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Correlations between Ratings and Technical Measurements in Hand-Intensive Work
Gunilla Dahlgren1, Per Liv1, Fredrik Öhberg2
1Section of Sustainable Health, Department of Public Health and Clinical Medicine, Umeå University, S-901 87 Umeå, Sweden.
Bioengineering (Basel, Switzerland)
|July 29, 2023
Summary
Observer ratings of hand activity and force better correlate with objective measures than worker self-ratings, suggesting observers are more reliable for assessing work-related musculoskeletal disorder risks.
Area of Science:
- Occupational health
- Ergonomics
- Biomechanics
Background:
- Accurate assessment of hand activity and force is crucial for preventing work-related musculoskeletal disorders (WMSDs).
- The reliability of subjective worker and observer ratings compared to objective technical measures remains unclear.
Purpose of the Study:
- To investigate the correlation between subjective ratings (worker self-ratings and ergonomist observer ratings) and objective technical measures of hand activity and force.
- To determine which subjective rating method, if any, is more reliable for risk assessment of WMSDs.
Main Methods:
- Fifty-nine workers performing hand-intensive tasks were video-recorded.
- Subjective hand activity level and force were rated by workers (Hand Activity Threshold Limit Value®, Borg CR10) and four ergonomist observers.
- Objective measures included wrist angular velocity (inertial movement units) and forearm muscle activity (electromyography root mean square values normalized to maximal voluntary electrical activation).
Main Results:
- Statistically significant correlations were found between self-rated hand activity and wrist angular velocity, and similarly for observer ratings.
- Observer ratings showed stronger correlations with objective measures of force compared to worker self-ratings.
- Observer ratings demonstrated higher overall correlation magnitudes, suggesting greater reliability.
Conclusions:
- Observer ratings of hand activity and force appear more reliable than worker self-ratings when compared to objective technical measures.
- Objective technical measures of wrist angular velocity and muscle activity are preferable to subjective ratings for assessing WMSD risks.
- Ergonomist observer ratings can be a valuable tool but should be complemented by objective data where feasible.
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