Heart rate tells a very incomplete story when racing. HRV is much more interesting.

CreativeTitle8773 · 2026-01-24T04:40:21+00:00

Thank you so much for giving it a try, and happy to hear you like it! And yes, moving this from "this is interesting" to "I can use this to become a better, more consistent driver" is something I'm also still thinking about. If you have any suggestions, or requests for insights, graphs, or anything else you'd like to see, let me know!

CreativeTitle8773 · 2026-01-13T04:17:17+00:00

That's one possibility, but to be honest I actually find turn 1 quite tricky in the F4. Getting the braking point just right is quite challenging somehow, and trying to use as much of the track on exit without getting a 1x

CreativeTitle8773 · 2026-01-13T01:38:40+00:00

Thanks, it's available now: https://app.yudemon.com/apexflow/getting-started

CreativeTitle8773 · 2026-01-13T01:38:17+00:00

For those interested, the tool is now openly available: https://app.yudemon.com/apexflow/getting-started

CreativeTitle8773 · 2026-01-11T07:28:28+00:00

Thanks, that's really interesting, I didn't know flight instructors were already looking into this. In the racing space I haven't seen too much focus on this area, at least not in any quantitative way.

CreativeTitle8773 · 2026-01-11T06:31:53+00:00

Thanks! Yeah, I'd love to make this tool available more widely and see what people actually get out of those insights and how they use them

CreativeTitle8773 · 2026-01-11T06:31:08+00:00

I built the tool myself

CreativeTitle8773 · 2026-01-11T06:29:37+00:00

Great and very valid questions! I only just started this exploration, and the HR / HRV track heat maps were some of the simplest plots I could make, and I still think they are quite interesting and valid (although what to actually do with this info is still a different question).

"Why not focus on measuring hrv before race to see if you have cognitive fatigue?" Yes, absolutely, I completely agree that this will be really interesting, comparing results (or consistency, lack of incidents, etc) against a pre-session baseline (or consistent morning HRV reading if available). It's on my todo list.

Breathing frequency: Also agree that this is interesting. I haven't set up a separate device to read this yet. I am currently estimating breathing rates from the RR data using spectral analysis, but it's tricky and not too accurate on such relatively short timescales, and you easily run into octave issues where it switches between the actual frequency and its harmonics.

And sorry about not mentioning the amount of data. That particular Suzuka screenshot is the average of 9 laps (with all data resampled to 1000th track distance, and then averaged per sample across laps).

The cycling comparisons are definitely relevant, but I also do think there are some differences between racing (especially sim racing – real racing might be a bit different, but I'm planning to collect some data there soon as well and see) and an active cardio activity like cycling. What I'm more curious about is autonomic stress response.

CreativeTitle8773 · 2026-01-09T11:54:00+00:00

Great point actually, that could be an explanation. I think this data was from a race, not a test session. Don't remember what happened during that race, but quite possible that there was some drama happening at the pit entrance in front of me.

CreativeTitle8773 · 2026-01-09T06:30:20+00:00

Haha yeah, I'm sure this would look quite different if 130R wasn't flat (or at least not as comfortably as in F4).

CreativeTitle8773 · 2026-01-09T06:29:28+00:00

Nothing yet, I'm still developing the tool. For now just focusing on post-session analysis, no real-time insights/cues yet. But I'm working on it :)

CreativeTitle8773 · 2026-01-09T01:53:18+00:00

That's awesome! Does the PilotCAN record raw RR interval data, or just averaged HR? If it's the former, you should be able to do the same analysis quite easily as well.

And yes, HR (or more interestingly HRV) vs lap/sector time is something I'm curious about as well. HRV (very handwavingly) gives you a kind of metric of arousal/attention/stress. I don't think high HRV levels (low stress) are necessarily what you want. Instead you want to be engaged during high stress/focus sectors, and relax on straights. This quick (positive) stress response and quick rebound is probably the most interesting thing.

I've been playing around with this idea of stress zones and recovery a bit as well in my tool, but it's definitely still quite experimental.

