Triple Support
Forward position
Characteristic features:
• The back is bowed or, in a stiff sitting position,
pushed forward
• The center of gravity of the upper body is in front
of the ilia
• With the thighs held virtually horizontal, the hip
angle, i.e. the sitting angle, is smaller than 90°
• The pressure within the abdominal area is raised
– Negative influence on the blood-flow return through
the abdominal area
– The muscles become statically flexed
If they are not straightened within a short period of time,
the upper body searches support through the arms which are
on the work surface (the center of balance returns to achieve
a relative relaxing of the muscles).
In the forward sitting position, the shoulder/neck muscles
have more strain as opposed to the middle or rear positions.
Straight position
Characteristic features:
• The center of gravity lies in the area of the ilia
• In general, this is a statically balanced sitting
position. The curve of the spine from lumbar to neck is relatively
small, and the muscles can relax. Breathing is deepened
(= Asian relaxing position)
In every form of work, bodily movement is necessary which
impairs the center of balance. In order to retrieve
the center of balance, the muscles must be put under tension.
These are the reasons why the middle sitting position is not
of much importance when discussing working positions.
Rear position
Characteristic features:
• Without a backrest, the pelvis is twisted back on
the seating area
• Open hip angle (related to the pelvic position), i.e.
it is greater than 90°C
• Depending on the position of the sacrum, there are
differences in the curve of the spine
The stronger the curve of the dorsal vertebra, the more adjustment
must be made through the neck. "Stretching" of the
spine is possible, but only with a lumbar support (back muscles
are relaxed). |
