[00:02] wearable market with their new Circa, but there are several important questions that cannot be answered by simply looking at the device. What happens, for instance, when you wear the Circa alongside another Garmin watch?
[00:14] Which device gets priority when you're recording data with both? Does the Circa use the same sleep stage tracking as Garmin watches? And does wearing it on measurements? Now, my sample should arrive maybe within the next hour or
[00:28] two. So, in this video, we're going to answer all those questions, then set up the Circa, and immediately put it through its first real tests. Now, for name is Rob, and I'm a post-doctoral scientist specializing in biological
[00:43] data analysis. And as always, that will be the focus of this video, data and data analysis. And once the Circa arrives, I want to test it during an outdoor run, an indoor cycling session, and some weightlifting. And I will
[00:55] compare its heart rate measurements against a reference device, an ECG chest strap, and show you the actual results, including where it performs well and where it might struggle. This will, of course, only be an initial impression of
[01:08] its performance. For my real testing, I want to do multiple rounds of each type of exercise, and also do outdoor cycling. And I also want to look at the sleep heart rate, heart rate variability, and sleep stages. I'll
[01:21] collect all that for a more complete set of data over the coming week or two for my first proper review. As before my Circa arrives, I want to go over some of the details that could be just as important as its raw measurement
[01:33] accuracy. I asked Garmin a fairly extensive list of questions about the Circa, including which optical sensor it uses, how its automatic activity detection works, whether its algorithms are adjusted from when you wear it on
[01:47] your wrist versus your biceps, and how the Garmin Connect app handles data when you use both your Circa and a Garmin watch. Now, Garmin has now sent me detailed answers, and several of those answers are really interesting. So,
[02:00] let's dive into those questions first, then once my Circa arrives, we'll set it up and start the testing. And let's start with the hardware. Now, according to Garmin, the Circa comes with the same Elevate V4 sensor you have in some of
[02:13] the cheaper Forerunner models, for instance. So, it's the fourth generation of its optical heart rate sensor, together with a skin temperature sensor. Now, that's not Garmin's newest optical heart rate generation. However, the
[02:25] doesn't automatically tell us how accurate the final readings will be, and we actually saw that these Forerunner models, these relatively cheap devices, were already really good. Now, the fit of the device, the placement on the arm,
[02:37] the algorithms, and the type of movement can have a substantial effect. And given that the Circa is quite light, it might actually do relatively well. That's exactly what I want to test during several very different exercises.
[02:49] fairly repetitive movements, which can cause interference in the signal. Indoor cycling tends to be a lot easier for the optical heart rate sensors, and challenging activity because of the wrist movement and tension. And of
[03:03] course, there's also a rapidly changing heart rate. Now, the Circa, compared to other screenless wearables, has a physical button. And out of the box, that button starts and stops a timed activity. Garmin says you can assign it
[03:15] to any one of more than 80 activity profiles supported by the Circa. The button also has some secondary functions. Three quick presses can put already be in pairing mode when it's first turned on. If you use an alarm,
[03:29] the button can snooze or dismiss it. You can also enable heart rate broadcasting in Garmin Connect, and then press and hold the button for 2 seconds to switch between broadcasting on or off. Holding it for longer should also place it into
[03:42] pairing mode, as I understand it. Garmin also says that additional button-related enhancements are planned for future releases, so more to come. Now, heart rate broadcasting works over both ANT+ and Bluetooth, and Garmin says it can be
[03:55] used with both Garmin and non-Garmin devices. That could make the Circa monitor, especially when worn on the biceps, for instance, during an indoor bike ride or compatible gym equipment. Now, one interesting detail from
[04:09] Garmin's battery explanation is that simply enabling heart rate broadcasting should only cause a relatively small increase in power consumption. According to them, the amount of time spent recording timed activities has a much
[04:21] bigger impact on battery life than heart rate broadcasting or connected GPS. The Circa can also detect certain activities automatically. Now, Garmin list of activities because according to them, that feature is continuously
