Race strategy

In my last post I had two weeks before the Edinburgh Marathon.  I knew I wasn't going to be 100% ready but a cold certainly put paid to that.  I only had a couple of 5 km runs the week before so I arrived at the race on Saturday rested, or was it rusty?  My objective was to get under 3hrs 45 to get a "best for age" for the London Marathon 2024.  Beth was hoping to get 3hrs 55 to qualify for Boston so we had a chance of running it together.
We discussed our strategy and I knew I needed to run 5min 22sec per km to achieve my target time.   That was going to be tough as I had no idea how my heart would react - hopefully the same as Manchester marathon and not the same as my slower training runs.  I new it was going to be a slow start so I pushed on and was bang on for my first km.  Beth had recommended I run steady 5:20 per km and hopefully be able to increase the pace towards the end  (she's ran more marathon's than me) - but I chose differently!  I'd decided to run on feel and not look at my heart rate. The 2nd km on 5:17 and 4:40 in the 3rd km.  I was building up "credit in the bank" knowing at some stage I'd start to slow down.  At 15 km I tripped over a speed bump and managed to cut my knee on the same place I'd stitches a few months earlier.  I immediately got back up and started running, I wasn't stopping for a cut and bruised knee.
By 26km I was starting to tire and my times increase over 5:20 but this was OK until KM 32 - 20 miles or the half way point as I refer to it.  The weather forecast was for 13 degrees but it was 19/20 degrees and people we getting medical treatment at the side of the road as the heat took people out.  My heart rate was good around 150 which is unbelievable but I was suffering.  I had brought salt tablets but couldn't find them and I knew my body was starting to fail.  But I still had the target within my grasp.  
I was hydrating and taking my gels but had to ask a Macmillan volunteer for water between feed stations and she was an angel and gave me her own.  This got me to the next check point but I was in serious trouble.  With 3 km to go I started walking as I realised I wouldn't make my target and I was worried that my body was leaning over to the left as though the left side had collapsed.  I had walked through the last two feed stations so I could get my gel and a full bottle of water in me but I weighed up the pros and cons and decided to quit the race.  That lasted 30 seconds as I thought I should jog in and finish the race or I'd regret it if I didn't.
From 39km on all my km's were over 6 mins.  I was struggling to stay upright and the crowd were amazing screaming encouragement to me.  It took everything within me to stay standing and not crash into the barrier on the left side.  I crossed the line in 3hrs 49 mins - 59 seconds slower than Manchester and 4 mins outside the London target.  I didn't care.  I could hardly walk now and was sat down by a medic and given water.  When I was ready to go back to get my bag I had horrendous cramp and took an age to get to the bag drop.
Beth had a tough day out and couldn't hold the speed she needed but came in with a respectable 4hrs and 4 mins.  Her pacing was much better than mine.
It's been a painful lesson but res assured, when we complete the Amsterdam Marathon in October I am going to stick to a strict pace and see how that goes for me.  What I can't understand is how my heart behaves better in a fast (for me) marathon and not in a slow jog around Strathy Park?  
But we have 5 days to recover before we take on the Full Tilt 58km ultra including 2 Munro's.  Obviously I will be taking it easy and much will depend on how my legs feel when I start running.  It will push us both following our marathon efforts.
Training is good but the real learning is when we are in the race.  I'm not an experienced marathon runner but I am learning fast.  I'm looking forward to Amsterdam and in July the new experience of the Highlander, Last one standing race.  I'll give more details on that one after my next race report.
I'm so glad I didn't give up but I wish I'd stuck to a disciplined pace.  Here's to the next race.  Bring it on.