Understanding and Preventing Repetitive Stress Injuries

1. Understanding and Preventing Repetitive Stress Injuries Brian Rouse MSPT, OCS

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

3. 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.gif

4. 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

5. Fighting Gravity http://www.posturepal.com/assets/images/sci2.jpg

6. 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

7. 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

8. Challenges in Ergonomics • Designing for “Average” • Lack of variance in work tasks • Time constraints for job completion • Costs of modifying environment

9. http://solutions.3m.com/wps/portal/3M/en_US/ergonomics/home/advice/workspacecomfortguide/http://solutions.3m.com/wps/portal/3M/en_US/ergonomics/home/advice/workspacecomfortguide/

10. 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

11. 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

12. 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

13. 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

14. 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

15. 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

16. 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

17. 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/

18. Task Modification http://www.uhs.berkeley.edu/facstaff/ergonomics/lab/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

19. 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)

20. 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

21. 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

22. Resources • University of California—Los Angeles http://ergonomics.ucla.edu/index.html • University of California—San 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/