Understanding and Preventing Repetitive Stress Injuries

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Understanding and Preventing Repetitive Stress
Injuries

• Brian Rouse MSPT, OCS

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Goals

• Understanding normal body function
• Identifying how position affects function
• Guidelines for workspace assessment
• Tips/exercises to improve body function

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Defining Ergonomics

• Involves adapting a task to a person, not making
  the person change for the task
• Altering the task, the environment, or both

http//www.wark.csiro.au/library/gifs/ergonomics.g
if
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Anatomic Efficiency

• Joints
• Two bones meet and move against each other
• Primary damage is from compression and friction
• Areas of joint loaded unevenly faster damage
• Muscles
• Control joint movement, hold body in place
• Work to produce forces or stabilize against
  gravity
• If too much work is performed muscle fails
• Focus of ergonomics is DOING LESS WORK

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Fighting Gravity
http//www.posturepal.com/assets/images/sci2.jpg
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Consequences of Poor Posture

• Cumulative Trauma/Repetitive Stress
• Itis means inflamed/overstressed
• Tendonitis, bursitis, synovitis, arthritis
• Tissues that work too hard will complain
• Permanent Body Changes
• Arthritis cartilage damage does not regenerate
• Disc degeneration does not reverse
• Nerve compression can block signals
• Carpal tunnel, pinched nerve, sciatica

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Ergonomics Made Simple

• Use body positions requiring less work
• Muscles sustain less damage from overworking
• Use other objects to hold body in place
• A muscle at rest cannot be overworked
• The Easy Way is the Best Way

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Challenges in Ergonomics

• Designing for Average
• Lack of variance in work tasks
• Time constraints for job completion
• Costs of modifying environment

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http//solutions.3m.com/wps/portal/3M/en_US/ergono
mics/home/advice/workspacecomfortguide/
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Guidelines Head/Neck

• Monitor positioned 20-30 from eyes
• Use arms length as a guide
• Top of monitor should be at/slightly lower than
  eye level
• Use document holders to read while typing
• Head should be centered over shoulders
• Use turtle method to draw head back

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Shoulders/Arms

• Shoulders/upper arms perpendicular to floor
• Elbows close to sides/torso, at 90 degrees
• Forearms on armrests, allowing shoulders to drop
• Do not rest on hard/sharp armrest edges

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Keyboard

• Keyboard trays for height/proximity
• Wrist needs to be neutral, not bent back
• Wrist rests pad hard desktop, hold wrist up
• Use only when not typing or mousing
• Float hands over keyboard while typing
• Mouse next to keyboard, easy to reach
• Move mouse with elbow/forearm, not wrist

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Chair Adjustment

• Chair height level
• Hips/trunk at 90 degree angle or slightly more
• Feet flat on floor
• Can use foot stool if needed
• Thighs should fit under desk
• Or keyboard tray if needed
• Seat pan should be 1-2 wider than hips on either
  side

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Chair Adjustment

• Backrest
• Position lumbar support in natural curve of back
• If insufficient, add towel roll/etc. behind curve
• Shoulder blades able to rest against chair back
• Should allow user to tilt back 15 degrees

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Common Mistakes

• Head position too far forward
• Monitor set at diagonal to worker
• Forearms not on armrests
• Shoulder blades off of backrest
• Lumbar curve in chair not flush with back
• Monitor set too low
• Feet not flat on floor/stool

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Considerations for Standing Tasks

• Alter height of workstation or user
• Have footrest to allow weight shift of legs
• Organize workstation to allow controls/tools to
  be in close proximity
• Have a chair in proximity, using for tasks that
  can be seated or just rests
• Use proper footwear and anti-fatigue mats

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Standing Workstations

• Precision tasks (writing) 5 cm above elbow
  height
• Light tasks (assembly) 5-10 cm below elbow
  height
• Heavy tasks (downward force) 20-40 cm below
  elbow height

Canadian Centre for Occupational Health and
Safety www.ccohs.ca.oshanswers/ergonomics/
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Task Modification
http//www.uhs.berkeley.edu/facstaff/ergonomics/la
b/tools.shtml

• 20-20-20 rule
• 20 minutes of work
• 20 second rest (bare minimum)
• Look away from screen
• Adjust schedule as able to break up work

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Desk Stretching

• Longer holds are better, try for up to 30 seconds
  when possible
• Perform before/after work, during breaks
• Order does not matter, just frequency (1 hours)

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Warning Signs/Symptoms

• Pain--severe intensity or long duration (2-3
  days)
• Changes in sensation
• Numbness, tingling, burning
• Unexplained weakness/fatigue
• Difficulty with coordination/clumsiness
• Abnormal swelling/redness

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Other Considerations

• Strengthening postural muscles with exercise
  (yoga, strength training, etc)
• Sleep and proper diet aid in prevention of injury
  and healing
• Health problems (hypertension, diabetes) can
  increase risk of injury development

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Resources

• University of CaliforniaLos Angeles
• http//ergonomics.ucla.edu/index.html
• University of CaliforniaSan Diego
• http//blink.ucsd.edu/Blink/External/Topics/Policy
  /0,1162,4008,00.html
• Canadian Centre for Occupational Health and
  Safety
• http//ccohs.ca/oshanswers/ergonomics/