How Realistic is a Marathon Negative Split?

An environment where you can be open & frank about your quest for speed

User avatar
jonovision_man
Bill Crothers
Posts: 2336
Joined: Tue Nov 25, 2008 5:42 pm
Location: Whitby, ON

How Realistic is a Marathon Negative Split?

Postby jonovision_man » Mon May 06, 2013 12:48 pm

I crunched some numbers from the Toronto Marathon (widen your browser to see whole thing) - very interesting IMO!

Code: Select all

Finish Time           Average Split     Avg split (% of total time)     Num runners     Num neg split     % neg split
<3:00                 0:05:02           2.92%                           28              4                 14.29%
3:00-3:20             0:06:46           3.53%                           101             5                 4.95%
3:20-3:40             0:09:39           4.25%                           239             9                 3.77%
3:40-4:00             0:11:53           5.14%                           334             13                3.89%
4:00-4:30             0:16:57           6.66%                           411             16                3.89%
4:30+                 0:24:24           9.94%                           508             5                 0.98%


So at the very pointy end of the field, there is the highest rate of negative splitting - but it's still only 14%. From 3:00 on, it's incredibly rare, 1 in 20 or 30 runners managed it.

Less than 1% of 4:30+ finishers negative split the race.

Now it of course must be noted that this marathon has a more challenging second half (downhill first 1/2, mostly flat second 1/2). But if you look at the percentages of the total time that the average person split, it's quite high - and goes up as the total time goes up.

So when planning a PB, maybe assuming a positive split isn't such a bad idea? Otherwise you're gambling that you're going to be in a very elite <5% of runners who manage the negative split...

jono
Visit my blog!

"If you want to be functional at 80, you better damn well pay attention at 40" -- Lew Hollander

User avatar
Jwolf
Kevin Sullivan
Posts: 37476
Joined: Fri Jul 29, 2005 10:02 pm
Location: Vancouver

Re: How Realistic is a Marathon Negative Split?

Postby Jwolf » Mon May 06, 2013 1:15 pm

Did you check to see for even splits, or within a minute of even?

To be fair that's what's usually suggested in order to get your best time. But I wonder, given the increasing temperatures on many marathon days, whether that's even reasonable? You'd have to stay pretty conservative in the first half and maybe that wouldn't get you your best time.

A friend of mine did just over 3 minutes positive split yesterday in Vancouver, and given the increasing temperatures I would guess it would have been hard for him do to much better. Even the elites who finished an hour earlier all had positive splits by 3-4 minutes or more on quick glance of the results. The race also has a net downhill in the first half.

Can you analyze that race too? ;)

(ETA: the friend I mentioned there finished in 3:24. I can imagine how much worse it would have been for those in the 4-5 hour range.)
Last edited by Jwolf on Mon May 06, 2013 1:48 pm, edited 1 time in total.
Support me in my fundraising for the Boston Marathon, Boston Public Library team:
https://www.crowdrise.com/o/en/campaign ... iferwolf11

User avatar
jonovision_man
Bill Crothers
Posts: 2336
Joined: Tue Nov 25, 2008 5:42 pm
Location: Whitby, ON

Re: How Realistic is a Marathon Negative Split?

Postby jonovision_man » Mon May 06, 2013 1:38 pm

Good point about the temperatures... Toronto went from single digits at the start to 18-20C by the finish, especially bad for the slower finishers (who would have spent more time in the heat).

Even splits - these were the people within a 1% positive split (not including any negative splitters):

<3:00 - 3 (10.71%)
3:00-3:20 - 12 (11.88%)
3:20-3:40 - 23 (9.62%)
3:40-4:00 - 17 (5.09%)
4:00-4:30 - 20 (4.87%)
4:30+ - 6 (1.18%)

Makes an even split look pretty realistic throughout more of the field, it seems.

