The heart rate sensor on the Garmin Cirqa screen-free tracker powers pretty much all the important stats you get from the device. It’s key to sleep tracking, your body battery and training readiness scores, and your heart rate variability readings.
So it must be accurate, especially as, unlike with the best Garmin watches, you can’t pair an external heart rate monitor to the Cirqa to get more accurate data if required.
That’s what I do with my Garmin Forerunner 970, even though it has a pretty reliable optical heart rate sensor built into the watch. I pair the Garmin HRM 600 chest strap to the Forerunner 970 for my workouts, because chest straps offer an extra level of reliability.
Unlike optical sensors, which use LED lights to measure your heart rate via your blood, with your pulse changing the power of the light that comes back to the sensor, chest straps use electrical signals directly from the heart. They are more accurate and faster to respond to changes in heart rate.
Testing the Garmin Cirqa’s heart rate accuracy
The Cirqa uses Garmin’s Elevate Gen 4 sensor, which is not the latest sensor in the brand’s line-up — most of its watches now use an Elevate Gen 5 sensor, but Garmin told us this was too large for the Cirqa at the launch of the strap.
Having spent the last couple of months testing the Garmin Forerunner 170, which also uses the Elevate Gen 4 sensor but has been accurate in my testing, I wasn’t concerned that it would lead to poorer results with the Cirqa.
I’ve had the Garmin Cirqa on my wrist for a couple of days, and to check the heart rate accuracy of the device, I’ve done two interval running sessions on the track, an easy run, and a strength workout.
I don’t yet have the bicep band accessory for the Cirqa, but I have tested it on my wrist and on my forearm. In general, optical sensors like this are more accurate in thicker parts of the body where there’s more muscle, and the higher up the arm, the more stable the sensor tends to be.
The forearm is usually a little better than the wrist, and the upper arm is better still, so the bicep band could well be a worthy extra purchase if you pick up the Cirqa.
Top marks on my easy run
First up, the easiest test I’ve done so far with the Cirqa — a 40-minute easy run. I’ve rarely seen errors from Garmin watches during this kind of run in recent years, so I expected the Cirqa to match up with the Garmin HRM 600 chest strap more or less perfectly. I wore it on my forearm for this test.
As you can see from the graph (created with the DC Rainmaker Analyzer), the Cirqa matched the chest strap beat-for-beat throughout the run and ended up with an average heart rate of 111.39bpm vs. 111.50 bpm on the chest strap. Flying colors.
Impressive during intervals
Interval runs are a tougher challenge for heart rate sensors because they have to track rapid rises and falls in heart rate. I did one session running 4 x 8min with 90 seconds recovery, and one with shorter intervals — 12 x 600m with 90 seconds recovery.
I’d expect to see a slight lag in the readings from the Cirqa compared to a chest strap, because the chest strap responds quicker to changes in heart rate, but otherwise I’d hope to see the same rise and fall in heart rate during the interval workouts.
In the workout with longer intervals, the Cirqa was pretty much spot on when I was running hard, but didn’t drop as low as the chest strap between most of the intervals.
When doing shorter reps, you can see that the Cirqa often took a little longer than the chest strap to rise to my higher heart rate when I started running hard, but it did track the rise and fall of my heart rate pretty well throughout the session.
I wore the Cirqa on my wrist throughout both these workouts, and overall I was impressed with the heart rate accuracy.
Mixed results during a strength workout
I wore the Cirqa on my forearm for the 15-minute strength workout I did, which was a mix of weights and bodyweight exercises done at a fairly slow pace, so my heart rate didn’t climb too high throughout.
The Cirqa struggled more in this session than on the run, though the differences between it and the chest strap are exaggerated on the graph because it’s a shorter workout and my heart rate didn’t vary that much — the average heart rate measured by the Cirqa was 89.31 compared to 92.62 on the chest strap.
Still, it didn’t follow the reading from the chest strap that closely. I think for strength training, the bicep band would be a useful upgrade for the Cirqa.
More testing to come
It’s still early days in my testing of the Garmin Cirqa and I want to do a lot more workouts with it, trying out the bicep band in particular, but it has proved quite reliable overall so far.
Outside of workouts, I have little doubt the sensor is accurate, and the average and resting heart rate readings I’ve seen during sleep in my first two nights with the device look good, though I’ve not tested this against another sensor yet.
Whether a screen-free tracker is the right option for you also depends on a whole load of other factors, but the heart rate sensor on the Cirqa has been good for me so far.
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