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Heart rate

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Badger
Badger
3 Feb
11:33pm, 3 Feb 2025
17,671 posts
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Badger
Are you connecting with Bluetooth or ANT+? With ANT+, the protocol requires heart beat event time and heart beat count in every message (though, as above, the heart beat time isn't required to be a precise RR interval!). Bluetooth doesn't require it, and has a flag to show whether RR intervals are being sent or not.

If I can ever persuade my Tickr Fit to pair with my watch via Bluetooth, I'll look at what comes out of that.
SPR
SPR
3 Feb
11:44pm, 3 Feb 2025
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SPR
That might be the issue! I actually have Bluetooth and ANT+ on but I've noticed my watch generally connects via Bluetooth. I think when I first got the watch I switched off the Bluetooth connection but it worked well for leaving my watch on the side for basketball so I left it on since then.

I also had a look at my runs and it wasn't as obvious as I remembered that the optical might be out. The R-R graph line is thicker for chest strap. The AVG R-R seemed reasonable but other numbers including 0 anomalies pointed to issues. The successive differences graph shows the optical isn't quite right for beat by beat.

This study suggests it's ok at rest though: researchgate.net
SPR
SPR
3 Feb
11:50pm, 3 Feb 2025
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SPR
Chest strap on the left, Verity Sense on the right.

Badger
Badger
4 Feb
1:30pm, 4 Feb 2025
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Badger
Very interesting! The Verity Sense successive differences plot looks quantised just because the differences are so small that you can see the millisecond quantisation of the RR intervals in the FIT file. The handful of bigger values on the chest strap is compressing that down too small to be seen. I looked at some chest strap output and zoomed it to +/10ms, and you see the same quantization, but a much wider distribution around 0ms, so maybe there's some filtering on the optical showing up there, consistent with the lower SDNN.
I think the absence of anomalies is a good thing; when I tried extracting RR intervals directly from FIT files, I found that there were points where the RR interval was double or triple what it should be, either because the HRM has missed a beat or because the watch hasn't picked up the transmitted data. That should be easier to differentiate in Bluetooth, because it batches RR data and sends it roughly once a second, rather than ANT+'s 4.06 Hz transmission which can lose single beats if one message is missed (the timestamp is repeated if there hasn't been a pulse between two message transmissions); the raw ANT+ data tells you because it includes a beat count, but that doesn't make it into the FIT file. Those points are the Runalyze anomalies (documented as a fractional change of more than +/-0.75 from the previous beat), and they are excluded from the graph, see examples below for the same activity from Runalyze and direct from the file. TLDR: 0% anomalies probably just means no dropped messages and either no missed pulses or effective filling in where they are missed. (Let me know if you'd like the code for extracting the RR intervals).
And finally, thanks for the reference - interesting! Impressive how close the Verity Sense is to the H10 for RMSSD and SDNN; that, and Figure 5, suggest that it isn't quantising to 60/pulse rate, where the E4 plot in Figure 5 shows that that unit is quantising the RR intervals aggressively.
Hm. I'm going to do another test run with the Tickr Fit, look at the successive differences then I might have to buy a Verity Sense, because it really looks as though it's more precise.
Runalyze:


FIT file data:


FIT file SDs zoomed to +/-10ms
Badger
Badger
4 Feb
1:56pm, 4 Feb 2025
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Badger
The above graphs are F7X, ANT+ connection to Polar H10 with a generous dose of electrode gel on the contacts.
SPR
SPR
4 Feb
10:14pm, 4 Feb 2025
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SPR
That last SDs graph fits with what I see from the chest strap when zoomed in. Switched off the Bluetooth connection for the Verity Sense on my watch and can confirm that HRV is being sent across ANT+. It does seem that the quantisation is more aggressive Vs a chest strap.

Funnily enough Polar won't let you extract HRV data from optical sensors via their app: support.polar.com
SPR
SPR
4 Feb
10:15pm, 4 Feb 2025
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SPR
Have you found much use for tracking HRV in exercise?
J2R
J2R
5 Feb
10:53am, 5 Feb 2025
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J2R
I have never been interested in tracking HRV for exercise. It's something I keep an eye on at rest, as a general health/stress marker. My next heart rate monitor will probably be the Polar Verity Sense or its successor, and I'll keep the H10 chest strap for more 'medical' monitoring (you can get a pretty good ECG from it, for example).
Badger
Badger
5 Feb
6:49pm, 5 Feb 2025
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Badger
@SPR The RR plot in Runalyze is mainly useful for telling me how well or badly the sensor did on that training session.
I don't think the HRV values are directly useful in exercise, but some of the Firstbeat documentation suggests that RR intervals feed into things like the VO2max calculation (mainly indirectly by using respiration rate and what's implied to be rate of change to work out which bits are steady state where the heart rate is up to date with the effort you're putting in), and I'd like to make sure I'm feeding that solid data, as I do find it reflects my training, fitness & weight status well.
@J2R indeed, I will shortly be logging the ECG on my phone during a run to help unpick what's going on with the anomalies in Runalyze; I am pretty sure it's just beats missed for one reason or another, either bad strap contact or dropped messages, but I'd like to be sure it's not my heart actually skipping beats.

I still use an HRM-Run some of the time; the one piece of data it has that nothing else does is L-R balance, which I like to keep an eye on when my left knee is grumbling, to make sure it's not affecting form too much.
Badger
Badger
5 Feb
6:49pm, 5 Feb 2025
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Badger
Tickr Fit workout time...

About This Thread

Maintained by Elderberry
Everything you need to know about training with a heart rate monitor. Remember the motto "I can maintain a fast pace over the race distance because I am an Endurance God". Mind the trap door....

Gobi lurks here, but for his advice you must first speak his name. Ask and you shall receive.

A quote:

"The area between the top of the aerobic threshold and anaerobic threshold is somewhat of a no mans land of fitness. It is a mix of aerobic and anaerobic states. For the amount of effort the athlete puts forth, not a whole lot of fitness is produced. It does not train the aerobic or anaerobic energy system to a high degree. This area does have its place in training; it is just not in base season. Unfortunately this area is where I find a lot of athletes spending the majority of their seasons, which retards aerobic development. The athletes heart rate shoots up to this zone with little power or speed being produced when it gets there." Matt Russ, US International Coach
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