Probably it does. Seville also attracts a lot of faster runners - almost 500 inside 2:45 this year, but from an overall field much smaller than the big majors.
Whether a strong field helps must be an individual thing, but I would imagine that most like me prefer a group to run with, up to a point. You just just have to be disciplined and let them go if it's too quick for you.

That's a great question. I thought about Beppu-Oita in Japan, but they "only" managed 381 men under 2:45 (while having 1182 men under 3:00, which is also pretty impressive). California International Marathon in 2022 had 547 men and women under 2:45, which is very respectable.

One of the problems with running with a group of fast people (Boston comes to mind) is that drinks tables are a mess and if you let your foot off the gas for even a moment, 50 people go by you just like that.

Also, in smaller racers the field spreads out and you get a standard distribution after 20 minutes. As long as you have three or four people running your pace that's usually enough to keep pace and work together.

Good luck in Valencia!

The Olympics and any other race with elite-only fields have the highest density of fast runners.

To really answer your question you would need to know the proportion of "fast runners" relative to the number of finishers. You would probably also need data on all participants' recent race results as a proxy to correct for races with faster or shorter courses.

1. I'd guess both the World Athletics Championship and the Olympic Marathon would have the highest density. For the 2023 World Athletics Championship Marathon there were 60 finishers in the men's race and the last place finisher ran a 2:31. For the 2020 Tokyo Olympics marathon there were 75 finishers with the last running a 2:44.
2. This would be a guess but I reckon it makes a big difference.

Looks like you found the race with the "most" faster runners, but as far as compared to field sizes, I think you got some good answers from others.

I tried to look up some old Boston results from the late 70's/early 80's, but couldn't find them. But there were 5 to 6+ thousand runners back then, and the qualifying time for under 40 was 2;50, and only one age group qualifying time for masters that was 3;10. So I would surmise that a shit ton of guys broke 2;45 back then, probably in the 1000's I would think. Unless everyone just treated Boston as a parade, because you already had to run near that just to get in.....

Add to the AG an insane pro line up too. Valencia is becoming the record race very fast!

If you're talking about absolute numbers of sub 2:45 runners I would have expected London, Berlin and Sevilla to also score really well under your definition.

Obviously the main drivers for a fast marathon are a flat course without sharp turns and optimal weather conditions for fast running. The races mentioned in this thread satisfy these requirements and are therefore popular among people wanting to race fast.

To your second question. I would say that a good number of fast runners would help by giving a bit of drafting benefit. Also, very few marathons provide pacers aiming for less than 3h.
But Pacers aren't always reliable. I've found myself with a 2:50 pacer starting off at 2:40 pace and you don't want that.

If a marathon becomes so big and busy with fast runners that you don't have space to run and can't keep an ideal line then you're better off choosing another marathon. Sometimes people group around pacers so it's often better to place yourself just before or just after a pacer.

For instance, the London marathon has a lot of fast runners but isn't the ideal marathon to run your personal best unless you can get really good wave placement. With the multi start areas it can get a bit crazy especially when the different groups join together.

Thank you all for the answers.
Re-density, I agree on all the points you make and obviously the Olympics or equivalent would be the marathon race with the highest density of fast runners. In hindsight, I probably chose the wrong and I just meant "the highest number of fast runners".

As for the benefit of running in a group, apart from the mental aspect, I found limited evidence of the actual quantification of draftng benefit.
Extract from one of the studies I found: "The energy cost of overcoming air resistance on a calm day outdoor was calculated to be 7.8% for sprinting (10 m/s), 4% middle-distance (6 m/s), and 2% marathon (5 m/s) running." So at a 6mn/mile marathon pace, there could be 4% energy saving by drafting one person on a non-windy day I believe. As for running into a headwind, it’s probably way more important. Any other input?

Good point about the water tables being a mess when you run in massive groups ;)

Some of the studies below
https://pubmed.ncbi.nlm.nih.gov/7380693/
https://physoc.onlinelibrary.wiley.com/...hysiol.1971.sp009381
https://pubmed.ncbi.nlm.nih.gov/27294604/

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It doesn't get easier, you just get slower
https://mymsracesironman.home.blog/

I preface this by saying that until you posted this question, I had never heard of the Valencia Marathon. However, your question got me curious. So, I dug up the course map (below):

[inline "Screenshot 2023-11-10 at 6.35.23 AM.png"]

It seems to me that there are quite a few opportunities for someone to "improve" their race time with this course layout. It's well known that runners cut courses all the time (e.g. Mexico City most recently). There used to be a very popular site dedicated to rooting out marathon cheats.

EDIT: map not showing up so here's the link.

https://www.valenciaciudaddelrunning.com/...cial-route-marathon/

Do you have any evidence? Is this just sour grapes that there are thousands of runners much faster than you?

I would argue that with some exceptions, most of us 2:4X and faster marathoners are not the general crowds that do this stuff. The cheating that you imply usually requires a split that it is abnormally faster than the runners standard pace between timing mats. i.e. a 2:45 guy going 3:52-3:55 for 30 km then all of a sudden averages 3:25 from 30-35 km or missing a mat altogether. Unless the runner can consistently cut the course by the same amounts consistently around all timing checkpoints (I doubt it) Have you come across any timing irregularities among these runners on say last year's results?

