Ergonomics Exam 1

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The average employer-sponsored premium for a family of four costs close to ___________ a year.

$13,000

Anatomical concerns

*wrist movement, *grip types, *static muscle loading

symptons associated with CTDs

-pain -restriction joint movement -soft tissue swelling

portable power tool controls

-start switch lockout

hazard controls for hand tools

-the right tool for the right job -know the hazards of the tool

Job Analysis step 1

1) break the job down into tasks and subtasks. Goald is to link excessive job demands to specific aspect of the job or work environment.

Estimated total costs for low back pain is approximately ___________________ annually.

16 billion

BMI Overweight

25-29.9

Optimum shovel angle is

32 degrees

zombie zone

3am to 6am

CO at rest

5-6 L/min

In just three years Medicare and Medicaid will account for ____% of all national health spending.

50

Approximately what percentage of Americans will suffer back pain in their lifetime?

80%

Fahrenheit conversion equation

9/5(X) + 32

BMI underweight

<18.5

Calculate the body surface area for an individual of 82 kg body weight and 180 cm height.

= 0.007184 * Wt0.425 * Ht0.725 =2.02 m^2

Obese

>30

Joint articulations

A junction between two or more bones.

Ganglionic cyst

A noncancerous lump, often on the tendons or joints of wrists and hands.

Biomechanics

A study that uses principals of physics to quantitatively study how forces interact within a living body.

Celsius conversion equation

(X-32) * 5/9

F = 9/5*C+32

C= 5/9(F-32)

non rotary force equation

F*Cos of the angle

M = -E (-+) R(-+) C (-+) S

S = change in heat body content C= convection heat exchange R= radiative heat exchange E= evaporative heat loss

zone B

Time limited compensation, increase in heart rate and body core temp

The Astrand nomogram is used as an indirect assessment of aerobic capacity.

True

A work space is

a three dimensional region surrounding the worker

kinetic energy (KE)

ability of a body to do work because of its motion

circadian rhythm

activity cycle based on 24 hour interval

Avoid static loads, but when it can't be avoided, employee should

assume a posture that gives them the best mechanical advantage

Acclamation

at least 5 days needed. Training, Medical Surveillance, Emergency Response Plan

Raynaud's phenomenon

bouts of white finger and painful sensations

Causes of trips and missteps

changes in elevation or levels, irregularities in walking surfaces, rumpled or rolled up carpets/ mats, carpets with curled edges, missing or uneven floor tiles and bricks

work practices

changes that minimize risks associated with their jobs

health status

chronic disease and acute illness should adjust schedule

heat stress PPE

circulating air systems ice cooling garments liquid cooling systems

prolonged work

continuous work; lactic acid does not accumulate fuel source: carbs and fats

The insertion bone generally moves when the muscle

contracts

Cardiac Index (CI) defined

correlation between resting CO and BSA

Common factors in flooring selection

cost, maintenance, load bearing, aesthetics

hyaline cartilage

cover where bones join

arc

curvilinear distance between points

strain injuries

damage to myofibers increased intracellur calcium release of pro and anti-inflammatory factors

anthropometry

data on body size and range of joint motion can be used to assess the appropriatness of workplace, equipment and product designs relative to workforce capacities for reach, grasp, and clearance.

kinematics

describes motions of the body w/o considering the forces causing the motion

Non rotary component

directed toward the fulcrum, parallel to the lever, and not contributing to the lever movement

Type 2a: fast oxidative

fast twitch, fatigue resistent

long bones

femar, fibia, humerous,

Cannon

fight or flight theory (1926)

Work equation

force * distance

Diarthrosis

freely movable: shoulder joint

Selye

general adaptation theory (1956)

Sylvia burwell

health and human services secretary

Heat stress symptoms

heat cramps heat rash heat exhaustion heat stroke

convection

heat gain or loss: from air

Synarthrosis

immovable: skull

Synarthrosis (joint articulation)

immovable; skull

Health and physical condition can...

impair a person's vision, judgment, and balance. for example: Age, Physical state, fatigue, Stress, illness, Medications, alcohol, drug effects, Blood sugar

Tenosynovitis

inflammation of tendon sheath

tendinitis

inflammation of the tendons

Circadian clock

internal clock

shift work

irregular hours

taking measurements

labels and drawing dimensions of workstations.

Static analyses

looking at the body at rest

static forces

looking at the body at rest

dynamic analyses

looking at the body in motion

dynamic forces

looking at the body in motion

Effects of slips, trips and falls to the employer

loss in productivity and business, increased industrial insurance premiums, costs associated with training replacement worker

circadian clock night

lowers body temp, slows heart, and changing hormone levels

According to the U. S. Department of Labor, slips, trips, and falls...

make up the majority of general industry accidents.

hypothalamus

manages body temp, release of hormones into the blood, wakefulness and sleepiness

PE equation

mass *gravity or weight * height

momentum

mass*velocity

Effort =

moment *time

do workers ever adjust to the night shift?

no

Thoracic outlet syndrome

occurs due to compression, injury, or irritation involving *subclavian vein, subclavian artery, and lower trunks of the brachial plexus

workplace hazards

physical hazards chemical biological

Biomechanics

physics, anthropometry, biology and physiology

What guidelines went into the lifting equation?

physiological; biomechanical psychophysical epidemiological

Niosh finding on job stress

poses a threat to the health and workers

managing work stress

primary prevention secondary prevention tertiary prevention

prime movers

producing desired movement

engineering controls

provide better light

Proprioceptors

provide information about the musculoskeletal system

Heat rash

red bumps from sweat, ex. belt line

circadian rhythm cycle

regular biological rhythm with a period of 24 hours

exposure to light

resets the circadian clock most effective

ear measurement

sensitive to environmental conditions

Ampiarthrosis

slightly movable

neglecting circadian rhythm

susceptible to colds and flu, chronic fatigue, neg effects on female reproduction, obesity, heart disease, accidents, stomach problems, depression, sleep problems

Intermittent Work

sustained effort for short periods of time followed by periods of rest. lactic acid build up. fuel: carbs

Energy

the ability of a body to do work

Class 1: Lever system

the joint (fulcrum) lies between the force point and the resistance point

Endurance

the length of time a person can exert a specified force

endurance

the length of time a person can exert a specified force

Calorimetry

the process of measuring the heat generated by an energy source.

