Ergonomic conditions of work

1. Conditions of work

2. Ergonomic conditions of work
• Knowledge of ergonomic conditions prevents
employee discomfort, fatigue, and physical
injury.
• Injury related to poor ergonomic conditions
can be prevented by designing the physical
work environment around the physical needs
of individual employees.
• Therefore, it is necessary to know the
physiological, psycho-sociological conditions,
and anthropometric ergonomic conditions.

4. Physiological conditions
• Physiology is defined as the
science that studies life
processes.
• The physiology of man explains
the functions of human body.
• It includes all chemical reactions
that occur in cells, the
transmission of nerve impulses
from one part of the body to
another.
• Using the movement of muscles
and other functioning of body
parts.

5. Physiological conditions
• Physiology of work is a special branch of physiology
limited to the body of a man who works.
• A man is most capable of making best sport (and
physical) results when he is about 25 years old.
• And of mental and organizational results when he is
about 45 years old.
• Rational usage of working capacity of man is a matter
of not only being humane but also being economical.
• If a man in his early age or when too old is entrusted
tasks to which he is not physiologically (physically)
equal to, it significantly affects the efficiency of human
life.

6. Physiological conditions
• Physiology of work studies the impact of work
on physiological processes in a man.
• It explores the consequences that arise in the
human organism under the influence of work
in different conditions.
• Its objective is to determine how to work and
be healthy, or how not to make the work be
the reason for the disease.

7. Physiological conditions

8. Physiological conditions
Work is performed in the interaction of three interrelated
factors:

9. Physiological conditions
• When the requirements of work are such that a man
can overcome them by making an effort, the
functional abilities of his body and his health are not
endangered and there is ergonomic balance.
• The physiology of work deals with

10. Defining the workload
• Loads can be physical, mental, and sensory.
• Physical work (the work of skeletal muscles) is
a major cause of physical load because of
work.
• Physical work means the work that a man
does while overcoming burden and resistance.
• Physical work can be dynamic and static work.

11. Dynamic work
• It is the work in which there is a change in the position of
the bones to which muscle is attached and which is, from
the mechanical aspect, characterized by the change of body
position in space.
• Fatigue rarely occurs in dynamic work because constant
contraction and de-contraction of muscles acts as a pump,
which accelerates blood circulation.
• At the beginning of dynamic work oxygen consumption and
heart rate suddenly increase.
• After a few minutes they reach the level that is maintained
steadily as long as the work is performed (steady state).
• Upon termination of work, the curve of oxygen
consumption and heart rate gradually drops to a value at
rest.

12. Dynamic work
• The evaluation of how difficult the work is can be
done by determining the energy consumption during
work. Energy consumption ranges from 4 to 6 kJ/min
at rest, and from 50 to 80 kJ/min during extremely
heavy physical work.
• Energy consumption is affected by gender, age, and
the level of how trained the workers are. According
to energy consumption, work can be:

13. Static work
• It is the work of muscles without moving in
space.
• It is also called a static effort because the
external mechanical effect equals to zero.
• During static, work consumes the energy to
tighten certain muscle groups, and they are
necessary to maintain the body position in
space (standing long, lifting tools, holding a
burden, etc.).

14. Static work
• Static work is characterized by lower energy
consumption compared to dynamic work, but it causes
fatigue and tiredness more rapidly.
• There is an increase in the tone of muscles that
perform the compression of blood vessels in static
work.
• Hence, circulation is more difficult, the supply of
nutrients is reduced the outflow of decay products of
metabolism is reduced and fatigue occurs more quickly.
• After completing the work, oxygen consumption
continues to increase and returns to the value at rest
very slowly.

15. Workload
• In evaluating psychological workload three
groups of factors are taken into consideration:
– unfavorable working environment
– job requirements and its organizational-technical
characteristics
– social changes and problems in everyday life

16. Unfavorable working environment
• Unfavorable conditions of working environment
such as noise, vibration, temperature, humidity,
brightness, etc. act negatively on the efficiency
and sense of comfort at work.
• In certain circumstances, their impact can be
subjectively perceived in a different way.
• For example, monotonous jobs with moderate-
intensity noise activate the body and have a
positive effect on performance.

17. Unfavorable working environment
• If many factors act at the same time the
ultimate effect can be different, i.e. they can
cause:

18. Job requirements and its organizational-
technical characteristics
• Dangerous, risky, complex, stressful, and
responsible jobs require appropriate abilities,
knowledge and skills of workers i.e. high degree
of engagement of psychophysical capacities of
workers.
• Psychological factors that influence these jobs
lead to psychophysiological effort, the size of
which depends primarily on job characteristics
(terms and conditions), but also on personality
traits.