Contact stress is damage to the tissue of the body caused by contact between soft tissue and a hard object. Contact stress may be internal or external. Internal contact stress may occur when muscles, nerves, tendons, or other soft tissue rub, or press, against bone or tendons in a way that causes the tissue to bruise or over-extend. External contact stress is most often caused by a part of the body coming into contact with a hard surface such as a desk or machinery. Tissue damage may occur as result of a single event or due to repeated exposure to the stressor over time. Prolonged exposure to contact stress can lead to the development of musculoskeletal disorders (MSDs). For this reason, workplaces should be designed to limit or prevent exposures to contact stressors.
The parts of the body with the least amount of protective tissue, such as fat or muscle, are most likely to suffer hard due to contact stress. As nerves or blood vessels are pinched or bruised, a person with a contact stress injury may feel pain or numbness. He or she may also suffer impair motion and stiffness.
In the workplace, contact stress can happen when an employee engages in a forceful exertion such as striking lever with their hand. The musculoskeletal system may also suffer damage due to prolonged exposure to less forceful stress. For instance, walking back and forth on a hard surface each day during an 8-hour shift may cause damage to the feet or knees. Maintaining an awkward posture may also cause contact stress. For example, someone who bends their wrists at an awkward angle when typing may develop carpal tunnel syndrome or other wrist injuries as a result. Repeatedly using tools such as pliers or levers with hard grips can also cause contact stress.