Class 2: lever system

the resistance is between the joint and the force point

Stroke Volume (SV)

the volume of blood ml/hr ejected from the left ventricle during a contraction

Work input

useful work output + against friction

circadian clock morning

wakes most people up

Anatomical Concerns (static muscle loading)

- Situations where arms are elevated or held for extended periods of time -results in fatigue, reduced work capacity, and soreness

take home message hand tools

- it is possible to quantitatively determine which tools minimize exertions -important tool parameters include: Mechanical advantage; balance and handle location; screw head; tool geometry; posture and work location; tool speed and reaction force build up time. -the best tools are the ones best matched to the task.

principles of tool design

- must perform effectively for intended purpose - must be properly proportional to body dimension of the operator - designed to match strength and work capacity of operator -it should not cause undue fatigue -it must provide sensory feedback to the user -its capital and maintenance costs should be reasonable

hand tool hazards

- using tools correctly -maintaining tools

Which of the following is the most likely reason that reported occupational musculoskeletal disorders have increased significantly since the mid-1980's?

-Changing economic base: heavy manufacturing to light manufacturing -Greater percentage of females working than before -Increase in citations in the mid 1980s by OSHA -Courts have decided that work-related musculoskeletal disorders are compensable

Anatomical Concerns (tissue compression)

-Compressive forces on palm or fingers results in ischemia, with resulting numbness and tingling of the fingers. -handles should have large contact surfaces. -finger grooves or recesses in tool handles should be avoided

Handle Properties

-Diameter: handle diameter should be 31-50 mm, with upper end for torque and lower end for dexterity and speed. -length: minimum of 100 mm, with 125mm being ideal -shape: optimal shape may depend upon task performed. T-handles have more torque than straight handles -grip surface, texture, materials -angulation: should be angled to maintain straight wrist

General Anatomical Concerns

-Gender: female grip strength ranges from 50-67% of male grip strength -handedness: 90% of population is right handed -Posture: torque exertion not significantly affected unless extreme postures. -repetitive finger action: trigger forces should be low, under 10N. 2 or 3 finger control operations preferred.

types of screw heads

-Phillips head screws require more force to keep the blade seated -flat head screws need less feed force, but there is a greater tendency to slip sideways -torx heads have advantages of Phillips and flat head screws -holds for manual and power tools.

Anatomical Concerns (awkward wrist position)

-Pronation decreases grip strength 12% -Flexion/extension decreases strength 25% -radial/ulnar deviation decreases strength 15%

Anatomical concerns (wrist)

-Radial deviation (bent horizontal in) - neutral - ulnar deviation (bent horizontal out) -Dorsiflexion (bent vertical out) -neutral -Palmar flexion (bent vertical in)

Seated workstation recommendations (circumstances)

-all items needed for routine task can be easily supplied and handled within the seated workstation. -job being performed does not require more than 40 cm forward or higher than 15cm above work surface -doesnt require handling large forces greater than 10 pounds -writing or light assembly -precision or fine manipulative movements need a level of stability

Ball peen hammer

-ball side made to flatten rivets -drive steel chisels, masonry chisels, nail pullers or concrete nails -used to shape metal and working rivets

Advantages of prediction metabolic rate

-does not interfere with workers job - can be used in the design stage of the job

effort reward imbalance (ERI) model

-effort given given at work and the rewards of the effort -imbalance can result in health risks - high ERI associated with high BMI

Take home message pliers

-ergonomic because the task to squeeze pliers and create strong compressive forces in the jaws is easier. -tasks requiring precise manipulation, fine motor control and little force may be better the other way.

Cylindrical handle grip

-grip strength (G) is sum of forces exerted to the handle surface -when turning handle, maximum torque is T=SD, where T-torque (N-M); S-shear/friction force (N); D-Handle diameter (m) (S=muG, where mu-coefficient of friction, G=grip (N)

Saws

-heavy sawing requires a power grip and repeated flexion /extension, where light sawing uses a precision grip and wrist manipulation. -a pistol grip is used for the heavy sawing power grip, while a cylindrical handle used for precision grip -Western saws usually cut while pushed through wood, while japanese cut on the pull. Jap saves more energy.

maintaining tools

-inspecting tools regularly to make sure they are in good condition. -replace tools that are worn, damaged or broken -sharpen edges of cutting tools so that they work more efficiently and pose less hazard to the workers

sit-stand workstations important considerations

-job requires frequent reaches more than 16 inches forward and more than 6 inches above the work surface -job consists of multiple tasks, some best performed in the sitting while others stand

Workplace designer should keep design factors in mind

-large variability in size of people in the work force population -understand the user population

take home message screwdrivers

-longer screwdrivers need less feed force than shorter ones when used with one hand -screwdriver length may accessibility challenges -feed force is also reduced by using two hands or using a nut driver.

