is NOT the sensible strategy to adopt.  Now if anyone is able to provide a counter argument to this amazingly clearly obvious data, then please leave a comment below.


How Much Slow Down During the Second Half of the Marathon?
So hopefully everyone should now fully understand and accept that adopting an even paced / negative split pacing strategy is reducing the likelihood of achieving ones target marathon finish time.  The very best non-elite road marathon runners, who are likely to be the best trained, the most experienced non-elite road marathon runners, DON'T DO IT, so why should other lesser trained, lesser experienced runners try to adopt an even paced / negative split pacing strategy?

So the immediate question that arises is then just how much should the marathon runner expect to slow down during the second half of the marathon?  This is where the marathon pacing calculator is so useful.  Yes, this is why I am spending time typing out this blog post, so potentially thousands of runners this coming Sunday are not disappointed, as they will therefore have some guidance on what pace to start out at, and what time they should pass through the half marathon mark.

As mentioned above, the marathon pace calculator uses the average percentage slowdown based on the data from the first 11,000 finishers, i.e. all runners that finish under four hours.  And the percentage slowdown used within the marathon pace formula varies for different finish times, with the very quickest runners, i.e. runners targeting a marathon finish time of sub 2:37 using a 5.06% slowdown, increasing for runners targeting a finish time slower than 3:17 using a 9.92% slowdown.

Now some people argue that adopting a positive split strategy, i.e. slowing down during the second half of the marathon can be "psychological demoralizing, as (the runner) is being passed by runners who are looking stronger and fresher".  However, the marathon pace calculator uses the average percentage slowdown, so if the runner completes the second half marathon with the exact percentage slowdown used within the marathon pacing formula, then they will overtake an equivalent number of runners during the second half of the marathon, equivalent to the number of runners that will overtake them during the second half of the marathon.  Which although slowing down and running the second half of the marathon slower, their actual race position will stay the same if the runner runs at the exact percentage slowdown used within the marathon pace calculator.

By adopting the marathon pace calculator average percentage slowdown pacing strategy, the running pace up to the half way point in the marathon will be quicker than if adopted the flawed even pace strategy.  How much quicker will this pace be?  Well the amount the pace is quicker is dependent upon the target marathon finishing time, as not only does the percentage slowdown vary dependent upon the finish time, but because the slowdown is expressed as a percentage, having a slower target finish time actually results in the runner slowing down more minutes during the second half.  So slower finish time runners will have to run at a quicker pace, to gain more minutes quicker during the first half of the marathon, in comparison to the even paced strategy runner.  Faster finish time runners don't have to gain as many minutes by running quicker during the first half.  The idea of having to run so many minutes faster during the first of the marathon may sound a bit daunting.  But remember if you decide to run the first half of the marathon at the slower, even paced strategy running pace, then sure it will feel easier to half way, but this isn't much good, as you only have a one in twenty chance of achieving your target finishing time!  So lets look at some specific examples.

The Sub Four Hour Marathoner
Running a sub four hour marathon adopting an even paced strategy requires a minute mile pace for every one of the 26 miles to be run at 9:09.  The runner would pass through half way in 1:59:59.

Using the ReSUltS marathon pace calculator which incorporates a 9.92% slowdown during the second half of the marathon.  For the first 13 miles of the marathon, the calculator requires a 8:43 minute mile pace.  The runner would pass through half way in 1:54:19, which would be five minutes and forty seconds quicker, yes 5:40 quicker.  What is the likely impact of running 5:40 quicker to half way?  Well if running 5:40 quicker to half way results in the runner setting a half marathon personal best time, then there is obviously something wrong.  Not that the ReSUltS marathon pace calculator is wrong!  No, the runners target finish time is obviously too quick.  And in this instance, no matter what pacing strategy the runner adopted, it is most probable that they would not achieve their target finish time.  Target marathon finish times must be realistic and based on some evidence / data, rather than just 'guessing' a time.  But generating target marathon finish times is a totally different topic.  What the ReSUltS marathon pace calculator assumes is that the target marathon finish time is realistic.

