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Health and Safety: Teaching Tools



Ergonomics is a science that matches work to the worker. Poor ergonomic conditions at work, home, school, or play can negatively affect our health. Ergonomics literally means "laws of work." The word ergonomics is made up of two Greek words: "Ergos" meaning "work" and "Nomos" meaning "laws." These "laws" of work are simple:

What is Ergonomics

Your physical capabilities must match the demands of the task you are doing. When this matching is in balance, it helps us stay healthy.

Poor ergonomic conditions at work, home, school, or play can negatively affect our health.


Human Capabilities

Human Capabilities

When determining the physical capabilities of a person, several factors must be taken into account. These include:

  • Physical fitness,
  • Age,
  • Size (height, weight, body dimensions),
  • Psychosocial (Level of fatigue, mood, and stress), and
  • Gender

Job Demands

Job Demands

Job demands are determined by examining five major characteristics of a job. These are:

Force - The amount of physical effort exerted (lifting, pushing, pulling, etc.).

Posture - the position of the body. Good posture places the body's structures (bones, ligaments, muscles) in positions to handle the most stress, and to ensure that tasks that require more force are completed by largest muscle groups

Repetition - Refers to the number of times a particular task must be completed

Environmental Conditions - such as being exposed to vibration, heat, or cold.

Time - which could refer to how long it takes a person to perform 1 task once, or it could refer to how long the worker's day is.

As a worker becomes exposed to more of these factors while completing a given task, their likelihood of exceeding their physical capabilities exponentially increase.



Once human capabilities and job demands are analyzed, these factors need to be weighed against each other to determine the most appropriate solution for the individual. Our bodies experience strain when the demands of our work exceed our capabilities. Prolonged strain results in pain and injury which may cause impairment and disability. Other aspects of matching worker capabilities to job demands include cognitive, perceptual, and motor skill capabilities.

Lack of Balance

Injury is the result of imbalance between job demands and human capabilities. Injuries tend to progress in stages:

  • The first indication of stress on the body is local muscle fatigue and soreness.
  • As we continue doing the same tasks, the pain progresses into aching, tiredness, loss of sleep, and difficulty in moving the body parts affected.
  • As the pain becomes an injury, we may not be able to do the work we normally do.

When you experience aches and pains from performing tasks, you should seek medical attention.



Sometimes stress can be a contributor to worsening the pain we can feel from poor ergonomic conditions. When our bodies are under stress, situations that would not normally cause muscle pain may cause injuries. Stress can come from school, personal or job pressures. These could be related to:

  • threat of violence,
  • peer pressure,
  • fear,
  • pressure to do well at school,
  • lack of job opportunities,
  • parental conflicts,
  • lack of exercise, and
  • changing world.

When you are under stress everything seems to go wrong. That is true with ergonomics as well. Stress causes you to lose focus or concentration on your work, resulting in the use of poor postures and work techniques.



Some of the most common types of injuries that happen in the workplace are called RMIs or repetitive motion injuries. The best way to prevent an RMI is to avoid situations or activities that cause RMI's. Common situations that cause RMI's include:

  • Working in awkward postures for long periods of time can lead to RMIs. Try to use a workstation that is the right height for you.
  • Working in the same posture (static postures), awkward or not, for long time can also lead to RMIs. Try to stretch or go for a walk (such as the kitchen for a drink).


  • Doing highly repetitious movements is an obvious cause of RMIs. Try to vary the types of movements you do and make sure that you use a variety of muscle groups. (For example: typing then playing the piano would not be a good break!)
  • Applying excessive force repetitively and for long periods of time can cause injury. Try to use only the amount of force necessary.
  • Pace your work. Working at a fast pace for a short amount of time may be worse than a slower pace for a longer period of time.
  • Long working hours without taking time to recuperate (rest breaks) can also lead to injury. Make sure your body has time to recuperate.

Prevention Exercises

Exercise helps prevent RMIs from developing or worsening.


Related Content

> Ergonomics > Introduction






> Other Ergonomic Subtopics