A good way to monitor your effort is wearing a heart rate monitor during the race. Figure out what your max heart rate for your age and gender (there are calculators online). During the race try to maintain the applicable 75%, 80% or 85% of that, meaning right around the same percentage. You will notice that you move a lot slower above tree line maintaining an 80% effort, then in the beginning, but your body has to work the same to keep that performance. Your heart rate will go up a little bit with time and dehydration, but if you are already in the 90% at the beginning for whatever reason, back off. If this is your first time on Pikes Peak be conservative with your target number and talk to your physician to make sure it is safe. With this in mind, train in at the same heart rate level. Now at sea level you will run a lot faster to reach %80, but you condition yourself to keep up a certain effort. This applies only to your cardio vascular system, not your muscles. Good Luck