What I noticed was that as I cracked near the end, others cracked with me. I wasn't getting passed as much as you'd expect someone ~30+s off their target pace to be getting passed, and I was still passing others! They always say the marathon is a 32km warm-up followed by the worst 10km race of your life, seems true for almost everyone, especially once the pace slows to my level. :)

jono
Visit my blog!

"If you want to be functional at 80, you better damn well pay attention at 40" -- Lew Hollander

User avatar
jamix
Bill Crothers
Posts: 1811
Joined: Fri Nov 05, 2010 9:18 pm

Re: How Realistic is a Marathon Negative Split?

Postby jamix » Mon May 06, 2013 10:26 pm

The harder second half wouldn't explain the large decrease of percentage of slower runners negative splitting....The temperature would have an effort for sure though as it gets hotter later in the day.

Nonetheless, I suspect even if the temperature remained constant, you'd still see the same trend. Slower runners have to spend more time on their feat and have likely trained less effectively than their faster counterparts. How can one negative split if by the first 1/2 you've possibly already been running for more than 2hours? Already these runners would be approaching the point of their longest LSD run which was probably run at a relaxed pace. How could they go even faster for another two hours, when you've already done 120 minutes at a pace that likely exceded anything you did in training?
2013 GOALS:

- Compete in the "Early Bird Sprint Triathlon" in May
- Run a 5km pb during the "Bushtukah Canada Day Road Race"
- Complete an Olympic distance triathlon
- Cycle > 33 km / hr during the cycle portion of a Sprint Triathlon.
- Stay healthy and happy

Races

April 28th: Manotick 10km (40:16)
May 18th: Ottawa Early Bird Sprint Triathlon (DNF)
June 8th: Riverkeeper SuperSprint (2nd overall)
July 1st: Bushtukah Canada Day 5km (18:37)

User avatar
Jwolf
Kevin Sullivan
Posts: 37476
Joined: Fri Jul 29, 2005 10:02 pm
Location: Vancouver

How Realistic is a Marathon Negative Split?

Postby Jwolf » Mon May 06, 2013 11:03 pm

jamix wrote:The harder second half wouldn't explain the large decrease of percentage of slower runners negative splitting....The temperature would have an effort for sure though as it gets hotter later in the day.

Nonetheless, I suspect even if the temperature remained constant, you'd still see the same trend. Slower runners have to spend more time on their feat and have likely trained less effectively than their faster counterparts. How can one negative split if by the first 1/2 you've possibly already been running for more than 2hours? Already these runners would be approaching the point of their longest LSD run which was probably run at a relaxed pace. How could they go even faster for another two hours, when you've already done 120 minutes at a pace that likely exceded anything you did in training?

Why do you get the idea that slower runners don't run more than 2 hours in training?

Many slower runners essentially run their marathon pace for their long runs. They do up to 30-35k at that pace, and plan to go longer at the same pace in the race.
Support me in my fundraising for the Boston Marathon, Boston Public Library team:
https://www.crowdrise.com/o/en/campaign ... iferwolf11

User avatar
MichaelMc
Bill Crothers
Posts: 1466
Joined: Wed Apr 16, 2008 5:07 pm
Location: Calgary

Re: How Realistic is a Marathon Negative Split?

Postby MichaelMc » Wed May 08, 2013 1:55 pm

Just because it isn't commonly done doesn't mean it isn't optimal. Few people are at their ideal weight, but being at ideal weight certainly helps your marathon time. To me barring a very odd course profile the halfs of the race should be very close. Perfect might be a 10 second negetive split, but for all intents within a minute either way hasn't cost you much.

The simple fact of the matter is it is hard to accurately predict how much you will have left after 36km of race pace running. Endurance is the ability to maintain effort levels: if you look at the percentage of 5K race pace you can hold for a marathon you will see a huge gap between Elites and average runners. An Elite marathoner is running pretty hard right from the start, so guaging how much to save is eaiser, furthermore experienced marathoners have a much better idea what their finish time might be. Runners who aren't highly motivated will end up positive split because it is painful to push for every second. The vast majority of runners tend to run more on the "hopeful" finish time than the "most likely".

