Treadmill: This is the most popular and most selling machine among fitness equipment. Treadmills are ideal as aerobic fitness equipment for all ages. Treadmills allow a person to walk, jog, or run indoors no matter what the time of the day or weather is. When buying a treadmill for home use, make sure you buy one that has a solid, smooth action, a steady pace, safety shut off, wide belt, and different incline settings.