Commonly Used Subjective Effort Scales May Not Predict Directly Measured Physical Workloads and Fatigue in Hispanic...

Area of Science:

• Occupational health
• Ergonomics
• Exercise physiology

Background:

• Hispanic migrant farmworkers face significant occupational ergonomic risks.
• Cultural differences in reporting effort and pain create uncertainty about standardized subjective assessment tool accuracy.

Purpose of the Study:

• To investigate the association between subjective ergonomic assessment scales and direct measures of physical effort and muscle fatigue in Hispanic migrant apple harvesters.
• To determine if widely used exercise physiology scales can accurately estimate metabolic load and muscle fatigue in this population.

Main Methods:

• Twenty-four apple harvesters participated in an 8-hour workday study.
• Subjective overall effort was measured using Borg RPE (Spanish) and Omni RPE (with relevant imagery).
• Local shoulder discomfort was assessed using Borg CR10, while muscle fatigue was measured using electromyography (EMG) and heart rate reserve (% HRR).

Main Results:

• Omni RPE showed correlation with % HRR, indicating a potential measure of overall exertion.
• Borg RPE correlated with % HRR post-break but not at the end of the workday.
• Borg CR10 for local discomfort was not correlated with EMG measures of muscle fatigue.

Conclusions:

• Subjective scales like Omni RPE and Borg RPE may be useful for assessing overall exertion in specific contexts for this population.
• The Borg CR10 scale is not a reliable substitute for direct EMG measurements of muscle fatigue in assessing local discomfort.