CES Human Factors & Biomechanics 2 — Questions and Answers
Question 1: What is the primary purpose of an electromyography (EMG) assessment in ergonomic studies?
- Measure muscle activation and fatigue during tasks (Correct answer)
- Evaluate joint range of motion
- Record heart rate variability
- Assess visual acuity
Correct answer: Measure muscle activation and fatigue during tasks
EMG measures electrical activity in muscles, allowing ergonomists to quantify muscle effort, identify overexertion, and document fatigue patterns during work tasks.
Question 2: Which factor primarily determines the compression load experienced at the L5/S1 disc during lifting?
- Horizontal distance of the load from the spine (Correct answer)
- Weight of the load only
- Height of the lift destination
- Duration of the lifting task
Correct answer: Horizontal distance of the load from the spine
The horizontal distance of the load from the lumbar spine is the primary multiplier of compression force at L5/S1, often having more impact than load weight alone.
Question 3: What does the anthropometric concept of 'design for the 5th to 95th percentile' mean in ergonomics?
- Designing workstations to accommodate 90% of the target population (Correct answer)
- Using only average measurements for design
- Designing for the smallest worker only
- Targeting the largest workers exclusively
Correct answer: Designing workstations to accommodate 90% of the target population
Designing for the 5th to 95th percentile means the workspace accommodates 90% of users, balancing practical design constraints with broad usability.
Question 4: Which type of muscle contraction is most associated with the development of localized muscle fatigue during sustained work?
- Static (isometric) contraction (Correct answer)
- Concentric contraction
- Eccentric contraction
- Plyometric contraction
Correct answer: Static (isometric) contraction
Static contractions restrict blood flow to working muscles, impairing oxygen delivery and metabolite clearance, leading to rapid localized fatigue.
Question 5: What is the 'action limit' concept originally developed for in ergonomics?
- Identifying acceptable manual lifting loads using NIOSH guidelines (Correct answer)
- Setting maximum noise exposure thresholds
- Defining lighting requirements for visual tasks
- Establishing vibration exposure limits
Correct answer: Identifying acceptable manual lifting loads using NIOSH guidelines
The NIOSH action limit was developed as a guideline to identify manual lifting conditions that exceed acceptable risk levels and require ergonomic intervention.
Question 6: Which segment of the upper extremity is most affected by thoracic outlet syndrome?
- Nerves and blood vessels exiting the thoracic outlet near the shoulder and neck (Correct answer)
- Wrist flexor tendons
- Elbow lateral epicondyle
- Finger extensor mechanism
Correct answer: Nerves and blood vessels exiting the thoracic outlet near the shoulder and neck
Thoracic outlet syndrome compresses neurovascular structures (brachial plexus, subclavian vessels) as they pass through the outlet between the collarbone and first rib.
CES Human Factors & Biomechanics 2
What is the primary purpose of an electromyography (EMG) assessment in ergonomic studies?