"Anti-fatigue mats" are designed to help a person who is working in a standing position for prolonged periods of time. Most anti-fatigue matting is a combination of an ergonomic pattern and a cushioning underlay. The cushioning causes constant subconscious balance checks and micro movements that stimulate blood flow through the legs and lower extremities. This results in better circulation and less fatigue. The cushioning underlay insulates the feet from the hard surface, cold floors, vibrations, moisture and sound. Their unique design encourages the user to make continual micro-movements which provides a wealth of health benefits, such as minimizing back pain, foot pain, weariness, stress, etc. Anti-fatigue mats are one of the approaches to prevent injuries, caused by working in a standing position. In a study at the Center of Ergonomics at the University of Michigan in 1987, ergonomist Mark Redfern concluded that different standing surfaces can have dramatic effects on physical fatigue. Workers who stood on anti-fatigue mats were able to reduce the level of fatigue and discomfort by as much as 50%. This type of mat is recommended by Occupational Safety and Health Administration. The range of common materials for manufacturing anti-fatigue mats includes vinyl, wood, PVC tubing, rubber, PVC closed cell foam, polypropylene, nitrile rubber. Anti-fatigue mats were initially used in factories and production lines where staff has to stand for the majority of their working shifts.