[00:02] Garmin Circa and you just can't wait to get it. Well, hold on. First, you need to make sure it actually fulfills all your wishes and that it actually performs well. Now, my full review will still take a week or two to complete
[00:16] since I want all the data I can get before making my judgement. However, if you want some early insights into the heart rate tracking performance both during exercise and sleep, heart rate variability measurements, and sleep
[00:28] stage tracking of this Circa, then this video is what you're looking for. Now, these are all the results I obtained for my first four days and three nights of Garmin Circa testing. So, strap in for those initial results. Now, for those of
[00:43] you that are new to the channel, my name is Rob and I'm a post-doctoral scientist specializing in biological data analysis. And as always, that will be the focus of this video. As I said though, the details of the results might
[00:56] still change a bit as I gather more data. However, this video will give you a first impression for those that are on the edge of deciding of whether or not they want to grab a Garmin Circa. At the end, I'll also share some of my personal
[01:10] experience and some of the quirks I've had with the Garmin Circa. And let's and let's start with some nighttime measurements, specifically the heart rate and heart rate variability data. Then, we'll move to the sleep stage
[01:24] at the heart rate tracking during exercise. By the way, you might have noticed this is not my normal studio. I'm actually turning 38 by the time day before. So, I'm here visiting my parents and this is my old childhood
[01:39] home. And this here is actually the room I grew up in when I was little. But, I have all the results here on my laptop, so let's take a look. And as I said, I the nighttime measurements because these are not shown in my initial review. And
[01:54] reference failed for one of the three nights. I do have three nights of data for the sleep stages. Along the horizontal axis, we have that reference, which is a Polar H10 ECG chest strap, which can measure my heart rate quite
[02:07] reliably. Along the vertical axis, we have the Garmin Circa. And if the two would perfectly agree, all points should be on or close to the black line. But we're looking in a super narrow window, so between, let's say, 42 and 52 bpm.
[02:21] And within that, the Garmin Circa was quite well able to distinguish my heart rate. We can actually take a look at some example nights right here. This is the first night I have data for, with the reference in red and the Garmin
[02:33] Circa in blue green. And indeed, over time, the patterns agree very well. Only the Circa sometimes detects a slightly higher heart rate for just a moment. And I think these might be moments when I get out of bed, and then
[02:45] slightly different from the way I calculate it, because I have to they put more emphasis on these high heart rates, potentially. We see the same for the second night right here. Overall, the patterns agree very well.
[02:59] the Garmin Circa is just good enough, or actually quite good. I would be harder is measuring heart rate variability, because you need to actually measure the individual distances between heartbeats. So, let's
[03:13] take a look at those results. Though, they are slightly worse in some ways. So, in the higher HRV range right here, the Garmin Circa tends to detect slightly lower values, so the reference is a bit higher right here. But overall,
[03:27] can actually see that we're looking at some of the individual nights. So, we have the Garmin Circa in blue green and the reference in red. And indeed, the reference in the higher heart rate range tends to be ever so slightly higher. But
[03:40] again, I have to guestimate here how Garmin calculates this. And overall, this is just looking very good. Also, the second night looks very good. But beginning, it has slightly too high HRV, at least compared to how I calculate it
[03:54] with the reference and here in the end slightly too low but overall the patterns agree very well and I just have nothing to complain about here. I'm heart rate variability measurements during the night and if you rely on
[04:07] those to get a better estimate of your recovery, I think these are quite reliable. But what about the sleep stage tracking? And this I tested using an EEG waves which is sort of a silver standard in testing and those results are
[04:21] displayed right here with the sleep stages as measured by the reference on top and the Garmin Circa on the left and if they would perfectly agree all values on the diagonal in yellow right here should be 100%. Deep sleep agreement
[04:34] really good at 77% so that's some of the best I've seen. Light sleep agreement okay at 64% and REM sleep agreement is the worst at and REM sleep agreement is the worst at 46% and more of what the reference said