There are lots of reasons why people DON'T run negetive splits, but what I dislike is using percentages of finish as a guage of what people should aim for. When runners start slowing down it is because their strength begins to fail, in my experience this results in form falling apart and efficiency dropping off dramatically. What I see frequently is a precipitous drop in pace (and increase in time) by running slightly too fast: we even saw it in the London Marathon with the best marathoners in the world. Logic, physiology, and studies all indicate the path to best time is a (nearly even) negetive split. HOW to do it is the trick.

User avatar
Jwolf
Kevin Sullivan
Posts: 37476
Joined: Fri Jul 29, 2005 10:02 pm
Location: Vancouver

Re: How Realistic is a Marathon Negative Split?

Postby Jwolf » Wed May 08, 2013 2:10 pm

MichaelMc wrote:There are lots of reasons why people DON'T run negative splits, but what I dislike is using percentages of finish as a gauge of what people should aim for.


This is a good point-- it's not relevant that only 5% or whatever can do it, because marathon pacing isn't a just a matter of chance.

What I wonder though-

do you think even splits becomes less doable (in a real sense, not in an observed sense) for longer marathoners? Or is the effect just more pronounced?

I remember reading somewhere that our brains can have a good sense of projecting optimal pace up to about 2.5 hours, but not beyond that. I know we can pick a pace to start that we might be able to hold, but there are so many variable that it ends up becoming more unlikely that we'll stay on pace.
Support me in my fundraising for the Boston Marathon, Boston Public Library team:
https://www.crowdrise.com/o/en/campaign ... iferwolf11

User avatar
jamix
Bill Crothers
Posts: 1811
Joined: Fri Nov 05, 2010 9:18 pm

Re: How Realistic is a Marathon Negative Split?

Postby jamix » Wed May 08, 2013 4:21 pm

MichaelMc wrote:Just because it isn't commonly done doesn't mean it isn't optimal.


I think your missing the point.

The question isn't "Why are the percentage of negative splits low in marathons?"

But rather;

"Why are the percentage of negative splits even lower among marathoners with slower finishing times?"

To me Jonovision-man's analysis suggests that running even or positive splits becomes an even more optimal race strategy the slower the marathoner is.
2013 GOALS:

- Compete in the "Early Bird Sprint Triathlon" in May
- Run a 5km pb during the "Bushtukah Canada Day Road Race"
- Complete an Olympic distance triathlon
- Cycle > 33 km / hr during the cycle portion of a Sprint Triathlon.
- Stay healthy and happy

Races

April 28th: Manotick 10km (40:16)
May 18th: Ottawa Early Bird Sprint Triathlon (DNF)
June 8th: Riverkeeper SuperSprint (2nd overall)
July 1st: Bushtukah Canada Day 5km (18:37)

User avatar
jonovision_man
Bill Crothers
Posts: 2336
Joined: Tue Nov 25, 2008 5:42 pm
Location: Whitby, ON

Re: How Realistic is a Marathon Negative Split?

Postby jonovision_man » Wed May 08, 2013 5:45 pm

MichaelMc wrote:Just because it isn't commonly done doesn't mean it isn't optimal.


Your implication is that 19/20 just got it wrong... I find that tough to swallow. Most marathoners I know are pretty diligent people and almost all buy the negative or even split thing- yet alarmingly few achieve it.

Surely we can glean something from that, other than just assuming they all blew it.

BTW I'm one of them! I paced for a reasonably even split yet fell apart. I suspect as you get into longer goal times and heavier people, the effect becomes more pronounced.

jono
Visit my blog!

"If you want to be functional at 80, you better damn well pay attention at 40" -- Lew Hollander

User avatar
MichaelMc
Bill Crothers
Posts: 1466
Joined: Wed Apr 16, 2008 5:07 pm
Location: Calgary

Re: How Realistic is a Marathon Negative Split?

