Strength and Perceived Effort in Repetitive Upper-Limb Tasks: An OCRA Method Analysis of 900 Workers

Area of Science:

• Occupational health and safety
• Ergonomics
• Musculoskeletal disorder prevention

Background:

• Work-related musculoskeletal disorders are a significant public health issue.
• The OCRA method is used to assess risks of repetitive upper limb actions.
• Subjectivity in perceived effort reporting can bias OCRA assessments.

Purpose of the Study:

• To investigate if measuring handgrip strength improves force assessment accuracy in the OCRA method.
• To reduce subjective bias in occupational risk assessments.

Main Methods:

• Handgrip strength was measured within the OCRA risk assessment framework.
• Data were stratified by age, gender, height, and handedness into percentile ranks.

Main Results:

• Significant differences in handgrip strength percentiles were observed between workers reporting high vs. low perceived effort (p=0.047).
• Perceived effort rates varied significantly with different handgrip strength levels (dominant hand: p=0.04; non-dominant hand: p=0.02).

Conclusions:

• Worker handgrip strength is a critical factor influencing perceived effort in repetitive tasks.
• Incorporating handgrip strength measurement enhances the OCRA method for assessing biomechanical overload.
• This study, with a large sample size, offers a significant advancement in occupational risk assessment accuracy.