Guest Author - virginia hixson
Awkward Posture: the body is placed in a non-optimal posture for doing a task. Awkward postures range from “ok to do but look for a better way” to “that’s ridiculous”. The scale is not precise or scientific. How awkward a posture has to be to be problematic depends on:
How long the posture has to be held
How frequently is must be used
How much force is required while in the awkward posture
Other things that have to be done at the same time
Physical constraints (in tight places)
Cumulative Trauma: (Also known as Repetitive Strain Injury or Repetitive Motion Injury). Injury caused by accumulation of small trauma over a period of time generally caused by doing the same motion repetitively and speedily or with excessive force.
Easy reach: Sitting back in your chair with your elbows against your body, with you palms down , bend your elbows to 90 degrees. Now keeping the elbow touching your body, rotate your arms in and out. Anything you can touch is within easy reach.
Ergonomic Chair: Chair manufacturers have agreed that they will use the term ‘Ergonomic Chair’ to refer to chairs that will adjust to fit everyone except those in the smallest 5% and largest 5% of the population. The most frequent population statistics used are from Army Recruits for the second world war.
Ergonomic Tool: Anything can claim to be ergonomic. There is no real requirement of design or construction for a tool to claim that label. Consider – Is the tool ergonomic for ME? Does it fit my hand? Does it work smoothly? Does it decrease the force I have to use? And then consider – Does using it place my hand or arm or body in an awkward position? Just because a tool is ergonomic for one person does not mean it is ergonomic for all. We do not all wear the same size shoe, or even the same style. Neither can we all use the same tools equally effectively.
Ergonomics: The study of work-particularly the study of how the human is affected by work. Frequently reduced to the physical, ergonomics also includes the psyche : both how state of mind affect the way work is done and how the way work is done affects the psyche.
Ergonomist: One who is trained in the Science of Ergonomics at a university level, including anatomy, physiology, work safety, biomechanics, work evaluation and modification, human computer interaction, perception, research, etc. Normally this is housed in either the Engineering or the Psychology Department.
Excessive Force: Force requirement of more than 2/3 maximal force of a particular muscle. This is rarely tested. Generally, ‘excessive force’ is a term used to indicate more force than an average person would comfortably manage.
Neutral Posture: For the ergonomist, Neutral Posture is the posture of least physical strain. If you think of a relaxed astronaut in Zero G, that is neutral posture.
Static Load (Static Position): Static load is the load on the muscle that is held over a period of time. Even in a relaxed position, muscle load builds up over time: the higher the static load, the more risky the job. Force and awkward posture increase static load.