The school of thought I think is that the body holds around 2 hours of glycogen in your muscles. If you go tearing off faster than you're body is capable of then that 2 hours becomes a lot less. Obviously not the same for everybody.
People replenish their diminishing energy stores with carbohydrates, with gels being the usual form as they're easy to digest as opposed to solid food.
I took 3 during Leicester marathon and at 7, 13 and 19 miles. I knew the gels were ok with me as I'd used them before but I really just copied when someone else took them and see if it worked. I wanted to get one in early around 40 mins so i wasn't leaving it until my energy stores were already on the way down.
Seemed to work for me although I never actually practiced during training though barring using them in a 20 mile race. Can't remember when I took them during that.
Get the marathon pencilled in SG! You already do a shed load of MP stuff!
Must admit, when doing blocks of goal MP stuff I tried to hit low 5.4X although it never actually felt comfortable in any session I did. That's prob the reason I never managed it.
Looking back to the 20 mile ace I did that I split up into 3 easy 7 at 'MP' 3 easy and 7 at 'MP', I averaged 5.54 for the 20 miles which turned out to be what I averaged for the marathon.
Like Dachs, when I ran my half PB I did 3-5 hilly 10 milers (about 900-1000ft of ascent) and averaged just under 6 min miling but that was turning myself inside out. I think doing them and it being coupled to doing 5k volume track sessions as I was trying to PB there it meant the first 8 miles or so of the half at sub 5.30 pace felt a doddle.
I dropped out Bus and gave told them to pass my number on.
Knackered from work, a complete lack of any sort of hill running, a mojo that has vanished and being a bit rough off a few pints meant 17 mile on the fells with nearly 5000ft of climbing in the midst of Hurricane Abigail didnt seem such a good idea.
Sealife centre instead with the the missus and daughter.
I'm sure you'll be fine SG. In a morning mine is usually around 40 bpm. Had it at 37 a few times.
That XC race at leamington looked epic. Saw the video of the bloke who lost his shoe in the knee deep mud with the crowd shouting 'leave the shoe! Leave the shoe!'
Tour of Pendle for me this week. Probably should be called Sould Destroying 17 mile yomp up a mountain'
Also got my entry to Auld Lang Syne fell race on New Year's Eve. Both Brownlee brothers usually there competing along with another triathlete mark Buckingham and that Varga bloke.