So for the sub four hour target marathoner, the runner would pass through half way in 1:54:19, which would be five minutes and forty seconds quicker, yes 5:40 quicker.  However, for every mile after the half way point, the even paced strategy runner must maintain the same 9:09 minute mile pace, even though they will start to fatigue, which every marathon runner will tell you occurs!  Whereas the runner that has adopted the positive split strategy, using the pacing plan proposed by the ReSUltS marathon pace calculator, for every mile after half way they are allowed to gradually slow down, as the fatigue gradually builds up.  One doesn't get to the half way point in a marathon and instantly become fatigued!  No, the fatigue builds up gradually.  So to mimic this gradual build-up of fatigue during the second half of the marathon, the required minute mile pace to achieve the target finishing time gradually gets slower.  So for those really challenging last six miles of the marathon, the positive split strategy runner is able to run the last six miles at the pace of: 9:41, 9:48, 9:55, 10:02, 10:09, 10:17.  Yes, they are able to slow down to a minute mile pace of 10:17 and still achieve their target finish time.  Doesn't that sound more realistic than the even paced strategy runner, still trying to run a 9:09 minute mile, the same pace they ran at the start when totally fresh, now nearly four hours later when absolutely exhausted from running 25 previous miles.

Yes, I know that the runner is highly unlikely to run exactly to the minute mile pace times provided by the ReSUltS marathon pace calculator.  Whether they slowdown at the same rate that the calculator forecasts, or at a quicker rate, but they don't start fatiguing until say mile 18, it isn't really important.  What is important is that the runner is able to slow down and still achieve their target finishing time.  What is important is that the runner accepts that slowing down during the second half of the marathon is a reality, and therefore must plan for it!  To 'dream', to 'wish' that they won't slow down, and therefore not plan for any slowing down, even though the very best non-elite marathon runners slow down during the second half, is just total foolishness!


The Sub Three Hour Marathoner
Running a sub three hour marathon adopting an even paced strategy requires a minute mile pace for every one of the 26 miles to be run at 6:52. The runner would pass through half way in 1:29:59.

Using the ReSUltS marathon pace calculator which incorporates a 6.57% slowdown during the second half of the marathon. For the first 13 miles of the marathon requires a 6:39 minute mile pace. The runner would pass through half way in 1:27:07, which would be two minutes and fifty two seconds quicker, yes 2:52 quicker.  Okay it is 2:52 quicker than the even paced strategy at half way, but this isn't massively quicker, which many people seem to misinterpret from the idea of adopting a positive split strategy.  Many people seem to interpret the positive split pacing strategy as 'going out at suicide pace'.  As you can see from this sub three hour marathon target example, getting to the half way point 2:52 quicker, yes, requiring more effort and focus, but I don't think it could be classified as being ridiculously faster!

However, for every mile after the half way point, the even paced strategy runner must maintain the same 6:52 minute mile pace, even though they will start to fatigue, which every marathon runner will tell you occurs! Whereas the runner that has adopted the positive split strategy, using the pacing plan proposed by the ReSUltS marathon pace calculator, for every mile after half way they are allowed to gradually slow down, as the fatigue gradually builds up.  And for those really challenging last six miles of the marathon, the positive split strategy runner is able to run the last six miles at the pace of: 7:08, 7:12, 7:16, 7:20, 7:24, 7:30. Yes, they are able to slow down to a minute mile pace of 7:30 and still achieve their target finish time. Doesn't that sound more realistic than the even paced strategy runner, still trying to run a 6:52 minute mile, the same pace they ran at the start when totally fresh, now nearly three hours later when absolutely exhausted from running 25 previous miles.

Hopefully, the above two examples have helped illustrate how the ReSUltS marathon pace calculator works, and it is provides guidance on a pacing strategy that represents what is a reality, the marathon runner getting fatigued as they progress through the marathon.  Now I haven't ever met a marathon runner that didn't fatigue as they ran the marathon to the best of their ability.  Fatigue occurs, it is a reality, no argument!  So surely as one fatigues then one should expect to start to slow down.  Surely this must now make sense!

As usual my short blog post has ended up near ultra length.  Sorry about going on and on, and no doubt repeating myself above many times.  Hopefully my more detailed and lengthy explanation of how the ReSUltS marathon pace calculator works, has helped to clarify why the positive split pacing strategy is clearly the strategy to adopt to maximise the likelihood of achieving ones target marathon finishing time!

Please spread the word on the ReSUltS marathon pace calculator, and how it takes the guess work out of deciding how much one should expect to slow down during the second half of the marathon.  And to those of you after reading all of the above, that still think that you should NOT expect to slow down during the second half of the marathon, I am sorry but I am unable to help you.