Repetitive tasks

-low force, extended muscle action -injuries generally rapid pain and fatigue

carpenters hammer

-made for driving and pulling nails -not all purpose hammer -not heavy enough to drive hardened masonry nails

grip span

-maximum grip achieved at 45-50 mm with parallel sides, and 75-80 mm with inward angled handles. -Maximum grip requirements should be less than 90 N.

what are the 4 thermodynamic processes

-metabolism -evaporation -radiation -convection

pliers

-most commonly used where the jaw is on the radial side of the hand -inverted grip allows greater span between thumb and index finger.

Anatomical concerns (grip)

-power grip -two point pinch -hook grip -lateral pinch -internal precision -external precision

minimize pressure on the forearms

-rounding and padding the edge -changing the work-surface height or the seat -providing arm rests -redesigning the job.

Standing workstation recommendations (circumstances)

-suitable leg room -involve handling objects weighing more than 10 pounds -job requires high, low or extended reaches frequently -requires frequent movement from one station to others -job requires the exertion of downward forces as in packaging and wrapping operations.

sit-stand workstation advantages

-taking body weight off legs -ability to avoid unnatural body postures -lower energy consumption ->reduce fatigue -less demand on the cardiovascular system -more stability for precision tasks or fine manipulative movements -ability to operate foot controls more easily, precisely and safely while maintaining good working postures

Shovels

-the blade is attached to the shaft through a socket -Handles have traditionally been a T-form but more recently a D-form -Leverage provided by the angle of the shaft from horizontal- called lift. (Optimal angle 32 deg) -blade size depends upon density of material to be shoveled. -optimum shovel rate of 18-21 scoops/min, with loads from 5-11kg

hand tool safeguards

-tool guards -handle design

hand tools

-tools are extensions of human hands -they enhance the capability and productivity of users performing tasks -poorly designed tools or using the wrong tools for the job can result in injuries, reduced productivity for the worker.

Factors leading to development of CTDs

-use of excess force during normal motions -awkward or extreme joint motions -high repetition of same movement -lack of sufficient rest

General principles for workstation design to think about

-what must the worker see while on the job? -what must the worker hear? -what must the worker perform? -what is the sequence of job activities? -what clearance are required? -what storage is required?

Constant numbers of BSA

0.007184 0.425(WT) 0.725(HT)

KE equation

1/2mass*velocity^2

Basal metabolism is

1/5th to 1/3 of a liter of oxygen consumed per minute, or 1.0 to 1.5 kcal of energy expenditure per minute.

MSD Cost

10 billion dolla

Over the last decade, employer-sponsored health insurance premiums have increased ____%

119 (4x the rate of inflation)

Slips, trips and falls make up

15 percent of all accidental deaths

Back injury cost

16 billion annually 25% of low back cases account for 95% of the costs

BMI normal

18.5-24.9

When did healthcare spending begin to rise at a very high level?

1980s

1Pa=

1N*m^-2

What is the maximum recommended energy expenditure that can be expected to continue for months or years

2,000 kcal

Basal Metabolism

2/3 energy consumed by fat; O2 level between 1/5 and 1/3 of a liter of O2/min

Bones

206 bones -long bones -short bones - flat bones -irregular bones

maximum heart rate

220-age

CO during heavy work

25-30 L/min

During work

25-30 l/min

The foot

26 total bones, 14 Phalanges, 5 Metatarsals, 3 Cuneiforms, 1 Navicular, 1 Cuboid, 1 Talus,1 Clacaneus

The hand

28 total bones, 12 phalanges in the fingers, 2 phalanges in the thumb, 5 metacarpal bones in the palm of the hand, 8 carpal bones in the wrist, 1 Sesamoid bone located near the head of the thumb metacarpal.

zombie zone

3 am - 6 am notorious industrial accidents

Heart rate recovery, as an indicator of fatigue, is measured how soon after work stops

3 minutes

Back injuries

30 mil exp low back pain 80% will suffer from low back pain

Between 2008 and 2018, the GDP is expected to increase ___% per year.

4.1

1 pound =

4.45 N = 0.45kg

Between 2008 and 2018, average increase in national health expenditures is expected to be ____% per year.

6.2

Anatomical Concern, handedness:

90% of population is right handed.

Force equation

= mass * acceleration F-N M-kg A-m*s^-2

Body surface formula

=0.007184*Wt^0.425*Ht^0.725

The given parameters are, F = 250N and R= 600N Mechanical advantage formula is

=2.4N

Ergonomics

A branch of science that focuses on the achievement of optimal relationships between workers and their work Environment.

Hypothalamus

A neural structure lying below the thalamus; directs eating, drinking, body temperature; helps govern the endocrine system via the pituitary gland, and is linked to emotion

force

A physical quantity that can accelerate and/or deform a body

Homeostasis

A tendency to maintain a balanced or constant internal state; the regulation of any aspect of body chemistry, such as blood glucose, around a particular level

scoliosis

Abnormal lateral curvature of the spine

About ____% of low back cases account for about ____% of low back compensation costs.

About 25% of low back injuries accounts for about 90% of low back costs.

Main objective of ergonomics

Achieve an optimal relationship between people and their work environment.

What occurred in the 80s to cause the steep increase of occupational musculoskeletal disorders?

Aging population More females in the workplace Changing economic base Increase in citations (OSHA) Court decision that MSDs are covered by workman's comp

Sprain

An injury in which the ligaments holding bones together are stretched too far and tear.

