Alta HR and Measuring My Heart Rate

[epstewart]

I just got an Alta HR with heart rate measuring. Some of the fitness equipment at my community center also measures heart rate. I got the Alta HR to check up on those measurements' accuracy. But when I tried that yesterday, I found that the Alta HR consistently registers a significantly lower heart rate than the various pieces of fitness equipment, which are made by Precor. The Precor measurements themselves are consistent from one machine to the next, When they are showing, say, 120 bpm, the Alta HR may be showing something like 110 bpm. As my heart rate goes up with further exercise, the difference between the fitness machines' measurements and the Alta HR's widens. The thing is, I have long been diagnosed with premature ventricular contractions (PVCs), which apparently are happening all the time, but at changing rates. My question is: Could the Precor machines and the Alta HR be responding to PVCs differently, and would that account for the discrepancy? Thanks.

[WendyB]

They use differently technology. So you really cant compare the two.

[epstewart]

Thanks. I happened to have a doctor's appointment yesterday, and as usual the nurse took my pulse reading. It was 84, based on 28 beats in 20 sec. My Alta HR said 86, so it is basically spot on. I did not ask the doctor about the possible effect of PVCs, as this was not my cardiologist and we had other things to discuss. But given that the Precor technology reads significantly higher than the Fitbit does for me, and the Fitbit seems to be right, I am hypothesizing that the Precor may be picking up my premature ventricular contractions and counting them as "extra" heartbeats. I have posed this question to the Precor website and will post back here with their answer. Unfortunately, if my hypothesis is correct, then I'm not achieving as high a "true" pulse rate when I do cardio exercise as I had thought ...

[melaniewymer]

I've found that the Alta HR measures resting heart rate pretty well but struggles with activity HR.  To get it to record it accurately you really do have to play around with where and how tight you wear it.  I've found if you shift it up your arm a bit - say an inch - and wear it tight but not uncomfortably so, (but so it doesn't move around) it's more accurate.  The Charge 2 is a little less fussy partly because it's larger and doesn't tend to shift around quite so much. Wrist based optical HR is never as reliable as a chest strap though, whichever brand you use. 

If HR whilst exercising is really important - more so than resting HR - then to be honest, a garmin device might be better. But, note that Garmin devices don't record non activity HR as often - could be every 10 mins or so, rather than every minute of so that Fitbit records. Apple also only records every 10 mins. 

[epstewart]

Thanks for the input. In what way can you tell if the Alta HR is struggling while measuring heart rate during activity?

I will check into devices with chest straps.

[FerdinandFitbit]

Hi there @melaniewymer @epstewart. Good to see you in the Community Forums! 🙂

In order to get the most accurate data from your Alta HR, I can recommend a few things:

As with all heart-rate tracking technology, whether a chest strap or a wrist-based sensor, accuracy is affected by personal physiology, location of wear, and type of movement.

For all-day wear when you’re not exercising, your tracker should usually rest a finger’s width below your wrist bone and lay flat, just as you would wear a watch. Fitbit’s PurePulse heart rate tracking system is designed to be most accurate when the tracker is worn on the top of your wrist.

For improved heart rate accuracy keep these tips in mind:

1. Experiment with wearing the tracker higher on your wrist during exercise. Because blood flow in your arm increases the farther up you go, moving the tracker up a couple inches can improve the heart rate signal. Also, many exercises such as push-ups cause you to bend your wrist frequently, which is more likely to interfere with the heart rate signal if the tracker is lower on your wrist.
   
2. Do not wear your tracker too tight; a tight band restricts blood flow, potentially affecting the heart rate signal. That being said, the tracker should also be slightly tighter (snug but not constricting) during exercise than during all-day wear.
3. With high-intensity interval training, P90X, boxing, or other activities where your wrist is moving vigorously and non-rhythmically, the movement may prevent the sensor from finding an accurate heart rate. Similarly, with exercises such as weight lifting or rowing, your wrist muscles may flex in such a way that the band tightens and loosens during exercise. Try relaxing your wrist and staying still briefly (about 10 seconds), after which you should see an accurate heart rate reading. Note that your tracker will still provide accurate calorie burn readings during these types of exercise by analyzing your heart rate trends over the course of the workout.

Keep that in mind when using your tracker for exercising and see if you notice any improvement.

Let us know how it goes!

[epstewart]

That stuff is good to know. Thanks.

I get it that getting an accurate heart rate while exercising is key. But if the Alta HR is in fac showing a heart rate at any particular time, is there any way to know that it's less accurate than at other times? So far, I think mine has been consistently accurate while I'm exercising, but the Precor equipment I use, while also consistent, seems to read (again, consistently) higher than the Alta HR.

[melaniewymer]

@epstewart I run regularly and roughly know what my HR should be for a
certain level of effort, plus when I’ve been testing the new fitbit I’ve
worn an apple watch and a garmin 730 (both have optical HR too). When HR
is out, it’s out by a long way - for example when I run my cadence is
around 175 - quite often if a HR device is struggling to work out the HR it
picks up the cadence instead - plus I’d be really pushing it if my HR is
continually 175 - normally for an easy run its around 129 so a substantial
difference. When I’m walking its about 85-95 so if I see 130 etc I know
that’s wrong too. Basically the HR is just locking on to the wrong ting.
When they’re all working correctly they are normally within around 5 beats
of each other.

Chest straps are great but probably won’t work for resting HR, just
activity HR.

--
Melanie Wymer
07795 183728

[epstewart]

Melanie, does repositioning the Fitbit or changing its tightness give you the correct HR?

[melaniewymer]

@epstewart It depends really. I find resting HR is absolutely fine not
particularly tight and near the wristbone, however for activities I find I
have to at least tighten it up and if that doesn't improve the accuracy
then shift it up by a little bit. Sometimes, I put it above my watch on my
other hand so it can't slip down - reads best there. It's trial and error
really. It seems to be harder to get a good reading in very cold weather.
I think the Alta struggles more than most because in order to get a good
reading I think it helps to stop light getting in around the sensor. The
Alta is so small with no overhang so I think this is hard, hence why
tightening helps a little. It's never going to be as good as a HR chest
strap but it's a darn bit more comfortable. I'm most interested in the
resting hr so for me this works a treat.

[epstewart · Accepted solution]

I submitted my question to Precor Support, and here is the extremely helpful information I received back:

Eric, here is some info from our engineering group regarding Precor equipment and PVC's:

"In general, PVC’s will be filtered out by the algorithm and won’t affect the heart rate.
If two PVC’s happen within 250msec, they’ll be ignored.
If the occurrence of PVC’s is less than once for about every 5 normal heart beats, the HR reading
won’t be affected at all. It will read normally, as if no PVC was present.

If there are many PVC’s, on the order of more than once per 5 normal beats, the HR system won’t
provide a reading at all.

Since this customer is getting a reading with our equipment, we suspect it’s more likely the Fitbit is reporting low."

Hopefully this information is helpful.

Thank you,
Mark
Precor Support

[FerdinandFitbit]

Thank you so much for sharing this with us @epstewart!

Great to see you around!

[krtcald]

I use a precor elliptical machine several times a week. My fitbit alta is WAY lower than what the elliptical shows. The discrepancy is significantly worse toward the beginning of a workout, then slowly gets closer but is still something like 10-20 points lower than the elliptical at the end of a 25 minute or so workout. 

Having used the alta HR for about 4 months now I think it is very slow to read when your heart rate starts to increase on a machine. It works best if I go for a run. I feel like to get it to show anything near an accurate heart rate on the elliptical I have to "shock it" by jogging for 5 minutes. Once my heart rate is up it will read better on the elliptical. Very frustrating.