This isn't for me, but a friend.
Buddy has a marathon in 2 weeks- he is concerned about whether or not he should carb load, and if so how?
Also he says "I guess what I'm most interested in, is the idea of doing a short intense workout 24-48 prior to the race which will trick my body into preparing for stress, thus making my body hold more carbs. Has anyone tried this or something similar and if so what were the results?"
Carb load = yes, begin 72 hours out, wean off about 8-12 hours out to clear digestive system. Don't run on an empty stomach. Include an increase in water consumption to make sure he's fully hydrated, especially if he lives in warm weather. Increase vitamin/mineral/electrolyte consumption so you don't flush the system clean.
You don't give specifics on the size/weight of your buddy, but there is a saturation point with carb loading. Water has to be taken in with the carbs. I wouldn't recommend any
intense physical activity within a 48 hour time window. Keep the blood moving and work on some stretching. NEVER underestimate the need for good shoes/gear. If he hasn't used Gu in his training, DO NOT use it in the race until you know how your stomach will react. Gu will draw a lot of water into your stomach.
There are many different ideas on water/sport drink intake during a race (water only for me). Look online and calculate what's needed based on his weight. If he hasn't practised drinking water on the run, he will need to walk at the water stations or run the risk of semi-drowning himself. After the race, use sport drinks or diluted fruit juice to replenish, then use water, ibuprofen and stretching to start flushing out soreness. Schedule a walk for the following day to move the soreness out of the muscles.
PM if you need more info. I probably have 20 fulls and 40 halfs under my belt.