DAvid michaels

Assistant secretary of labor

Ergonomics

Biomechanics & anthropometry; physiology & psychology; Epidemiology; physics; engineer tech; chemistry biological sciences math

thomas frieden

CDC director

CI equals

CO/BSA

At rest

Cardiac Output is 5-6 l/min

Heat stress PPE

Circulating air systems, liquid cooling systems, ice cooling garments

Circumference

Closed curvilinear surface around a body part.

What does NIOSH do?

Conducts research and makes recommendations for work-related injury prevention.

Job demand- control theory

Considers the psychological job demands and characteristics of the job related to decision making and skill usage.

Intermittent work

Consists of sustained effort for short periods of time followed by periods of rest. Fat plays a minor role, proteins are negligible. Energy supply is anaerobic. Lactic acid results.

Prolonged work

Continuous work typically involves sub-maximal efforts for a several hours. Energy comes from carbohydrates and fats, Lactic acid does not accumulate, Anaerobic glycolysis is not needed during steady state work activities.

Workplace redesign

Correct working posture by adjusting the workstation to the height of the worker - manual crank or power lift

CTD's

Cumulative Trauma Disorders

Arc

Curvilinear distance between points.

secondary prevention to stress

Detecting stress and improving stress management, Relaxation techniques, Stress education Stress management, Health promotion

Work Physiologists

Devise work systems that allow individuals to accomplish their work without developing excessive fatigue, on a day to day basis.

Reach

Dimensions that determine the maximum space allowable for the human who operates equipment in the workspace.

Clearance

Dimensions that determine the minimum space required for a human to perform work activities in the workspace.

Height

Distance along Z-axis, from floor or seat to a specific point on the body.

Depth

Distance between landmarks in the anteriorposterior surface, along X-axis.

Breadth

Distance between points on left and right sides of body.

Length

Distance between two points on a single body segment.

primary prevention to stress

Eliminate the sources of stress, Redesign job/work environment, Flexible work scheduling, Fair work policies, Participative management, Reward sharing

Person Environment fit model (theory)

Emphasizes interaction between the individual and their environment, as well as their perception of the environment. Lack of fit results in stress.

What is the General Duty Clause 5A(1)?

Employers must keep their workplaces free from recognized serious hazards.

Thoracic Outlet syndrome

Entrapment of the brachial plexus/subclavian vessels passing from base of neck through the armpit.

Ergonomics

Europe

Kyphosis

Exaggerated over-curvature of thoracic area of vertebral column

Rotary force equation

F*sin of the angle

There is currently a federal law, which places strict requirements on employers to help eliminate musculoskeletal disorders, called the Ergonomics Standard.

False - the ergonomics standard was rescinded by the Congressional Review Act in 2001

Ergonomics is a fairly new study that began in the early 2000s.

False, Ramazzini studied the health of workers in the 1700s.

What is FICA?

Federal Insurance Contributions Act- tax supporting social security and Medicare; taken out of employee and employer pay

Anatomical concern, gender:

Female grip strength generally ranges from 50-67% of male grip strength

Which of the following is the most important application of Ergonomics?

Fitting the task to the person, not fitting the person to the task.

MA=

Force Arm Resistance Arm

Stress

Force applied to one unit of surface area. 1 Pa = 1 N * m-2

Mechanical Advantage is calculated is the

Force arm / Resistance arm

Friction

Force exerted tangentially by surface of one object on another and resists motion of either surface relative to the other.

impulse =

Force*time

Tissue compression

Forces on palm or fingers results in ischemia, with resulting numbness and tingling of the fingers. Handles should have large contact surfaces. Finger grooves or recesses in tool handles should be avoided

National health expenditures 6.2%/yr increase

GDP 4.2%/yr increase

Body size Variability

Gender Age Race/Ethnicity

Excess junk food...

Gives you a temporary sugar-high, can leave you tired and fatigued

The root origin of the word "Ergonomics" comes from...

Greek, meaning Laws of Work

Heat stress index

HSI = (M +\- C +\- R) / Emax, 2 Factors: Temperature and Humidity

Handle properties

Handle diameter should be 31-50mm, with upper end for torque and lower end for dexterity and speed. Length: minimum of 100mm, with 125mm being ideal. Shape: optimal shape may depend upon task performed. T-handles have more torque than straight screw driver handles.

_________________________ are the fastest growing expense for employers.

Health insurance costs

Economists have found that rising health care costs correlate with significant drops in ____________________________.

Health insurance coverage

The formula for cardiac output is:

Heart rate x Stroke volume

Radiation

Heat gain or heat loss

Metabolism

Heat gain; physical activity of the worker, depends on the job or as paced by the worker

Evaporation

Heat loss

How did the workforce change in the 80s?

Heavy manufacturing ---> light manufacturing service, knowledge-based economy

Seven of the most Common Work Risk Factors for Developing CTDs.

High Rates of Manual Repetition, Excessive Manual Force, Awkward Posture, Insufficient Recovery Time, Sustained Muscle Loading, Vibration, Temperature

Heat stroke

Hot dry skin, with rectal temp, > 104 F

Phalen's test

In this test the patient is asked to put the backs of his/her two hands together and acutely flex his/her wrists for one minute. Development of tingling in the fingers is a positive sign of CTS.

most qualified persons for shift work

Independent workers, More adjustable to changes in working conditions, High self-esteem, Young, Healthy

Arthritis

Inflammation of a joint

Myosotis

Inflammation of muscle

Physical work capacity

Is the maximum capabilities of the physiological systems to produce energy for muscular work.

Effort

Is the product of torque (moment) times time duration in which force is sustained. = M * t = F * dv * t

Work Physiology

Is the study of the functions of the human affected by muscular work stresses.

