Ergonomics
follows a very simple basic model that derives from physics: When you impact
any body with a certain stress, the body will react with a
corresponding strain. For example,
when you push a wooden stick that is fixed at one end from the side (= stress), it will get bowed (= strain). When we release the stress, the stick will become straight again. This means
that the strain will release, too.
But if the stress exceeds a certain threshold, the
strain can overcome the resistance of the stick, so that it will break. This
limit to damage defines the maximum stress that the wooden stick can bear.
When we transfer this simple model to working conditions,
it must be modified in a couple of points.
On the
stress side, standard methods have a typical stress. But on the strain
side, people are individuals:
They have
different attributes like gender, age, height, weight, power… In
practical life, these attributes are regarded to be invariable.
Everybody
has his individual abilities and strengths. The same job that is easy
for somebody can be difficult for another person; we say that the first person
is more talented for this job than the other one.
Most jobs
require a certain technique. Skilled persons can reach results that will
never be possible for unskilled persons.
These three
factors together – attributes, abilities and skills -form the capability
of the person. If their capability fits the demands of the standard method, the
strain is low. If not, strain will keep accumulating…
But due to organic
reasons like health, conditioning, tiredness, hunger and time of the day, the
strength can vary. We call that: disposition. On the other side, motivation
also has an important influence on. Both together are called: readiness for
work.
While
capability is the potential of any given person, readiness is the percentage of
that potential actually activated.
When the
worker can manage his workload independently, he can find the right pace to
keep strain at an acceptable level.But sometimes the strain exceeds
that level. For example, when the worker is pushed to reach a certain
performance that is beyond his long-term capacity or when he is so motivated
that he does not realize that he is overreaching.
Then the
strain will accumulate.
To remain
with our simple model above, we look for a permanent work loadthat
can be coped with on a day-by-day basis until the worker retires. If the actual
strain momentarily exceeds this permanent load, it will not be a problem. In
real life, this happens very often. It can even improve the training and
exercise (conditioning). But at the end of the day there should be a
balance between periods of excessive strain and periods of lower strain (recovery).
Otherwise, overload will accumulate and result in damage.
Based on
this model, there are various possibilities to lower the strain. It is up to
the manager to combine them in the best possible way, by:
- providing enough time for breaks
adequate to the type and quantity of strain (recovery);
- encouraging physical and psychological
fitness through proper exercise and diet (conditioning);
- creating ideal working conditions to
increase readiness
- adapting work assignments to the
physical and psychological capacity of each worker;
- the ultimate measure is to assign
tasks and to adjust the workloads according to each worker’s individual
capacity.
But when we
have different technical options for performing a certain job, we should prefer
the option that fits best the capacity of the available workers.
