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Glossary

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Abduction: Movement of a limb away from the body's midline axis, such as elevating the elbow or raising the arm to the side.

Administrative Control: Any procedure that significantly limits daily exposure by control or manipulation of the work schedule or manner in which work is performed. Administrative controls include but are not limited to job rotation, use of rest breaks or alternative tasks, job enlargement to increase task variability, redesign of work methods, and adjustment of work pace or number of repetitions.

ANSI: The American National Standards Institute. ANSI has been responsible for the development of design guidelines for computer workstations (ANSI/HFS 100-1988), and draft guidelines for ergonomics (ANSI Z365).

Anthropometry: The study of physical dimensions in people, including the measurement of human body characteristics such as size, breadth, girth, and distance between anatomical points. Anthropometry also includes segment masses, the centers of gravity of body segments, and the ranges of joint motion, which are used in biomechanical analyses of work postures.

Anti-Fatigue Mats: Mats or padding on the floor designed to reduce stresses on the feet and leg when standing for long periods. Cushioned insoles for shoes can be viewed as “portable antifatigue mats.”

Awkward Posture: A deviation from the neutral position of any particular joint.

Back: The trunk of the body from below the neck (cervical spine) to the tailbone (sacrum). The back includes the upper and lower back.

Biomechanics: The study of the effects of internal and external forces on the human body in movement and rest.

Bursitis: Bursae are lubricating pads separating tendons from bones in parts of the body. Bursitis results when a bursae is inflamed. The inflammation may be the result of repetitive or forceful exertions at that joint.

Carpal Tunnel Syndrome: A specific Cumulative Trauma Disorder (CTD) occurring as the result of compression on the median nerve that travels through the carpal tunnel in the heel of the hand. Symptoms can include tingling and numbness in the hand, and loss of dexterity and strength in the hand.

Center of Gravity: The center of mass of an object that determines its symmetry and ease of handling.

Contact Stress: Exposure of a body part to a hard or sharp surface repetitively or forcefully at a workstation or tool. Contact stress has been associated with Cumulative Trauma Disorders.

Continuous Work: Work activities that are sustained and uninterrupted, e.g., in dynamic work, the sustained pattern of work without rest or light effort breaks. Continuous work, especially when the work is demanding, results in earlier fatigue than does intermittent work.

Cumulative Trauma Disorder (CTD): A CTD is a bodily injury associated with repeated biomechanical stress over time.

Cycle: A time interval during which a regularly occurring sequence of events is completed. A cycle can be the time to complete a job with many tasks or the time to produce one unit.

DeQuervain’s Disease: Inflammation of tendon coverings on the side of the wrist and base of the thumb which can result in swelling or pain when moving the thumb.

Discs: Gelatinous plate-shaped protectors that act as shock absorbers for the bones of the spine. Disc-related injuries to the back result from the deformation of the discs, including bulging and rupturing of the discs.

Duration: The continuous time a task is performed without an adequate rest break.

Dynamics: The biomechanical aspects of the human body in motion.

Engineering Controls: Physical changes to work stations, equipment, materials, production facilities, or any other relevant aspect of the work environment that reduce or prevent exposure to risk factors.

Epicondylitis: Tendonitis of the elbow (“tennis elbow”).

Ergonomics: A discipline that involves fitting the job to the worker and not the worker to the job. It is the science of adapting workstations, tools, equipment and job practices to be compatible with the individual worker and thus reduce the risk of injury due to risk factors.

Ergonomics Program: Application of ergonomics in a system that includes the following components: health and risk factor surveillance, job analysis and design, medical management,
and training.

Extension: The straightening of a joint whereby the angle between adjacent bones usually increases. Exceptions are extension of the feet and wrists.

Fatigue: The reduction in performance ability caused by a period of excessive activity followed by inadequate recovery time. Muscle fatigue is accompanied by a buildup of lactic acid in the working muscle.

Flexion: The bending of a joint whereby the angle between adjacent bones usually decreases.

Force: The mechanical effort to accomplish a specific movement or exertion. Force may be either external (a force applied, voluntarily or involuntarily, to the surface of the body) or internal (tension within muscles, tendons, and ligaments).

Ganglionic Cyst: A fluid-filled lump under the skin that can occur in the wrist as a result of DeQuervain’s Disease.

Heat Stress: Exposure to a hot environment that reduces the capability for sustained activity and speeds up fatigue.

Hyperextension of the Shoulder: Extension of the shoulder in which the upper arm is actually behind the back: for instance, when reaching behind the back for an object.

Hyperextension of the Spine: Extension of the trunk beyond the upright, forming a more extreme backward arch and changing the distribution of pressure on the spinal discs; for instance, in work done above shoulder height.

Incentive: In work situations, a pay plan whereby performance above the standard level for a job is financially rewarded up to some fixed level. An example of an individual incentive would be on some piecework tasks, where performance is measured by the number of good units produced per shift by an individual employee; group incentives are when the performance of a production team or a department is rewarded.