Postby MichaelMc » Wed May 08, 2013 8:34 pm

jonovision_man wrote:
MichaelMc wrote:Just because it isn't commonly done doesn't mean it isn't optimal.


Your implication is that 19/20 just got it wrong... I find that tough to swallow. Most marathoners I know are pretty diligent people and almost all buy the negative or even split thing- yet alarmingly few achieve it.

Surely we can glean something from that, other than just assuming they all blew it.

BTW I'm one of them! I paced for a reasonably even split yet fell apart. I suspect as you get into longer goal times and heavier people, the effect becomes more pronounced.

jono


The only thing we can know is that they didn't run a negative split, not that it was a GOOD thing they didn't. You say you paced for an even split, and that you didn't run one. Sorry to say this, but by definition 1) you didn't actually pace for an even split and 2) if that was your intent, you "blew it". Some people plan a positive split, many plan an even or negative split (as you say) and obviously from your stat fail to achieve it. Not sure what is so hard to believe.

Yes the longer you run, the harder it is likely to be to accurately predict the correct pace to start at. It isn't actually all THAT hard to run one: start out MUCH too slow and it is a sure thing. I'd have to double check, but I'll guess 75% or more of my marathons have been even or negative. First one was huge positive, then ran 4-5 negative/even split marathons before over-reaching. Last one was an intentional positive split (about a minute). Good experiment if you run a number of marathons is start the next one at the AVERAGE pace of your last one: see if you end up faster or slower. To be really accurate you'd need same fitness, course and conditions but it might be interesting.

User avatar
jonovision_man
Bill Crothers
Posts: 2336
Joined: Tue Nov 25, 2008 5:42 pm
Location: Whitby, ON

Re: How Realistic is a Marathon Negative Split?

Postby jonovision_man » Wed May 08, 2013 9:25 pm

I'm not convinced it's so black and white. Seems to me the longer it take you, the more fatigue will accumulate and the less possible finishing at your average pace becomes... I'd like to see some science/studies involving us 3.5+ hour folks.

jono
Visit my blog!

"If you want to be functional at 80, you better damn well pay attention at 40" -- Lew Hollander

User avatar
Jwolf
Kevin Sullivan
Posts: 37476
Joined: Fri Jul 29, 2005 10:02 pm
Location: Vancouver

How Realistic is a Marathon Negative Split?

Postby Jwolf » Wed May 08, 2013 10:36 pm

jonovision_man wrote:I'm not convinced it's so black and white. Seems to me the longer it take you, the more fatigue will accumulate and the less possible finishing at your average pace becomes...

I don't think anyone will argue against this.

But if you slow down in the second half, that just means your desired average pace was too fast to maintain. If you started slow enough you would would be able to hold the pace the whole time.

The only question then is would that slower starting pace with even splits give you an overall faster time than the faster start but positive split. Michael is saying that the even pacing will give you a better time overall because you lose more than you gain by starting faster than average. And most experts agree. The fact that most people DON'T do it this way just means that most people start too fast to maintain a consistent pace. It doesn't mean that that was the better way.
Support me in my fundraising for the Boston Marathon, Boston Public Library team:
https://www.crowdrise.com/o/en/campaign ... iferwolf11

User avatar
jonovision_man
Bill Crothers
Posts: 2336
Joined: Tue Nov 25, 2008 5:42 pm
Location: Whitby, ON

Re: How Realistic is a Marathon Negative Split?

Postby jonovision_man » Thu May 09, 2013 5:54 am

Jwolf wrote:.

But if you slow down in the second half, that just means your desired average pace was too fast to maintain. If you started slow enough you would would be able to hold the pace the whole time.

The only question then is would that slower starting pace with even splits give you an overall faster time than the faster start but positive split. Michael is saying that the even pacing will give you a better time overall because you lose more than you gain by starting faster than average. And most experts agree. The fact that most people DON'T do it this way just means that most people start too fast to maintain a consistent pace. It doesn't mean that that was the better way.


