Ergonomics

Introduction to ergonomics

• The term ergonomics is derived from two greek words : ergon meaning work and nomos meaning natural laws or rules

• So ergonomics means the laws of work • The ergonomics aims

to design techanical systems and tasks in such a way as to improve human safety, health, comfort and performance.

• Ergonomics is the scientific study of people and their work

• It based on the study of human characteristics which included recognition of human capacities , abilities, habities and limitations.

• The limitation may be due to structure, function and behavior

• Then application of this knowledge to the work place design including design of tools, equipment and the total environment

• The term man machine interaction in the human machine system (HMS) or work place is the understanding of the interaction between people and the machine they used .

• Ergonomics provides a good match between people and their environment which can result in better and more efficient human performance as well as the enhancement of health and safety .

The benefits of ergonomics• Improving the quality of life• Improving the quality of all human related activities• Good ergonomics minimizes product costs and human

errors and maximizes user satisfaction and health• It makes the job safer by prevent injuries and illness• makes the job easier by adjusting the job to the

worker

• Makes the job more pleasant by reducing physical and mental stress

N.B physical stress to the body parts like ms, joints, bones….cause injuries which called repetitive strain injuries (RSIs) or cumulative trauma disorders (CTD) like carpal tunnel syndrome, bursitis, tenosynovitis and epicondylitis.

Ergonomics contributes to the prevention of injuries, disability and reinjure

• So It is therefore important in all stages 1- pre – injury stage called primary prevention which

emphases should be considered on designing a safer human machine system via designing safe environment

2- in the post - injury stage. called secondary prevention . It contributes to the rehabilitation and management of trauma and disorders through effective comprehensive rehabilitation with the goal of preparing the individual to return to a productive lifestyle within a safe environment

3 - in the post – rehabilitation stage called tertiary prevention . In this case emphasis is made on the design of effective programs to prevent reinjures and to ensure that the subject continues to 1- maintain functional capacities and 2- perform in safely in work

N.B• good engineering , awareness and physical

fitness are the three common factors in all of these stages of prevention

• The ergonomics is good in solving the problems associated with posture

Summary • Ergonomics is highly relevant to preventive and

occupational medicine, the management of musculoskeletal injuries and rehabilitation

• It help people to understanding their abilities and limitation and teaching them how to perform safely, effectively and comfortably within the environment

• An ergonomist is a trained subject who has an experience in ergonomics and its application . An ergonomist can study human capabilities in relation to work demand in the human-machine systems(HMS)

• There are specific ergonomic standards which are applied in companies and industrial sectors . The most common one is the international standardization organization (ISO)

environments

Machine

Human

Pushing is preferred than pulling

• Pushing force is directed posterior on the spine

• so the bending moment is also posterior this moment is counteract by the abdominal ms which have the larger lever arm measured from the center of motion than the erector spinae ms

• so the required force is small

• when the abdominal ms become tensed to resist the bending moment, the intra-abdominal pressure increase and the intra-thoracic increase this will decrease intra-vertebral disk pressure and decrease the load on the erector spinae ms

Push force

Rectus force

Body wt

Erector force

Pull force

Erector force

Body wt

Disk load Disk load

How to carry objects with maximum efficiency and least harms

Choosing the seat

Choosing the object’s hand design

Correct Incorrect