OK, this is good to hear. 170 didn’t sound as serious as some of the heart rates I thought I’ve heard before. But I’m not an MD. I’m glad alternative explanations have been advanced.
Maybe if there were other things described like light-headedness as a primary example. Again, I think we’re reaching for other explanations when the simplest one is probably correct. This isn’t an unusual phenomenon, particularly for people who don’t have a ton of (recent) race experience.
If I had a nickel for every marathoner I’ve heard about that thought they were going to bank a few seconds every mile early on and PR by a few minutes that ended up running like 20 minutes slower because of it, I’d have a TR subscription.
Not a bonk, and to bring it back to the excitement angle, my highest HR ever was during the first 8 minutes of a 9 mile descent. So we leave a little mountain town and start a 9 mile descent. The narrow road has bad pavement, rock debris, and potholes. And incredible views of a deep river canyon in the Sierra mountains. Had to use brakes to keep speed down.
First 2 minutes my HR was 111bpm. And then for the next 6 minutes, with only 3 watts of average power, my HR shot up to 186bpm. Hit 184bpm for 2 minutes. Completely unaware until after the ride. My peak HR after going all-out (outside or ramp test) is 175bpm.
Seeing that freaked me out, and I went and had a heart checkup. I’ve had 2 other incidents (2020 and 2021), not as high and much shorter, and on those my Apple Watch confirmed the readings from heart rate chest strap. But again no bonk.
I can’t explain any of those, except for excitement over roads/cars in 2 cases. The other incident it was hot and I was mentally agitated about something at work.
Personally I’d get a checkup instead of worrying, but thats me. You mentioned Apple Watch, and FWIW I’ve turned on a-fib tracking (you have to say “I’ve been diagnosed with a-fib” and it burns a little more battery). Did that for more frequent all-day HRV tracking (to feed other apps), but it gives me some peace of mind just in case. If you enable that on AW, you’ll get weekly notifications if you do that (mine on Monday mornings), If everything is normal you will get a weekly notice saying something like 2% or less.
I’ve got a nickel for you at least. Only run one stand alone marathon and the first mile is probably within the top 5-10 fastest mile’s I’ve run ever; alongside dedicated mile attempts and 5ks.
Lesson in not going out too fast as well as not trusting the pacers. The 3:00 pacer (who I was trying to keep in sight, I was targeting 3:05) ran something like a 5:15 mile. Realized unless I slammed on the brakes I was going to run well under 6 for the opening mile. If I could’ve stopped at 18 miles I would have.