How did you find the Sirpoc Marathon progression run 12 days out?

I'm about 12 days out from Chicago where hopefully I'll run a sub-3:20. I hit a 1:35:27 5 weeks ago and have been getting laser focused in that 4:40-4:45/km range.

This special block is pretty dense - I ran the 5x5km as a 5x17 min and hit 4:43/km; two days later ran the Medium Long Run with 30 min @ Sub T and also hit 4:43/km; two days after that came the Progression Run - in the book, as an 3x8K continuous - 92%, 93%, and finally 100% at MP. I chose to run at as 30 min blocks.

To be honest I was feeling kinda shaky and nervous for this one. I made sure to fuel enough the day before and take another opportunity to practice fuelling at pace with my race day plan. I chose a 1km lake loop, mostly flat on gravel.

I set my Garmin to alert me when I was too fast or too slow, but surprisingly the alarms didn't really go off. I found I could dial in the pace and just kept an eye on my HR instead and decided not to look at pace too much, except when the alarm went off.

For the first 30 min blocks my HR stayed just above LT1.

For the second 30 min block it hovered right between LT1 and LT2.

Some thoughts started coming into my head, like - this is the longest at pace I've done this whole block since NSM is all about breaking it up with walk breaks. It was a little scary and definitely the thought came into my mind that this felt harder than the 5x17 min. But I still managed to stay on pace and the HR wasn't really spiking or anything.

And finally for the final block, I had to run another 30 min at my race pace for Chicago after having run 60 min at pretty close to race pace and thought, man there's no way; I'm gonna blow up. But I ran the first loop, then the next, then the next. HR crept up to the upper band of LT2 but never quite exceeded it.

Came to the end and cooled down and I checked my splits:

First 30 min: 5:01/km @ 150bpm average (94% MP vs. goal of 92%)
Second 30 min: 4:55/km @ 155bpm average (96% vs goal of 93%)
Final 30 min: 4:43/km @ 163bpm average (100% of MP)

While it was probably in my opinion the hardest workout of the block, James was right in saying it was a massive confidence booster. I totally thought I would blow up, but didn't, and hit my paces.

That being said, based on how that last rep felt, it feels a touch too hot to be sustainable. I am a little skeptical of hitting 4:44/km on race day for the full 42.2km and I'm honestly probably gonna run by RPE/feel. I'm anxious of blowing up and having a bad day, so I'm not terribly attached to that pace. Let me know if you think I should just YOLO haha.

What's been your experience of the progression run?