the presentation gives an overall view of energy expenditure

1. GRADES OF WORK
PRESENTED BY
RAM KUMAR R
SAHUL HAMEED H

2. BASIC CONCEPTS
MUSCLE PHYSIOLOGY
There are three types of muscles namely
1. Striated or skeletal muscles
2. Cardiac muscles
3. Smooth muscles
Most vigorous activities are carried out by skeletal
muscles, which are attached to the bones.
Cardiac muscles are present on the walls of the heart.
Smooth muscles are seen on the walls of blood vessels
and internal organs.

3. MUSCLE METABOLISM
Energy is required for muscles to contract, this energy is
provided by the food that we eat and digest, primarily the
carbohydrates and fats.
Carbohydrates are converted to glucose and stored in
liver.
In liver the glucose or glycogen is broken down to liberate
energy for muscle contraction.
The muscles does not consume the energy directly but
through conversion of ATP to ADP, which releases energy
required for cells.
Cretinine Phosphate (CP) is a immediate source of
energy useful only for short duration.

4. BASAL METABOLISM
Metabolism is a chemical process by which
foodstuffs are converted into heat or mechanical energy.
Muscles convert 30% of energy liberated into mechanical
work and remaining 70% as heat.
Body requires a certain amount of energy just to stay
alive without doing any physical work, this is called Basal
Metabolic Rate (BMR)
For 70 kg male – 1.2 kcal/min
For 60 kg female – 1.0 kcal/min
BMR depends on
 Body size
 Age
 Sex

5. RESPIRATORY RESPONSE
The respiratory response is to increase the rate of
breathing and volume of air inspired with each breath
At rest oxygen consumption is less than 0.5 L/min
At extremely heavy work it is about 5.0 L/min
The body cannot instantaneously increase the amount of
oxygen consumption, it occurs in gradual stages.
During this period the anaerobic glycolysis and depletion of ATP
and CP stores provide energy to the muscles and the body
experience oxygen debt.
“Oxygen debt is the amount of oxygen required by the muscles
after the beginning of work, over and above which is supplied to
them during work activity”
This debt is repaid during the resting period

6. CARDIO VASCULAR RERSPONSE
Increased cardiac output
In order to provide more oxygen, more blood must
flow to the muscles, to do this the heart must pump more
blood per unit time.
It can be done in two ways
By increasing heart rate
By increasing stroke volume
Cardiac output at rest is about 5 L/min
Cardiac output during heavy work 25 L/min

7. INCREASED BLOOD PRESSURE
The consequence of increased cardiac output is increase
in blood pressure during physical work
The adrenal glands release hormone called
catecholomines that strengthen the heart beat and
increase blood pressure.
REDISTRIBUTION OF BLOOD FLOW
Accompanied by increase in cardiac output and blood
pressure there is a redistribution of blood flow throughout
the body

8. DISTRIBUTION OF BLOOD DURING RESTAND WORK
Part of the body Blood flow distribution (%)
Resting Heavy work
Muscles 15-20 70-75
Skin 5 10
Brain 15 3-4
Bones 3-5 0.5-1
Kidneys 20 2-4
Digestive system 30-25 3-5
Heart muscle 4-5 4-5

9. MEASURES OF PHYSIOLOGICALSTRAIN
Oxygen consumption (uptake)
one litre of oxygen liberates approximately 5 kcal of
energy, thus by measuring the oxygen consumption we can
directly estimate the energy consumption

10. EXPERIMENTALDATA- International Journal of Physical Education,
Fitness and Sports
Parameters Service
sector (n
=136)
Mean
(±SD)
Manufactur
ing sector
(n = 49)
Mean
(±SD)
Experimental
group (Service
sector +
Manufacturing
sector) (n =185)
Mean (±SD)
Validation
group (n =100)
Mean (±SD)
Age (yrs) 46.7
(±8.10)
44.4
(±10.88)
46.1 (±8.95) 49.4 (±9.74)
Height
(cms)
164.4
(±6.36)
165.6
(±4.78)
164.7 (±5.99) 165.0 (±5.3)
Weight
(kgs)
63.1
(±11.54)
66.1
(±10.72)
66.1 (±10.72) 66.1 (±10.40
Physical Characteristics

11. Parameters Service sector
Mean (±SD)
Manufacturing
sector Mean
(±SD)
Experimental
group Mean
(±SD)
Validation
group Mean
(±SD)
Resting HR
(beats.min-1)
72.2 (±16.29) 71.0 (±7.96) 72.3 (±16.69) 71.5 (±16.49)
Resting VO2
(ml.kg-1.min-
1)
5.5 (±1.30) 5.0 (±2.26) 5.6 (±1.27) 5.3 (±1.27)
HR max
(beats.min-1)
154.0 (±17.00) 166.0 (±15.99) 158 (±21.84) 159 (±21.11)
VO2 max
(ml.kg- 1.min-
1)
27.3 (±4.15) 34.8 (±5.99) 33.0 (±5.61) 31.5 (±5.99)
Pre-work and maximum values of heart rate and
oxygen consumption

12. Maximum Aerobic Power
Maximum Aerobic Power is defined as the highest
oxygen intake an individual can attain during exercise while
breathing air at sea level
Increasing the rate of work causes a linear increase
in oxygen intake, to a point , after which oxygen uptake
level off. Further increase in work rate will no longer
increase oxygen uptake.