Types of muscle contraction

Isometric concentric eccentric

Engineering solutions

Job redesign; repetitive tasks performed in awkward postures. Enlarge tasks requiring different movements; Design fast-paced tasks with work cycles longer than 30 seconds; Avoid keeping the same posture

Sit-stand work stations

Job requires frequent reaches more than 41 cm (16") forward or more than 15 cm (6") above the work-surface & Job consists of multiple tasks, some best performed in the sitting position, and others while standing.

Niosh model of job stress

Job stress leads to injury and illness

Commonly effected body parts

Knee, Ankle, Foot, Wrist, Elbow, Back, Shoulder, Hip, Head

Most work related injuries occur in the lumbar spine

L5-S1 most common L4-L5 second most common

Ergonomics

Laws of work (greek)

Shovel lift

Leverage provided by the angle of the shaft from horizontal

Lifting index (LI)

Load weight (L)/ RWL

__________________________ has increased significantly over the past 30 years, while the incidence of low back pain has stayed the same.

Lost time from work

Most work-related injuries occur in the

Lumbar spine, vertebrae L5 to S4

MA = R/F Thus MA = Force Arm/ Resistance arm

MA = Mechanical Advantage R = resistance overcome F = force exterted

Mechanical advantage equation

MA= R/F Where: MA = mechanical advantage R = resistance overcome F = force exerted

high strain jobs associated with highest risk of

MSD's and stress related health issues

Evaluation of Muscular fatigue

Manifested by aches and pains followed by reduced movement and weakening of the muscle(s).

Grip span

Maximum grip achieved at 45-50mm with parallel sides, and 75-80mm with inward angled handles. Maximum grip requirements should be less than 90N.

Which nerve passes through the carpal tunnel and produces the symptoms of carpal tunnel syndrome upon impingement of this nerve?

Median

L5-S1(lower back)

Most common site of work related back injuries

Abduction

Movement away from the midline of the body

Adduction

Movement toward the midline of the body

Principles of tool design

Must perform effectively for intended purpose, be properly proportional to body, dimensions of the operator, Designed to match strength and work capacity of operator, It should not cause undue fatigue, It must provide sensory feedback to the user, capital and maintenance costs should be reasonable

John howard

NIOSH Director

NIOSH

National Institute for Occupational Safety and Health; under US Department of Health and Human Sciences

Footwear

Needs to be suitable for the environment

Raynaud's disease

No symptoms due to other underlying diseases, Laboratory evaluation is normal, normally no strucutural changes in vessels, trophic changes are uncommon

__________________________ are the leading cause of work disability.

Occupational MSDs

OSHA

Occupational Safety and Health Administration; under US Department of Labor

Fall

Occurs when you are too far off your center of balance.

Symptoms associated with CTDs

Pain, Restriction of joint movement, Soft tissue swelling

Heat cramps

Painful spasms of the muscles. Heavy sweat during work

Heart rate recovery

Phase 1 = 1 min phase 2 = 2 mins phase 3 = 3 mins

Administration controls

Planned work time, self-determination, recovery allowances, scheduling work

RWL = LC*HM*VM*DM*AM*FM*CM

RWL = recommended weight limit LC = Load Constant HM = Horizontal VM = Vertical DM = Distance AM = Asymmetric FM = Frequency CM = Coupling Multipliers are not greater than 1.0

Roots of ergonomics

Ramazzini (1700s) vapors and irregular motions

Basal metabolism

Rate of metabolic activity of a subject after 12 hours fasting and 8 hours resting. The basal rate is generally considered the level of energy expenditure required to keep an individual alive and functioning but not performing external work

Energy expenditure

Recommended total energy expenditure of 2000 kcal during work as a maximum that can be expected for work to continue for months or years.

Engineering controls

Reduce metabolic rate, change clothing requirements, reduce temperature and humidity, increase air motion, control radiant heat(insulation)

The weight of the lever, surrounding tissues and counterforce is defined as?

Resistance

Which of the following is a flat bone?

Ribs

Heat Stress Hygiene

Self determination fluids lifestyle and diet health status training

Intervertebral disks

Separate the vertebrae, Are composed of a tough, fibrous ring, Is filled with a viscous fluid (consistency not like jelly, more like crab meat) Act as shock absorbers between vertebrae, Provide flexibility for vertebrae, Most fragile parts of the spine (especially the Lumbar region)

static muscle loading

Situations where arms are elevated or held for extended periods of time, Results in fatigue, reduced work capacity, and soreness. Optimum work posture is when elbow is at 90 degrees.

Amphiarthrosis (joint articulation)

Slightly movable: intervertebral joints

Reach (static measurement)

Special arm-hand distance in particular posture.

Common types of injuries

Sprains, strains, Bruises, contusions, Fractures, Abrasions, lacerations

Work rest scheduling

Standard workload in United Kingdom and USA is equivalent to the workload generated by a man of average physique walking without carrying a load in a straight line on level ground at a speed of 4 mph

Cardiac Output (CO)

Stroke Volume* Heart Rate

Cartilage

Supports body structure and is avascular

Raynaud's phenomenon

Symptoms due to other underlying diseases, Laboratory evaluation is abnormal, structural changes often present, trophic changes are common

Wet Bulb Globe Temperature

Takes into account radiated heat, therm wrapped with wet cloth

Anatomy

That branch of science which deals with the body's structures, including muscles, bones, tendons, ligaments, and other structures.

