A brief tangent

Well, the spring racing season is in full swing, eh?

Reading each weekend’s blog posts chock full of race recaps and PRs is one of the highlights of my week.  However, I keep seeing one little thing that consistently bugs me.

Typically it goes something like this:

“It was a great race, but I was so mad because the course was apparently too long!  My Garmin read 26.4 miles when I finished!  What the feck!”

Umm…long course?  That seems unlikely.

Race courses are generally measured as the shortest ground distance one could possibly travel from the start to the finish.  For many reasons, the path that most people take is slightly longer:

Attempting to run as efficiently as possible relative to the shape of the course is often referred to as running the tangents.  Note that depending on the nature of the course and its turns, this might require hugging a turn very tightly.  Or it might require running in a straight line, as would be the case if your course were shaped like a python:

I want to run a Python-themed race, in which we all completely gorge ourselves afterward.  Who’s with me?


So there are tangents.  But why does that mean that my course couldn’t possibly have been too long?

Well, because the organizers probably put a lot of time and effort in to making sure it was exactly the right distance  (along the tangents).  If it’s a USATF-certified course, it will have been measured (and re-measured) using a highly accurate calibration bicycle according to the organization’s very specific and strict procedures.

I’m not saying that every race course in the universe is 100% accurate.  I know I’ve run the occasional po-dunk 5K where the course was apparently designed by the town sheriff’s dog and the finish line was marked by a guy sitting on a cooler – and the distance was clearly not as advertised.

But for any semi-large or USATF-certified race?  The course length is almost certainly accurate.  In the case of major marathons and half marathons, it’s probably accurate.  (Another sanity check: is the course is Boston qualifier?  If so, it’s probably accurate.)

Ok, so say I ran circles around a bank of porta-potties in the middle of the race and logged some extra mileage.  Why doesn’t that count?

It just doesn’t.  Not when you’re running a race.  Sorry.  We all start in the same place and finish in the same place.  Being efficient about it is part of the competition.

But what about my Garmin?  Does it lie?  How can I ever trust it again?

GPS watches are great training tools, but they are not perfect.  Even if you somehow managed to run every centimeter of the course as efficiently as possible, your Garmin could still be “off.”  A few things to consider:

(1) Garmins hate tall buildings.  And tunnels, and underpasses, and clouds, and Ke$ha.  (Ok, maybe the last one is just me projecting.)  But really: all of those things can throw your Garmin off.  Such is life.

(2) Garmins hate turns.  I learned this one the hard way the first time I took my Garmin on a track workout.  I’d known that the unit wasn’t totally accurate and might overestimate my distance a bit, but I was shocked at the magnitude of the discrepancy (and at the time even questioned the accuracy of the track’s length).

But no, the track was fine, of course.  My Garmin just got its panties all in a bunch every time I’d go around a curve.  (Which, on a track, is approximately 50% of the time.)

Since people who are much smarter than me have already explained the geometry behind this this much better than I ever could, I’ll just send you to this link if you’re curious about it.  (Thanks, Kristin, for originally pointing that one out to me.)

(3) Garmins measure from high in the sky.  The course is measured on the ground.  And unless you’ve mastered the power of human flight (which would be, um, pretty rad), you are running on the ground.  The GPS’s readings are an simply an estimation of your path on the ground from a point (or, rather, multiple points) in the sky.  The ground measurement wins.

Okay, so how do I stop myself from running a gazillion extra miles when I race?

Here are a few things you can do to maximize your on-course efficiency:

(1) Run the tangents.  Or at least try to.  Duh.  Although this can be tricky sometimes and isn’t always straightforward.  For example, say the most direct path is to take a curve as close as possible – but often the inside of the turn is crowded, meaning you end up in a logjam if you try to take it tight.  So you can either run a little more distance and maintain your pace or mash through the traffic and slow down.  Depending on the circumstances, either one could be faster.  It’s a crap-shoot!  But hey, at least it gives you something to think about while you’re running!

(2) Run smaller races.  Smaller crowds = less of the dodge and weave game.  Plain and simple.

