The incline feature on treadmills challenges the cardiovascular system which is always a plus. Even if you are overweight or recovering from an injury, you can adjust the incline so that you still receive a challenge tailored to your circumstance. Working out on an incline causes your lungs to breathe deeper and increases blood flow to the lungs and heart.
If you want powerful, well-defined arms, don't just focus on the biceps! Building a strong set of triceps needs to be a priority. Another often forgotten about area (especially for women) are the shoulders so this workout will have you flexing like a pro in no time!