Cardiac output

The amount of blood (in liters per minute) ejected into the main artery by the left ventricle per unit time

The Carpal bones and the tunnel

The carpal bones form a small u-shaped "tunnel" on the palmer side of the wrist. This tunnel is covered by a transverse carpal ligament. Between the bones and transverse carpal ligament passes all the flexor tendons, blood vessels, major nerves (including the median nerve), and related tissue, that operate the hand.

Torque

The effect of a force producing rotation about an axis. Measured by product of the force and perpendicular distance form the axis of rotation to the line of action of the force.

Class 3: lever system

The force point lies between the join and the resistance

Lever system class 3

The force point lies between the joint (fulcrum) and the resistance

Basal metabolism

The minimal amount of energy needed for sustaining life.

Domino effect

The more people work during the night the more people have to work during the night

Anaerobic threshold

The point at which lactic acid (from anaerobic glycolysis) begins to accumulate in the blood at levels above the basal rate of lactic acid production.

Respiration

The process of exchanging carbon dioxide and oxygen between the body and the environment.

What's OSHA's primary goal?

The reduction of injuries and illnesses in the workplace.

Physiology

The science of the body's functions, including metabolism, muscle mechanics, oxygen and nutrient distribution, temperature regulation, nerve transmission, cognition, and other functional activities.

Anthropometry

The study of the dimensions and physical characteristics of the human body.

rotating shifts

The work schedule requires the employee to work more than one shift, that is, employees switch from one to another according to a certain cyclic pattern of shift rotation.

Tinnel's test

This methods is performed by tapping the median nerve at the wrist. Tapping a compressed median nerve induces tingling in one or more fingers in the hand afflicted with CTS

Causes of trips

Transitioning from one type of flooring to another with less traction, freshly waxed surfaces, highly polished floors

Tertiary prevention to stress

Treatment and recovery from stress related illnesses, Counseling services, Employee assistance programs

Anatomical concern, repetitive finger action:

Trigger forces should be low, under 10N. Two or 3 finger control operations preferred.

Human factors

US and Canada

Factors leading to development of CTDs

Use of excess force during normal motions, Awkward or extreme joint motions, High repetition of same movement, Lack of sufficient rest

Slip

When there is too little friction or traction between your feet (footwear) and the walking or working surface, and you lose your balance.

Fall to lower level

When you fall to a level below the one on which you are walking, working, or standing.

Fall at the same level

When you fall to the surface you are walking or standing on, or fall into or against objects at or above the surface.

Trip

When you step down unexpectedly to a lower surface (Misstep) and lose your balance, e.g., stepping off a curb

Trip

When your foot (or lower leg) hits an object and your upper body continues moving, throwing you off balance.

Physiological demand on workers theory

Workers should not exceed 50% of their energy expenditure capacity during the work day to avoid becoming physiologically strained during the work day. Margin of safety is that workers should not exceed 33% of their expenditure capacity for the work day

STAT basis of Anthropometry

Xp(pth percentile of value of the variable X) = X(sample mean) + Zp(standard normal value corresponding to the pth percentile of value X) *S(sample standard deviation)

Sweating rate

[BWi-BWf+ingestion (kg) ]/ Time (hr)

De Quervain's syndrome

abductor pollicis longus and extensor pollicis brevis tendons

potential energy (PE)

ability of a body to do work because of its position or state

Behaviour's

actions you choose and control (e.g., working safely) - can contribute to a slip, trip, and fall injury if you set yourself up for one.

fluid replacement

adequate hydration

Two processes in which the muscles get energy

aerobic and anaerobic

Job analysis step 2

after the job is broken into tasks determine if work methods, the workstation, tools and equipment required to perform each task may cause a musculoskeletal injury or illness

increase of MSD since 1980

aging work population greater % females heavy to light manufacturing increase of citations by OSHA MSD covered worker comp

axial skeleton

all bones except legs and arms

Maximize muscle efficiency and skillfulness in performing heavy workload

allow as much "range of motion" as possible

administrative controls

allow for shorter shifts additional days off for 3rd shift have workers get home before sunrise always rotate shifts in a clockwise direction provide equal benefits provide training and counseling

Step test

alternative method for estimating VO2max (VO2[L/min] = mL*body weight*1000mL)

Muscle Fatigue

amount of lactic acid plays a part in localized fatigue

Shiftwork

anything outside of regular 9 to 5, usually nights

appendicular skeleton

arms and legs

Heart rate stability

average for a workday should be less than 110 bpm, peak less than 90% mass HR

Effort-Reward imbalance model

balance between what what someone is putting into a job compared to what they are getting out of the job

skeletal system consists of

bones cartilages

Expert assessment

can quickly perform a needs assessment and provide quick and accurate recommendations

increased metabolic rate

can work at lower temperatures

short bones

carpals, tarsals

Peritendinitis

central region of the tendon

circumference

closed curvilinear surface around a body part

secondary prevention

detecting stress and improving management of stress -stress education -stress management -health promotion

non rotary force

directed toward the fulcrum, parallel to the lever, and not contributing to the lever movement

Height

distance along z-axis from floor to specific point on the body

depth

distance between landmarks in the anterior posterior surface

breadth

distance between points on the left and right sides of body

Length

distance between two points on a single body segment

Ideal mechanical advantge

distance moved by force/ distance moved by load force arm/ resistance arm

oral measurement

do not eat or drink 15 min before measurement, have mouth closed

elastic cartilage

ears and nose

Greatest damage occurs to muscles during

eccentric contraction

stress creates larger amounts of cortisol (a stress hormone) that can in turn reduce the body's ability to

effectively fight off sickness and disease

primary prevention

eliminate source of stress -redesign environment -flexibe work schedule -participative management -reward sharing

