Module 3. Workload

Question 1

Estimates the extent of physical activity

Answer 1

Energy Expenditure

Question 2

All energy in the body utilized during physical activity produces ___

Answer 2

Heat

Question 3

Strenuous activity means ___ energy requirement

Answer 3

Greater

Question 4

5 ways to measure/estimate energy expenditure

Answer 4

1. Direct Calorimetry
2. Indirect Calorimetry - O2 Analysis
   3.Indirect Calorimetry - CO2 Analysis
3. Calculations of Energy Expenditures
4. Heart-rate Measurement

Question 5

• Body heat output as a measure of energy expenditure
• Body heat output is measured under laboratory conditions
• Can be impractical due to the required setup

Answer 5

Direct Calorimetry

Question 6

• Measurement of oxygen uptake
• Requires information on volume of expired air
• Analysis of oxygen content in expired air
• Air volume determined through a spirometer
• Estimation of energy based on equation by -J. B. Wier

Answer 6

Indirect Calorimetry – O2 Analysis

Question 7

Formula for Indirect Calorimetry - O2 Analysis

Answer 7

Energy = (Vstp [Oi - Oe])/20
Where
Energy is in kcal/min
Vstp = volume of air expired in L/min
Oi and Oe = Percentages of oxygen in inspired and expired air, respectively

Question 8

Gas analysis of carbon dioxide content in expired air
* Most methods use infrared properties of carbon dioxide with an instrument, capnograph

Answer 8

Indirect Calorimetry – CO2 Analysis

Question 9

Two things to take note for this calculation:
* Accurate account of all activities and time spent for each in a day
* Metabolic cost of each activity

What type of method in estimating energy expenditure?

Answer 9

Calculation of Energy Expenditures

Question 10

Formula for Total Energy Expenditure

Answer 10

Total Energy Expenditure = E time spent per activity (min) x metabolic cost per activity (kcal)

Question 11

How are activities recorded in calculating energy expenditures

Answer 11

Detailed questionnaire – might be unreliable (dependent on memory; may exaggerate)
* Diary techniques – subject records daily activities in a diary (minute by minute or 5-minute periods); an observer may be employed to log activities

Question 12

Indirect measurement of energy expenditure
* ___ and energy expenditure are related
* - May greatly vary based on activities (e.g., lifting a sack of rice vs lifting piece of paper)
* - May also vary based on muscle groups used (e.g., walking vs lifting weights)
* - Can also be affected by physical fitness (e.g., athletes expend more energy)
* - Emotion, body temperature, type of drinks can also affect ___
* Range of variation among population is large
* - Solution is to group/subdivide people

Answer 12

Heart-rate Measurement

Question 13

Heart-Rate Measurement Formulas

Answer 13

Male = -55.0969 + (0.6309HR) + (0.1998Weight) + (0.2017*Age) / 4.184

Female = -20.4022 + (0.4472HR) - (0.1236Weight) + (0.074*Age) / 4.184

HR in bpm; Weight in lbs; Age in years

Question 14

Normal Resting Heart rate of a healthy adult is between ___ to ___ bpm

Answer 14

60 - 100

Question 15

Healthy athletes have even lower normal resting heart rate – can go as low as __

Answer 15

40

Question 16

Heart rate guidelines based on intensity of activity

Answer 16

Moderate intensity physical activity = 64% - 76% of Max HR

Vigorous intensity physical activity = 77% - 93% of Max HR

Question 17

Estimation of Max Heart Rate

Answer 17

220 - age

Question 18

• A scale used to know perceived intensity of an activity, such as exercise or physical/manual labor
• Developed by Gunnar ___ for rating exertion and breathlessness during physical activity
  
  • Reflects how hard the activity is through heart rate and respiration, perspiration and muscle exertion

Answer 18

Borg Rating of Perceived Exertion (RPE)

