From The Ergoweb® Learning Center

Definitions in Ergonomics

I am often asked to define what I do: Ergonomics. As soon as I begin with an explanation using terms such as anthropometry, and risk factor, I notice the questioner’s eyebrows furrow in confusion. By the time I start throwing out terms like OSHA, MSD, and ANSI, the person who questioned me is already walking away sorry that they ever asked.

If anyone asks you to define what you do with ergonomics, give them a copy of these definitions before you begin.

Administrative Control – Procedures and methods, set up by the employer, that significantly reduce exposure to risk factors by altering the way in which work is performed; examples include employee rotation, job task enlargement, and adjustment of work pace.

ANSI– American National Standards Institute. A private, non-profit membership organization that coordinates voluntary standards activities. ANSI assists with standards-developers and standards users from the private sector and government to reach agreement on the need for standards and establish priorities.

Anthropometry– Anthropometry is the branch of the human sciences that deals with body measurements.

Awkward Posture -Posture is the position of the body while performing work activities. Awkward posture is associated with an increased risk for injury. It is generally considered that the more a joint deviates from the neutral (natural) position, the greater the risk of injury.

Cumulative Trauma Disorders (CTDs) – Term used for injuries that occur over a period because of repeated trauma or exposure to a specific body part, such as the back, hand, wrist and forearm. Muscles and joints are stressed, tendons are inflamed, nerves pinched or the flow of blood is restricted. Common occupational induced disorders in this class include carpal tunnel syndrome, epicondylitis (tennis elbow), tendinitis, tenosynovitis, synovitis, stenosing tenosynovitis of the finger, DeQuervian’s Syndrome, and low back pain.

Engineering Control – Physical changes to jobs that control exposure to risk. Engineering controls act on the source of the hazard and control employee exposure to the hazard without relying on the employee to take self-protective action or intervention. Examples include: changing the handle angle of a tool, using a lighter weight part, and providing a chair that has adjustability.

Ergonomics – According to Ergoweb: The science of work. Ergonomics removes barriers to quality, productivity, and safe human performance by fitting products, tasks and environments to people.

Ergonomic program – A systematic process for anticipating, identifying, analyzing and controlling ergonomic risk factors.

Force – The amount of muscular effort required to perform a task.
Generally, the greater the force, the greater the degree of risk. High force has been associated with Work Related Musculoskeletal Disorders at the shoulder/neck, the low back and the forearm/wrist/hand.

Human Factors – A term synonomous with ‘ergonomics’, is the branch of this science that began in the US and focuses on cognitive performance of humans.

Manual Material Handling – Lifting, carrying, and moving materials without mechanical aide.

Musculoskeletal Disorders (MSD) – Injuries and disorders of the muscles, nerves, tendons, ligaments, joints, cartilage and spinal disc; examples include carpal tunnel syndrome, rotator cuff tendonitis, and tension neck syndrome.

NIOSH – National Institute of Occupational Safety and Health. NIOSH is the institution that provides scientific data upon which OSHA makes recommendations.

RSI – Repetitive Strain Injury
RMI – Repetitive Motion Injury
UECTD – Upper Extremity Cumulative Trauma Disorders
WRULD – Work Related Upper Limb Disorder

Occupational Injury – Any injury such as a cut, fracture, sprain, amputation, etc., which results from a work-related event or from a single instantaneous exposure in the work environment. Examples of injuries or disorders that can be work related include:

  • Carpal tunnel syndrome (CTS)
  • Rotator cuff syndrome
  • De Quervain’s disease
  • Trigger finger
  • Tarsal tunnel syndrome
  • Sciatica
  • Epicondylitis
  • Tendinitis
  • Raynaud’s phenomenon
  • Carpet layers knee
  • Herniated spinal disc
  • Low back pain

OSHA – Occupational Safety and Health Administration. The mission of the Occupational Safety and Health Administration (OSHA) is to save lives, prevent injuries and protect the health of America’s workers. To accomplish this, federal and state governments must work in partnership with the more than 100 million working men and women and their six and a half million employers who are covered by the Occupational Safety and Health Act of 1970.

OSHA 200 Log – An OSHA-required form for employers to record and classify occupational injuries and illnesses, and note the extent of each case.

Repetition – Repetition is the number of a similar exertions performed during a task. A warehouse worker may lift three boxes per minute from the floor to a countertop; an assembly worker may make 20 units per hour. Repetitive motion has been associated with injury and worker discomfort.

Generally, the greater the number of repetitions, the greater the degree of risk. However, there is no specific repetition limit or threshold value (cycles/unit of time, movements/unit of time) associated with injury.

Risk Factor – Actions in the workplace, workplace conditions, or a combination thereof, that may cause or aggravate a Work Related Musculoskeletal Disorders; examples include forceful exertion, awkward postures, repetitive exertion, and environmental factors such as temperature.

Segmental Vibration (Hand-Arm Vibration) – Vibration applied to the hand/arms through a tool or piece of equipment. This can cause a reduction in blood flow to the hands/fingers (Raynaud’s disease or vibration white finger). Also, it can interfere with sensory receptor feedback leading to increased handgrip force to hold the tool. Further, a strong association has been reported between carpal tunnel syndrome and segmental vibration.

Work Related Musculoskeletal Disorders (WMSD, WRMSD) – Injuries and disorders of the muscles, nerves, tendons, ligaments, joints, cartilage and spinal disc due to physical work activities or workplace conditions in the job. Examples include: carpal tunnel syndrome related to long term computer data entry, rotator cuff tendinitis from repeat overhead reaching, and tension neck syndrome associated with long term cervical spine flexion.

More definition and other general ergonomics information is available at