BMI equation

english = weight/h(in)^2 *703 metric= weight/h(cm)^2

Work stress prevention

ensure workload in workers capabilities and resources design jobs to provide meaning, stimulation and opportunites to use their skill clearly define worker roles and responsibilities

Hand tools

extent of human hands, enhance the capability and productivity of users performing tasks

Type 2b Muscle Fiber

fast glycolytic: fast twitch fatigable

Type 2a Muscle Fiber

fast oxidative - fast twitch fatigue resistant

Type 2b: fast glycolytic

fast twitch, fatigable

Whole muscles contain a mixture of

fiber types

The segment between the point of force exertion and fulcrum is called the

force arm

Ideal mechanical Advantage

force arm/resistance arm

Actual mechanical advantage

force exerted by machine or load/force used to operate machine

job analysis specific tasks

force, posture, frequency, duration or work and recovery period, and vibration and cold temperature.

Actual mechanical advantage

forced exerted by load/ force used to operate machine resistance/effort

Biomechanics used to analyze

forces and torques; strength limitation; to predict stressful work postures and conditions

Internal forces

forces generated by or acting on muscle, ligaments, etc

internal forces

forces generated by or acting on muscles, ligaments, and joints

Kinetics

forces that act on the body that cause movement

kinetics

forces that act on the body that cause movement

things to look for in an ergonomic tool

forces, movements, thermal and vibration exposure

1.5 million families subject to ___________ due to rising healthcare costs

foreclosure

Pushing and pulling forces are the same order of magnitude whether the arms are held out sideways or

forward

Diarthrosis (joint articulation)

freely movable; shoulder joint

zone A

full compensation, steady state, steady heart rate

least qualified for shift work

gastrointestinal problems, respiratory disorders, nervous disorders, Abnormal fatigue after short work exposure, Past the age of 45, especially if they have health problems, Pregnant

external forces

gravitational or from objects lifted, lowered, pushed, or pulled

Injury to muscles

greatest damage during eccentric contraction -strain injuries -repetitive task

Of the total spending for the US, the largest percentage of money is spent on _________________.

healthcare

Heart rate recovery from Brouha Phase 1

heart rate (in bpm) during the second 30 s of the first minute

Heart rate recovery from Brouha Phase 2

heart rate during the second 30 s of the second minute

Heart rate recovery from Brouha Phase 3

heart rate during the third 30 s of the third minute

radiation

heat gain or loss: from objects

Convection

heat gain or loss; by ambient air flow

metabolism

heat gain: physical activity

Evaporation

heat loss: relative humidity and air velocity across the skin

active jobs

high demand and high control

active jobs

high demands and high control

High strain jobs

high demands and low control

iso strain model

high strained and low social support

high strain jobs

highest risk of MSDs high demand and low control

Worst candidates for shift work

history of: gastrointestinal problems; respiratory disorders; nervous disorders, pregnant >45 abnormal fatigue after short exposure

health insurance premiums

increased 119% over the based decade

Best candidate for shift work

independent workers more adjustable to changes in working conditions high self esteem young healthy

Bursitis

inflammation of a bursa, often characterized by difficulty of movement in body joints

Bursa disorders

inflammation of synovial sacs in elbow, shoulder, knee

sweating rate

initial bw- final bw + ingestion (kg)/time (h)

Each tendon is attached to an origin bone and an

insertion bone

person environment fit model

interaction between the individual and their environment as well as their perception of the environment - lack of fitness results in stress and psychological and physical symptoms

Strain index

job demand/ worker capacity

When you are stuck in a job and unable to leave due to the benefits; inability to move throughout the job market

job lock

Radial tunnel syndrome

lateral elbow

Lever system class 1: the joint

lies between the force point (where the muscle pulls on the lever) and the resistance point (the weight to be lifted)

External forces

lifting, lowering, push, pull

passive jobs

low demand and low control

low strain jobs

low demands and high control

passive jobs

low demands and low control

low strain jobs

low demands high control

Grip strength

maximum momentary squeeze force exerted on a hand dynamometer

Body Mass Index (BMI)

measure of body fat based on height and weight

Direct calorimetry

measurement of heat generated by a person in a box chamber

direct calorimety

measurement of heat generated by a person in a box chamber.

Indirect calorimetry

measurement of metabolic rate usually by oxygen consumption rate.

indirect calorimety

measurement of metabolic rate usually by oxygen consumption rate.

Arthritis of joints is due to

mechanical stress

Carpal tunnel syndrome

median nerve

Back injury stats

most frequently injured; account for nearly 20% of all injuries and illness in the workplace

Kinematics

motions of the body w/o considering force

synergist

muscle that contract at the same time as the prime mover (muscle assist)

Myotendinitis

muscle-tendon junction

Synergists

muscles that contract at the same time as the prime mover

Antagonists

muscles that relax or counteract to slow the action of a prime mover

Prime movers

muscles whose contraction is the primary agent in producing desired movement

Antagonist

muslce that relax or counteract to slow the action of a prime mover

Muscle disorders

myalgia, trigger points

Body temperature measurements

oral and ear

Bones and cartilage

osteoarthritis

Wet bulb globe temperature (WBGT)

outdoor = 0.7 NWB + 0.2GT +0.1DB Indoor = 0.7 NWB + 0.3GT

Effects of slips, trips and falls to the worker

pain, lost wages, temporary or permanent disability, reduced quality of life, depression