I have seen the videos of the Mexico City and honestly they all look like pedestrian runners. I am also aware of all the cheating idiots that do this stupidity to get BQ. But again, unless you show us a bunch of timing paces abnormalities among the results of this particular marathon, you are just making stuff up.

Randomly clicking through results and here's one that stood out
https://www.valenciaciudaddelrunning.com/...22-marathon-ranking/
5K0:18:160:18:163,4010K0:36:340:18:183,4015K0:54:530:18:193,4020K1:13:040:18:123,38Half1:17:030:03:583,3725K1:31:170:18:123,3830K1:49:120:17:553,3535K2:06:560:17:443,3340K2:24:180:17:233,29META2:31:510:07:323,26Some insane negative splitting going on for the last 20k...just saying

Why did it stood out?

So this person went 1:17 half and made it to the finish line just under 2:32...so he did the second half on negative split just under 1:15 and you automatically think this person cheated ?. Not saying they did or didn't but this is not a blatantly suspicious performance. Some fast older and experienced marathoners that I personally know of race like this. Just saying.

In terms of absolute numbers, probably yes -- that is really impressive and I didn't know about Valencia! Based on what I see, there were 21563 finishers in 2022, so that's also a blistering 6.8% of the field going sub-2:45. Wow!

In terms of % of fast runners for marathons available to a "normal" runner (e.g., not Olympics or Olympic trials or Worlds), Califormia International Marathon (CIM) and Grandma's are two that are known as super fast in the US and are used by many as Olympic trial qualifiers or PR races. CIM last year had 550 runners sub-2:45 out of 7986 finishers, or about 6.9% of the field running sub-2:45. Just about at the Valencia % but smaller by a factor of ~3. Grandma's this year was 330 sub-2:45 out of 6690 finishers, or 4.9% below 2:45, so somewhat lower in terms of %.

Boston would be down around 3% of the field going sub-2:45, so considerably lower density of fast runners at the top end. Agree that historical (1980s?) Boston might have been faster (but was also very hard to get into, so debatably "available to a normal runner").

Japan has some qualify-only type marathons with faster than BQ required times. The numbers from the WMMs could be skewed by weather. Chicago is fast when it gets good weather. Boston's start time makes it tough to run fast unless you catch a cool day with a tailwind. I can't think of anywhere that would have ~1500 sub-2:45s. CIM is usually very competitive for its size. McKirdy Micro is a bit of a cheat code but it was set up for people to chase OTQ times.

Valencia is getting super popular because it's fast/flat, is a certified course (not downhill), and gets good weather. Perfect recipe for sub-elite types not looking to waste 1 of their 2 or 3 marathon efforts/year.

I ran the Valencia marathon last weekend.

1 951 runners went sub 2h45. This is absolutely amazing, especially compared to the numbers I referenced above (in 2022, 1 464 runners went sub 2h45 in Valencia, 776 runners in Berlin, 844 in Boston, 630 in Tokyo and 866 in Chicago)

I crossed the line in 2h41. I thought I was going to run in a small pace group. I did not. Instead, I ran in a continuous line of runners, wide as half the size of the road, from start to finish. Quite amazing, inspiring and humbling to witness so many strong athletes ! and most definitely the strongest amateur field in a big city marathon

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It doesn't get easier, you just get slower
https://mymsracesironman.home.blog/

"6mn/mile marathon pace" (gets a 2:37 btw, well lower than 2:45) the speed in m/s is <5m/s so any "energy saving by drafting one person" is not 4%, it's less than 2% (as the study you quoted says). And that will depend on the athlete staying real close. This would not be fun for 160 minutes and likely be more of a disadvantage than an advantage.
The benefit of a field with plenty of athletes in a pace window is the psychological benefit of being to run with others for long stretches, and pick up or slot in with other fellow travellers if the pace is a tad too slow or too quick. Try to lever that company for motivation by simple interaction. I benefited from that in my (the) first London bitd.

Indeed it is like this

That would be the Ineos Marathon in Vienna, where the average finish time in 2019 was under two hours.

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<The Dew Abides>

I used to live in Valencia and think it would be a very nice place to run. Did you enjoy the scenery and views of the city?

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https://www.strava.com/...tes/zachary_mckinney

I really enjoyed Valencia as a city: beautiful old city centre with many nice cafes and restaurants. Loved the main park going through the city like a green river, perfect option for a run. It was a great option for a getaway weekend.

However, I didn't really enjoy the marathon experience : very limited options for food or drinks at aid stations and at the finish line, i thought the course went through too many roundabouts and turns, and the most scenic part is at the end where I was too cooked to enjoy it unfortuantely (my bad!)

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It doesn't get easier, you just get slower
https://mymsracesironman.home.blog/

Consider relative/total wind speed too. If you are running into a headwind, and tuck behind someone, the savings are not negligible. At 16 kph (3:45/km, ~6 min per mile) running into a 10-20 kph (some wind) the savings of running behind someone are significant. Top marathoners going 21 kph will save even more from pacing/drafting.