[04:35] changing. In general, higher intensity activities are more likely to be detected because they have much clearer patterns in changes in heart rate and movement. And an activity needs to last at least 15 minutes before it can be
[04:48] detected automatically. Importantly here, Garmin says that the classification is personalized. So, when you review, confirm, or correct detected activities, the system uses your history and your movement patterns to improve
[05:01] future classification, so similar to how Fitbit does it, for instance. Garmin says users should expect adaptation to take a few weeks and require multiple completed. So, it's not something that they can properly judge from one or two
[05:14] workouts, and this should be interesting to evaluate over a much longer period. Now, another key feature of the Circa is that it can be worn on either the wrist or on a biceps band. They actually call it an armband. The band does not
[05:29] wearing it. Instead, you have to select the wearing location in Garmin Connect under the Circa's user profile setting. You can also change the wearing location for an individual activity. Now, Garmin says its algorithms are adjusted based
[05:43] on that selected location, including specific adjustments to the sleep stage algorithm as well when the device is worn on the upper arm. Now, Garmin expects that the wrist and the upper arm placement should provide comparable
[05:57] sleep results. Of course, this is something I would like to put to the test for myself. Most companies are pretty clear on the fact that biceps measurements usually are better for heart rate specifically, though at night
[06:09] it might be less of an issue. Now, most features do remain available when you're wearing it on the upper arm. The two exceptions that Garmin mentions are wheelchair pushes and rep counting during workouts. Now, Garmin also told
[06:22] basically the same one that is currently used by its watches as well. Although there are slight differences in how this tuned for the wrist versus the upper an interesting option for sleep tracking, especially for people who find
[06:37] the device on the wrist uncomfortable at night. I will therefore want to compare not only the heart rate and heart rate variability, but also the sleep stages during the night on both the wrist and the biceps. Now, Garmin might have
[06:49] that their Index sleep monitor is also worn on the biceps, so they should have algorithm. Though, of course, that device uses a newer Garmin sensor. Now, the Circa also has a smart alarm like many of the devices now do, and that
[07:03] alarm creates a 30-minute window and tries to wake you in an optimal point between when you say you want to wake up and that 30 minutes. Now, according to really affect battery life much. Now, it'll be interesting to see if this is
[07:16] very reliable and also how strong that vibration is. Now, one of my biggest questions was how does Garmin Connect handle the Circa data when you're also using a Garmin smartwatch, for instance, a Forerunner
[07:28] or maybe you have a more outdoor Garmin watch. Now, Garmin's answer is that the system relies primarily on your classification of the primary wearable setting. If two Garmin devices record the same data at the same time, the
[07:42] device that's selected as your primary wearable is used to break that tie. So, daily health metrics such as sleep, body battery, steps, and other overlapping measurements that you're taking are primarily decided based on what you set
[07:55] is your primary wearable, so the band or the watch. So, Garmin doesn't actually merge simultaneous measurements, it actually just takes the priority one. But, Garmin says that switching between the Circa and a watch during the day
[08:08] should not create significant gaps because its true up synchronization system does keep the data aligned across devices, and if you're only wearing one, that Garmin specifically gave is probably the most logical use case, so
[08:22] day and during sleep, and then you can watch for your workouts where you have built-in GPS needed, a display, and maybe training guidance. Garmin says that there's not much additional benefit
[08:36] to wearing both devices at the same time because again, where data overlap, Garmin Connect will prioritize the primary wearable rather than combining them. There's also an important rule for overlapping activities here. If the
[08:49] Circa automatically detects an activity, but you manually record an activity from another Garmin device, and it's synchronized for the same period, Garmin Connect will not display the automatically detected Circa activity.
[09:02] That should prevent duplicate workouts from appearing in the app without you In theory, this all sounds reasonably straightforward, but we've seen some to see how smoothly this works in real use, especially when moving between the
[09:17] Circa, a Garmin watch, and maybe even external devices connected to these how that works. Finally, Garmin says there's up to 10 days of battery life, but of course, the actual battery life will depend heavily on how it's used.