(3) Avoid races with lots of turns.  It’s far easier to stick to the tangents on a course made up mostly of long straightaways as opposed to frequent turns.  Although they’re still not perfect.  At the Shamrock Half, I managed to pick up 0.06 miles (according to my Garmin) even though it was basically an out-and-back course, and I was at the front of the pack where the crowds were thin.  In a 5K a few weeks ago, by comparison, I picked up almost 0.10 (obviously, over just three miles).  There were a lot of turns in the 5K.

(4) Minimize side trips.  Obviously you must balance your need for fluids with your desire for efficiency, but every time you dart across the road to hit a water stop (or say hi to your friends on the sideline, or poop, or barf, or do yoga, or whatever) you add distance.

(5) Plan for it.  If you’re racing with your Garmin, build that extra distance in to your expectations.  If the course has mile markers, you will probably notice how far “ahead” you’re getting throughout the course of the race, especially if it’s a longer race.  Don’t let it take you by surprise and it won’t disappoint you.

(6) Ignore it. You’re out running your first marathon and you just want to have fun?  Who cares if you tack on a few extra minutes!  If it makes you happy, by all means, go high-five your friends.  Efficiency isn’t always everything.  Just don’t complain about the “extra” distance afterward.

Thanks for tuning in to my little Sunday PSA. I know this topic has probably been beaten to death elsewhere, but it seemed like reminder might be in order.  If I’ve missed anything or you have any other thoughts/tips, please feel free to share!

And, of course, congrats to everyone who raced and/or PRd this weekend!  (And slightly lesser accolades to those of us who sat around and drank beer!)

45 responses to “A brief tangent

  1. “I want to run a Python-themed race, in which we all completely gorge ourselves afterward. Who’s with me” <– I believe I already do this. Now I have a name for it. Thank you.

  2. Thanks for the explanation! I read something similar in a book about running. I can’t remember what book but it gave a description of the best way to run a race efficiently.

    I don’t have a Garmin. I use a Polar HRM for heart rate and calories burned. That’s pretty much all I need. When I was running a lot I did want a Garmin but never got one. I also used the Nike+ app on my phone. It was NEVER accurate with mileage no matter how much I calibrated it.

  3. ah. if only you could teach me how to use my Garmin so that I could eventually distrust it. So far, I can turn it on. d’oh.

  4. True story: I once read a race report where the reporter gave her “actual” marathon time and then her “recorded” time. As in, what her Garmin said when she hit 26.2m on the Garmin, and then what her chip time was.

    • Ha! I’ve seen that too. This gives me some good ideas for other times I should be listing in my race reports:

      –perceived time: how long it FELT
      –deserved time: the time in which I feel I deserved to have finished
      –ideal time: the time in which I WOULD have finished if X, Y and Z hadn’t happened…

      • I love it. In fact, I think I’m not even going to bother racing from now on. I’m just going to compile my race stats based on what WOULD have been.

        5k time I probably could run: 30 minutes
        time saved because I got a good night of sleep: 2 minutes
        time saved because the course was flat: 30 seconds
        time saved because weather was good: 1 minute
        time slowed down because of overcrowding at the start: 15 seconds
        As you can see, my 5k that I didn’t run yesterday totally SHOULD have been a 27:45.

      • I’m totally stealing this idea for my next race report.

        I like the idea too of not even racing and just writing the report of how the race would have gone. My race photos will be much cuter that way.

  5. And when in doubt about course length: upload it and LOOK AT THE MAP in Garmin connect. You’ll likely see yourself running over trees/cars/etc and generally not being on the road.

    • Oh yeah, definitely. And those elevation spikes are telling, too. I’m not spiderman – I didn’t run up the side of that building and back down….

  6. I remember being wicked confused I first few races with a garmin. I was super indignant about “long” races for a few months until it was explained. This does a much better job of it than the explanation I received. However, explain which mat is the chip start – there are always two and it’s confusing (because that split second is going to make a huge difference haha!).

    • Good question! Seriously. I always assume it’s the first one and the second one is just a back-up or something, but I have no idea. Anyone know what the deal is there?