Like I said, I'm not entirely convinced that 95% of marathon runners don't know what they're doing... it's possible, but it's also possible that slowing near the end and positive splitting is nearly inevitable, and the amount you may need to slow down early to avoid it would produce a slower overall race time.

As for the" experts" - they don't tend to study the 3:00+ crowd... what works for a 2:15 or 2:30 marathon may not be what works for someone who is running for an hour or more after those people are finished!

jono
Visit my blog!

"If you want to be functional at 80, you better damn well pay attention at 40" -- Lew Hollander

User avatar
Double Bellybuster
Bill Crothers
Posts: 2867
Joined: Fri Aug 28, 2009 10:34 am
Location: Udora, Ontario
Contact:

Re: How Realistic is a Marathon Negative Split?

Postby Double Bellybuster » Thu May 09, 2013 8:04 am

Toronto on Sunday is a bad example, Jon. Downhill first half, shadeless back third and a day with increasing temperatures. And we all knew that - I intentionally went hard the first half when I normally try to run even splits.

Pete Pfitzinger has some good writing on this in Advanced Marathoning, which I can loan you if interested. My recollection is that the gist of what it states is that on a flat course with fairly even temperatures that while 1:15:00/1:15:00 splits for a 2:30:00 marathoner is optimal, it would be something like 1:44:40/1:45:20 for a 3:30:00 marathoner. For the non-elite, it takes a marginally greater percentage of Lactate Threshold late to maintain an even pace due to reduced stride length, body cooling, etc. and theorizes that % of LT is what you want to keep even. But is is not a huge difference - it is something like 1-2 seconds per K.

If you hit a cold and rainy spring marathon that keeps temperatures from increasing, you will find even pacing is attainable or approaching attainable if you gauge your goal pace appropriately. In our area, Sudbury in May and perhaps Massey in July are marathons that have decent chances of cool weather throughout.
I am fortunate to have Running Free as a sponsor. I like to keep silly stats and maps of my Daily Neighbourhood Tours, Races and Marathons run in a Silly Yellow Shirt.

User avatar
jonovision_man
Bill Crothers
Posts: 2336
Joined: Tue Nov 25, 2008 5:42 pm
Location: Whitby, ON

Re: How Realistic is a Marathon Negative Split?

Postby jonovision_man » Thu May 09, 2013 9:03 am

Double Bellybuster wrote:Toronto on Sunday is a bad example, Jon. Downhill first half, shadeless back third and a day with increasing temperatures. And we all knew that - I intentionally went hard the first half when I normally try to run even splits.


Above I also posted those within 1% of a negative split - which should account for that (1% is a lot!). Still very low numbers.

BTW, someone else did similar analysis (but didn't go as far as breaking it down by finish time):
http://www.stridenation.com/2012/12/30/ ... ive-splits

I'm betting it's typical that something in that 90% positive splits will be seen in most marathons.

Double Bellybuster wrote:Pete Pfitzinger has some good writing on this in Advanced Marathoning, which I can loan you if interested. My recollection is that the gist of what it states is that on a flat course with fairly even temperatures that while 1:15:00/1:15:00 splits for a 2:30:00 marathoner is optimal, it would be something like 1:44:40/1:45:20 for a 3:30:00 marathoner. For the non-elite, it takes a marginally greater percentage of Lactate Threshold late to maintain an even pace due to reduced stride length, body cooling, etc. and theorizes that % of LT is what you want to keep even. But is is not a huge difference - it is something like 1-2 seconds per K.


Interesting. I know for myself, I found that my heart rate on the flatter (non-downhill) sections early in the race was in the 150's (vs my max of ~195bpm), where later in the race that same pace had me well into the 170's... I don't think it's just running out of energy, maybe Mr. Pfitzinger knows why. :) Certainly the heat would have contributed.

jono
Visit my blog!

"If you want to be functional at 80, you better damn well pay attention at 40" -- Lew Hollander

User avatar
MichaelMc
Bill Crothers
Posts: 1466
Joined: Wed Apr 16, 2008 5:07 pm
Location: Calgary

Re: How Realistic is a Marathon Negative Split?

