CIEE Ergonomic Principles & Evaluation Techniques 5 — Questions and Answers
Question 1: The 'Revised Strain Index' (Moore & Garg) was developed to predict the risk of which specific category of occupational disorder?
- Low back disorders from heavy lifting
- Distal upper extremity disorders such as carpal tunnel syndrome and tendinitis (Correct answer)
- Lower extremity disorders from prolonged standing
- Whole-body vibration disorders from vehicle operation
Correct answer: Distal upper extremity disorders such as carpal tunnel syndrome and tendinitis
The Strain Index was designed to assess risk for distal upper extremity musculoskeletal disorders, including disorders of the wrist, hand, and forearm.
Question 2: When using a checklist-based ergonomic screening tool such as the OSHA Ergonomics eMatrix, a 'red' risk rating for a task typically triggers which response?
- Documentation only, with reassessment scheduled in 12 months
- Immediate detailed ergonomic analysis and priority engineering controls (Correct answer)
- Worker rotation to a different task pending annual review
- Mandatory medical surveillance for all exposed workers
Correct answer: Immediate detailed ergonomic analysis and priority engineering controls
A red (high) rating on ergonomic screening tools indicates unacceptable risk requiring immediate detailed analysis and prioritized engineering intervention.
Question 3: In ergonomic evaluation terminology, 'task cycle time' is important primarily because:
- It determines the worker's hourly pay rate under incentive systems
- Shorter cycle times generally mean higher repetition rates, which increases CTD risk (Correct answer)
- It is used to calculate the Composite Lifting Index for multi-task jobs
- It defines the allowable rest-to-work ratio for all manual tasks
Correct answer: Shorter cycle times generally mean higher repetition rates, which increases CTD risk
Shorter cycle times indicate higher repetition frequency, which is one of the primary ergonomic risk factors for cumulative trauma disorders.
Question 4: Which ergonomic principle supports the design of hand tools with a pistol-grip angle of approximately 15–20 degrees for horizontal power grip tasks?
- The tool should maximize the worker's grip force potential by straightening the wrist
- The angled grip positions the wrist in a more neutral posture, reducing flexor tendon stress (Correct answer)
- A pistol grip reduces tool weight to below the 1 kg fatigue threshold
- The angled handle allows better visual alignment with the workpiece
Correct answer: The angled grip positions the wrist in a more neutral posture, reducing flexor tendon stress
A 15–20° angled pistol grip maintains the wrist closer to neutral flexion/extension, reducing mechanical stress on flexor tendons and carpal tunnel contents.
Question 5: During an ergonomic assessment, a worker's Nordic Musculoskeletal Questionnaire (NMQ) results reveal high prevalence of neck and shoulder symptoms. The evaluator's most appropriate next step is to:
- Refer all symptomatic workers immediately to occupational medicine
- Conduct a detailed biomechanical analysis of tasks with high neck and shoulder postural demands (Correct answer)
- Implement a general stretching program for the entire workforce
- File an OSHA 300 log entry for each reported symptom
Correct answer: Conduct a detailed biomechanical analysis of tasks with high neck and shoulder postural demands
NMQ symptom prevalence data directs the evaluator to focus detailed biomechanical analysis on the body regions and tasks most likely contributing to those symptoms.
Question 6: According to ergonomic guidelines for manual material handling, the maximum acceptable push/pull force for initiating movement of a cart on a level surface should generally not exceed:
- 5 kg for women and 8 kg for men under any conditions
- Initial force of approximately 20 kg and sustained force of 10 kg for the general working population (Correct answer)
- 25% of the worker's body weight as an absolute standard
- The force required to move the load at a pace faster than 1 m/s
Correct answer: Initial force of approximately 20 kg and sustained force of 10 kg for the general working population
Snook and Ciriello's Liberty Mutual tables indicate that initial push/pull forces for cart movement should generally not exceed approximately 20 kg (initial) and 10 kg (sustained) to protect most workers.
Question 7: An ergonomist recommends implementing a job rotation schedule to reduce musculoskeletal risk. The key criterion that makes job rotation an effective administrative control is:
- Workers earn higher pay during rotation, increasing motivation and reducing injury claims
- Rotation transfers workers to tasks that stress different muscle groups, reducing cumulative exposure to any single hazard (Correct answer)
- Rotation eliminates the need for engineering controls by distributing risk across the workforce
- Workers develop greater strength over time by being exposed to a variety of high-demand tasks
Correct answer: Rotation transfers workers to tasks that stress different muscle groups, reducing cumulative exposure to any single hazard
Effective job rotation reduces cumulative exposure to any single ergonomic stressor by rotating workers to tasks that demand different muscle groups and postures.
CIEE Ergonomic Principles & Evaluation Techniques 5
The 'Revised Strain Index' (Moore & Garg) was developed to predict the risk of which specific category of occupational disorder?