# Why is the Edinburgh Half Marathon world record eligible?

In order for times set in a road race to be eligible for a world record, the course needs to satisfy some rules, two of which are:

• The start and finish points of a course, measured along a theoretical straight line between them, shall not be further apart than 50% of the race distance.
• The overall decrease in elevation between the start and finish shall not exceed 1:1000, i.e. 1 m per km (0.1%).

See rules 31.21.2 and 31.21.3 here. The purpose of these rules are to avoid athletes getting a world record time by being aided by an overall downhill course or having a constant tailwind in a point-to-point course.

In this document there is a list of marathons and half marathons around their world, alongside with an indication as to whether or not they satisfy the downhill/separation rule. I noticed that the Edinburgh Half Marathon is included as compliant with the rule (and therefore a theoretical world record set on this race would be valid). However, if we look at the race information page, specifically the elevation profile, we see that it drops from about 90 m to 10 m, i.e. about an 80 m drop, which is far higher than the 21 m maximum permitted for a half marathon (1/1000 of 21 km).

Plotting the start and finish points on Google Maps, we come to a similar conclusion about the elevation drop.

So my question is: Despite all this, why is the Edinburgh Half Marathon still considered Rule 31.21 compliant?

I also want to note that World Athletics' list has been updated this year and the couse has been unchanged for several years, and is set to remain unchanged for the 2021 edition of the race (this year's edition was cancelled due to COVID-19).

Another surprising fact is that the Edinburgh Marathon – which takes place on the same day and has the same start and finish points – is not even included on World Athletics' list, neither as compliant or non-compliant with the rule. The elevation drop of ~80 m is still too much for a marathon, put proportionally less than the half marathon since the course length it is double the distance.

As a side note, when looking at the route map on the race information page, it may also give the illusion that the half marathon violates the 50% separation rule since the course heads mostly eastwards. However, by using the measure distance tool in Google Maps, we find that the straight line distance is about 9 km – so it is safe by about 1.5 km.

Up until now, the times set in the Edinburgh Marathon and Half Marathon do not come close to the world records and it seems very unlikely that a world record will be attempted in Edinburgh in the near future. However, the course being world record eligible can influence non-professional runners who are considering running it as a PB attempt, since it means that whatever time they achieve is "valid" as a PB (compared to, say, a race going from the top of a 2000 m mountain pass to sea level, which would be considered "cheating" since the massive elevation drop will probably make everyone several minutes faster).

• Good question - I don't know why it's listed. It's odd that the full isn't listed at all - most races are listed under both distances, even if one doesn't qualify. I almost wonder if there's a second half marathon that's being confused with it, but it doesn't seem likely (and nearly all races on Edinburgh seem to be quite a bit downhill, which is not surprising given the terrain).
– Joe
Dec 7, 2020 at 4:06
• You're right, this is weird. You've documented this so thoroughly that I feel like the most-likely explanation at this point is that World Athletics included the race in the list (or noted it as rule 31.21 compliant) in error. Oct 6, 2021 at 14:38

This answer has been significantly improved based on insights from @olmomiau.

The Edinburgh Half Marathon never used a world record eligible course.

Points to consider:

1. No world records have been reported from this course yet, so the scrutiny wasn't enormous.

2. They advertise: "With a descent of almost 90 metres to near sea level, we believe this is the fastest half marathon route in the world."

• Well, if it is, then it has to beat, among others, very many advertised "downhill half marathons" that manage to drop anything from hundreds of meters to over two vertical kilometers.

• Very many events advertise using the identical claim of being a "fastest half marathon route in the [you guessed it] world". They may differ in their degree of fastestness and halfmarathonness.

3. The general profile of the Edinburgh Marathon in recent times is the initial mostly descending three or so miles through the city, followed by a much longer distance in East Lothian that's very flat at near sea level. The Half Marathon generally copies the first half of the Marathon, which makes it twice less likely to conform with Rule 31.21.3 than the Marathon. Read on for details.

4. It was not always like this. A hilly full marathon course from the eighties changed, as of 2007, into a course advertised as having a 40 metre initial drop (compliant with Rule 31.21.3 for the Marathon but not for the Half), and a similar course was then used till 2017 (or even 2018? - the link URL suggests 2018 but I don't trust that hint), after that switching to the present 90 metre drop course starting on Potterow, not counting the 2020 and 2021 editions which went virtual because of Covid and thus very thoroughly ineligible for any records beyond personal bests.

5. Even the 40 meter drop Marathon route used a double start with only one of the starting points (London street) compliant for the full Marathon, but the other starting point (Regent street) exceeding the maximum allowed drop even for the full Marathon. This might not stand in the way of Rule 31.21 for the full marathon as the faster waves were starting from the lower starting point.

6. The Edinburgh Marathon held the IAAF Bronze Label from 2013 to 2017 as the only road race in Scotland ever; the concurrently organized half marathon never enjoyed the distinction. From 2018 on, none of the Edinburgh races are listed. (World Record eligibility is a requirement for a Bronze Label, but not vice versa.)

7. There is at least one differently named half marathon run in a superficially similar mix of Edinburgh and East Lothian environments currently offering a more modest but still non-compliant overall elevation drop.

8. If you don't know whether Rule 31.21.4 was followed, then Rule 31.21.3 becomes rather pointless. In plain English, if you don't know whether the course was correctly marked in the streets, then it doesn't matter whether it looked compliant on the maps.

9. You are looking at a 2020 edition of certain document, i.e., an edition from a year in which no event EMF Edinburgh Half Marathon was actually run. We can conclude that Rule 31.21.4 wasn't followed that year, although whatever the original plan has been is anyone's guess - we can reasonably interpolate between 2019 and the same route planned for 2022, or we could speculate that a course change was being proposed for 2020 and never materialized. If you have earlier editions of the document, or if you talk to whoever provided it to you, you could likely find out how that entry came into being.

Suggested conclusion: Personal bests, for non-professionals, are eminently informal personal records. Hobby runners will achieve more if they spend more time running than studying World Athletics rules for road races. If somebody submits their half marathon time from Edinburgh as a qualification proof for another event, which happens all the time, it's not cheating unless they are misrepresenting the circumstances of their publicly tracked accomplishment somehow. It's up to the recipient of such a proof to evaluate whether they care about Rule 31.21.3, and how much. Likewise for any boasting rights and so on.

• It used have a double start in Regend Road and London Road (see here) and that was until 2017. London Road is at ~40 m but Regent Road is at least 70 m and the finish is only ~5 m; thus one of the starts was not even compliant back then (for the full marathon). They used this elevation graphic which shows a <40 m drop but of course completely disregards the Regent Road start. Aug 31, 2021 at 12:49
• @olmomiau - Thank you! This is getting really interesting. I'll rewrite my answer or upvote yours (if you care to post one) whichever you prefer. Aug 31, 2021 at 13:56