Field testing the Garmin 310XT


People who know about my running problem know that I am also not disciplined. Running is way too fun for me to treat it with real goals and stuff. My goals for running are pretty simple: go somewhere cool and enjoy doing it. Of course I could take the train and accomplish that same task, so there is the component of the sheer motion of running that I absolutely love. The rhythm of running is a beautiful thing to experience, and I am thankful every day that I am able. That said, it also turns out that, perhaps owned to my scientific and analytical nature, I am intensely curious about all the sorts of numbers that one can assign to running. How fast am I going? How far did I go?

When I first got a heart rate monitor (HRM) about three years ago, I was intrigued by the simplicity of the measurement. My first HRM was a Suunto T3, and I managed to wear out the heart rate strap and break it after about a year. As a replacement I moved up to the Polar RS200, a watch that is marketed as running specific and even features a dot matrix running man on the time display. Polar are clearly the heart rate gurus, having invented the technology so many years ago, but the pace of technology has quickly learned to keep up, for the most part. The RS200 was not without its shortcomings, which took me about a year of running to fully appreciate. It only holds the last 16 workouts. It has 3 lines of data. The lap button isn’t fool proof on the run. And most importantly, to get any notion of how speed and distance progress over the course and during a run, one has to rely on a crude approximation given by the speed and distance sensor that attaches to the shoe, powered by 2 heavy AAA batteries that frankly didn’t last a month of running.

It was fun while it lasted, and while I’ve had my eye for awhile on the Garmin Forerunners, I wasn’t ready to go for it until Garmin caught up in the following, relatively minor areas: battery life and heart rate strap comfort. For GPS technology tracking distance and, combined with time, speed, it is incredibly appealing, considering the amount of trail running I do, where it is hard to estimate distance, especially given the amount of time I spend lost and running around in circles. Figuring out pace and “performance” is always tricky, and I admit I like to know at the very minimum how far I’ve gone and how long I was out there.

Enter the 310XT. It sounded like the answer to all of my problems, and I couldn’t have gotten ahold of one fast enough. Just in time to be a pacer at my first ultramarathon, the Vermont 100, I put it through a couple of short runs to get used to it and familiarize myself with it. Additionally, I was able to use it for the entire 17 hours and 22 minutes I was pacing at the race (63 miles) on a single battery charge. While I didn’t quite push it to the advertised 20 hours, 17 is not bad and at least plenty for all races up to about 60-70 miles. I guess I’ll have to have a strategy for 100 milers.

I was able to change the visible data fields on the fly, which was valuable when I did not want to lose my session. Unlike the Polar, which I invariably stop by accident during even hour long workouts, the function of the buttons on this unit are clear and responsive. I didn’t make that mistake in 17 hours with the Garmin.

I saw Garmins all over the course at the race, by the way — mostly 305s, with the occasional 405. It’s clearly the training tool of choice for ultrarunners, though many people bring two to cover the entire race.

Weight. The weight of the watch was a non-issue. It’s bulkier than the Polar or a normal wristwatch, but surprisingly it was not overly cumbersome.


GPS Lock. The GPS fix was incredibly impressive. Once the new location was kind of learned by the watch, it seems to remember which satellites would be easiest to connect to, making subsequent connections easily. I calibrated the watch by simply turning it on and letting it find satellites as soon as I got to Vermont, and when I turned it on for the run, it registered distance and speed almost immediately.

I had made the mistake on my first run with the watch to not let it find the satellites before taking off, and as a consequence it took about 0.55 miles to figure out where it was. Worried at first that this would be a 2 minute wait at the beginning of every run, I was incredibly pleased with the instant on technology seen on subsequent runs in the same location. You can save a bunch of locations, too, and I think that’s probably telling the watch what satellites to try out for an immediate fix.

Not once while tramping through the wooded, unmarked trails of Vermont did I lose the GPS signal.

Accuracy. There have been reports of unclear accuracy with respect to the watch. The only tests I’ve done include running routes of known distance, as measured by another imperfect system, manual route mapping on Google Maps. However, the distances turned out on known routes in Google Maps have ranged from very close (within 0.1 miles over 8 miles – 1%) to spot on, so I’m starting to really trust the GPS’s distance readings.

Elevation. I’m inclined to think that the elevation reported by the GPS is meaningless. This is based on “known” course profiles (how were they measured, I wonder) that were wildly lower than what the GPS reported. Additionally, topographic data on Google Maps do not seem to be at all in line with the GPS. I tend to believe the topographic maps on this issue, because they rely on static radar data. Barometric pressure data, while not perfect, does not seem to favor GPS data on this issue either.

Uploading. This procedure is unnecessarily cumbersome. In addition, the online PDF manual was required to get any idea of how it was supposed to work. Granted, their Mac support is relatively new, so there are bound to be issues. On the Mac, you download the Garmin ANT software from the website, along with the Garmin Training Center software. After installing these, you can run the Garmin ANT Agent and plug in the ANT USB stick to the computer. On the watch itself, you have to set a setting to be able to send data. After you have recorded a workout on the watch and saved it (by resetting the watch, a session is automatically saved), simply holding the watch near the USB stick is enough to initiate the data transfer. I think the way this works is that the data is transferred from the watch to the USB stick and then to the computer. It therefore exists in 3 distinct places.

While this sounds reasonably straightforward, I found that the Garmin ANT Agent often seemed to freeze mid-transfer with no clear sign of progress for long periods of time. Sometimes it would transfer and other times it would not. When it would go through, it was not as fast as it probably should be, based on an expectation of wireless data transfer speeds.

Garmin has a great online tool that allows you to track runs, view the GPS map on a Google map, and use a lot of other interesting features. My favorite of these is the run playback, which goes through the run and can show how your heart rate and pace are changing along the run. It’s valuable to see at what points you struggled and felt good.

In addition, the online training log that I use,, has Forerunner integration and allows you to upload the Garmin information from the USB stick to the website. Instructions are available on that site.

Ultimately, my first impression is that the Garmin 310XT is an excellent tool for training and tracking data, perhaps the best solution for runners currently available. For all of these reasons, it seems to be a more compact and satisfying solution than both of my previous watches.


2 thoughts on “Field testing the Garmin 310XT

  1. Elwyn Garaza

    Thanks, Spherical Cow –

    That was a great review. I was working through all the other ‘professional’ sites, and they seemed to just copy the box cover copy. This review was practical and let me know how the watch compares with other watches I was looking at, and the true-to-life issues a runner/triathlete will face with the watch. This was the article that helped make the decision!

  2. Matti

    Thanks for the review that was based on a real field test. Anyways, now that you have had this watch for a while could you post a follow-up of some sort. Still satisfied? I’m also a grad student so I really don’t want to drop over $300 for a watch that does not work like I want to. Again, thanks for the great review. -Matti

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