Week 2: Occupational Biomechanics Flashcards
What is the goal of occupational Biomechanics
Design tasks that do not exceed the capacity of the musculoskeletal system
- Improve performance
- Reduced Risk of Injury
Components that can be changed to achieve main goals of occupational Biomechanics
- Tool Design
- Workplace Design
- Job Design
- Worker/task matching
- Material Handling
What is ergonomics
- Scientific discipline concerned with the understanding of interactions among humans and other elements of a system
- applies theory, principles, data, and methods to design in order to optimize human well-being and overall system performance
- Promotes holistic approach in which considerations of physical, cognitive, social, organizational, environmental and other relevant factors are taken into account
What is the difference between occupational biomechanics and Ergonomics
- Both recognize a multi-disciplined approach to understanding the worker: work interface
- Ergonomics can be broader including environment, cognitive issues, social, organizational elements
History of occupational biomechanics in the 1700s
- Berbardino Ramazzini founder of occupational medicine
- Published first comprehensive work on occupational disease
History of occupational biomechanics Pre-1900s:
- Most manufacturing and farming was done as a craft industry in which the worker was a craftsman and produced the entire product from beginning to end
History of occupational biomechanics in the industrial revolution
- The invention of electricity and the assembly line was a dramatic change in the way people were selected for employment, the types of tasks that were performed and the relationship between the worker and the product
- Production increased dramatically by having many workers performing partial steps and working in shifts around the clock
- Worker was fit to the task
- Removed if injury or could not perform
- Conditions were not controlled
History of occupational biomechanics in the second half of the 20th century
- Government started compensating injured workers and charging corporations premiums
- Became economically important to create a safer workplace
- American with Disabilities Act require employers to make reasonable accommodation to tasks to not discriminate against those with disabilities
- Fitting worker to the task switched to fitting the task to the worker; better design of occupational tasks and assembly line
Def: Occupational Biomechanics
- The examination of human disorders and performance limitations produced or aggravated by the mismatching of human physical capacities and the performance requirements in industry
- The study of the physical interaction of workers with their tools machines, and material so as to enhance the worker’s performance while minimizing the risk of musculoskeletal disorders
Work-related MSK disorders
- Disorders of the muscles, tendons, discs, ligaments, and nerves, caused by occupational tasks
- other names include: strains, sprains, ergonomic disorders/injuries, occupational overuse syndrome, repetitive motion disorders, repetitive strain injuries, cumulative trauma disorders
- Most frequently injured body part is back, second neck, commonly caused due to chronic overexertion
Causes of work-related MSK disorders
- Force
- Awkward posture
- Time, repetition, duration
- Mechanical stress
- vibration
- Environment
Force as a cause for MSK disorder
- External forces: typically applied at hands or caused by gravity
- Internal forces: Muscles and passive tissue (outcome depends on tissue loaded)
- Acute injuries = high forces which exceed tissue tolerance
- Chronic injuries = lower forces combined with repetition
what can awkward posture lead to?
- Isometric loading
- Overloaded muscle and tendons
- Pinching or impingement of tissues
- Increase moment arm of load (increase moments of force = increase internal forces)
- Asymmetrical tissue loading
Pinch grip
- Uses the smaller, weaker muscles in the fingers to apply the force
- With pinch grip, one or more fingers oppose the thumb to grasp an object
Power Grip
- Uses larger, stronger muscles in the forearm to perform the task
- With a power grip, the hand is wrapped around the object with the thumb overlapping the fingers
Repetition as a risk factor for MSK disorders
- May lead to progressive decrease in tissue tolerance level
- May not allow sufficient time for recovery
Duration as a risk factor for MSK disorder
- Accumulation of fatigue and tissue damage
- May lead to decreased coordination and tissue stability
Rest schedule as a risk factor for MSK disorders
- Rest leads to recovery from fatigue and tissue damage
Def: Repetition
The time quantification of a similar exertion performed during a task
Risk of injury proportionality
ROI= force x repetition x duration / tissue tolerance
High Force Injury
- Specific instance of high force above tissue tolerance
- Acute in nature
Low, repetitive force injury
- Repeated low applied force across long time period
- slow decline in tissue tolerance until it is below force level
Low, constant force injury
- Low force applied constantly across a period of time
- Tissue tolerance decreases over time until it is less than applied force
Mechanical Stress
Pressure to the skin and soft tissues from direct contact with parts, tools, fixtures, etc.
- Sustained, prolonged use of hand tool