A treadmill is an exercise machine for running or walking while staying in one place. The word treadmill traditionally refers to a type of mill which was operated by a person or animal treading steps of a wheel to grind grain where power was input into the mechanical system (see treadwheel.)
The machine provides a moving platform with a wide conveyor belt and an electric motor or a flywheel. The belt moves to the rear allowing a person to walk or run an equal, and necessarily opposite, velocity. The rate at which the belt moves is the rate of walking or running. Thus, the speed of running may be controlled and measured. The more expensive, heavy-duty versions are motor-driven (usually by an electric motor). The simpler, lighter, and less expensive versions passively resist the motion, moving only when the walker pushes the belt with their feet. The latter are known as "manual treadmills".[1]
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The first treadmill designed to diagnose heart and lung disease was invented by Dr. Robert Bruce and Wayne Quinton at the University of Washington in 1952. Dr. Kenneth H. Cooper's research on the benefits of aerobic exercise, published in 1968, provided a medical argument to support the commercial development of the home treadmill and exercise bike.
Among the users of treadmills today are medical facilities (hospitals, rehabilitation centers, medical and physiotherapy clinics, institutes of higher education), sports clubs, Biomechanics Institute, orthopedic shoe shops, running shops, Olympic training centers, universities, fire-training centers, NASA, test facilities and training rooms of police and army, gyms and even home users.
Treadmill ergometers are now mainly with motor drive. Most treadmills have a running table with sliding plate. Before and after the race table, there are two shafts. Between the shafts and the running deck a running belt is stretched.
Safety standards for treadmills are the IEC EN 957-1 and IEC EN 957-6.
For medical treadmills applicable norms, standards and guidelines are the Medical Device Directive (MDD), European Guideline 93/42 EEC, European Guideline 2007/47 EEC, IEC EN 60601-1, EN 62304, EN 14971 and the machinery directive 2006/42/EC.
Medical treadmills are class IIb active therapeutic devices and also active devices for diagnosis. With their very powerful (e.g. 3.3 kW = 4.5 HP) electric motor powered drive system treadmills deliver mechanical energy to the human body through the moving running belt of the treadmill. The subject is not changing his horizontal position and is passively moved and forced to catch up with the running belt underneath his feet. The subject can also be fixed in safety harnesses, unweighting systems, various supports or even fixed in and moved with a robotic orthotic system utilizing the treadmill.
Medical treadmills are also active measuring devices. They measure the heart rate of the subject. When connected through interface with ECG or ergospirometry or blood pressure monitor (BPM) or EMG they become a new medical system (e.g. stress test system or cardiopulmonary rehab system) and measure also the ECG, VO2max, breath volumes, blood pressure, muscle activity and various other vital functions.
Most treadmills have a “cardio mode”, where a target heart rate is defined and the speed and elevation (load) is controlled automatically until the subject is in “heart rate steady state”. So the treadmill is delivering mechanical energy to the human body based on the vital function (heart rate) of the subject.
A medical treadmill which is also used for ergometry and cardiopulmonary stress test as well as performance diagnostics is always a class IIb medical device either when used as stand alone device in a medical environment or when used in connection with an ECG, EMG, Ergospirometry or blood pressure monitoring device.
On the running deck the subject is moving, who adapts to the adjustable speed of the belt. The running deck is usually mounted on damping elements, so the running deck has shock absorbing characteristics. By a lifting element, the entire frame including treadmill running deck will be raised and thus simulates a pitch angle for uphill running. Some treadmills also have the reversing of a running belt for the purpose of downhill loads. Most treadmills for professionals in the fitness area, run for table sizes of about 150 cm long and 50 cm width, a speed range of about 0 ... 20 km/h and slope angle of 0 ... 20%.
For athletes larger and more stable treadmills are necessary. Sprinters reach with some weight relief temporarily speeds of up to 45 km/h must therefore run on a large deck of up to 300 cm in length and have up to 100 cm width. At high physical exertion and increased risk of falling a fall stop unit is required to prevent a fall of the subjects or patients. This fall stop device is usually implemented by a safety arch on which a rope is attached to an electrical switch. A harness bears the subject preventing from falling and shuts down the running belt.
In treatment centers treadmills are used with built-in seats left and right for therapists, for example, so the therapists then can move the legs of a stroke patient in order to simulate walking movements and learn to walk again. This is called manual locomotion therapy.
Oversized treadmills are also used for cycling at speeds up to 80 km/h, for wheelchair users and in special applications with thick running belt for cross-country skiing and biathlon, where athletes perform training and testing exercise with roller ski on a running deck of up to sizes of 450 x 300 cm.
As a cardiovascular exercise:
As an indoor activity:
As a machine:
As it is basically a conveyor belt, the treadmill can be used for activities other than running. If horses are being tested (especially in jockey racing) they will be put on a specially constructed treadmill. Large treadmills can also accommodate cars. Treadmills can also be used to exercise dogs that are accustomed to running on a conveyor; however tying the leash to the treadmill should be avoided as it can cause serious injury.
Advanced applications are so called omnidirectional treadmills. They are designed to move in two dimensions and are intended as the base for a "holodeck". There are several solutions which were proposed and research continues because some issues remain unsolved, such as large size, noise and vibration. There are parallel developments being conducted by researchers working on projects sponsored by the Department of Veterans Affairs to create virtual reality environments for a wheelchair trainer in order to promote therapeutic exercise.[7]