Signing Off
I will sign off with a quote that I have signed off with previously when discussing the foolishness of the negative split pacing strategy.  The quote is from Tom Williams, one of the hosts of the excellent MarathonTalk podcast.  Yes, I am an avid listener of MarathonTalk and have been for the last three or so years.  Pretty well all of their advice on the show is sound quality advice, which assists thousands of runners to achieve their running goals, EXCEPT ONE, their celebration of the negative split.  For some unknown reason, they are just totally off the mark here!

It just so happened that last Sunday, Tom Williams ran the Greater Manchester Marathon and crossed the finish line in an excellent 104th place overall, with an official chip time of 2:53:04.  Did Tom, a massive supporter of the negative split, achieve a negative split in running 2:53:04.  Yes, indeed he did!  Using his chip time, he ran the first half marathon in 1:27:04, and then ran the second half marathon in 1:26:00.  So a negative split of 64 seconds!  Fantastic!  That is, if you believe that the negative split is the sign of a well run marathon.  And with MarathonTalk taking this view, no doubt there will be huge celebrations on MarathonTalk this week!

However, how did Tom manage to achieve this 64 second negative split?  Simple really, by running the first half marathon so slowly, which although he ran the second half marathon 64 seconds quicker, his overall finish time is quite a bit slower, (possibly up to four minutes slower), than the marathon time that one would expect that he should be able to achieve, based upon his recent 10 mile road race time of 60:54.  A ten mile road race finish time of 60:54 should definitely correspond to a quicker marathon time than 2:53:04.  How much quicker is debatable, and one could look at various marathon predictor websites, which produce a range of predicted marathon times from 2:49:03 to 2:51:19.  The precise likely marathon finish time isn't really that important.  The important 'take home' message is that Tom only managed to achieve a negative split by running slower than his true current marathon potential.

Listening to Tom on MarathonTalk, I know that he publicly stated that he wasn't going to race the Manchester Marathon to the best of his ability.  Yes, this is fine.  But hopefully Tom and his co host Martin will not massively celebrate his negative split achievement, as the negative split has only been achieved due to not running as quickly as he could.  And celebrating the negative split pacing strategy, will encourage the thousands of MarathonTalk listeners to adopt the totally wrong pacing strategy, if they wish to maximise their chances of achieving their target marathon finish time.

(Please Note:  I have just listened to the first portion of this week's MarathonTalk episode, and I would just like to congratulate Tom and Martin for not celebrating Tom's negative split.  No doubt with Tom in the past being such a supporter of the negative split, that it must have been so tempting to massively celebrate his negative split achievement.  Maybe Tom has changed his views since 2011, and now 'has his money on' the positive split.  Now accepting that the negative split is only achieved by running the first half of the marathon slower than ones ideal pace.  Anyway I just wanted to thank Martin and Tom for not encouraging their thousands of listeners to adopt a negative split pacing strategy for London Marathon. Stuart - 10th April, 2014)

So finally here is Tom's sign off quote from 2011.  And Tom, if you are reading this, please leave a comment below, letting us know what your 2014 views are on the ideal marathon pacing strategy.

“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.

All the best to everyone running this Sunday's London Marathon.

Stuart


PS  The Elite Marathoner World Record Argument
The following is a small section on why what elite marathon runners are able to achieve is not relevant to the non-elite runners.  Because as always when it comes to justifying the even paced / negative split pacing strategy argument, this is the one argument that is also provided, and as expected was included in comments that were left last week.

From Brett: "The point I was trying to make was to look at all the current records in distance running - if they all are even to slightly negative splits, that has to mean something.  For example, the current marathon world record is around 2:03 and was an even split to nearly the second."

"In the USA, we also had the 100 mile track record broken a couple times in the last few months. The first time it was broken (Jon Olsen), he ran two 50 mile splits within 2 minutes of each other. The latest time the record was broken a few weeks ago (Zach Bitter), he ran a slight negative split of a few minutes in the second 50 mile section. So as best I can tell, this same behavior is seen across ultramarathons and down to half marathons and 10ks as well."

 In case you haven't seen my reply to these World record arguments, I will simply paste the comment I left in response to Brett's World's best approach below.

