I don't know, the more I think about it the more I believe getting there early is a good idea. Yes, you will exert more energy, but at a change of altitude that big you're probably going to experience some altitude sickness which happens the first day of two you are there. If you show up a day early the chance of getting sick during the race is pretty big. I live in Golden, CO which is at about 5,600 feet and when friends come visit half of them feel at least a mild effect of the altitude difference. The Leadville 100 starts at 10,500 feet and climb 14,000 from there so you'rr definitely going to feel it big time. I went up to Leadville this February for a bike race (lost of Pugsley's, it was cool) and right out the gate felt it big time. At that point I'd lived in Golden for at least 3 months so I was somewhat acclimated. Although the theory behind showing up a day early sounds solid, I just don't know how well it would work. I'd still say show up early to get over the altitude sickness, and if any training is done make sure it's short and low heart rate. Or you could always come to Golden and kind of get used to the altitude there first, and I'd be happy to take you on a tour of the trails we have to offer!