The Cardio Zone: Treadmill program is designed to improve your leg strength and cardiovascular endurance, as well as help you trim your waist and sculpt lean muscles. The workouts are designed to be done on a treadmill and guide you to change the incline level and effort level throughout. Just image higher inclines being steeper hills! Whereas effort level refers to how much you are huffing and puffing, to increase this, just increase your speed. This program includes both treadmill walking and running, but if running is not your thing, you can still complete the workouts by walking the whole thing and adjusting your incline and effort as recommended. Improve your cardiovascular health and get in the zone with these hill, interval and endurance treadmill workouts.