Understanding Heart Rate

Posted on by mrsoltys

So I just got a Garmin, mostly to record long rides on strava without killing my phone battery.

But I'm also a bit interested in the Heart Rate data craze.  So far, everything i've found on heart rate training seems anecdotal at best: "Subtract your age from 220..."  That's about where I stop reading.  It seems like this formula is a good guess, but I just spent $150 on a device that actually measures and records my HR in real time!

Strava's heart rate data for my ride was disappointing at best, i'll explain more in a second

Anyhow, in honor of my new toy I went on a 5 hour mtn bike ride over some pretty challenging terrain.  Strava gave me a disappointing amount of stats on my heart-rate.  Garmin at least tried to calculate zones, and tell me how much time I spent in each zone, but i still don't really get what it means. Or how it calculated the zones in the first place for that matter.  At any-rate, the data is a little weird because it's hard to believe I spent an hour and a half in the highest zone, and 2 hours in an anaerobic state...

Garmin's data was a little more detailed... but still mysterious

So, being a good PhD student, I dug into my Garmin and got the data into matlab. (Trust me: Garmin doesn't make this easy). I then plotted the data into a histogram to look at my heart rate data. A side note: I just binned the heart-rate for each bin, however the Garmin seems to record at non-standard intervals. There were enough data points that I felt this wasn't a huge deal.

Histogram of heart rate data from the garmin. The zones are indicated by red dotted lines and the average heart-rate is indicated by the dotted line.

A couple things to note: The average heart rate does not really show what's going on in the total workout (Although it is interesting to note that there is a peak located right near the average heart rate).  Also, it's hard to tell from the garmin, and impossible to tell from strava, that I spent most of the time on the ride at a heartrate around 166, right on the border of "zones 4" and "5".  This seems to be a good indicator of what my body felt was a hard yet sustainable pace.  The peak around 155 seems to indicate another place my body felt comfortable working at, at a slightly lower pace...

Anyhow, this is just a first dive into heart-rate data for me.  Any training experts have any other advise in looking at their heart-rate data?