On my 705 you set the zones on the unit. If you program your workout using zones then presumably if your zones are different on the computer than on the unit you will get the unit zones during the workout. I don't like to use the zones because when it shows your power during the workout it shows it as what zone you are in rather than the power you are at. I don't find "zone 4.5" very useful for telling me what I am doing, personally. So I just program the workouts in on the unit directly with explicit power targets.