"When in any other situation does the club level athlete, the 'average' person (although I dislike the word average but I think it makes the point clear) try to mimic what the World's best can do. Whatever activity; e.g. scoring a maximum 147 break in snooker, cycle racing at top-end pace for hours every day for near 22 consecutive days around and over the alps of France, or managing to descend to an ocean depth of 214 metres on one single breath. Yes, regardless of the activity, 'average' people do not expect to be able to replicate these amazing feats. So please explain to me, why is it that when it comes to running road marathons, that it is assumed that the 'average' person, who is not a full-time athlete, who does not have the same opportunities to prepare, the same resources, the same environment, and dare I say, the same genes, that this 'average' person can then achieve the same as the World's best, I just don't understand! Could someone please explain this logic."  Stuart Mills, last week.

The most important thing to remember is that you, me, and pretty well every other reader of this blog post are not the World's elite, so what the World elite do is not relevant.  How the World elite manage to achieve what they do I just don't know, and to be honest, neither do the sports scientists really know.  What they can achieve is at times just unbelievable, e.g. often 'throwing' in a mega super quick 5km split shortly after halfway in a marathon.  But the key thing to take away from what these World elite do, is that they are so different to you and me, that it isn't worth trying to work out how they do it.  Trying to compare myself to them is just total foolishness, although some people do seem to want to do this when it does come to both running an even paced race or even better a negative split.  Yes, it is good for the ego to compare that you achieve the same pacing strategy as the World elite, but the fact that one is only able to achieve an even paced or negative split pacing strategy by running the first half of the race so slowly is just 'ego massaging'.  Many people can run the last mile or quarter mile of a marathon quickly if they run earlier portions of the race slowly.  The aim is to run the entire 26 miles as fast as possible not just the last mile!

Wednesday, 2 April 2014

A Helpful Marathon Pacing Calculator

Hi,

Yes, back again, so soon, but tonight's post is quite timely, as in the UK this weekend there are the Brighton, Manchester, and Blackpool road marathons.  Then next weekend there is the London marathon and also the Jersey marathon.

My plan tonight is to simply introduce  a web page which has a marathon pacing calculator which may help many runners who are racing a road marathon in the next two weeks.  

When it comes to running a road marathon, there are probably two things that cause the most discussion amongst marathon runners:  nutrition, and pacing.  Out of the 125 posts I have published on my UltraStu blog, by far the posts that have generated the most comments and discussion have been to do with race pacing.  From  my third ever post that introduced some of my ideas on pacing for ultra trail races it created a little bit of a stir.  But my road marathon pacing analysis based on the first 25,000 finishers at last year's London Marathon really created quite an animated response, with some readers feeling sorry for me in that I was so confused "Sorry Stu, this article shouts out that you don't understand how to go about analysing pacing strategies."  and other readers just simply coming to the point with "OMG, what utter BS", which I presume means "Oh My God! What Utter Bull Shit!"  Although maybe I am confused and it should have been interpreted as "Oh My God! What Utter Brilliance. Superb!

Well over the last four years of writing on UltraStu, I have learnt that even if many people disagree with my ideas, it doesn't actually mean that my ideas are wrong, as there are usually other people who agree with them, and most important, at the time of writing I obviously thought my ideas were good.  Now nearly a year later, re-reading my two blog posts on road marathon pacing strategy, (post I, and post II), I am still TOTALLY  convinced that what I wrote back then makes total sense.

It was therefore quite pleasing that when chatting to Tim, a follower of my blog, when he commented that he really liked my London marathon pacing analysis and that he also thought that it could be hugely beneficial to thousands of runners to help them achieve their marathon target time.  He then offered to turn my ideas from my blog post into a marathon pacing formula which would calculate mile split times for every one of the twenty six miles, to ensure that runners remained on target to achieve their target time, with the formula based on real life data from tens of thousands of runners.

Yes, I know that it is only a few days to this weekend's marathon, but I would expect even at this late stage, there will be thousands of runners just not sure what pace to start out at, in order to achieve their goal finish time.  I guess most marathon runners would have heard of the negative split, i.e. running the second half of the race slightly quicker than the first half of the race.  And many may like that idea, as it is frequently promoted as the best strategy within running magazines or on running podcasts.  Or perhaps if the negative split strategy seems a bit too ambitious, then many runners may favour the even split approach.  Where the runner maintains the same running pace throughout every one of the twenty six miles.