[09:31] for instance, can reduce the total battery life by as much as a couple of days, although the exact effect varies by factors such as movement, perfusion, and skin tone. And Garmin's battery 10-day assumption includes approximately
[09:45] 30 days of timed activity per day, so not a lot of activity, but not little. And both manually started and automatically detected timed activities have a measurable impact on your battery consumption. Now, connected GPS and
[09:58] heart rate broadcasting do add some power usage, but Garmin says duration of the timed activities is probably the most important factor. So, those are the know from Garmin and they shared from me before I received the device, and I'm
[10:12] really excited. It should be here within an hour or so now. There are some promising ideas here, particularly the option to wear the band on the upper arm and the integration with Garmin Connect while using it also with another watch,
[10:25] and of course to broadcast your heart rate to another sensor, especially if on the biceps that's performing really well. But again, specifications and feature descriptions can only tell us so much. What I really want to know is how
[10:38] good the data are. So, the Circa should arrive soon. As soon as it does, we will take a quick look at the device, pair it with Garmin Connect, go through the most important settings, and check how the wrist and upper arm placement option
[10:51] works if we can find it in the settings. After that, I'll take it outside for a run, then use it on my Zwift bike for an indoor cycling session, and test it while lifting weights. I will then compare those recorded heart rate
[11:03] reference device and show you the results. Now, my plan is to wear the Circa in the beginning on the wrist of my non-dominant arm, so Garmin didn't share a biceps band yet. That should
[11:15] arrive maybe in a week or so, so all the first testing will be on the wrist. Be aware that most of my testing off-screen this device is long-term is on the biceps just because that provides better heart rate measurements, and I want the
[11:27] device to be tested at its peak. So, let's wait for that bell to ring.
[12:01] so let's unbox it, set it up, make sure it's set to the left non-dominant wrist going to do the exercises. Now, it's your standard Garmin box for their
[12:13] cheaper devices, I would say. Usually, the more expensive ones come in these kind of square boxes, at least lately. Cheaper ones like the Forerunner series usually come in these similarly sort of triangular-shaped
[12:27] triangular-shaped boxes. Now, this device is on loan from Garmin. I am seeing if I can buy it from them, but otherwise, it needs to go back to them after a month or two. I also ordered about three of my own, but it
[12:41] all takes a long time to get delivered here in Europe. I think I tried to order from four different companies now, or three uh from Amazon and some local ones, and it all takes months to get here. So, I'm
[12:55] happy that Garmin was able to loan me one of their devices. So, as you can see, it uses the standard Garmin ports from Garmin, so you can use any of your Garmin chargers. So, theoretically, when I turn it on, it should be in pairing
[13:09] mode, and there are already wearables in this account, so I want to see how it goes when pairing an extra device, if that gives any issues or not. At the moment, my Forerunner 70 and Forerunner 570 are connected.
[13:28] That worked. Flawlessly and even the color is correct to the one that I color is correct to the one that I received. So now, as you can see, it's set up and we want it to be our primary wearable.
[13:43] I'm not a wheelchair user. Yes. Okay, so that's good. So I'm going to wear it on my wrist for now on my left arm. So here I set up a few of my favorite activities. It can be up to 10.
[13:59] So let's sync it up and let's see if any updates are required. I'll set it all up workout and then quickly we're already getting to the results. So I'll do all for the video. So let's see some b-roll
[14:13] of me running and indoor cycling and weightlifting and then we're going to get to the results. So it's several hours later and the results are in, the very initial results I should say. And we're going to take a
[14:26] that running session and that weightlifting session. And to start with the running session right here, we have the reference device in blue-green,
[14:38] which is the Polar H10, and the Garmin Circa worn on the wrist in red. And this is the time along the horizontal axis and my heart rate along the vertical axis. And I did several intervals and all of
[14:53] these were more or less correctly detected by the Garmin Circa. So really nothing to complain about here. I did have the issue where it lost connection while I was cycling, so I had to stop it early. I think it would have been fine
[15:07] data, but I just want to make sure not to lose any data. So that was the one hiccup I had here. The good thing is the Circa does appear to work even when you don't have internet. So that was an issue I had
[15:20] even needed internet to stop the exercise. I'm not sure if that's still the case, but that could be an issue if you're doing really big outdoor hikes and you don't have a connection. But so far, this is looking good. By the
[15:34] way, if you're also keen on getting yourself such a cool Zwift indoor bike, either the whole bike or just the trainer part, there's now a big sale going on. If you want to use it, use my affiliate link up here or down here.
