I wear Skins compression shorts and have found them to work really well - before wearing them I always suffered from cramp in my legs in the latter stages of marathons and often on longer runs, but since wearing them I haven't cramped up once.
and as Welsh Alex suggested, the best way to prepare for it is to run in the outfit before hand, even if it's only for a very short distance - that way you'll find out what chafes / rubs etc. If you're a guy (sorry I can't tell from your profile!?) then another good idea will be to cut a "fly" into your costume incase you need to stop for a pee...
As for the rest of your training I would say wear more clothes than you would normally would to get used to running while hot.
Raj - another way to break up the longer runs is to "pick up" a couple of friends along the route.
I've run 8 marathons, the first seven of which were all around the 5 hour - 5 1/2 hour mark, and always struggled with the long runs during training. But last year I had a couple of friends join me on my longest runs for a few miles each. They also each had water etc with them, which saved me from carrying it...
Doing it this way I managed to complete one run at 20 miles and one at 22 and knocked 30 minutes off my PB.
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Drummond
