15-11-2012, 10:57 AM
ERGONOMICS
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ERGONOMICS-What is it?
Derived from two Greek words:
“Nomoi” meaning natural laws
“Ergon” meaning work
Hence, ergonomists study human
capabilities in relationship to work
demands
History
As early as 18th century doctors noted that workers who required to maintain body positions for long periods of time developed musculoskeletal problems.
Within last 20 years research has clearly established connections between certain job tasks and RSI or MSD.
What two elements are at work?
Static work: musculoskeletal effort required to hold a certain position, even a comfortable one.
Example: sit & work at computers; keeping head and torso upright requires small or great amounts of static work depending on the efficiency of the body positions we chose.
Force: amount of tension our muscles generate
Example: tilting your head forward or backward from a neutral, vertical position quadruples the amount of force acting on your lower neck vertebrae
Increased force is d/t increase in muscular tension needed to support head in a tilted position
3 Main Ergonomic Principles:
Work activities should permit worker to adopt several different healthy and safe postures.
Muscle forces should be done by the largest appropriate muscle groups available
Work activities s/b performed with joints at about mid-point of their ROM (esp. head,trunk,UE)
FACTS
The average person working at a keyboard can perform 50,000 to 200,000 keystrokes a day
Overexertion, falls & RMI are the most common cause of workplace injury
An average of 125,000 back injuries due to improper lifting each year.
Muscles overuse results in tiny tears in the muscles and scarring; these contribute to inflammation and muscle stiffness
A Bit of Anatomy !!
Overuse and small repetitive movements ie: CTD, RSI, MSD disturb balance of muscles, tendons, ligaments and nerves
Brachial plexus: nerve group that supply muscles and skin of UE, course down side of front of neck and become median, ulnar and radial nerves.
Nerves send signals to muscles to contract
When nerve compressed feel sensation somewhere b/w point of compression and fingertips