There are typically three to five buttons on a treadmill. The most common buttons are the start/stop button, the speed button, and the incline button. Some treadmills also have a heart rate monitor and a pre-set program button. The start/stop button is usually the largest button on the treadmill and is used to turn the treadmill on and off. The speed button is used to adjust the speed of the treadmill belt. The incline button is used to adjust the incline of the treadmill, which can be beneficial for burning more calories or working different muscle groups. The heart rate monitor button is used to track your heart rate while you are working out. The pre-set program button is used to choose a workout program that has already been programmed into the treadmill.