13. Heart Rate
There is a linear relationship between oxygen
consumption and heart rate.
A few wires attached to a person and a telemetry or
recording can easily measure heart rate, that can be used to
estimate oxygen consumption, which in turn can be
converted to energy expenditure.

14. GRADES OF WORK
• Grades of work is the measurement of energy required to
carryout the task
• The energy requirement varies from individual to
individual based on physical structure, sex, age.
• The energy requirement for same work differs based on
the geographical location and the working environment.

15. GRADES OF PHYSICAL WORK BASED ON ENERGY
EXPENDITURE LEVEL
Grade of
work
Energy
expenditure,
kcal/min
Energy
expenditure,
8 h (kcal/day)
Heart rate,
beats per
minute
Oxygen
consumption,
L/min
Rest (sitting) 1.5 <720 60-70 0.3
Very light
work
1.6-2.5 768-1200 65-75 0.3-0.5
Light work 2.5-5.0 1200-2400 75-100 0.5-1.0
Moderate
work
5.0-7.5 2400-3600 100-125 1.0-1.5
Heavy work 7.5-10.0 3600-4800 125-150 1.5-2.0
Very heavy
work
10.0-12.5 4800-6000 150-180 2.0-2.5
Unduly heavy
work
>12.5 >6000 >180 >2.5

16. ENERGY COST PER DAY FOR VARIOUS OCCUPANTS
occupation energy expenditure (kcal/day)
Mean Minimum maximum
Laboratory technicians
Male 2840 2240 3820
Female 2130 1340 2540
University students
Male 2930 2270 4410
Female 2290 2090 2500
Male only
Construction
worker
3000 2440 3730
Steel workers 3280 2600 3960
Coal miners 3660 2970 4560

17. ENERGY EXPENDITURE FOR DAY TO DAYACTIVITIES
Activity Energy expenditure (kcal/min)
Sleeping 1.3
Sitting 1.6
Standing 2.25
Walking(level) 2.1
Cleaning/ironing 2.0-3.0
Cycling(16kmph) 5.2

18. ENERGY REQUIREMENT FOR VARIOUSACTIVITIES IN
INDUSTRY
ACTIVITIES ENERGY(kcal/min)
Inspection 1.6
Testing(sitting) 2.2
Testing(standing) 2.7
Construction 4.0
Driving 4.2
Manual material
handling
5.0
Cutting 6.8
Pushing 7.7
Lifting 8.5
Working near
furnace
10.2

19. FACTORSAFFECTING ENERGY CONSUMPTION
Methods of work
The energy cost for certain type of work vary with
the manner in which the work is carried out.
The methodology of work carried out varies based
on the method of carrying load and oxygen consumption
rate associated with it.

20. WORK POSTURE
The posture of workers while performing some task
is another factor which influence the energy consumption.
Musculoskeletal disorders (MSDs) are common
health problem throughout the world. Assessment of
exposure levels to MSD risk factors can be an appropriate
base for planning and implementing interventional
ergonomics programs in the workplace.
In many rapidly developing countries, where labor is
cheap, proper occupational hygiene and posture analysis
methods are often neglected. Proper sitting arrangements
and work environment are seldom provided

22. Continued…
Repetitive processes and manual material handling
are the major problems in the hand tool manufacturing.
Therefore, musculoskeletal disorders (MSDs) are related to
such high repetitive processes and working in bad posture.
Thus, to improve the efficiency of the workers their
posture needed to be assessed and corrective measures
should be adopted to avoid the musculoskeletal disorders

23. WORK RATE
• Another factor that affect the energy consumption is work
rate or the pace of work
• Repetitive work can be carried out upto certain pace until
which heart rate is maintained, above which heart rate
increases appreciably and the work load can cause
fatigue and other physiological changes in the human
body

24. CASE STUDY-AN ANALYSIS OF EXPERTS' RATINGS
OF ERGONOMIC STRESS (International Journal of Industrial
Ergonomics)
INTRODUCTION
Jobs which expose workers to excessive ergonomic
stresses can cause a variety of occupational health problems
including fatigue, discomfort, and disability. These stresses may
result from awkward posture, excessive force demands, highly
repetitive actions and/or excessive energy expenditure.
In the United States, musculoskeletal disorders are ranked near
the top of conditions requiring medical treatment: Specifically,
musculoskeletal disorders are ranked:
• Second among reasons for seeing a physician,
• Third among disorders requiring hospital
surgery, and
• Fifth among reasons for visiting hospitals.

