How long is a piece of string?
Actually don't go there.
I see this question come up time and time again on Facebook and ultra running forums. Mostly I see answers of two types.
An ultra marathon is anything over 26.195 miles
An ultra marathon is a bit more than that.
There is hardly a water-tight definition as to what an ultra is. It does seem like it is a piece of string type of question. For example is 26.197 miles an ultra? If you ran a marathon but at some point diverted from the blue line and went for a wee or to get a drink and ended up running an extra 20 metres would you say that you ran an ultra?
No? Why not? Is the reason because it is not officially measured as an ultra and therefore you can not say you ran an ultra? Does the category of your run depend entirely upon "official" measurement of the distance?
If I were to organise a race that was officially recorded as 26.3 miles would I be able to say that it was an ultra marathon?
No? Why not?
For me the definition of what exactly is an "ultra marathon" is as ridiculous as the whole idea of a marathon in the first place. Let's remember that a "marathon" is allegedly based on a distance run by a greek messenger 2500 years ago where he ran 24 miles and died at the end. He certainly didn't die at the end of the run and it is unlikely that this 24 mile run happened in the first place. It was only made to be 26.2 miles because of the laziness of the King of England in 1908. Let's face it, 26.2 miles has no relevence in terms of human capability or even historic significance. It is just a made up number. A 26.3 mile run is only the distance between 2 lamp posts in a street more than a 26.1 mile run, yet one run "counts" as an ultra marathon and the other "counts" for nothing. At least according to some clubs in the UK.
For me, I would categorise runs according to human (not contrived) limits. These categories would be something like the following.
Sprinting - How far can you run where the only thing limiting you is your maximal power. This is sprinting. Probably tops out at around 200m. This is Usain Bolt territory.
Lactate running - This is running at a really fast pace such that the limiting factor will be your ability to flush lactate out of your body and also to take enough oxygen. Here we are talking about 800m running.
I think there is a type of running which is 3k-10k running here which I don't have a name for but is Mo Farah type running. It might be called middle distance running.
Endurance running - The limiting factor here is running out of glucose and converting to fat burning. Typically we hit "the wall" at around 15-20 miles of running. I would say that endurance running is anything up to this human threshold of 15-20 miles.
Day Running - One you are burning fat, you are pretty much in the same mode of running for hours and hours. At this point it's basically running and eating from 15+ however many miles. At some point during this run you will pass the "marathon" distance which is as significant as a unicorn is in Darwin's theory of evolution.
However I think there comes another type of running. One that takes into account the human limit of the Circadian Cycle. Humans have evolved with/because of the 24 hour day and running outside of this is a different type of running. Say running for 18 hours or more where humans are normally expected to sleep, that is a different type of running, one where we are fighting sleep deprivation.
So, what is "ultra" running? It is whatever... let the bean counting accountants decide it. For me, running becomes a different thing after 15-20 miles, or 2-3 hours and then different again after 18 hours.
Do you want to join my club? Just answer one question. Do you give a shit?