[04:47] being a light sleep instead by the Circa. So that's the sleep stages struggled most with and actually more than some of the other recent devices I've tested so the Forerunner 70 and 170 and these have the same sensor so I
[05:00] you will see in some of the example nights Garmin basically detected no REM most of these nights. Well let's first take a look at deep sleep which agreement was quite good. So all the deep sleep detected by the reference on
[05:15] top is marked in blue purple and also marked in the same color on the bottom measured by the Garmin Circa. And what you can see is that basically all of the also detected as deep sleep by the Garmin Circa but just a bunch of extra
[05:31] also see that for the second example night right here. So deep sleep good but where results get weird. So for this night right here for instance the first
[05:43] three quarters of the night no REM sleep was detected so the REM sleep as marked by the reference is on top and then I took the same marking on the bottom. You can see that only here at the end the Garmin circuit detected some RAM sleep,
[05:56] but very little and not exactly correctly positioned. And if we take a look at this second night right here, again for the first two thirds of the night no RAM sleep was detected, but the last two seconds agree rather well. For
[06:09] this last example night no RAM sleep was detected for the first half of my night, rather well. So, Garmin seems to struggle more with RAM sleep for the first half of my night than the second half. Now, this is personal to me, but I
[06:22] find it interesting to see. So, you decide what you make of it. I'm actually I already asked them some questions. If I have more info, I will let you know. the same algorithm actually as on the Forerunner 70 and 170. So, I would
[06:37] expect with more testing that results get better. And here we have an overview of a lot of the testing I've done where the best devices are the watch at top right. Let me zoom out a little bit. So, along the horizontal axis we have the
[06:49] average sensitivity over those three stages and along the vertical axis the worst sleep stage out of the three. So, it's not doing really bad, but also not as good as some of my more recent Garmin testing of the Forerunner 70, but also
[07:03] video will come out soon. So, it's somehow a little bit lower. Again, I don't know if this is by chance. It's not like it's doing really bad, but instead of being second tier it's closer to third tier, but higher end of third
[07:17] tier. So, not sure what to make of this. I'm really curious with my full review when I might have 7 to 10 days, which again I would want more, but I can do curious if it then moves up a little bit and gets closer probably to the results
[07:30] of the Garmin Forerunner 70. I might even exclude these first three nights just to start fresh for that full review. So, the heart rate tracking performance is pretty okay, but not great. Somewhat middle class to higher
[07:43] middle-class in terms of heart rate tracking. Close to second tier, but not quite where the 470 was, for instance. But, what about heart rate tracking during exercise? This is probably one of the main reasons many people get a
[07:56] Garmin. So, I roughly doubled my data now compared to my initial review, and I actually want to start with indoor cycling, where we now have two indoor very good. So, if the reference is on
[08:09] vertical axis, and if they perfectly agree, all points should be on or close to the blue line. This just looks very good with a correlation of 0.99, which is very close to the maximum of one. So, that looks very good. Now, you already
[08:22] saw this example spinning session. Now, the second example spinning session also deviation in the beginning, but very minor. Nothing that would influence how I train. So, this is just good. Happy with this. But, what about running? Here
[08:36] we saw some artifacts in the initial review, and that's this run right here, and there you could see it struggled a little bit in the beginning, and also didn't really have, at least most likely I didn't have according to the
[08:49] reference. But, now I did a more steady run, and this actually looks really good. So, here they agreed very well, even when I took a break in between. So, and then a slower half after, and it didn't lock on to my cadence, so that's
[09:03] those two now leads to a correlation of 0.93, which is pretty okay, or pretty good, I would say. It's not perfect yet, but I expect with more runs that the results will probably look more like this, because I usually run more similar
[09:17] to this. I normally wouldn't do these very short intervals, but that might be Garmin struggles with a little bit more, at least on my body. But, what about biking outside? This we haven't seen in my initial review, and this actually