Rotary component

perpendicular to the lever and contributing to the lever's movement

Rotary Force

perpendicular to the lever and contributing to the levers movement

heat stress administrative controls

planned work time self determination recovery allowances scheduling work

_______________ is defined as the muscle that has the most influence in one direction on the joint it acts on. For example the _____________ in flexion of the forearm is the bicep.

prime movers

Classification of skeletal muscles

prime movers antagonists synergists

pushing force > than

pulling force

lever system

pulling on the involved insertion bone acts as a lever and the join as a fulcrum of the lever

Muscle spindles

receptors sensitive to change in length of the muscle and the rate of that change

heat stress engineering controls

reduce metabolic rate change clothes req reduce temp and humidity increase air motion control radiant heat

The segment between the resistance and fulcrum is called the

resistance arm

fibrous cartilage

ribcage and intervertebral disks

Flat bones

ribs, skull

Waist Circumf

risk increase when: >40 inches men >35 inches women

physiology

science of body's functions including metabolism

anatomy

science which deals with the body's structures

thomas e perez

secretary of labor

In all the other areas of ergonomics we have been taught to make engineering, work practice, or administrative changes, not to discriminate against workers - except

shift-work

Heat exhaustion

skins feels clammy and moist, complexion is pale and muddy. Symptoms; fatigue, nausea, headache, giddiness

what can be done for those that must work 3rd shift

sleep having a life away from work immune system healthy digestive system diet and exercise healthy heart playing it safe

lifestyle and food consumption

sleep, alcohol and diet

Ergonomic factors in flooring selection

slip resistant, trip potentials, standing fatigue, shoe/floor interactions, noise reduction

Type 1 Muscle fiber

slow twitch oxidative (maintain posture; long duration; low intensity)

reach

special arm hand distance in particular posture

Rigid bodies

static and dynamic analyses

Tension neck syndrome

static trapezius contraction in precision work

self determination

stop when uncomfortable

Anthropometry

study of the dimension and physical characteristics of the human body.

Cartilage

supports body structure Avascular

Neglecting circadian hygiene

susceptible to colds and flu chronic fatigue negative effects on the female reproductive system greater tendency of obesity heart disease accidents stomach problems depression sleep problems

health effects of stess

symptoms: headache; sleep disturbance; upset stomach diseases states: cardio musculo psycholo increased injury

Insertional tendinitis

tendon-bone interface, eg. Lateral epicondylitis

Muscles are attached to the bones by

tendons

Isometric contraction

tension generated during muscle activity, but no change in length

Isometric

tension generated during muscle activity; no change in length

Concentric

tension generated in muscle while shortening

Concentric contraction

tension generated in muscle while shortening

Eccentric

tension generated while muscle is lengthening

Eccentric contraction

tension generated while muscle is lengthening

potential energy

the ability of a body to do work because of its position or state. ( = m * g = W * h) where m=mass, h = vertical distance, g = acceleration due to gravity, W = weight lifted .

Kinetic energy

the ability of a body to do work because of its motion. ( = 1/2m * v^2) where m = mass, v = velocity

Metabolism

the collective chemical process of the conversion of foodstuffs and oxygen into mechanical work and heat.

Cardiac index

the correlation between resting cardiac output and body surface area.

Aerobic capacity

the maximum level of oxygen uptake (VO2max) in liters per minute or milliliters of oxygen per kilogram body weight per minute.

grip strength

the maximum momentary squeeze force exerted on a hand dynamometer

Calorimetry

the process of measuring heat generated by an energy source

job demand control theory

the psychological job demands and characteristics of the job related to decision making and skill usage.

Lever system class 2

the resistance is between the joint (fulcrum) and the force (insertion) point

over 17% of all disabling work injuries are...

the result of falls

velocity

the time rate of change in displacement (Km*h^-1)

acceleration

the time rate of change in velocity (m*s^2)

resistance

the weight of the lever and its surrounding counter force (antagonist muscle) and the external load

A work space is a-

three dimensional region surrounding the worker

When the spine is in a natural position, it forms

three natural curvatures in a double-S shape

Anatomical concern, posture:

torque exertion not significantly affected unless extreme postures.

Tertiary prevention

treatment and recovery from stress related illness -counseling services -employee assistance programs

Cubital tunnel syndrome

ulnar nerve at elbow

Guyon's canal syndrome

ulnar nerve at wrist

zone C

uncompensated heat storage, Steady rate fatigue and failure, high increase in core temperature

Minimize pinch grips

use whole hand; Hold an object near to the center of gravity for better balance; Provide flanged support on handles; Avoid excessive forces; Minimize exposure to vibration and cold temperatures; Automate repetitive tasks when technologically and economically feasible.

Type 1: slow twitch oxidative

used to maintain posture long duration low intensity tasks often found at work.

physiological data

useful if jobs involve repetitive lifting, load carrying and general use of large muscle groups. data: maximum aerobic capacity declines with age

Strength data

various populations and muscle groups have been published and can be found in several sources

Hand/arm vibration syndrome

vasoconstriction in the hands and fingers "white finger" syndrome

irregular bones

vertebrea

Calculate BMI for an individual of 68 kg body weight and 165 cm.

weight (kg) / [height (m)]2 =24.98

efficiency equat

work output/ work input

Xp=x +Zp*s

x = sample mean s = sample std dev Xp = pth %tile value of the variable X Zp = standard normal value corresponding to the pth %tile value of X

Statistical Basis of Anthropometry

xp = x + zp* s where: x = sample mean s = Sample standard deviation Xp = pth percentile value of the variable X Zp = standard normal value corresponding to the pth percentile value of X


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