Postby MichaelMc » Thu May 09, 2013 11:16 am

Guess we'll have to agree to disagree. Everybody I have coached has managed to run even splits. This includes 250lb runners running 4+ hours and people running in the 2:40's, and all of them went faster that way. My opinion is it is both possible and optimal, just not common.

I have read Pfitzinger's opinion and even exchanged e-mails on the subject; he didn't have a lot of information to back up his position, but I didn't convince him either.

User avatar
jonovision_man
Bill Crothers
Posts: 2336
Joined: Tue Nov 25, 2008 5:42 pm
Location: Whitby, ON

Re: How Realistic is a Marathon Negative Split?

Postby jonovision_man » Thu May 09, 2013 12:52 pm

MichaelMc wrote:Guess we'll have to agree to disagree.


I don't agree to that! :) You may well be right, I just don't have enough evidence either way to convince myself that negative is always best.

jono
Visit my blog!

"If you want to be functional at 80, you better damn well pay attention at 40" -- Lew Hollander

alexk
Bill Crothers
Posts: 1202
Joined: Sun Jan 31, 2010 8:33 pm

Re: How Realistic is a Marathon Negative Split?

Postby alexk » Thu May 09, 2013 2:16 pm

MichaelMc wrote:Guess we'll have to agree to disagree. Everybody I have coached has managed to run even splits. This includes 250lb runners running 4+ hours and people running in the 2:40's, and all of them went faster that way. My opinion is it is both possible and optimal, just not common.

I have read Pfitzinger's opinion and even exchanged e-mails on the subject; he didn't have a lot of information to back up his position, but I didn't convince him either.


I've been giving this thread a lot of thought and something in Michael's last comment brought it all together for me: the word coached. People who are coached likely have a race plan and a realistic time goal. If race conditions aren't optimal, they likely adjust the plan. Those of us who aren't coached (me included) probably have a tougher time making smart, objective adjustments.

ETA: I also ran in Toronto on Sunday. I had a plan but got caught up in the excitement and all the talk about banking time. I went out way too fast (for even a cooler day) and I knew I'd pay for for it. Luckily, I managed to hang on enough to get a small PB. Still, I would have enjoyed the 2nd half a lot more had I stuck to my plan! I don't regret my 6 minute (yikes!) positive split though. It reminded me to respect the marathon distance. Next time I'll stick to the plan & aim for better pacing :).

I've yet to run a negative split marathon (but have in the HM/10K) but have a run a few close to even split races. I felt much better in those final 10k than I did on Sunday!
We train more joyfully and productively when we focus on the now, rather than on our future race day performance. It's a long road from here to there with many miles to go. We need to run each one. Accept where you are today and simply be thankful for the work you've accomplished. KA

User avatar
Double Bellybuster
Bill Crothers
Posts: 2867
Joined: Fri Aug 28, 2009 10:34 am
Location: Udora, Ontario
Contact:

Re: How Realistic is a Marathon Negative Split?

Postby Double Bellybuster » Thu May 09, 2013 2:56 pm

alexk wrote:Those of us who aren't coached (me included) probably have a tougher time making smart, objective adjustments.


In the Internet age, there are tools without a formal Coach. The McMillan calculator for example is right on. I can race a 5K and it will tell me exactly what I can do in a 10K. Same 10K to Half Marathon. But a Marathon is hard to train for. McMillan assumes comparable training for each distance. While us worker bees can get in 30K/week w/intervals for a 5K of comparable quality to 60K/week w/tempo for a Half, running 110K per week including quality speedwork for a Marathon would get most of us divorced, fired and/or injured.

Where McMillan will normally suggest I can run a Marathon in approx. Double my Half time plus ten minutes, when I realize my training limitations and pace myself at Double my Half plus fifteen minutes, I am as optimal as me and my spare tire can get at that time.
I am fortunate to have Running Free as a sponsor. I like to keep silly stats and maps of my Daily Neighbourhood Tours, Races and Marathons run in a Silly Yellow Shirt.

