I have been making a research in running books and running resources on the Internet on the basis of cut-off times of Marathon and Ultra Marathon Races. It seems that I could not see any “authority” or “regulation” in the IAAF or IAU Manuals and Protocols as to what is the accepted formula in the declaration of cut-off times in every race.
Without any basis, I have the impression that this “rule & regulation” in a running race, whether road or trail, on the prescribed cut-off time is arbitrary and based on the decision of the Race Organizer/Race Director.
On the part of a Race Organizer in a busy City Marathon Race, a six-hour cut-off time is a standard period for a 42K distance. This will minimize the time for the closure of main streets from vehicular traffic. The lesser time for the roads and streets are closed, the better for the riding public and commuters. It will also lessen the time of exposure and involvement of security, medical, marshals, and volunteers and other administrative and logistic supports for the race.
Obviously, this is true also to ultra marathon distance races but with longer and extended period of cut-off times.
Comrades Marathon (90K), the oldest ultra marathon, had an 11-hour cut-off time for so many years until it was extended to 12 hours since 2003. Aside from being the largest ultra road race, it is also the hardest in terms of elevation profile and with a very restrictive cut-off time.
The North Face Ultra Trail du Mont-Blanc (UTMB), 166K ultra trail race, has a cut-off time of 46 hours.
Western States 100-Mile Endurance Run, also a ultra trail race, has a cut-off time of 30 hours.
Jeju International Ultra Marathon 100K Race, a road ultra, has a cut-off time of 16 hours.
Miwok 100K Ultra Trail Run has a cut-off time of 16 1/2 hours. Most of the 100K ultra trail distance races in the USA has a cut-off time of 16 hours.
Singapore’s Sundowm Ultra Marathon 100K Race, a road ultra, has a cut-off time of 16 hours.
Bulldog 50K, an ultra trail race, has a cut off-time of 9 hours. Most of the 50K ultra trail races in the USA have a cut-off times of 9 hours.
Headlands 50-Mile Trail Run has a cut-off time of 14 hours and this is true to almost all the 50-milers except for the JFK 50-Mile Endurance Run which has a cut-off time of 18 hours ( based from tradition and history).
The Hardrock Ultra Marathon, the officially dubbed as the hardest ultra trail race in the USA, has a cut-off time of 48 hours.
The Barkley Marathons (100-mile trail race), the unofficial hardest ultra trail race in the USA, has a cut-off time of 60 hours, however, each loop which has a distance of 20 miles must be completed in 12 hours. It is a “lucky” year’s edition if there is a “survivor-finisher” for this race. Since its first edition in 1986, only nine (9) had finished the race up to this year.
Surprisingly for this year, the Badwater Ultramarathon has reduced the cut-off time from 60 hours to 48 hours! There was no reason in its website for the said dramatic change, however, its registration fee had increased from $ 850 to $ 995.
In my opinion, the cut-off times give an impression on the degree of difficulty of the race to the participants and at the same time provide a status of distinction for the said race.
For the runners, cut-off times serve as their lowest target time to finish. They should not be satisfied to finish the race way beyond the prescribed cut-off time. Finishing any Road or Trail Race must be defined strictly as Finishing the required Distance within the prescribed Cut-Off time. A runner is fooling himself or herself if he/she brags about finishing a race way beyond the cut-off time. For the Race Director, runners who finish the distance beyond the cut-off time are considered as DNF (Did Not Finish).
Simply stated, a runner must train and prepare to finish a race within the cut-off time.