      • They’re redundant mats; both for ‘missed chips’ (mats have a limited height, and may have a limited concurrent read rate) and for the possibility that one of the mats fails completely. Both are hooked up to the computer and your last cross/first finish are taken. (source)

        Old military adage; “Two is one, one is none.”

        Considering how worked up runners get about completely botched times, I’m surprised they don’t have 30 of those things.

      • (sorry can’t figure out how to reply directly to the comment below)…Thanks so much! I know it hardly makes a difference in terms of the actual start/finish times. It’s definitely more of an emotional rather than logical need to know which timing mat “matters.” As someone said, if I’m PRing by seconds, it’s not really a PR except for the shortest flattest straighest course. I mean c’mon I don’t do anything straight let alone run straight.

  7. What about those of us that PR’ed this weekend and then sat around and drank beer? Best of both worlds in my opinion!

  8. I’m on board for the python-themed race! I think I could handle that…especially the post-race happenings!

    It took me a while to figure this all out but yeah, a GPS is not always going to tell the truth. Actually, it is seldom dead on.

    What I don’t get is how my GPS and the course can have identical finish times, a distance difference of only 0.01 and still have a pace difference of 9/mi (chip time) and 8:53 (GPS time). Unless the chip pace was really gun pace…? I have no idea, I like my GPS pace better so I’m sticking with that for egomanic purposes!

    • Weird? Calculating pace based on distance + time is straight math, so there really shouldn’t be any discrepancy there…if you plug things in to a pace calculator (like this one: http://www.coolrunning.com/engine/4/4_1/96.shtml) what does it say?

      The only thing I can think of is that they’re actually using gun time, or that there was only a chip mat at the finish. (So they’re basically just using the chips to record the finishers in order…I ran a 5K once where this was the case and it was an unwelcome surprise, LOL.)

  9. THANK YOU. I know too many people who record their “race time” (what the results say) and their “official” time (when their garmin registered the distance).

    It annoys me to no end when people are upset about this. Is it that big of a deal to have an extra 0.2miles? Geeze. That will realllllly dilute your avg pace in a marathon…

  10. I agree – I ran Charlotte’s Thunder Road Marathon & tried to run it as efficiently as possible (difficult trying do weave around thousands of people) & ended up running 26.4ish miles. Although it would’ve been nice to run it as close to 26.2 as possible, I did have fun waving to my family, taking a turn wide to say hello to friends 🙂 People do get their panties in a wad though….

  11. An obsession with accuracy is really unhealthy; unless you run alongside a marked steel rod of a fixed length on flat terrain, you have significant error in every measurement you make. So really, just like body weight, it’s more important to worry about the trends.

    If you can’t beat your race PR by more than the typical error measurement of a race chip timing system, then you didn’t beat your PR. I mean you probably are already running a different course, on a different day, with different air temp, different air pressure, wind direction, humidity and a hundred other variables that are affecting the ‘truth’ of your record more than a few meters of distance.

    • Very true. Remember when people used to focus on beating the other people around them? LOL.

      (I say this as someone who is totally guilty of Garminstalking and actively trying to break the habit….)

  12. Agree, the reports from this weekend bothered me as well. But I did run a half in October, and on the straightest, flattest road an extra .10 of a mile got tacked on. At I attributed this to the above reasons, but then I found out that every single person with a Garmin at this race got that exact same extra .10 at the exact same spot — on the straight road. The rest of the miles (with many more turns and weaving) were far more accurate than that one section. That did bother me because I really do think there was an error. But who knows.

  13. best blog post of the year, hands down! i never wear my Garmin during races because i *know* the GPS distance isn’t going to match the official race distance.

    +1,000 to this: “Remember when people used to focus on beating the other people around them? LOL.”

  14. AMEN. Garmin is not magical.

  15. Considering that my Garmin on auto-pause lets me stop to GU/water, do a few pigeon poses, or scream at wayward tourists around the monuments without penalty, it’s less an atomic clock-accurate portrayal of my running performance than an essential tool in self-esteem building.

  16. I LOVE this post!! It drives me a bit crazy when people assume a major marathon (or 10K or whatever) obviously has its course measured incorrectly because THEIR garmin said 26.48 at the end.

