Are Iron-Distance Courses Really 140.6? Read This Before You Get That Tattoo.


I have been racing triathlons for about ten years.  However, I have only just learned, while writing my most recent post (about GPS and race distances), that, unlike the strict regulations for measurement of running races, triathlon distances can have a great deal of inaccuracy.  I have since scoured the internet looking for specific regulations about how race directors of triathlons are required to measure distances in their courses.  First of all, it is very difficult to find any information at all on this topic.  In other words, while USA Track and Field and the Association of International Marathons and Distance races have easily accessible and highly detailed information about how courses are measured, such information is hard to find for such organizations as the World Triathlon Corporation (the owners of the Ironman and Ironman 70.3 races) and USA Triathlon.  Where instructions about course measurement are available, the level of rigor does not appear to approach running-only races.  For example, the International Triathlon Union (ITU) has a manual for run course measurement inside of the Event Organizer Manual which is nominally based on the rules of the International Association of Athletics Federation.  A cursory review of ITU’s manual reveals less rigor in such critical areas as calibration and repeated measurement of the course.  Indeed, the International Association of Athletics Federation suggests adding 1/1000th of the race distance to every kilometer of the race, to prevent short measurements.  This convention has been institutionalized in certified marathons, such that marathons are always certified at a length 42.2 meters longer than 42,195 meters.  Such suggestions and conventions appear to be absent in most triathlon run courses.  In the manual for Triathlon Ontario:  “The course should be measured with a GPS or Jones Counter.  Measurements by car odometer or bike computers are not recommended.”  (see my discussion about the accuracy of GPS)  According to a quote from Xtri (the link to the source no longer works), the German Triathlon Union allows for a deviation in course length of plus or minus 10%.  Can you imagine the uproar if, after months of training, someone finally runs a sub-two hour marathon, only to later find that it was 10% short?  This amount of error is, apparently, permissible in triathlon.  Practically speaking, however, most deviation is probably well under 10%.

This amount of error in run course distances in triathlon begs the question: why do participants permit it?  First of all, most participants do notice some inaccuracies, but it does not appear to be common knowledge that up to 10% deviation may be permissible in the rules.  However, most importantly from the participant’s perspective, race performances and the rankings that result, like the elegant ranking system of USA Triathlon, are internally controlled by by the race results and not by the actual distances.  In other words, participant’s performances are measured with regard to each other and not with regard to the actual race distances.

So, why do correct distances matter if rankings are internally controlled?  There are a lot of reasons.  For example, if a participant attempts to crunch numbers, like I do, to measure race performances and the success of training plans to improve each of the three disciplines of triathlon, these numbers may be meaningless (along with performances in each discipline, I also usually record my ranking, within my age group, in each discipline – but this is dependent upon who shows up to race).  If a participant uses GPS data, this is vulnerable to the inaccuracy of this type of measurement.  Online programs, like MapMyRun, have their own inaccuracies. Another reason why accuracy matters is the ability to compare performances between different races or between the same race run different years.  There are a few Ironman and Ironman 70.3-brand races that are USATF certified: the World Championship course in Kona, Ironman Louisville, and Ironman 70.3 Poconos.  But this is only 3 out of 41 Ironman and Ironman 70.3-brand races in the United States.  Yet another big reason why correct measurements are important is the ubiquitous “70.3” and “140.6.”  Should the bumper magnets read “63.3-77.3” and “126.5-154.7”?  Imagine the Chicago Marathon selling a hat that reads “23.6-28.8”.

This discussion has not included the inaccuracies in measuring swim and bike courses, but these measurements are treated with much less rigor than run courses in triathlon.  As a personal example, last year I was lucky enough to participate last year in the USA Triathlon National Age Group Championships in Milwaukee, in the Olympic distance.  I am not a very fast athlete and I don’t know if I will ever qualify again.  So one of the benefits, I thought, of participating in this race is to know exactly how I was doing in each distance.  I got out of the water in under 27 minutes, which is fantastic for me.  I learned a week later that the swim course was believed to have been measured too long (not too short).  Furthermore, in a search of USA Track and Field’s certified courses, this USAT championship event has not had its run course certified.

This, I believe, reveals the core issue in the lack of accurate measurement of triathlon courses: confidence.  I really don’t care if the run or swim are a little long or short, just inform me.  I understand that adding another two miles to a bike course may land the course in another jurisdiction with additional fees and regulations, or adding a little loop to the run may detract from the aesthetic of the run, or the transitions have to be in certain types of locations that, then, limit the arrangement of the swim, bike, and run.  But if I think I am running a 10K Olympic run course, it must be 10K.  If I am one of the thousands (tens of thousands?) of people who have 140.6 apparel or tattoos, the course had better be 140.6 miles.  Indeed, the distances are part of the branding of the events.  Finally, as my wife, who is an 11-time marathoner and 3-time ultra-marathoner says: “it is just wrong for a marathon to not be a marathon, ask for a discount!”


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