How to improve HR accuracy?

bonniejo

So I just got the charge HR to replace my dead zip. I did my usual workout this morning (a combination step and strength class), which is pretty grueling, and it stated that I only burned 350 calories during the hour. This is the same number I burned in a pretty easy zumba class last week. Is that right? It doesn't seem right. At my peak HR (about 200 or maybe higher by my manual count) there was no heart rate on my charge HR, just dashes. At another point in the class, the charge HR said 150 BPM but my manual reading was between 170 and 180 (and I was breathing pretty hard).

I would try using a chest strap HRM but they don't seem to work for me, since my displayed HR is usually 0 (the HRM part doesn't touch my skin well because my ribs elevate it or something). It used to work if I wore it on my back, but since I've gotten to a lower BF% that doesn't work either.

It also recorded about 1000 fewer steps than my zip did with an average workout. Of course, every workout is a little different, but it seems really off. Are there ways to improve the accuracy of the heart rate monitoring? I wore it pretty tight 2-3 inches above my wrist the whole time. It slipped a few times but I wiped the sweat off and pushed it back up. Thanks

_Tzefira_

I find I have to wear my HR higher than suggested during workouts. I have a small wrist and a large size HR, and I wear it up high on my forearm (about to second-to-last notch). It works well there. Sometimes if it gets very sweaty it freaks out a little with the dashes and I have to swipe the sweat off, then it catches back up again.

For normal activity I leave it down at my wrist.

heybales

The Zip was known for having great sensitivity, better than some of the others.
So it easily could have been inflated for the active non-walking stuff.

bonniejo

heybales wrote: »

The Zip was known for having great sensitivity, better than some of the others.
So it easily could have been inflated for the active non-walking stuff.

What about the HR? It just seems odd to have the same burn for a light zumba vs an intense circuit class. And it didn't seem to catch my HR at all when it was too high.

heybales

Sensor works well for some, not so well for others.

And need to look at avgHR, not the calorie burn, because the burn is based on that.
Your avgHR for circuit class could easily not be that high, same as with intervals.
And especially if it's missing the higher values to include in avgHR.

And since HR calorie burn formula are based on steady-state aerobic, same HR for 2-4 min, you'd normally get inflated on that circuit workout anyway, so perhaps missing those higher highs is getting it closer to accurate.

W_Stewart

heybales wrote: »

Sensor works well for some, not so well for others.

And need to look at avgHR, not the calorie burn, because the burn is based on that.
Your avgHR for circuit class could easily not be that high, same as with intervals.
And especially if it's missing the higher values to include in avgHR.

And since HR calorie burn formula are based on steady-state aerobic, same HR for 2-4 min, you'd normally get inflated on that circuit workout anyway, so perhaps missing those higher highs is getting it closer to accurate.

Does this mean the HR would be more accurate for something like a steady powerwalk, but it might not track the calorie burn accurately if I periodically climbed some stairs or picked up my pace during the walk? For example, say I go on a 1 hour walk. I have a steady heartrate for the first 20 minutes but then I climb 7 floors (equals 14 flights) of steps which gives me a significant uptick in my heartrate. I then keep walking and my heartrate settles down.


I was hoping the Fitbit HR would track the calorie burn as a function of varying heartrate. If not, is average heartrate still going to be a good measure in my scenario?

heybales

Depends on how fit you are really.

Notice what the HR is for the normal pace of steady powerwalk.
Now increase the pace and notice the HR.
Even at increased pace, it should shoot up high and slightly lower to the real level needed after some minutes. So during that time it was inflated for actual level needed.
Now lower pace back to prior level, and watch how long it takes HR to lower back to prior level for that pace. So during that whole time of lowering it's inflated for actual level needed.

Now slight differences in walking not going to be bad at all, or 1 flight of steps.

But take a typical Insanity or P90X or intervals or weight lifting, where the HR is constantly going up and down by huge amounts and level of effort is not constant for the 2-4 minutes it would even take for the HR to reach the actual required level.
Now you have a HR that is inflated by 15-20 bpm easily, and if that workout is 30-60 min, your calorie burn difference could easily reach 200-400 inflated depending on your weight.

I have a Garmin and can examine my per sec HR on way up or down, and during intervals with about 50 bpm spread, HR has about 30-40 sec lag time to reach required level, and about 45-60 min to fall back down 40 bpm, and then another 60 to drop the final 10.
So I have a personal calorie burn formula based on VO2max test and that personal timing for my fitness level, to get a better estimate of calorie burn when I do those types of workouts.
Because it can add up.

realityhack

Fitbit recommends wearing the HR higher on your arm and slightly looser during workouts to catch the heart rate correctly. Of course they coupled that with a ridiculously short band.
They also clearly state that the HR may not pick up your heart rate during martial arts, boxing, etc where there is a lot of arm movement / jerking.
Walking around even up stairs etc it should be accurate.

My experience has been even with low arm motion I can only get it to track with my Polar chest band up to about 130bpm.

It also seems like the HR takes a longer average than some other devices so it may lag a bit. Just my guess based on personal experience.