A few weeks ago, Garmin released their new HRV measurement tool for the Fenix/Epix lines. It measures your HRV during sleep. (You can see some other wearables that measure HRV here.)
I won't go into a lot of details on what HRV is, but it's the variance in time between the beats of your heart. In case your nervous system is balanced, the HRV levels will be high (indicating healthy levels). In case the HRV is low, then it's a result of the sympathetic system signaling due to high levels of stress among others.
I started looking at my HRV levels since, and to my surprise, after a few days, I started having lower levels than usual. (see the first orange result, which indicates lower than usual levels)
On the third day, I had a headache, and I started being suspicious.
I checked my sleep levels, and basically, there was no REM activity during my sleep - the sleep score was quite bad.
Also, my training readiness was as follows:
My watch was indicating that I should not be training, since something was going on. I also checked my resting heart rate, and it was 5% higher than usual.
Hence, my HRV was lower, my RHR was higher, and my sleep and my training readiness were extremely low. And all these changed before having any symptoms.
I went in for a COVID test - and it was positive.