ABXF
Tom Longboat
Posts: 410
Joined: Sun Jun 01, 2008 3:54 pm
Location: Ottawa
Contact:

Re: How Realistic is a Marathon Negative Split?

Postby ABXF » Thu May 09, 2013 3:38 pm

My first mary, a 3:58 at age 40, was a negative. 8) 2012's 3:12:39 had a 4:53 half/half difference or paces 4:29/4:45 for first 30K and last 12.2K. :shock: :wink: Judging by 1:31:xx at Army that Fall, prolly had about 1:31:00 half on course/conditions similar to the mary, which McMillan computerates to a 3:11:31. I do like to go more even 8) on the shorter stuff and prolly as I got closer to the sub-3 territory that would be happening alot more in the mary aswell.

User avatar
turd ferguson
Ben Johnson
Posts: 28512
Joined: Tue Nov 29, 2005 12:11 am
Location: It's a funny name
Contact:

Re: How Realistic is a Marathon Negative Split?

Postby turd ferguson » Thu May 09, 2013 3:39 pm

At the end of the day, does it matter?

I'll give an example - my first marathon I was well-trained and rested, I ran a slight negative split in just under 4 hours. Let's say 2:01 - 1:59.

A later marathon, I trained harder, did more speedwork and tempos, but ended up missing a couple long runs and not tapering at all because of insane work. I ran roughly a 1:45 first half and a 2:00 second half.

The second race didn't go as well as it could have because of disrupted training, but by the only thing that really matters (the big clock at the end) it was a better race than the first.
I can get that the negative split is a good indicator of good training on race day, but I don't get it as an end in and of itself.
"Human beings, who are almost unique in having the ability to learn from the experience of others, are also remarkable for their apparent disinclination to do so." - Douglas Adams

User avatar
erinmcd
Bill Crothers
Posts: 2573
Joined: Mon Jan 04, 2010 12:20 pm
Location: Brighton ON

Re: How Realistic is a Marathon Negative Split?

Postby erinmcd » Thu May 09, 2013 3:48 pm

I've got nothing more than personal anecdote to add to this discussion, but this being the internet, why not?

My last marathon was a 2 min neg split, where my previous 4 were all pretty big positive splits- at best 6 mins, at worst 14 mins.

I attribute my negative split to 2 things (mainly). First, I did marathon pace runs every week in the training cycle, so my body was used to running at exactly that pace when I had tired legs. I'm sure that made a big difference for me this time around.

The other thing is that I ran a pretty controlled pace for the first 27K. I paid close attention to my pace, and the few times I noticed it creeping up I backed off, and went through 1/2 at about 2 seconds/km slower than my target pace, and held on to that pace until about 27-28K, then picked it up. I had previously bought into the idea of banking time, but I truly believe that is way too risky for me.

One other thing (which may be attributed to a weak mind) is the mental aspect- all of my previous marathons got really mentally tough toward the end- where any thought of a time goal would go out the window and I'd just want it to end. This time around, I pulled out my ipod at about 28K. I know the purists don't like stuff like that, but hearing Rush and The Hip helped keep me in my happy place, and I never had the mental struggle.

So, there's my $.02.
Keep on rolling, just a mile to go. Keep on rolling my old buddy, you're moving much too slow.

User avatar
ian
Jerome Drayton
Posts: 5973
Joined: Sat Jul 26, 2008 4:44 pm

Re: How Realistic is a Marathon Negative Split?

Postby ian » Thu May 09, 2013 8:20 pm

I've had a bunch of experience with negative splits, even splits, and positive splits. Negatives are fun, evens are probably the most effective and the most comfortable, and positives tend to be the default unless you have a pretty solid mileage base and an iron disposition.