25. KEY FINDINGS
Chaffin (1972) found that jobs requiring repeated
moderate or heavy whole body exertions can lead to
discomfort, loss of coordination, loss of strength, and
strain on the cardiovascular system.
Jobs requiting sustained postures or repeated use of
specific muscle groups can lead to a general loss of
coordination, localized muscle discomfort, and
cardiovascular strain
Eight out of ten adults experience back pain during their
working careers, resulting in significant medical and
compensation costs

26. ERGONOMIC STRESSES OF INTEREST
1.Manual materials handling (MMH) activities
This category included stresses associated with
strength-demanding materials handling tasks (e.g. Lifting,
carrying,pushing,pulling,etc.) which could lead to
overexertion injuries of the back and other body regions.
Analysts were instructed to focus their attention on
the magnitude of the forces exerted and the body geometry
maintained during materials handling tasks in order to
estimate the likelihood of overexertion musculoskeletal
injuries.

27. 2. Upper Extremity (UE) activities
This category included stresses associated with
actions of the hands, arms, and shoulders that could lead
to cumulative trauma disorders, such astendinitis, synovitis,
and carpal tunnel syndrome. Analysts were instructed to
focus their attention on the frequency, force, and posture
associated with hand-intensive tasks. Other factors, such
as exposure to vibration and localized mechanical stresses
were also considered when estimating the likelihood of an
upper extremity injury.

28. 3. Posture
This category included non-neutral postures of the
trunk, neck, and/or shoulders that could lead to localized
muscle fatigue and/or musculoskeletal disorders.
Analysts were instructed to focus their attention on
the trunk (flexion, lateral bending, or twisting), the neck
(flexion, extension, twisting, or lateral bending), and the
shoulder (flexion or abduction). Temporal aspects, such as
frequency and duration of these non-neutral postures, were
also considered by the analysts in order to estimate the
potential for injury.

29. 4. Metabolic energy expenditure and whole body fatigue
This category included work activities requiring high
levels of energy expenditure which could lead to excessive
loading of the cardiovascular system and whole body
fatigue, such as climbing or repetitive/prolonged lifting of
heavy loads.
Analysts were also instructed to consider
environmental effects (e.g., heat stress) when estimating
the potential for job-induced whole body fatigue.

30. SCORING SYSTEM ADOPTED
Insignificant. Jobs given this rating were judged to be
free of potentially harmful ergonomic stresses in the
category of interest. The expert believed that the job was
sufficiently safe that no follow-up action (i.e., additional
analyses and/or job modifications) would be required or
necessary.
Moderate. Jobs given this rating were judged to present
moderate ergonomic stresses in the category of interest.
The expert believed that follow-up analyses using
quantitative methods were justified to confirm perceptions
and to determine the necessity for design and/or work
methods changes.

31. High. Jobs given this rating were judged to present major
ergonomic stresses in the category of interest. This rating
indicated that the expert believed the probability of injury
was sufficiently high to justify immediate, detailed follow-
up analyses. Furthermore, the expert believed that high
priority should be given to redesigning the job in order to
eliminate or reduce the level of ergonomic stress
CONTINUED..

32. CASE STUDY-A STUDY ON PUSH-PULL ANALYSIS ASSOCIATED
WITH AWKWARD POSTURE AMONG WORKERS IN AEROSPACE
INDUSTRY (International Journalof Research in Engineering and Technology)
INTRODUCTION
Manual material handling (MMH) such as lifting
heavy products, reaching materials, bending forward
their back when doing tasks, and pushing or pulling
excessive loads because those tasks require a stable
position and large degree of freedom. Pushing and
pulling activities are one of the activities for MMH that
can increase the risks of back pain problem. The
pushing and pulling activities is a frequent activity for a
great segment of the workforce, including hospital
workers, manufacturing workers, construction workers,
forest workers, etc. Moreover, both of these activities
are associated with the awkward posture.

33. Awkward posture can be theorized as a discomfort
posture because it is harmful position for human body
when a joint is not in its neutral range of postures and
make muscles are either shorter or longer than resting
length. When joints are exposed to postures that involve
range of movement near the extreme positions, the
muscles around the joint are stretched or compressed. If
the exposure to extreme postures is prolonged, the
muscles do not immediately return to their resting length

34. AWKWARD POSTURE AMONG WORKERS IN AEROSPACE
INDUSTRY

35. TOOLUSED FORANALYSIS OF POSTURE
The analysis of posture is done using CATIA ergonomic
analysis tool
The analysis is used to analyze the maximum acceptable
and sustainability force when workers push or pull each
mould.
The feature used from this tool to do the analysis is Push-
Pull Analysis feature. Besides that, the comfort level of the
working posture also analyzed by using this tool. But, the
comfort level is analyzed by using RULA feature.

36. Demographic of workers participated in the study
Criteria Mean (SD)
Gender Male
Age 25.7 (5)
Mass (kg) 64.5 (10.9)
Height (cm) 174.2 (7.3)
Experience (year) 4.7 (2.7)

37. Awkward posture for pushing and pulling activity

38. RESULTSAND DICUSSION
Push-Pull Analysis from CATIA
V5R19 software
RULA analysis of right body
region for push-pull
activity

39. THANK YOU