Everyone's advice to me in past threads helped me this past week.
I slowed a ton of my running down to 9:30-9:40 (a few 7-mile days at 9:30-9:40 pace and a few smaller runs at the same speed) and it truly felt EZ, like no effort at all. Felt fresh at the end of the runs, no tight legs. I had been running faster (8:05-8:20 pace up to that point) and was stuck in a middle ground--too fast for EZ runs and too slow for true threshold and interval pace, etc. I average 40-45 mpw, with a past high of 50 a few weeks ago, but have dropped it down to 40-45 just to be safe.
Went out for what my normal long run at 12 miles this past Saturday, didn't look at my watch until halfway in, and just went by feel, and got this:
6 miles 46:55
10 miles 77:08
12 miles 1:32:02
I felt strong and was curious to see how I'd come in for the half, so I ran another 1.1 miles and felt great, finishing in 1:40:22. My PR is 1:39:02, set in 2018. I use MapMyRun with Google Maps, so while it may not be 100% accurate, it's close.
I didn't even feel sore the next day. I finished but immediately calculated my heart rate with my finger to the pulse and multiplied by 4. The HR was around 150-ish. I'm 37.
This gives hope that tons of EZ mileage really works as a base. It's much more freeing knowing you can just relax during the EZ miles and stack miles with no issues, and when speedwork time comes, I will be ready.
Went out for an 8-miler today and went at the same effort level as last week's EZ runs; the average pace now is about 9:15-9:00. I don't have a Strava, HRM or anything besides a wristwatch. I run by feel and only check splits at certain points; I then map my runs on MapMyRun (desktop only) afterwards.
So yes, I'm now a big advocate of slowing down EZ runs when the schedule calls for EZ runs.