Stairmaster is the brand name of exercise machines, which includes stepping machines or stair steppers and revolving stairs.
Brought to fame by StairMaster which introduced the StairMaster 5000, a rotating staircase machine, sometimes called a step treadmill. In February 1986, Tri-Tech introduced the StairMaster 4000 PT at IHRSA in Nashville, Tennessee. The 4000 provided two pedals with independent motion to simulate stair climbing. The movement of the pedals was summed into a common rotating shaft and delivered to an alternator to provide electronic speed control (as opposed to mechanical speed control in the earlier machines).
The popularity of the 4000 soon overshadowed that of the rotating staircase machines and defined the future of stair climbers, even to this day.