Runners: How do I know for sure that my HRM is giving me an

aweightymatter

As a tiny bit of background, I am running my first half-marathon in almost exactly a month, and I've been training seriously since this past September. For Christmas, I got my first heart-rate monitor. It's a Garmin FR 60 watch bundle with the foot pod and everything.

Today I decided to wear it around during my normal daily activities (I know, possibly crazy) to see what my resting heart rate and calorie burn were for an average hour of sitting around, driving, and just generally being passively alive. According to my HRM, my resting heart rate was throughout the 70s today, and it apparently takes me an average of about 80 calories an hour just to sit around on my butt and exist.

Anyways, I was out doing leisurely stuff today. By the time I got home and ready to run it was 10:30 p.m., so I hit the treadmill. (I don’t run by myself outside late-night because my neighborhood is not that well-lit and full of reckless drivers and rapist-ready shrubbery.)

I ran a little over 6 miles at a 1% incline at my usual easy, slow pace for 69 minutes total -- intervals of 2 minutes at 5.2 mph, then 1 minute at 6.0 mph. My heart rate monitor said I burned 970 calories?! Subtract like 80 or 90 calories for the average burn per hour or just living — and that’s still 880 or 890.

No way did I burn 890 calories in 69 minutes of not-that-fast running, I thought… I checked on MFP and the site gave me a burn of 756 for the same activity. So then I remembered that I forgot to calibrate my foot pod, d’oh! I’m sure running on the treadmill and not actual distance contributed to this, but the foot pod readout overestimated by total distance by about 2 miles.

Throughout the whole thing, my heart rate readout fluctuated between 175 and 186 — average was about 176 or 177. I ran two minutes very slowly at 5.2 mph, then 1 minute 6 mph, through the whole workout.

Those heart rates also seem very high for those speeds, don’t they? I wasn’t huffing and puffing or anything; these are very easy speeds for me.

Thoughts from other HRM users? I will calibrate the foot pod properly tomorrow on pavement and do my full run outside to try to fix the distance discrepancies. But besides that, how do I know if my actual heart rate readout is accurate?

Forgot to give other relevant info at the beginning of the post: I am 27, female, 5'6", 154ish lbs with an okay amount of muscle.

heybales

The HRM part I'd trust normally, but that does seem very high for your description of the level of effort.
And kudos on that being an easy run for you! You are so ready for the half.

The calories may not be based on HR at all.
For a test, go outdoors and let it get GPS fix, start a running workout, and then walk to car, get in, and drive a couple miles.
Get out and stop workout.

Now upload data and see what the calorie estimate was. Don't worry about wearing the HRM, unless you are curious what it does while driving.

Also, calorie burn based on HR, if the system actually did that, is only accurate from about 90 to about 150, that is a straight line correlation. Outside that it looses accuracy greatly.
So your around the house stuff was probably off, and it appears the calorie estimate was probably off during jog too.

You might try finding the re-discover option for the strap. I forgot a couple times on bike rides, and would start the monitor on the bike while not standing close enough, or running back inside, letting it get GPS fix. I forget it is also trying to find paired sensors to use.
And then I come in later. During that first part of the ride before re-discovery, the values are WAY off. Going up over 225, then bottoming out at 40, like it's just trying to find my sensor that wasn't there during turn-on.

aweightymatter

The HRM part I'd trust normally, but that does seem very high for your description of the level of effort.
And kudos on that being an easy run for you! You are so ready for the half.

The calories may not be based on HR at all.
For a test, go outdoors and let it get GPS fix, start a running workout, and then walk to car, get in, and drive a couple miles.
Get out and stop workout.

Now upload data and see what the calorie estimate was. Don't worry about wearing the HRM, unless you are curious what it does while driving.

Also, calorie burn based on HR, if the system actually did that, is only accurate from about 90 to about 150, that is a straight line correlation. Outside that it looses accuracy greatly.
So your around the house stuff was probably off, and it appears the calorie estimate was probably off during jog too.

You might try finding the re-discover option for the strap. I forgot a couple times on bike rides, and would start the monitor on the bike while not standing close enough, or running back inside, letting it get GPS fix. I forget it is also trying to find paired sensors to use.
And then I come in later. During that first part of the ride before re-discovery, the values are WAY off. Going up over 225, then bottoming out at 40, like it's just trying to find my sensor that wasn't there during turn-on.

Thank you so much for the response! I knew intuitively by how I felt that it didn't seem right, considering my estimated max heart rate is only slightly higher than that (188-192ish).

I'm not worried too much about my calorie burn just sitting around, but I was curious about getting my resting heart rate. So if it's telling me my resting heart rate is in the 70s, can I still trust that generally -- never mind the calorie burn -- or should I assume it's probably inaccurate since it's under 90?

Anyways, I am going to try the car thing and then also re-sync the watch and the strap and do my next workout properly outdoors to compare. Thanks again.

heybales

Just remembered the other effect I had when the 2 didn't seem to be matched up.

I'd start and hit a HR that seemed correct for level of effort, just getting under way.

Then it would rocket up way above my alarm for upper HR, that's what kept getting my attention.

Then I would hit a stop light, and it would go down where expected.

Take off again and slowly rise as expected, but then keep going way higher than I was really at.

My Garmin doesn't have seconds for me to have confirmed the HR. If yours does, might just confirm, or use the treadmill timer and just do a 6 sec measure to see if really close.

I replaced battery, no help. Several rediscoveries actually, no help. But was already on the ride under high volt electrical wires, which I imagined was the reason for problem.

Or, I was having a heart problem. Being read correctly until I warmed up. Doesn't make sense.
Turning on unit while standing there was only solution.

aweightymatter

Just remembered the other effect I had when the 2 didn't seem to be matched up.

I'd start and hit a HR that seemed correct for level of effort, just getting under way.

Then it would rocket up way above my alarm for upper HR, that's what kept getting my attention.

Then I would hit a stop light, and it would go down where expected.

Take off again and slowly rise as expected, but then keep going way higher than I was really at.

My Garmin doesn't have seconds for me to have confirmed the HR. If yours does, might just confirm, or use the treadmill timer and just do a 6 sec measure to see if really close.

I replaced battery, no help. Several rediscoveries actually, no help. But was already on the ride under high volt electrical wires, which I imagined was the reason for problem.

Or, I was having a heart problem. Being read correctly until I warmed up. Doesn't make sense.
Turning on unit while standing there was only solution.

Sorry, but could you clarify about testing it using the treadmill? My Garmin does display seconds for the workout session... But do you mean seconds for the actual heart rate?

So if you turned on the unit while standing still, and then got going, was it accurate? Or was it just inaccurate in general once you reached your fastest speed?

This sounds similar to what I experienced, I think. The rate would go up during my faster minute, and then continue to supposedly rise even after I had been back down to the slower speed for at least a minute.

heybales

Oh good, if you got seconds displayed somewhere, so manually just take your pulse and confirm if unit is reading correctly, or close enough. My problem was I never had anything with seconds to confirm, but I knew it wasn't that high just manually feeling it.

If I was standing waiting for GPS fix, and within range, it seemed I could get going and it would be accurate.

If I got unit turned on and was elsewhere while it came on, and then got going, bad news.
If I tried to re-pair it on the road while moving, bad news.
Since my ride already started, I never tested just turning it off and on again while in place waiting.

Your issue seems similar then. I was thinking with multiple sensors (cadence for me, footpod for you), it may have problems getting the HRM paired if not within range, or perhaps with other interference going on.
Just theory.

If new and under warranty, I'd ask for swap. Mine has taken 2 yrs to start experiencing that, hate for it start right off. Makes you wonder how bad it could get.