Tuesday, June 7, 2011

I Love My Garmin, but the HRM Could Be Better

As I've said before, I used to be the kind of triathlete who felt that there was no need for a personal GPS device.  Then, a little over a year ago, my wife bought me one for Christmas, and my triathloning has never been the same.

Garmin 310xt with HR strap, HR transmitter, and USB ANT+ Stick
I absolutely love my Garmin 310xt, and can't really believe that I went so long without buying this type of device.  It takes all of the guess work out of my training.  At least, it's supposed to.  Since I began this year's IMAZ training, I've noticed that my 310xt has been having some issues in regards to monitoring my heart rate.  The rest of the device has been working great.  It's only the HRM portion that has been acting up.  I didn't notice this problem until earlier this year because the training I did in hopes to qualify for the Boston Marathon was all based on my pace...I didn't really look at my heart rate much.

To make a really long story as short as possible, my 310xt would read my heart rate correctly for about 45 minutes or so, then it would start showing my heart rate to be less than 80, and sometimes in the 50's (which I know for a fact is wrong, because my resting HR is around 56, so it can't be that low during a workout!).  Here's a classic example of the problem:

Taken from the Mickey Marathon (Disney World Marathon), in January 2011.
Surprisingly enough, it doesn't always happen.  In fact, the day before the above example, I ran a half marathon and my 310xt made it for an hour and forty-five minutes before it dropped my heart rate down to the 20's.  

I tried searching the internet, including the Garmin forums, for solutions.  The odd thing that I found was that HR problems are pretty common, but it's almost always with HR spikes, usually created from flapping jerseys, static, or some other outside interference.  Only a handful of people were reporting the same problem I was having.

I contacted Garmin product support and was given the typical no-brainer solutions at first...update software, try different shirts, reposition the monitor, etc.  I explained that I had tried all of the typical solutions, and nothing had worked.  Eventually, they suggested that I send in my 310xt unit (not the HR strap) to be exchanged for another unit.  Technically, I'm outside of my warranty, so I was just going to go along with whatever they said.  I received a refurbished 310xt about 10 days later (and seriously missed having it for those 10 days!), and got right to testing it out.

I've done about 10 or so workouts now, and unfortunately, this unit is not really working any better.  It hasn't dropped my HR down into the 20's yet, but it is still reading around 50 beats per minute low at times.  Here's a video of a recent run I did on a treadmill, wearing both the Garmin HRM as well as a Polar HRM for comparison:

Essentially, having my heart rate being displayed incorrectly isn't really that big of a deal.  The only time it really comes into play is when I'm trying to stay in a certain heart rate zone (which is the majority of Ironman training).  Since my 310xt hasn't really been reading correctly, I have just been using "perceived effort".

So, now it's time to contact Garmin product support again to see what their next suggestion is.  I really have no idea what could be causing this, or what any possible solutions might be.  It seems like maybe there's some problem either with my HR strap, or the HR transmitter.  It might be a while before I am able to put out an update on this one, as there will probably be some mailing of items back and forth.  But rest assured, as soon as they either tell me that I'm out of luck, or solve the problem, I'll be sure to write a post about it!  Until then, happy training!


  1. That's so annoying! How long had you had your 310XT when that started happening? So far, my HR monitor has been pretty reliable, but I'm sure that posting this means that I'm going to have problems, starting tomorrow!

  2. Hey David! I went back and did a quick scan of all my workouts over the last two years, looking for workouts that appear to have low average heart rate (relative to what the workout was, of course). And seems that the issue with my Garmin started some time around October/December of 2010, which means my Garmin was 1 year old. Hopefully I just have a faulty transmitter, and you don't experience any of this!