[15:47] channel. Thank you so much for considering, but let's finish this and take a look at the results. So for indoor cycling, which tends to be an easy exercise for devices to track, this very initial test does look very
[16:01] good. So if it continues like this, I would be perfectly happy with the Circa. harder and I made it quite hard this time. So I did a lot of intervals, very short intervals, and then stopped for a
[16:15] have my heart rate all over the place, also going faster and slower sometimes. And as you can see, it generally looks good, but there were a few moments where
[16:28] reference. So again, the ECG chest strap is in blue-green and the Garmin Circa in red. And much of the time, it followed along quite well, and it was able to detect all of the dips in my heart rate, which is where many devices struggle.
[16:42] deviation. Right here, while I was still running, it detected the dip in my heart rate. Here, there was a slight delay picking up on increase in heart rate. And a few moments where it detected
[16:54] quite a high peak in heart rate. And for me, it is not likely I would get to a heart rate of, let's say, 170, cuz for me, that's all-out running, and at this point, I was not running all out. These are still relatively minor differences,
[17:09] and I'm really interested to see when I do maybe five or six runs, what these results will look like. But this again says to me that it's likely better to wear it on your biceps. Now, I just heard that my biceps band will not get
[17:22] here until 6 weeks from now. So, I'll see if I can get some other solution to make a biceps band, maybe. But, I'll do my best to get that as well. But, my first testing will be on the wrist just because I cannot get a biceps band from
[17:35] Garmin at this point. So, it will take a while to get those better results likely from the biceps. But, as I said, I'll try to make it quicker. So, for running, I would say the results are a bit mixed. They're not terrible, but I'm curious to
[17:48] see if these weird artifacts keep happening because as we just saw in my testing of the Garmin Forerunner 70, and as you will see soon in my testing of the Forerunner 170 Music, which has the same sensor, I didn't have any of those
[18:02] issues. Now, for weightlifting, I didn't have high hopes because basically no device on the wrist is doing that well for weightlifting. Indeed, many of the times that I had a peak in my heart rate, the Circa wasn't fully able to
[18:15] detect those peaks, but it was able to detect more than I thought it would. Though, there's also this weird artifact here where it detected an early high peak. So, it likely detected roughly double my heart rate. Just an artifact
[18:28] we more often see in devices. Overall, for this simple exercise like indoor cycling in this initial test, it's almost perfect. Running again somewhat future testing does. Of course, maybe this one time it wasn't perfectly
[18:42] positioned on the wrist, who knows. What I did do is I wore a long sleeve over it to give it a better chance of not being interfered by the sunlight. Overall so far, I'm not disappointed. I would have wanted slightly better running results,
[18:56] but as I said, these are super initial. So, these are just the results I got in one day. I just wanted to show you my initial results because I was excited about testing this device. More testing to come. Also, check out other
[19:08] reviewers. But, if you do end up getting yourself the Garmin Circa, or maybe instead you want a Fitbit Air, or a Whoop Strap, or Amazfit Helios Strap, another device, or anything at all on Amazon for that matter, even something
[19:23] beans, and you want to support the channel, use one of my affiliate links down below, many of which give you the best discount possible. Of course, don't forget to subscribe and like this video, but given that you watched this video, I
[19:36] think you will like this video on the Fitbit Air, and this video on the 80 Fitbit Air, and this video on the 80 Sleep Pod.