Ergonomics 

the study of the fit between the worker and the work environment, which includes the tools and materials used, the tasks performed and the environment in which the work is performed. 

Cognitive Ergonomics 

mental processes (memory, perception, reasoning) as they affect interaction in a community 

Organizational Ergonomics 

optimization of socio technical systems including their organizational structures, policies, and processes. 

Physical Ergonomics 

human anatomical, and some of the anthropometric, physiological, and bio mechanical characteristics as they relate to physical activity 

1. Anthropometrics and characteristics of the worker

2. Characteristics of the work space
3. Physical attributes of objects to be manipulated
4. Other environmental concerns 

• Nature of the work task
• Constancy of effort (time and symmetry)
• Torque generating capacity of worker
• Repetition of the task
• Awkward postures required to complete the task or assumed by the individual doing the task (their own poor posture)
• Variable production levels
• Velocity and acceleration required for the task
• Force required to perform the task or control the equipment/tools
• Changing work schedules
• Increasing risk of musculoskeletal disorders based on the: Frequency, Duration of exposure, Intensity 

1. Tasks that are below the Action limit
2. Tasks that are above the Action limit

3. Tasks that are Above the Maximum Permissible Limit 

nominal risk for most workers. More than 99% of male and 75% of female workers have the strength to lift this much weight 

unacceptable risk to most workers without administrative engineering controls (engineering controls are always preferred) 

hazardous so that all workers would be at an unacceptably high risk of injury 

position in which minimum stress is applied to each point. In upright posture (standing), a correct posture is associated with optimum alignment and minimum muscle activity. 

posteriorly convex curves noted in the thoracic and sacral spine. Called primary curves do to presence at birth. 

posterior concave curves note in the cervical and lumbar spine. Called secondary curves due to development later 

the angle formed by the surfaces of the superior and inferior vertebra of a particular region of the spine. 

from the angle formed by a line from the PSIS to the ASIS and the horizon.

Normal angles range 7-16 degrees.

Abnormal lateral bending of the spine in the frontal plane. The lateral bending is coupled with rotation in the transverse plane towards the side of the convex.