    Count me in for the python race. 😀

  17. great post! I kind of suck at running the tangents, but maybe it’s because so many races here are really crowded. After NYC marathon, I think my garmin read something like 26.5 miles, but my only thought was “Dang, you suck at running the tangents. Must follow colored lines next time.” not “OMGZ I’m calling NYRR so they re-measure the course of the world’s most popular marathon and change my time!” LOL

  18. Love this post so much. Maybe it’s because my Cross County coach was awesome (still remember things he told me all these years later) and told us to run the course efficiciently. Same thing with track races of longer distances. Hey, guess what? Don’t run in lane 8 the whole way when you can move into lane one after the first turn! I guess I have always understood the concept. Even though I am bad at math.

    I think this post should come in the Garmin manual.

  19. Hilarious post, but so sad that you had to write it. Come on, people, of course Garmin is going to be different than the official results. We can’t all run the exact line measured!

  20. I’ve run two races with a Garmin. For the LA Marathon last week, I tacked on an extra .25. I know that was just running inefficiently, weaving to stay out of ankle-deep puddles (if possible), getting aid, and not running the tangents because they were way too crowded. On the other hand, I ran what was supposed to be an 18-mile race/LA training run and it was over half a mile short according to Garmin. Does that ever happen to anyone?

  21. Loved this post. Great combination of facts and wit. Psss, my GPS app hates Ke$ha too 🙂

  22. Pingback: An Overly Wordy Report…Without Pictures! «

  23. hahaha, thanks for the PSA!! I heard SO many people complaining about the long course at National Half this weekend. Nope, you just didn’t run efficiently. In a half I always expect to run an extra .1 and always aim to get as close to 13.1 as possible, but in a large event its just not possible to run a perfect-to-the-tangents race.

  24. HAHAHA I actually thought that after my 5k. My phone said 3.32, and I was like, “WTF?” Thanks for the explaination; I learned something today : )

  25. great post, love your point, but here’s my beef.

    I PR’d this weekend, 1:30 flat for a half marathon. My garmin read 13.36, and I ran as straight and narrow as humanly possible, barely a single dodge for water. Further, the race was in my neighborhood, in routes I’ve run hundreds of times, so I know there are no high-rises causing GPS issues or what-not.

    Also, the only mile that was off (1.2 miles instead of 1.o) was the first mile, and the rest were perfect. I’ve talked to others who clocked exactly 13.36 too.

    So I blame race officials for not realizing how freakin anal runners are. I think the course was off. Just my 2 cents

  26. can’t agree more. i was irritated enough to remark to one individual recently who claimed to have run a full extra km in a HM “Who gave you that Engineering degree again?” sometimes i feel that people should be forbidden from wearing personal electronic gizmos in races. especially people in my time group (i.e., slow, middle aged, people).

  27. This comment is totes irrelevant to the blog post but…I just wanted to say HAI because I started reading your blog like 5 months ago, and it inspired me to register for a 10km race which is now happening in a week and a half. So, thanks for being rad and teaching me running etiquette! I promise to be a well-behaved rookie.

  28. Pingback: Race Routes Are Not Too Long : Beaches Runner | A Running, Fitness and Fun Blog

  29. As a former complainer of distance issues, but now a staunch believer in the ‘course is accurate’ I totally dig this post. So instead of writing about it, I just linked to your blog instead 🙂

    ~ Dave
    ( Beaches Runner )

  30. Pingback: more horrible for you (bikini season edition) « Cheaper Than Therapy

  31. Pingback: Weekend Mix Tape Volume 12 « My Running Shorts

  32. I couldn’t help but notice you got off on a ‘tangent’ talking about tangents.

    In case anyone cares, GPS monitor devices estimate distances covered by collecting data points of our positions many many times over the miles we run. For some reason, the way most GPS monitor devices are programmed when you make a hard turn (usually a quick 90-180 degree turn) our gps devices lose track of the data points. Read this article for more detailed information.

  33. It’s great your Garmin has panties; my Garmin is jealous.

  34. Pingback: a “race” recap « Cheaper Than Therapy

  35. Pingback: How Not to Train for a Half Marathon « Queer Vegan Runner

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