could be the buid up of lactic acid in your muscles if the course was extra hilly...also, I've tried almost all the sports drinks and lucozade seems loaded with sugar (I agree with Mr. Puffy's comments)..
have you run lots this week? It could be just a bad training run. Don't be too disheartened by it!
from home to Hyde-Kensington-Green-St. James Park (partial loops) to the Thames. Crossed Westminster and attempted to run thru crowds south East, turned around ran towards Vauxhall on south side, crossed bridge headed East crossed south on hungerford bridge. headed east to tower bridge...looped through tower of london area, headed west along thames to westminster completing loops of parks. Added an extra mile in Kensington Park to get the full 20.
(wanted to run 18 miles in Richmond Park, but the tube stations were not running and I didn't know how to get there by bus)
Zonked around mile 11-12, but stopped for water and was ready to finish the rest...at mile 18, felt unusually strong and went for the 20.
I agree, I don't much like taking food or water either.
were you dehydrated? I ran long yesterday and started to zonk at mile 14 (andI had an adequate breakfast)...after stopping for water I was refueled and ran over 20 mi.
It could also be that the raisins aren't breaking down in your system as needed.
I would recommend gels, but you have to practice taking them since a few people cannot handle them in their stomachs (plus you must take gels with water so they will hit your system faster). for gels they say that they are needed every 45 min during a race of 10 miles or longer.