Bruce Protocol
There are actually 6 stages of the Bruce Protocol, but the usual CAA one is only the first 4. Stage 1 is 1.7mph with the gradient set at 10% Stage 2 is 2.5mph at 12%. Stage 3 is 3.4mph at 14%. Stage 4 is 4.2mph at 16%. I find that the main problem at stage 4 is discomfort in the legs, particularly if you're short and have to keep walking when you would normally be jogging. Having a daily brisk walk for a week or so beforehand can certainly help to make things more comfortable on the day.