E RGO -T EAM A PPROACH TO P ARTICIPATORY E RGONOMICS
© SafetyNet Centre for Occupational Health & Safety Research Memorial University, 2012 Developed by: Scott N. MacKinnon, PhD Edited by: David M. Antle, MSc, PhD (candidate)

Ergonomics, Joints, Motion and Postures  We have to understand how the body moves in order to evaluate work tasks and their potential role in WMSDs.  Ergonomists have core terms for body movements for use in the analysis of work tasks.  Knowledge of these core terms is essential for effective job analyses and for clearly communicating the results of our analysis to others. 2

Why core terms?
 Describing how a person moves and performs a task is difficult.
 It is more difficult if we use loose or different terms  Common, carefully defined terms can reduce the risk of confusion and help improve understanding.  Exercise:  Describe, in words only, how you would move your upper arm to throw a baseball  Is your description the same as your partners? 3

Motion and Postures  Joints (elbows, knees, wrists, etc.) play a key role in motion  A joint can move in 3 different ways – we call them planes
of motion
 A “forward to backward motion” plane  A “side-to-side motion” plane  A “twisting motion” plane  The way a joint is constructed influences the planes through which it can move.  Move your shoulder and your elbow. How many planes can your shoulder move in? What about your elbow?
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Motion and Postures  • Motion involves moving our trunk or a limb.
If a joint is moving we call it “dynamic” - it is changing position. • • Postures entail holding a body segment in a particular position. If a joint is held in one position we term it to be “static” - it is a non-moving posture.  Both postures and motion can, in certain circumstances, contribute to the risk of injury  Job analyses need to distinguish clearly between postures and motion. 5

Motion and Postures • • When describing motion, each joint will have movements/postures in at least one plane.
We determine what is happening at each joint by breaking down the movements/postures in each plane of motion.
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Forward – Backward Motions / Positions
Flexion Neutral Extension
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Side to Side Motions/Postures
Right Lateral Bend Neutral Left Lateral Bend
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Twisting Motions/Postures
Left Twist Neutral
Right Twist 9

Terms for Motions/Postures • • • • • In a forward-backward plane: Flexion is a motion/position that is moving towards/held in an area in front of you Extension is a motion/position that is moving towards/held in an area behind you • • • In a side-to-side plane: Trunk and neck - Lateral bending Shoulder - Adduction and abduction (towards the body versus away from the body) Wrist - Radial and ulnar deviations (movement towards and away from the bones in the forearm) • • • In a twisting plane Trunk and neck - Right and left rotations Shoulder - Lateral and medial rotations Forearm - Pronation and supination 10

The Neck - Forward / Backward Motion and Position
Flexion Extension
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The Neck - Side to Side Motions / Positions
Right Lateral Bend Left Lateral Bend
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The Neck – Twist / Rotation Motions / Positions
Right Twist/Rotation Left Twist/Rotation
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The Torso – Forward / Backward Motions / Positions
Flexion Extension
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The Torso - Side to Side Motions / Positions
Right Lateral Bend Left Lateral Bend
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The Torso - Twist / Rotation
Left Twist/ Rotation Right Twist/ Rotation
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The Shoulder – Forward / Backward
Flexion Extension
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The Shoulder - Side to side
Adduction Abduction
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The Shoulder – Twist / Rotation
Medial Rotation Lateral Rotation
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The Elbow – Forward / Backward
Flexion Extension
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The Shoulder – Twist / Rotation Medial Rotation Lateral Rotation
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The Forearm – Twist / Rotation
Twist occurs by the two bones in the forearm (the radius and the ulna) crossing each other
Supination Pronation
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The Wrist – Forward / Backward Extension Flexion
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The Wrist - Side to Side Radial deviation Neutral Ulnar deviation
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Palms / Fingers - Pinch
Pulp Pinch Lateral Pinch
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Palms / Fingers - Pinch
Pinch (Palm)
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Palms / Fingers - Press
Finger Press Press
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Palms / Fingers - Grasp
Grasp
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Describing Motion
Keep in mind a joint can have motion in different planes at the same time! For example: Your shoulder can be in flexion and abduction at the same time.
Try it......
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Exercise 1:
Try an example...
Throw a ball.
Identify and explain:  The plane (s) of motion  The joint (s) involved  The term for the movement and/or posture 30

Exercise 2:
Pair up into smaller groups. Take turns performing an action and have your partners tell you which postures/ motions are being performed at each joint in the various plane(s) of motion.
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Exercise 3:
Observe the “Pan wash video”. When she reaches for the pan, explain the motions / postures at the:  neck  torso  right shoulder  right elbow  right forearm  right wrist  right hand 32