Now I won't repeat my views on this totally flawed idea, as you can read these within my two blog posts from May last year.  But it does still absolutely amaze me how seemingly clever people think that one should still be able to run at exactly the same running pace after 20 - 26 miles, as the pace they would run at when totally fresh, as if fatigue doesn't exist!  It seems so obvious, that the only way this even pacing can be achieved, is if the pace run at the start of the race is just far too easy.  It has to be so much slower than one is really capable of, to be able to allow for the fatiguing affects of running 20 - 26 miles to equally balance the amount of time the runner at the start of the race is deliberately going slower per mile.  To put it simple.  If runners didn't fatigue during a marathon race, then an even paced strategy would be the result.  But fatigue does occur during a marathon.  Ask pretty well every marathon runner.  Therefore to achieve an even paced strategy, one has to run the miles at the start of the race at the pace that they feel that they are able to achieve when they are near exhaustion at say around the 25 mile mark.  One has to deliberately slow themselves down at the start when not fatigued, just to ensure that they aren't running too quickly at the start, otherwise there would be no chance at all at running at anywhere near the same pace when near exhaustion 25 miles later!

Sorry if the above paragraph is a bit jumbled.  I just found it quite hard trying to explain something which seems just so obvious that it shouldn't really need explaining!  Anyway, I did say that this post was going to be short, so lets finally go to the marathon formula calculator, available on the following website:

http://rsusmf.appspot.com


The web page calculator is titled the ReSUltS Marathon Formula.  Yes, implementing the pacing strategy that the formula calculates, runners are MUCH, MUCH more likely to achieve the result they want, i.e. their target marathon time.  Adopting the even split, or even worse the negative split pacing strategy, then as the data from last year's London Marathon demonstrates, runners are therefore 96% likely to FAIL!  Yes, I will repeat it in words, just to make it that much clearer.  Adopting the even split pacing strategy, has a NINETY SIX PERCENT chance of FAILING.

To those of you running a road marathon in the next two weeks,  I strongly ask you to consider is it wise to follow a strategy with only a 4%, yes ONLY a FOUR PERCENT chance of succeeding.  Weigh up the odds.  Look at the data. Fatigue does occur!  Slowing down during a marathon IS A REALITY, due to the gradually developing fatigue as the race progresses, especially during the final third of the race.  Talk to any marathon runner, that is when the marathon starts really getting challenging.  But somehow, one isn't meant to slow down, even when massively fatigued!  Is that reality?  No not for 96% of the runners!

The  ReSUltS Marathon Formula. therefore gives the marathon runner clear guidance on how much one should expect to slow down as the runner fatigues during a road marathon.  The amount of slowdown isn't a guess, nor a dream (i.e. not slowing down), but based on the data of over 10,000 runners, with the amount of slowdown being dependent upon the runner's target marathon finish time.  Just use the arrows at the top of the web page to enter your target marathon time, and with one click, your pacing strategy is calculated.  As simple as that!  All the guess work removed.

No doubt there will be many people who will still think that I write "Utter Bull Shit".  But everyone is entitled to their views.  However, I find it so disappointing, that over the next two weeks, so many marathon runners  will not achieve their target marathon time.  Not because they were not capable of achieving their goal time, but for many, simply because they followed an unrealistic pacing strategy and simply ran the first half of the marathon too slow, i.e. running at a pace slower than they could have actually ran at.  Hopefully the ReSUltS Marathon Formula calculator will help increase the number of marathon runners achieving their goal time.

If you know some runners that are running a marathon in the next two weeks, then forward them the link to the ReSUltS Marathon Formula web page, http://rsusmf.appspot.com especially if they are thinking that they can achieve an even split marathon, whilst at the same time, running a marathon time that truly represents what they are capable of achieving.

I will sign off with a quote that perhaps helps illustrate the logic some people apply in justifying that the even paced split is obviously the correct pacing strategy.

"No offense to hundreds of thousands of runners, but quite frankly I don't care that 95% of them run positive splits. The real question should be could they have run a faster time if they would have run more even splits? And again, who cares if it was even a PR - could that PR have been a better PR?"
Brett, 2011 ( A comment left on a previous post)

All the best to all the runners running a marathon in the next two weeks, especially those at Brighton.  I will be cheering you on loudly on Sunday morning, hopefully in the usual Brighton marathon sunshine.

Stuart

Sunday, 18 December 2011

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