Well this thread makes me feel better.
Marathon #8for me, 5th Major, 1st Boston
PR 2:51 (London 2016)
Ran 2:54 in NYC 2016
Got in Boston with good training, but just on flatlands (no hills where I live).
I knew the course would make me pay a price for that.
From training I knew I was in 2:49 shape - ran a 35:08 10K just 3 weeks before Boston, and 17 days out ran a good workout (21 miles @6:32/mile + 1km @5:54).
Hottest training run was @ 12c - and I hate running (racing/quality training) when the sun is out.
Raced with Adidas Boston Boost (200miles old).
So, race morning I tried to execute my plan and went out @ 6:30.
Pace felt uncomfortable for the heat at first, then I felt better after mile 10.
Tried to drink a lot and threw lots of water on the head for cooling down.
After mile 15 my calves started to burn, but I managed to go on well till the Newton Hills, where hills #2 and #3 knocked me out on a muscular level (calves). So till mile 20 I was right on pace.
Up Heartbreak I had a thought "now it should be easier" - this is where I was wrong (as written in the book 26.2 miles to Boston" - as my legs (calves) were done because of cumulative fatigue, and downhill running hurted.
Long story short, I could not hold the pace anymore and struggled the last miles - also realized I was missing my A objective so my brain started to accept any other goal and slowed down to prevent any cramp in my calves, to close in 2:53.
At first I was not so satisfied, but then thinking about all the ingredients (heat, topography, training on flatlands, 1st Boston) and reading other runners, I guess I should be ok with my effort and performance.
For the record, it is Friday and I am still hobbling (calves done).