AEP Biomechanics and Anthropometry 2 — Questions and Answers
Question 1: Which type of anthropometric data accounts for the range of body positions and movements that occur during actual work tasks?
- Normative anthropometry
- Functional (dynamic) anthropometry (Correct answer)
- Static anthropometry
- Comparative anthropometry
Correct answer: Functional (dynamic) anthropometry
Functional or dynamic anthropometry measures body dimensions during movement and task performance, capturing the actual reach envelopes and postural variations encountered in real work conditions.
Question 2: In a static biomechanical model, the sum of moments about a joint in equilibrium must equal:
- The body weight of the worker
- The compressive force on the spine
- Zero (Correct answer)
- The gravitational constant times mass
Correct answer: Zero
In static equilibrium, the algebraic sum of all moments (torques) about any joint must equal zero, a fundamental principle used to solve for unknown muscle and joint forces.
Question 3: Which muscle group serves as the primary antagonist to back extensor muscles during loaded forward flexion?
- Quadriceps
- Abdominal muscles (rectus abdominis and obliques) (Correct answer)
- Gluteus maximus
- Hamstrings
Correct answer: Abdominal muscles (rectus abdominis and obliques)
The abdominal muscles create an opposing moment that helps control forward flexion and contribute to intra-abdominal pressure, reducing the load on lumbar extensors during lifting.
Question 4: The 95th percentile male value means that:
- 95% of males fall below this measurement (Correct answer)
- 5% of males are taller than average
- The measurement exceeds the 95th percentile female value
- Only 5% of males can safely perform the task
Correct answer: 95% of males fall below this measurement
A 95th percentile value means that 95% of the reference population (in this case, males) have a measurement at or below that value, while only 5% exceed it.
Question 5: Static strength is best described as:
- The maximum force exerted during a rapid, single movement
- The maximum force sustained against a fixed, immovable resistance over a brief period (Correct answer)
- The endurance capacity of a muscle group over extended repetitions
- The force generated during an isokinetic contraction
Correct answer: The maximum force sustained against a fixed, immovable resistance over a brief period
Static (isometric) strength is the maximum force a person can exert against a fixed resistance over a brief, standardized time period, commonly used in job demands analysis.
Question 6: When performing an ergonomic assessment that requires comparison of worker dimensions to a workstation, which data source is most appropriate for a US adult workforce?
- ANSUR II (Army Anthropometric Survey)
- NHANES (National Health and Nutrition Examination Survey)
- Civilian American and European Surface Anthropometry Resource (CAESAR)
- All of the above are valid US adult anthropometric data sources (Correct answer)
Correct answer: All of the above are valid US adult anthropometric data sources
ANSUR II, NHANES, and CAESAR are all recognized sources of US adult anthropometric data; selecting the most appropriate depends on the workforce demographics being modeled.
Question 7: Intra-abdominal pressure (IAP) during lifting is believed to contribute to spinal stability primarily by:
- Compressing the lumbar vertebrae together for rigidity
- Creating an extension moment that partially offloads the erector spinae (Correct answer)
- Increasing intervertebral disc height to reduce shear
- Activating the multifidus to directly oppose compressive forces
Correct answer: Creating an extension moment that partially offloads the erector spinae
Elevated intra-abdominal pressure acts like an inflated balloon in the abdominal cavity, generating a slight extension moment that reduces the demand on the lumbar extensor muscles and therefore spinal compression.
AEP Biomechanics and Anthropometry 2
Which type of anthropometric data accounts for the range of body positions and movements that occur during actual work tasks?