“A guy walks into a bar…”  is a typical form of what has been called the “bar joke.” A marathon runner variation is:
     
“A marathon runner walks into a bar. The bartender asks, ‘Why the long race?’”
   
This is a variation of the popular version involving a horse: “A horse walks into a bar and the barman says, ‘Why the long face?’” “A marathon runner walks into a bar. Barman says ‘why the long race?’” was posted on Twitter by David J E Wood on September 9, 2011. “A marathoner goes into a bar. Bartender says, ‘Why the long race?’” was posted on Twitter by Mando Lines on June 24, 2013.
   
“Pheidippides runs into a bar,the barman says ‘why the long race?’” was posted on Twitter by Ally on December 4, 2013. “Pheidippides runs into a bar, exhausted. Barman says ‘Why the long race?’” was posted on Twitter by Gordon Penis on December 12, 2013. Pheidippides is said to have run from Marathon to Athens to deliver news of the victory of the battle of Marathon (in 490 BC).
   
       
Twitter
AKA J
@Jaloopa23
Replying to @BertSwattermain
@BertSwattermain a horse walks into a bar after running a marathon. The bartender says “why the long race?”
3:54 PM · Sep 4, 2011
   
Twitter
David J E Wood
@DavidinJail
A marathon runner walks into a bar
Barman says “why the long race?”
5:14 PM · Sep 9, 2011
   
Twitter
Andrew Adamson 🏴󠁧󠁢󠁳󠁣󠁴󠁿🇪🇺🇺🇦
@yabadabadrew
#walksintoabar A marathon runner walks into a bar.  Barman says “Why the long race?”.
1:59 PM · Nov 22, 2011
   
Twitter
Ade Clarke
@Literally_Ade
Replying to @drakestonehotel
@drakestonehotel Marathon runner, Paula Radcliffe runs into a bar… The barman says “Why the long race?”
6:29 AM · Nov 28, 2011
   
Twitter
Tuna Fische
@drakestonehotel
A Marathon walks into a bar….........Why the long race ?
6:29 AM · Nov 28, 2011
     
Twitter
Manda
@Mangowe
Replying to @MrBoffly
@MrBoffly @MissTerrapin A marathon runner jogs into a bar and the barman says, ‘‘Why the long race?’‘
12:06 PM · Mar 9, 2012
   
Twitter       
Ganofo
@gadrumkeynofo
Replying to @_Enanem_
@_Enanem_ Marathon runner walks into a bar. The barman says “Why the long race?”
8:51 AM · Apr 14, 2012
 
Twitter
Tim O’Neill
@dezignguy
A marathon runner goes into a bar.
The Barman asks “why the long race?”
6:57 PM · Dec 2, 2012
 
Twitter 
Mando Lines
@Mando_lines
A marathoner goes into a bar. Bartender says, “Why the long race?” Repeated just for @gretchenpeters.
12:16 PM · Jun 24, 2013
 
Twitter
Cody Braun
@ItsCodyBraun
A marathoner walks into a bar and the bartender is like “hey buddy, why the long race”
4:46 PM · Sep 4, 2013
       
Twitter
Ally
@MrAllyJam
Pheidippides runs into a bar,the barman says “why the long race?”
5:22 AM · Dec 4, 2013
 
Twitter
Gordon Penis
@God_in_Person
Pheidippides runs into a bar, exhausted.
Barman says “Why the long race?”
8:35 PM · Dec 12, 2013
 
Twitter
AlexMoorse 📚🏃🎶
@esroomxela
RT “@meandmybigmouth: Pheidippides walks into a bar. The barman says “Why the long race?”” ba-dum-tish! #vlm14 #sponsoradancer #extramile
5:41 PM · Jan 28, 2014
 
Twitter
Frankie Lee
@FranklyFraggle
Replying to @Pundamentalism
“@Pundamentalism: A marathon runner staggers into a bar. The barman says, “Why the long race?”.” 1 for @Marathonchamp
6:02 PM · Nov 25, 2014
 
Reddit—Jokes 
Posted by u/Theevildead May 30, 2015
A marathon runner walks into a bar..
The bartender says why the long race?
         
Twitter
Whimsical Wordsmith
@Whimsical84
A marathoner walks into a bar and gets asked “Why the long race?”
8:26 PM · Dec 13, 2017
 
Twitter
Conor Kane
@ConorKane0909
Marathon runner walks into a bar.
Barman says, “why the long race?”
2:59 PM · Nov 1, 2018
 
Twitter     
Jon Teckman🇺🇦
@Jontwothreefour
Pheidippides runs into a bar in Athens. The barman says “Why the long race?” #CheerUpItsFriday
1:02 PM · Jul 12, 2019
 
Twitter
Michael Williams
@RocketMooses
An ultramarathon runner stumbles into a bar, covered in mud, and heaving for breath.
The bartender looks the guy up and down and says, “Hey buddy, why the long race?”
11:08 PM · Aug 19, 2020
 
Twitter
Matt Prestenberg
@thetrees1975
Replying to @MichelobULTRA
A marathon runner walked into a bar.  The bartender said ‘why the long race?’  #TeamULTRA #Sweepstakes
4:38 PM · Nov 17, 2020
 
Reddit—Dadjokes
Posted by u/WhatProtomolecule March 15, 2021
A marathon runner walks into a bar and the barman says
Hey why the long race?
   
Twitter
Whimsical Wordsmith
@Whimsical84
A marathoner runs into a bar. The bartender asks “Why the long race?”
4:49 PM · Jul 5, 2021
 
Reddit—Dadjokes
Posted by u/english_rocks February 26, 2023
A marathon-runner walks into a bar, and the barman says…
...“why the long race?”