CES Human Factors & Biomechanics 1 — Questions and Answers
Question 1: Which joint is most commonly stressed during prolonged overhead work tasks?
- Shoulder (glenohumeral) (Correct answer)
- Elbow (humeroulnar)
- Wrist (radiocarpal)
- Hip (coxofemoral)
Correct answer: Shoulder (glenohumeral)
Overhead work requires sustained shoulder elevation, placing high mechanical load on the glenohumeral joint and surrounding rotator cuff muscles.
Question 2: What does the term 'neutral posture' refer to in ergonomics?
- A position that minimizes mechanical stress on muscles and joints (Correct answer)
- Standing perfectly upright at all times
- Avoiding all movement during work tasks
- Using maximum joint range of motion
Correct answer: A position that minimizes mechanical stress on muscles and joints
Neutral posture describes body positions where joints are near their mid-range, minimizing mechanical stress and reducing injury risk.
Question 3: Which biomechanical principle explains why a longer lever arm increases the force needed by muscles?
- Torque principle (Correct answer)
- Newton's third law
- Pascal's law
- Hooke's law
Correct answer: Torque principle
Torque equals force multiplied by lever arm distance, so a longer lever arm requires greater muscle force to maintain equilibrium.
Question 4: What is the recommended maximum acceptable reach distance for frequent work tasks at seated workstations?
- Within the primary work zone (elbow radius) (Correct answer)
- Full arm extension
- Beyond shoulder width
- At or above shoulder height
Correct answer: Within the primary work zone (elbow radius)
Frequent tasks should be performed within the primary work zone, approximately the elbow radius from the body, to minimize shoulder and trunk loading.
Question 5: Which cumulative trauma disorder is associated with repetitive pinch grip and lateral wrist deviation?
- De Quervain's tenosynovitis (Correct answer)
- Carpal tunnel syndrome
- Lateral epicondylitis
- Trigger finger
Correct answer: De Quervain's tenosynovitis
De Quervain's tenosynovitis involves inflammation of tendons controlling thumb movement and is aggravated by pinch grip combined with radial or ulnar deviation.
Question 6: In spine biomechanics, which lumbar motion creates the highest intradiscal pressure?
- Flexion combined with rotation (Correct answer)
- Pure extension
- Lateral bending only
- Neutral standing posture
Correct answer: Flexion combined with rotation
Combined lumbar flexion and rotation generates the greatest intradiscal pressure and is a primary mechanism for disc injury and low back disorders.
CES Human Factors & Biomechanics 1
Which joint is most commonly stressed during prolonged overhead work tasks?