Question 19

Original Borg RPE has a scale of __ to ___

Answer 19

6 to 20

Question 20

Later revised to ____ or ____, has a scale of __ to ___

Answer 20

Category Ratio Scale (CR10 Scale)
Modified Borg Dyspnoea Scale
0-10

Question 21

Method of Use of Borg RPE

Answer 21

• Participants are asked to rate their exertion of activity based on the scale
• Taking into consideration feelings of physical stress or fatigue
• Focusing only feeling of exertion, not on the pain experienced
• Number in scale connotes intensity of activity; tells us if participant should speed up or slow down movements/activity

Question 22

Occupational and non-occupational risk factors can lead to ___ and ___

Answer 22

musculoskeletal disorder (MSD)
work-related musculoskeletal
disorder (WMSD)

Question 23

Factors that can result in the formation of MSD or WMSD

Answer 23

• Local soft tissue fatigue
• Sufficient blood flow in these soft tissues
• Sufficient recovery from fatigue

Question 24

Three factors must be considered to evaluate work or tasks

Answer 24

1. Force / Forceful exertion
2. High task repetition
3. Sustained awkward posture

Question 25

Higher force requirement = ___

Answer 25

Higher Risk and higher muscle effort and higher muscle fatigue

Question 26

Control Methods for forceful exertion

Answer 26

* Engineering controls – mechanical assists, adjustable height lift tables and workstations, powered tools, ergonomic tools * Work practice controls – carts and dollies to reduce lifting/carrying, sliding objects instead of lifting/carrying, eliminating reaching obstruction

Question 27

Higher task repition = ___

Answer 27

Higher Risk

Question 28

General cycle time that makes tasks repetitive

Answer 28

≤ 30 seconds = repetitive

Question 29

Control Methods for High Task Repetition

Answer 29

* Engineering controls – goes hand-in-hand with improvements in other factors * Work practice controls – proper work technique to minimize MSD risk * Job rotation – to reduce duration, frequency and severity of MSD risk * Counteractive stretch breaks – for recovery from fatigue

Question 30

High Awkward posture =

Answer 30

higher force on joints; overload muscles and tendons

Question 31

Joints most efficient when operating closest to ___

Answer 31

mid-range of motion of the joint

Question 32

Repetitive and Outside mid-range of motion = ___

Answer 32

higher MSD risk

Question 33

Control Methods for Sustained Awkward posture

Answer 33

Engineering controls – modify workplace to reduce awkward posture * Work practice controls – proper techniques in doing a task; work procedures following proper posture should be implemented * Job rotation and job enlargement – increasing variety of work reduces repeated or sustained awkward postures * Counteractive stretch breaks – rests and stretching to allow recovery from fatigue

Question 34

What is awkward posture?

Answer 34

* Body position is non-neutral * Extreme ends of range of motion * Joints eventually become weaker; muscles out of balance * Tasks become even more physically demanding; adds unnecessary stress to the body

Question 35

Where is the power zone?

Answer 35

* Close to the body * Between mid-thigh and mid-chest height * Arms and back can lift the most with least amount of effort * Lifting outside power zone → risks and injuries ↑

Question 36

Occurs if tools and materials are placed outside the "Power Zone"

Answer 36

Awkward Posture

Question 37

2 different methods in evaluating posture in the workplace

Answer 37

1. Rapid Upper Limb Assessment (RULA) 2. Rapid Entire Body Assessment (REBA)

Question 38

* developed in England in 1993 * Only in 1998 it was first applied * Tool focuses only on posture * Using the tool can help predict risk of upper extremity MSD - Hand - Wrist - Elbow - Shoulder - Back The tool uses a scoresheet to derive a ___ "score" A composite score is calculated based on individual components in the tool

Answer 38

Rapid Upper Limb Assessment (RULA)

Question 39

RULA is mostly applicable in ergonomic assessment of ___

Answer 39

seated tasks, high repetition tasks or continual such as - office workers in the workstation - Assembly workers in an assembly line

