Similarly to exercises bicycles, modern treadmills are widely used at home and fitness centers. Unlike ancient treadmills or treadwheels, which were efficient as punishment devices for hardened criminals sentenced to hard labor, modern fitness treadmills are designed to combine extensive exercising with utmost pleasure and enjoyment. Classical manual treadmills resist the motion when sportsmen push the belt with feet, whereas advanced models of walking or running exercise machine have a platform with a conveyor belt which is driven by electric motor. It helps to measure and to control the speed. In addition to their traditional fitness functions, treadmill ergometers may perform a range of medical and therapeutic ones. State-of-the-art models come with high definition LCD screens which help you to control your workout settings and serve as an entertainment system. It can be easily connected to your iPod or iPhone, so you may listen to music or watch videos while exercising. In addition, it serves as a USB charging station. Some models boast a set of ready-made workout programs which adjust intensity of training.