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69 Cards in this Set
- Front
- Back
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Anthropometry falls between with human sciences?
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Ergonomics and Human Factors
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Anthropometry definition
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science of measurement of body size
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Forearm length measurement
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elbow-to-fingertip distance
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stature measurement
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starts at floor on which the subject stands and extends to the highest point on the skull
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height measurement
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vertical point-to-point, straight - line
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breadth measurement
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horizontal point-to-point, straight-line
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distance measurement
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straight-line, point-to-point measurement between landmarks on the body
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curvature measurement
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point-to-point measurement following a contour
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Measurement considerations
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accounting for clothing based on environment; neutral position; account for functional work positions
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Modern techniques for measurements
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Photograph, video, laser-based anthropometry
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Natural sources of variation
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by stature, shape, condition (pregnant), and age
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What is a reach envelope?
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functional area your arm can move
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What's included when designing for the worst case?
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includes lots of people, with high variation
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What's included when designing for the average case?
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includes 50%, less variation
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What's included when designing for the best case?
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includes 5%, very little variation
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#1 rule when designing something?
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Know who you're designing/marketing for
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Traditional reach envelopes?
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measure from middle knuckle to elbow then elbow to shoulder; tip of finger bc not leaning forward
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Our job for designing as IEs
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Ergonomics, Safety, Human Factors
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When designing something, where do we start?
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Start at a midpoint or a stationary point (e.g. hip with car, feet with workstation)
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2nd rule when designing:
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get to neutral posture (most comfortable)
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Definition of biomechanics
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uses laws of physics and engineering concepts to describe motion undergone by the various body segments and the forces acting on these body parts during normal daily
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Occupational Biomechanics definition
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interacting with the environment around you that pertains to a job
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Criteria for lifting on the job
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51 lbs and lower depending on the job
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List the range of motion measurement methods (2)
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Goniometry and Spatial Imaging (photography - 2D and motion capture - 3D)
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Traditional factors affecting range of motion data
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age, gender, anthropometric dimensions, multi-joint muscle effect (e.g. spine) - range of motion from all joints acting together, BMI - more space taken up, less range
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Three types of lever systems in the body
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First Class Lever, Second Class Lever, Third Class Lever
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First Class Lever
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Center of rotation (fulcrum) is located between the resistance (load) and force (muscle) on either end of the lever, e.g. head
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Second Class Lever
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Fulcrum is located on one end with the resistance located between the fulcrum and force (muscle), e.g. ankle
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Third Class Lever
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Fulcrum located on one end with the force in between the fulcrum and the resistance, e.g. elbow
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Types of Biomechanical models (4)
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-Planar (2D) Static - single body segment, two body segment, non-parallel force, internal force, multiple link
-3D Static -Dynamic (2D) - single segment, multiple segment -Special Purpose - foot slip model, low back, wrist and hand |
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Load
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Application of vertical load applied to a horizontal distance
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Measuring shoulder - start at?
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Hands
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Measuring low back - start at?
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feet
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Types of controls:
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Administrative Controls - rules, hiring employees, programs
Engineering controls - typically physical changes (conditions, environment) |
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Levels of Controls:
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1. Fail - Safe - "Low level", preventing nothing, barriers or dilution only (administrative, stickers, memos)
2. Preventative - "Mid Level". guarding/limiting (guard around turning shaft) 3. Exclusionary - "High Level", eliminate it (remove condition entirely) |
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Physiology:
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Study of the functions of the body parts, i.e. How the body parts work
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Exercise/Work Physiology:
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The study, description, evaluation, and explanation of the physiological changes in the human body resulting from either a single or repeated series of exposure to work stresses
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Exercise Physiology:
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Goal - maximize the physiological efficiency of the target population
Target population - fit, healthy, young, and motivated Environment - optimal or controlled |
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Work Physiology:
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Goal - to ensure worker can perform task efficiently and safely within the environment
Target Population - all kinds of people Environment - usually not optimal or controlled |
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We use work physiology to enhance efficiency by:
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Monitoring energy expenditure and avoid excess fatigue
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We use work physiology to ensure safety:
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do not push people beyond their physical limitations
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Three categories of workload system changes:
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1. Circulation - increases with work
2. Respiration - increases with work 3. Blood - decreases some or stays same with work |
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VO2 =
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HR * SV * (a-vo)
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Metabolic Rate:
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Starts at 2500kcal/day and increases according to work level
Basic Metabolism = 1500 Leisure = 1000 |
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5 Factors affecting physical performance:
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1. Environment - Altitude, high gas pressure, heat, cold, noice, air pollution
2. Psychic Factors - Attitude, motivation 3. Training - adaptation 4. Somatic factors - sex and age, body dimensions, health 5. nature of exercise - intensity, duration, rhythm, technique, positions |
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Two types of fatigue
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1. central - nerve related (fingers lock up after vibration)
2. peripheral - muscle related |
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Effects of aging:
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Decline starts at about 30 yrs
Progressive loss of muscle mass Lost of muscle tissue replaced by fat Decrease in maximal strength Diminishing of muscle reflexes |
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Designing for efficiency:
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- use heart rate to evaluate energy usage
- use Maximum Aerobic Capacity - design work for light to moderate energy expenditure |
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Maximum Aerobic Capacity
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The maximum metabolic rate (or oxygen uptake) that an individual can obtain while breathing air at sea level.