Question 40

predicts the risk of developing MSD or WMSD but for entire body (which includes lower limbs)

Answer 40

Rapid Entire Body Assessment (REBA)

Question 41

REBA evaluates

Answer 41

* Required or selected body postures * Forceful exertion * Type of movement, action, repetition, and coupling

Question 42

the institution that provided the lifting equation guidelines for evaluating two-handed manual lifting tasks

Answer 42

National Institute of Occupational Safety and Health

Question 43

* is the weight of the load that nearly all healthy workers can lift over a substantial period (e.g., 8-hour work shift) * recommendation for preventing an increased risk of developing lower back pain

Answer 43

Recommended Weight Limit

Question 44

Maximum weight to be lifted under ideal conditions is ___

Answer 44

23 kg

Question 45

RWL considers six factors for lifting weight to reduce the maximum of 23 kg

Answer 45

* A load of 51 lbs / 23 kg * Lifted in the sagittal plane * The load is at a height of 75 cm above the floor * The load is held 25 cm in front of the body * The load is to be lifted no more than 25 cm vertically * There is good coupling of the load

Question 46

Six coefficients to reduce RWL to account for task factors Determined using biomechanical models of spinal loading

Answer 46

H = horizontal distance of hands from midpoint between ankles in cm V = vertical height of the hands from the ground in cm D = vertical distance of lifting vertically (where the load is being lifted to) in cm F = frequency or time between lifts, in mins or secs A = angle of asymmetry of the load in relation to the body, in degrees C = hand-to-load coupling (quality of grasp based on type of handle)

Question 47

RWL equation

Answer 47

LC x HM x VM x DM x AM x FM x CM Where LC = load constant HM = horizontal multiplier VM = vertical multiplier DM = distance multiplier AM = asymmetric multiplier FM = frequency multiplier CM = coupling multiplier

Question 48

Load Constant

Answer 48

23 kg

Question 49

Horizontal Multiplier

Answer 49

25/H cm

Question 50

Vertical Multiplier

Answer 50

1 - 0.003 |V-75| cm

Question 51

Distance Multiplier

Answer 51

0.82 + (4.5/D) cm

Question 52

Asymmetric Multiplier

Answer 52

1 - 0.0032A degrees

Question 53

Frequency Multiplier and Coupling Multiplier

Answer 53

refer to tables, FM - lifts/min

Question 54

Answers the question, “Is the weight too heavy for the task?”

Answer 54

Recommended Weight Limit (RWL)

Question 55

Answers the question, “How significant is the risk?”

Answer 55

Lifting Index (LI)

Question 56

Lifting Index based on results of the RWL equation

Answer 56

Lifting Index = Actual Load/ RWL where actual load is in kg

Question 57

If LI < 1.0

Answer 57

the task does not increase the risk of injury

Question 58

* If LI ≥ 1.0

Answer 58

some workers are at risk of injury

Question 59

If LI > 3.0

Answer 59

many/most workers are at high risk of injury, leading to low back pain and injury

Question 60

Higher Lifting Index = ___

Answer 60

Higher risk of injury

Question 61

If RWL < Actual Weight of load, determine which factor(s) contributes the highest risk, then modify lift

Answer 61

Lowes multiplier values = factors of highest risk

Question 62

The lifting (or lowering) equation and LI can only be used when

Answer 62

1. Task/work involves two-handed lifting 2. Worker is in comfortable lifting posture 3. The environment is comfortable enough for lifting, including the floorings

Question 63

Limitations of the LI Formula

Answer 63

1. Only one hand is used 2. > 8 hours 3. When seated or kneeling 4. In a restricted workspace 5. Unstable objects (e.g., buckets, liquid containers) 6. Involving pushing or pulling 7. Using wheelbarrows or shovels 8. Objects of extreme temperature 9. Poor footing/foot coupling (may cause risk or fall)