[09:30] competition. We have a correlation of 0.94, and most points are on or close to If there's deviation is more below the blue line than above it, so more often is likely to low heart rate. But if we take a look at those sessions, we can
[09:45] see most of the intervals were caught with some minor deviation. Also in this session right here. So bike riding looking very solid so far and the lighter weight of the Epix Pro here might play a part in it doing better
[09:57] than some other Garmin devices with the same sensor and even though with a newer sensor. So that's heart rate tracking during exercise. I didn't do an extra weightlifting session, but as we saw in my initial review, there are the tension
[10:09] signal. So So in general, Garmin devices on the heart rate tracking during weightlifting. But most devices don't do And that brings me to one thing that I
[10:23] haven't been able to try yet and that's the biceps band. By this point, I've ordered five different ones from five different companies and I'm seeing which one arrives first, but all indications are it will take weeks before I can test
[10:35] it on the biceps. The downside is here that the Epix Pro doesn't use a typical size of connectors for the band. So if you see the band right here, you can see that these connectors right here are rather small. So not the best probably
[10:52] for getting a generic band. I searched online. I couldn't find a generic band yet that fits this size. I think a normal size would be like 22 or 26 mm, but this is much smaller. So if you know about any biceps band not from Garmin,
[11:05] let me know and I will buy it and get the testing done also on the biceps. Because usually devices do perform better when they're worn on the biceps. measurements. The sleep stage tracking might actually be a bit worse because
[11:18] the algorithm Garmin might be less optimized towards that, but if you change it in the settings, it should take it into account. So make sure that you set both your wrist, so non-dominant versus dominant, and whether you're
[11:30] wearing it on your biceps, on your wrist, that will influence performance. For me, overall so far with this initial test, I'm pretty happy. It's not perfect by any means, but the heart rate tracking is pretty okay, probably good
[11:44] enough for me. The sleep stage tracking is the one thing that could be better, variability measurements during the night also looks pretty good. There are a few weird things that have happened so far. So, the one thing is that one of
[11:56] the exercises I tried to manually log with the button just wasn't recording. I'm not sure what's going on, and it actually takes quite a while each time to sync the Circa with my phone, a bit longer than some other devices, and in
[12:08] some moments this has been a bit annoying. Nothing really bad. Overall, comes to heart rate tracking, it's pretty okay, and I'm super curious to see what it does in the biceps because this could be one of the best Garmin
[12:23] devices out there for heart rate if it improves on the biceps, a lot better even than some of their more premium devices on the wrist just because this location for measurements is a lot better in general. Now, otherwise, of
[12:35] course, you're still dealing with the normal Garmin app, so you need to like that it is a little bit clunky in some regards because they need to take into account so many types of devices that they make, and it's sort of historically
[12:47] developed. So, for a general data overview and interpretation, I'm not personally the biggest fan of the Garmin app, but as a data aggregation app, it's really good, and I love how many devices I can connect to this and later look
[13:01] back at how my exercises went and how my trainings went. Now, stay tuned for my full review on the Garmin Circa. This was just a quick update I wanted to provide you with because I thought the data was just super exciting, and I had
[13:13] to do it on my laptop right here with a very improvised setting here in my old bedroom. Now, don't forget to subscribe if you want that update, and it would and leave a comment. Now, if you do decide to order yourself a Circa, maybe
[13:27] you want the Fitbit Air, an Apple Watch Ultra 3, or another watch on Amazon, use my affiliate link down below to support the channel without it costing you any extra. Or if you decide to get another device like the Whoop Strap, the Aura
[13:41] to get the best discount possible, my channel and support your wallet at the same time. Now, given that you watched this video on the Garmin Circa, I really recommend checking out this view on the
[13:55] Garmin Forerunner 70, which is almost the same price as the Circa but has a screen and did really well in my testing. And check out this video on the testing. And check out this video on the Eight Sleep Pod.