AEP Core Knowledge Areas 2 — Questions and Answers
Question 1: Which biomechanical principle explains why bending at the waist to lift a load significantly increases lumbar disc compression compared to bending at the knees?
- The moment arm of the load is longer when the spine is flexed forward (Correct answer)
- The load weighs more when held away from the body's center of gravity
- Knee flexion reduces gravitational force on the load
- Hip extensors are weaker than lumbar extensors
Correct answer: The moment arm of the load is longer when the spine is flexed forward
When the spine flexes forward, the horizontal distance (moment arm) from the lumbar spine to the load increases, dramatically multiplying the compressive force on the discs.
Question 2: A workstation assessment reveals a keyboard tray positioned so the worker's elbows are bent at 110°. What is the primary ergonomic concern with this configuration?
- The elbows are too far from the torso, increasing shoulder load
- Elbow flexion beyond 90° increases forearm extensor muscle activity and carpal tunnel pressure (Correct answer)
- The angle is within the acceptable range of 90–120°
- Wrist extension will be reduced in this position
Correct answer: Elbow flexion beyond 90° increases forearm extensor muscle activity and carpal tunnel pressure
Elbows flexed beyond 90° can elevate pressure within the carpal tunnel and increase muscle activity in forearm extensors, raising cumulative trauma risk.
Question 3: In the NIOSH Revised Lifting Equation, what does the Asymmetry Multiplier (AM) penalize?
- Loads that are asymmetrically shaped or irregularly packed
- Twisting of the torso away from the sagittal plane during the lift (Correct answer)
- Horizontal distance from the body's midline to the load
- Frequency of lifts that alternate between left and right hands
Correct answer: Twisting of the torso away from the sagittal plane during the lift
The AM accounts for trunk rotation (asymmetry angle) during lifting, which increases spinal loading beyond sagittal-plane lifts.
Question 4: What is the primary purpose of conducting a Rapid Upper Limb Assessment (RULA)?
- To calculate the maximum acceptable weight of lift for a job task
- To screen upper-extremity posture and muscle use for MSD risk (Correct answer)
- To measure metabolic energy expenditure during repetitive tasks
- To quantify noise exposure levels affecting the upper body
Correct answer: To screen upper-extremity posture and muscle use for MSD risk
RULA is an observational screening tool that scores upper-limb postures, muscle use, and force to identify musculoskeletal disorder risk levels.
Question 5: According to anthropometric design principles, a workstation designed for the 5th to 95th percentile accommodation would exclude approximately what percentage of users?
- 5%
- 10% (Correct answer)
- 1%
- 15%
Correct answer: 10%
Designing for the 5th–95th percentile range accommodates 90% of the target population, excluding the extreme 5% at each tail (10% total).
Question 6: Which control measure represents the highest level of the ergonomics hierarchy of controls?
- Providing anti-fatigue mats for standing workers
- Redesigning the job task to eliminate the hazardous motion entirely (Correct answer)
- Training workers in proper lifting techniques
- Requiring workers to use back support belts
Correct answer: Redesigning the job task to eliminate the hazardous motion entirely
Elimination—removing the hazard at the source through job or process redesign—is the most effective control at the top of the hierarchy.
Question 7: A manufacturing worker develops lateral epicondylitis (tennis elbow). Which job factor is MOST directly associated with this condition?
- Whole-body vibration from operating a forklift
- Repetitive wrist extension and forearm pronation/supination under force (Correct answer)
- Static neck flexion from looking down at a monitor
- High-frequency hand-arm vibration from pneumatic tools
Correct answer: Repetitive wrist extension and forearm pronation/supination under force
Lateral epicondylitis is strongly linked to repeated or forceful wrist extension and forearm rotation, which overload the common extensor tendon at the lateral epicondyle.
AEP Core Knowledge Areas 2
Which biomechanical principle explains why bending at the waist to lift a load significantly increases lumbar disc compression compared to bending at the knees?