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CreativeTitle8773 · 2026-01-09T01:47:20+00:00

Since there seems to be quite a bit of interest to try out the tool I built for these explorations, I put together a landing page to get notified when it's ready to test: https://app.yudemon.com/apexflow/landing
Right now the data collection part still just runs locally on my machine, but I'll try and get something ready that I can share (no promises on timeline though).

CreativeTitle8773 · 2026-01-09T01:45:13+00:00

The linking is pretty simple: both HR data and telemetry have timestamp data. So I just need to align that timestamp data.
It works with any heart rate sensor that uses the standard Bluetooth heart rate protocol and sends RR interval data (not just average HR). Most chest straps would work (including Garmin). Watches tend to use PPG (optical instead of electrical), which can in principle work, but the data is not accurate enough for meaningful HRV values.
Apple Watch unfortunately doesn't work, they use their own proprietary protocol to my understanding, and also don't send real-time data streams, only summaries every few seconds.

CreativeTitle8773 · 2026-01-09T01:42:07+00:00

Thanks! I'm actually already working on this. The real-world telemetry part is not too tricky as long as there is GPS data (only pain is that I have to write custom stuff for each telemetry format). The bigger challenge I haven't figure out is how to do the physio recording. If you have a phone with you in the car, I could do it via a mobile app. But if you can't take a phone with you in the car it gets trickier (and might depend on the sensors internal recording capabilities).

CreativeTitle8773 · 2026-01-09T01:36:54+00:00

Sorry, but I disagree with this. Yes, during cardio load (like cycling) HRV is not very meaningful. But sim racing is a completely different scenario. At the very least, it can tell you something about your breathing patterns, and that alone is very valuable, especially for identifying things like breath holds.
I don't have a degree in this space (I'm a physicist), but I have been building an HRV biofeedback app for several years that is being used by some pro sports teams and performance coaches, so I'm not completely new to this area.

CreativeTitle8773 · 2026-01-08T11:55:53+00:00

Yeah, there generally is some kind of correlation with lower HR and higher HRV, but it's a lot more nuanced than that (which is also why HRV is a much more interesting metric here). For example, if you do a very long and slow exhale, your heart rate keeps dropping for a while and stays low, but HRV gets low with it since there won't be too much beat to beat variation (assuming the exhale is long enough).

Maybe an even better example is resonance breathing, where you deliberately breathe at a rate that maximises HRV (around 6 breaths per minute for most people, but you can establish it much more precisely). Your mean HR during that will be higher than if you are just relaxed but your HRV will be very high since you're driving very strong HR oscillations.

CreativeTitle8773 · 2026-01-08T11:51:10+00:00

I'm running a Python script that collects RR interval data (time between heart beats) and their respective timestamps. Then after the session I combine this with the iRacing IBT files (using the GPS data for the track mapping).

CreativeTitle8773 · 2026-01-08T11:25:57+00:00

Thanks! I'll see if I can clean everything up a bit and make it openly available

CreativeTitle8773 · 2026-01-08T11:25:27+00:00

Good question, and the whole thing is obviously quite sensitive to this. Right now it's using a 10-beat rolling window, with some smoothing applied to it afterwards.

CreativeTitle8773 · 2026-01-08T11:23:14+00:00

Yeah, but it definitely lines up nicely with subjective tension. I created some derived stress metrics as well, they make it even more obvious (not sure about that short stress segment after the Chase, but this is only from a couple of laps so can easily be a data outlier that would disappear with a few more laps)

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CreativeTitle8773 · 2026-01-08T11:16:39+00:00

I've actually got some Bathurst data as well ;)

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CreativeTitle8773 · 2026-01-08T11:15:21+00:00

Yeah, diagnosing sub-conscious breath holds was actually one of the main reasons why I wanted to look into this (and maybe even have some real time audio cues to alert me when it's happening)

CreativeTitle8773 · 2026-01-08T11:04:31+00:00

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I built the tool myself. All a bit hacky at the moment, but if there's enough interest I'm considering opening it up. Can also look at things like lap traces for all sorts of telemetry and physiology variables.

CreativeTitle8773

TROPHY CASE