Grant fisher 20 mile long run at 5:30 average, 133 heart rate

It means absolutely nothing. Seriously, this is not a hard run for a sub-27 guy. It's about 85% of his likely marathon pace. That's like a 3-hour marathoner doing a 20-mile run at 8-minute pace.

Was just top 10 at a marathon major in his debut. Give him time, thats a solid start.

My equivalent of that comes with higher heart rates, but I may just have an inaccurate watch or higher max

Hold my Diet Coke

Or how it was recorded. Is this wrist based? Chest? Bicep?

Not much, it was an easy run until the final few miles.

A longer tempo at 4:35/mile would actually give insight.

Also if the weather is even slightly warm, you'll have plenty of cardiac drift over the course of a 20-miler. You're also right that it's very hard to compare HR between individuals.

FWIW, I looked at my log and found a run where I did 25 miles averaging 6:38 pace (85% of my 5:40 MP so similar relative intensity to Fisher's run). My HR averaged 135 for that run, so it checks out. It was a moderate progression run, and also fairly hilly, so my HR probably would've been a bit lower if I had run it evenly on flat ground. That was a pretty easy run.

Do you know his max HR?

If it is 160 then 133 is very different run to if it is 190.

How was he measuring? Watch or chest strap?

It means he's feeling confident in his build-up to this half-marathon race following his DNS @ Millrose due to bronchitis.

Enough so, he just shared an IG reel giving us another update, running 105-115 miles/week vs his normal 100 for track training.

Grant rarely shares training details on his social media. When he does, really good races have followed.

So, appears he's hinting at a really good one on Sunday (3/15).

And now, a 3rd update within the past 2 weeks, this time a half-hour training video:

https://www.letsrun.com/forum/flat_read.php?thread=14083046&page=1

Do you post and then delete it? Very strange.