Job Enlargement: Adding duties to a worker’s job to reduce exposure to specific stresses of repetitive or physically strenuous jobs.

Job Rotation: Alternation of a worker’s tasks with other tasks as a means of reducing specific stresses of repetitive or physically strenuous jobs.

Joint: A body part where two bones meet and are connected by ligaments.

Lateral: Toward the side of the body away from the midline.

Ligaments: Fibrous structures that connect bones to bones, providing support while allowing flexibility and movement.

Log 200: An OSHA form employers are required to fill out summarizing workplace injuries and illnesses. (Currently posted at the Cheadle Hall basement and at Environmental Health and Safety.)

Lower Extremity: The hip, thigh, knee, leg, ankle, and/or foot.

Manual Handling: Manual Handling refers to any handling task involving the human body as the “power source.” Manual Handling includes lifting, lowering, pushing, pulling, carrying, and holding.

Median Nerve: The nerve that travels through the carpal tunnel of the wrist and services the thumb and first three fingers of the hand. Inflammation of the median nerve is the definition of carpal tunnel syndrome.

Muscle: Body tissue which contracts to produce movement or force.

Musculoskeletal System: System composed of bones, ligaments, tendons and muscles.

Nerve: Transmitters of feeling and movement from body to brain.

Neutral Position: The body position which minimizes stresses on the body. Typically the neutral posture will be near the mid-range of any joint’s range of motion.

Pacing: Controlling an employee's rate of movement through external means, such as a continuous conveyor moving at a fixed speed, production pressure, peer pressure, or pay incentives.

Personal Protective Equipment: Gloves, padding, or eye glasses worn and used for the purpose of controlling risk factors.

Pinch Grip: One of several types of grips which do not allow the hand to fully encircle the object being handled.

Power Grip: A grip allowing the four fingers and thumb to encircle the object. This grip will generally maximize power on the part of the worker.

Pronation: The action of rotating the forearm so that the hand is palm down.

Range of Motion: The limits of movement defined at a joint or landmark of the body. Stresses on the connective tissues at a joint increase as the joint moves towards the limit of its range of motion.

Radial Deviation: Bending the wrist toward the thumb side.

Raynaud’s Syndrome: A progressive color change of the fingers in response to cold or vibration, due to decreased circulation (also known as vibration syndrome or white finger).

Recovery Time: Work periods when task demands are light or when rest breaks are scheduled, permitting a person to recover from heavy effort work such as prolonged fixed postures.

Redesign: Changes to an existing workplace or to production equipment to make it suitable for more employees; also, the reexamination of job requirements and their patterns of occurrence. Redesign is more expensive than incorporation of ergonomic principles in the initial design of a job.

Rest Allowances: Recovery time, including regularly scheduled work breaks, usually provided in jobs where heavy physical work or exposure to environmental extremes occurs. Rest allowances are built into the job standard so that productivity ratings recognize the need for additional recovery time in these jobs.

Risk Factors: Conditions of a job, process, or operation that contribute to the risk of developing CTDs.

Static Exertion: Static exertions refer to physical exertions (gripping, holding a posture) in which the same position or posture is held throughout the exertion (also referred to as "static loading").

Supination: The action of rotating the forearm outward so that the hand is palm up.

Task: A subunit of a job or the group of activities that accomplishes the work objective or job.

Tendonitis: Tendons connect muscles to bones. Tendonitis is the result of the inflammation of tendons at a body part.

Tenosynovitis: Swelling and inflammation of the sheath that surrounds certain tendons. The sheath produces a lubricating fluid for the tendon; tenosynovitis results from a decreased capacity to produce this lubricating fluid.

Torque (Moment): A force that produces or tends to produce rotation; the rotational force about a point (e.g., torque is the force required to tighten a bolt). Excessive torque forces have been associated with CTDs to the upper extremities, particularly the elbow.

Trigger Finger: Tendons in the finger joints can swell due to overuse, “locking” the finger into a fixed position.

Ulnar Deviation: Bending the wrist towards the little finger side.

Upper Extremity: The hand, wrist, elbow , arm, shoulder, and/or neck.

Vibration: The oscillatory motion of a physical body. Localized vibration, such as hand-arm vibration, is produced by contact with powered tools or equipment or with vibrating structures. Whole-body vibration occurs while standing or seated in vibrating environments or objects, such as trucks or heavy machinery.

Work Cycle: The work cycle consists of an exertion period and a recovery (or smaller exertion) period necessary to complete one sequence of a task, before the sequence is repeated.

Work Methods: The physical methods used to perform the tasks of a job, such as reaching, gripping, using tools and equipment, or discarding objects.

Work Recovery Cycles: The job pattern that defines how work is organized with respect to lighter tasks or rest. High work/recovery ratios, measured as continuous time on each type of activity, have higher potential for fatigue.

Workstation: The entire area accessed by a worker when performing a specific task or job cycle.