I am a marathon runner, and I routinely mention this not (just) to prove that those memes about runners always talking about running are absolutely correct: We do.
I do it because I’ve gotten there by using technology. ChatGPT training helped me comfortably run half-marathons, while the Apple Watch and iPhone helped me track all my training runs and races. Gadgets and AI made it seem easier to run marathons, and I’m not about to stop anytime soon.
I have to bring that up to explain, again and again, how much the Apple Watch Series 10 is disappointing me. I’ve been thrilled with Apple’s latest wearable flagship when it comes to battery life and charging speed. These are great upgrades over my Apple Watch SE, which I abandoned once its battery health dropped below the 80% mark.
However, the Apple Watch SE never gave me reasons to question its ability to record heart rate data correctly. Meanwhile, I’ve experienced several issues with the Apple Watch Series 10 heart rate, which I’ve written about extensively in the past few months.
What usually happens during training sessions is this: The heart rate sensor will not display the actual heart rate for several minutes at the start of the session. Sometimes, this will happen throughout the session, whether it’s a run or a walk. It doesn’t matter what the type of exercise is, really, and I’m not the only one to experience it.
But Monday’s 12km run gave me another reason to worry about the accuracy of the Apple Watch Series 10’s heart rate sensor.
It was all a regular run, where I had planned to do anywhere between 10K and 15K, at a moderate effort. As it is customary with runners, especially those fearing the Apple Watch Series 10 would not record data accurately, I checked the wearable soon after I started running, only to see it fail to display heart rate data. Of course.
I then decided to keep checking it every few minutes to see whether it started recording information. Soon enough, I got the stats in the top image. Six minutes into my run, my Watch told me my heart was racing at over 150 beats per minute, despite the slow pace I was giving that first kilometer. I had to snap a picture, and by the time I fumbled with the phone, it had reached 171 beats per minute.
I didn’t feel like my heart was beating that fast. Seeing the stat might give others a reason to worry. Your heart shouldn’t be racing like that, that early into a running session.
I was curious to see how high it would go, suspecting the heart rate sensor was having issues. Soon after I took that pic, the heart rate settled at around 127 beats per minute.
A look in the Fitness app shows that the massive hike early in the run was recorded just as I had experienced it.
As you can see, I then increased the effort progressively and then took a short break for a gel after about 6K. My target for the session was staying in Zones 3 and 4, therefore between 140 and 165 beats per minute.
As a longtime Apple Watch user, I’m annoyed to see the heart rate sensor on a flagship device fail this often. I don’t appreciate the gaps in readings, which, by the way, happened again a few minutes after that 171 max, as seen in the graph above. And I don’t appreciate seeing the wrong readings.
Could my heart rate have gone up before settling? It’s always possible for such readings to appear early in a training session. But it’s unusual to see such a high heart rate.
For comparison purposes, here’s what my heart rate readings look like for the last marathon I ran:
Back to Monday’s run, the Watch should have rather attempted to save my life and send me to the emergency room after giving me that reading.
The whole thing felt like the Apple Watch Series 10 was taking a guess at my heart rate after a few minutes of not showing any readings. It’s like it decided to show some random values before actually performing readings.
Now, here are the stats for Monday’s run, which I’m using to explain my next points.
First, I ran much faster during this session without going all out, and my heart rate never went as high as it supposedly did during that sixth minute. I was perfectly fine, but I definitely felt the extra effort.
Second, how am I to trust those averages? If those initial readings are wrong, which I suspect they are, they mess up the average pace and heart rate. This, in turn, probably impacts the calorie algorithms. In the long term, these stats will affect the health and training trends of the watch registers.
I’ll also repeat what I said before. If the heart rate fails to take readings during training, how do I know it’s taking enough readings while I’m at rest? And if it is, how do I know they’re accurate?
I don’t want to question the data that comes from the Apple Watch like this because then I’ll question its ability to save my life one day.
I could buy a different heart rate sensor to use during runs and then compare the readings with those of my Apple Watch Series 10.
As before, I’ll note I’m running the latest watchOS 11 beta. Whatever is causing these heart rate reading issues, Apple hasn’t fixed it since I started noticing them.