Ergonomics, Anthropometry, Biomechanics and Physiology

Ergonomics

• Ergonomics is the science of work, encompassing the people doing it, the methods used, the tools and equipment involved, the workspaces, and the psychosocial elements of the work environment.
• The term "ergonomics" originates from the Greek words "ergos" (work) and "nomos" (natural law).

Anthropometry

• Anthropometry is the science of measurement that establishes the physical geometry, mass properties, and strength capabilities of the human body and its applications.
• The word is derived from the Greek terms "anthropos" (human) and "metrikos" (pertaining to measurement).

Occupational Biomechanics

• Biomechanics studies forces acting on the human body.
• The aim of occupational biomechanics is to quantitatively assess musculoskeletal stress during work to determine the level of associated risk.

Physiology

• Physiology examines how the human body operates during physical activity, focusing on vital processes carried out by living organisms and the functions of their constituent tissues and cells.

Physical Ergonomics

• Physical ergonomics primarily deals with human anatomical, anthropometric, physiological, and biomechanical attributes as they relate to physical activity.

Cognitive Ergonomics

• Cognitive ergonomics focuses mental processes, such as perception, memory, reasoning, information processing, and motor response, as they affect interactions between humans and system elements.

Organizational Ergonomics

• Organizational ergonomics, also known as macroergonomics, optimizes sociotechnical systems by focusing on organizational structures, policies, and processes.

Grip Strength

• Maximum grip strength occurs at neutral supination.
• Minimum grip strength occurs with flexion pronation.

Tendons

• The body raises the production of synovial fluid lubricants within the tendon sheath to reduce friction within the tendon

Tools and Measurement

• A grid board, consisting of crossing lines attached to vertical walls that meet at right angles, is employed to measure anthropometric variables.
• Hinge joints are present at the elbow and knee

Measuring Equipment

• Anthropometers: Graduated rods with sliding edges used to measure bony landmarks that cannot be easily projected onto grids.
• Goniometers: Anthropometric instruments used to measure the range of motion in a joint.

Anthropometric Baselines

• Breadth: An anthropometric baseline measurement that is a point-to-point horizontal measurement running across an entire body or a body segment

Spinal Column

• Smaller angles between the thighs and the body correlate with greater kyphosis
• The spinal column in side view has forward bends (lordosis) in the chest area and lumbar section and a backward bend (kyphosis) in the cervical.

Muscles

• Adenosine triphosphate (ATP) is an organic compound neccessary for producing power producing muscular contractions
• Faster muscle movement results in greater reduction in force capability
• Brief rest periods are more beneficial than long, infrequent ones
• As a rule, 50% of muscle strength is available for about 1 minute
• Muscles at their resting length have the minimum capacity to generate force
• Flexion is the main movement of synovial joints that folds the body into the curled-up fetal position

Head position

• In the Head in Frankfurt Plane, the head is straight, pupils are on the same horizontal level, and the Ear-Eye Line is angled 15 degrees against the horizon.

Workstation Design

• The min-max strategy is not suitable for workstations, tools, and tasks that are designed to fit the average group of the population.

Trauma

• Cumulative trauma develops from the repeated application of force to a structure, leading to wear beyond its tolerance level

NIOSH Lifting Equation

• The frequency multiplier in the NIOSH Lifting Equation refers to the rate of lifts or lowers per minute, influenced by task duration and the object's vertical location.
• A maximal load constant of 23kg is permissible with the 1991 NIOSH Lifting Guide
• In computing for recommended weight limit, vertical multiplier does not refer to the vertical travel distance from the start to the end points
• L refers to the actual weight being lifted or lowered in the equation LI = L / RWL
• The asymmetry multiplier in the NIOSH Lifting Equation relates to the angle of body twisting during the lift.
• The revised NIOSH lifting equation is not applied to the following conditions, except lifting/lowering for eight hours
• If DM < 1.0, increasing the vertical distance between the origin and destination of a lift is not a correct analysis.

Illumination

• Illumination is the amount of light striking a surface, measured in footcandles (fc).
• Illumination decreases as the square of the distance from the light source increases
• Luminance is the amount of light reflected and is measured in foot-lamberts (fL).
• Mahogany work surfaces have lower reflectance compared to surfaces with a medium yellow finish.

Vibration and Noise

• Human tolerance for vibration decreases with longer exposure
• The combined noise exposure dose should be less than or equal to 100%. For example, a worker exposed to 95 dBA for 3 hours and 90dBA for 5 hours has a combined exposure is 138%.
• A worker exposed to 95 dBA for 3 hours and 90dBA for 5 hours has a Time Weighted Average (TWA) sound level is 92 dBA

Human Error

• A "Mistake" is a form of human error where one is aware of a problem, forms a faulty plan in solving it, and does the wrong thing while believing it to be correct.

Musculoskeletal Disorders

• Carpal Tunnel Syndrome is a widely spread Musculoskeletal Disorder(MSD) common to electronic assemblers because their wrist position of requires constant wrist flexion, similar to the wrist position of computer mouse users.

Overview of ergonomics as the science of work, anthropometry in physical measurement, occupational biomechanics assessing musculoskeletal stress, and physiology examining human body function during physical activity.