I've also paced a number of marathoners over the years, ranging from sub-3 paces, to BQ paces, to make-sure-my-brother-doesn't-die-in-his-first-marathon pace. My usual strategy (fine-tuned according to the experience, training, and temperament of the runner) is to start with a time goal which is slightly more conservative than might be predicted by a 10K or 21K race time, as most runners simply do not have enough mileage to validate such a prediction. Next, I pace out the first half a couple of minutes ahead of schedule, but still slightly slower than the best-case MP predicted by a calculator. This gives the runner an outside chance to have a great day, but more often than not, we'll fade a few minutes in the last 10K and hit the goal. Physically, it's close enough to the optimal strategy not to split hairs over, and psychologically, I find that inexperienced marathoners do better with the late race fatigue when they know that there is a tiny bit of cushion.

User avatar
Jwolf
Kevin Sullivan
Posts: 37476
Joined: Fri Jul 29, 2005 10:02 pm
Location: Vancouver

How Realistic is a Marathon Negative Split?

Postby Jwolf » Thu May 09, 2013 10:23 pm

ian wrote:I've had a bunch of experience with negative splits, even splits, and positive splits. Negatives are fun, evens are probably the most effective and the most comfortable, and positives tend to be the default unless you have a pretty solid mileage base and an iron disposition.

I've also paced a number of marathoners over the years, ranging from sub-3 paces, to BQ paces, to make-sure-my-brother-doesn't-die-in-his-first-marathon pace. My usual strategy (fine-tuned according to the experience, training, and temperament of the runner) is to start with a time goal which is slightly more conservative than might be predicted by a 10K or 21K race time, as most runners simply do not have enough mileage to validate such a prediction. Next, I pace out the first half a couple of minutes ahead of schedule, but still slightly slower than the best-case MP predicted by a calculator. This gives the runner an outside chance to have a great day, but more often than not, we'll fade a few minutes in the last 10K and hit the goal. Physically, it's close enough to the optimal strategy not to split hairs over, and psychologically, I find that inexperienced marathoners do better with the late race fatigue when they know that there is a tiny bit of cushion.

This is perhaps the best overall description that I have read. Kind of a compromise between optimal and reality for most runners.
Support me in my fundraising for the Boston Marathon, Boston Public Library team:
https://www.crowdrise.com/o/en/campaign ... iferwolf11

User avatar
mas_runner
Bill Crothers
Posts: 2339
Joined: Tue Jun 02, 2009 5:37 pm
Location: Hull, QC

Re: How Realistic is a Marathon Negative Split?

Postby mas_runner » Wed May 29, 2013 8:06 pm

This is a very interesting discussion and pertinent to me. 9 minute positive split on Sunday (1:47/1:56). I have only run 2 marathons so don't have very much experience at all and earmarked 3:45 to be my goal (calculators for my HM put me at 3:35). I decided to test just how good my endurance was by going out at 3:35 pace and see how long I could hold it. The answer was roughly 30 kilometers.

I don't really have enough experience to say whether if I had gone out more conservatively that I would have fared better or whether I would have struggled at the same point. It did feel like what was slowing me down was less muscular and more in the joints (knees/ankles), I didn't get the burning quads until much later in the race and my groin/hip muscles didn't hurt at all this time (they were very sore in my first marathon).

I guess I just need more data to see whether it was a good strategy or not, as to whether I would have got sore and slowed down as a function of distance rather than speed.
PBs
5th Sep 2015 - Run Ottawa free 5km - 21:05
21st Jun 2015 - UR 4 Men's Cancers 10km - 45:45
16th Jun 2013 - UR 4 Men's Cancers 15km - 1:11:44
16th Apr 2016 - MEC 10 miler - 1:20:21
12th Apr 2015 - EY R4R Half Marathon - 1:41:15
26th May 2013 - Ottawa Marathon - 3:43:51

2017 races - coming up
7th May - Defi Entreprise 10km
28th May - Ottawa Half Marathon
17th Sep - Army Run Half Marathon


Return to “The Speed Zone”

Who is online

Users browsing this forum: No registered users and 1 guest