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MAC: The Basics - three types of testing
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1. maximum test - bike ergometer
2. submaximal test - tread mill 3. estimator/heart rate test - step test |
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MAC: The Basics - Criteria for testing
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- workload must involve large muscle groups
- workload must be measureable and reproducible - test conditions must be reproducible - test or workload must be tolerated by normal, healthy people - mechanical skills needed to perform the workload must be uniform and common in tested population |
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MAC: Maximal Test
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Concept: increase workload until VO2 "levels off"
- estimate workload and "drop person on it" - use gradual increases in workload - very accurate - dangerous - motivation dependent - extend maximal limit |
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MAC: Submaximal Test
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Concept: Establish an individual's MAC based on task performance at submaximal levels
- stress individuals at submaxial levels - record HR and VO2 for each load - estimate MAC on basis of max age predicted heart rate - less accurate than Max Test - less dangerous than Max Test |
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Percent Working Capacity (PWC)
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A measure of the effect of a task relative to an individual's maximum capacity
PWC = Task VO2/MAC *100% |
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Workers "self pace" at:
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33 - 44% of MAC for 8-hour shifts
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Common task and design criteria is:
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33% of MAC with HR of 105-115 beats/min
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Musculoskeletal Disorders (MSDs)
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Occupational medicine job-related injuries and disorders of the muscles, nerves, tendons, ligaments, joints, cartilage, spinal disks"
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Common MSDs
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Carpal Tunnel
Rotator Cuff De Quervain's disease - specialized case of tendosynovitis in thumb Epicondylitis - tennis elbow tendinitis - tendons become lock due to sheath swelling Raynaud's Syndrone - "white finger" Herniated spinal disk Thoracic Outlet - compression of nerves and blood vessels b/w the clavical and 1st &2nd ribs Deep Vein Thrombosis - pooling of the blood in the legs and feet from low level vibration Ganglion - bible thumber |
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Identification:
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Passive, Active, "Anticipative" Surveillance
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Analysis:
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Determining job attributes that could increase the probability of occurrence of the injuries
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Evaluate:
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To perform in-depth risk factor evaluation to quantify risks associated with specific tasks
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Factors affecting MMH
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Worker Characteristics, Material/Container Characteristics, Task Characteristics, Work Practices
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Assumptions Underlying NIOSH Lifting Guide
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Smooth Lifting
Moderate width objects unrestricted lifting postures good couplings favorable temperature conditions |
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Things To Look for when Studying MMH
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W - amount of weight being lifted
P - posture while lifting H - horizontal location of load V - vertical location of hands when load is picked up D - Distance load is moved up or down A - amount of twisting done when load is moved F - how often load is moved E - environment |
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Frequency Multiplier
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Based on vertical component
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Coupling Multiplier
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Good
Fair Poor |
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Deficiencies in NIOSH Guide
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- no consideration of asymmetrical lifting
- no consideration of inertial forces - no provision for push-pull activities |
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REBA
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Rapid Entire Body Assessment - quick and systematic assessment of the complete body postural risks to a worker (accounts for Lower Body)
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RULA
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Rapid Upper Limb Assessment - quick survey method for use in ergonomic investigations of workplaces where MSD's are reported
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