The right position implies sitting up straight with the back fully adjoined to the seat. Besides, it should be easy for a driver to reach the pedals with his feet with his slightly bent hands placed on the steering wheel.
Such position the most natural for a person; it helps the driver not to feel fatigue on long journeys, and provides a clear overview, as well as requires less effort while driving.
When the seat is placed too far back from the steering wheel, the driver's
back has no support and his muscles are strained all the time. In addition,
relatively weak forearm and hand muscles get the most load, while the more
powerful shoulder muscles are underused, what reduces the range of possible
motion. Inefficient distribution of the arm muscles load can also occur
when the steering wheel angle is too low.
When the seat is installed too far from the pedals, the driver has to catch up to them constantly holding on to the steering wheel, what prevents from the option to turn rapidly. Besides in such a situation the visibility is poor.
It's not very good also when the seat is installed too close to the wheel.
The driver has to bend his legs so that it's becoming difficult to control
the pedals. Hands, in their turn, can't get the free control over the steering
wheel is such a position.
The level of the driver's muscle force while pressing the pedal changes
depending on the back cushion angle as well as on the height of the seat.
If it is too low, the driver strains his back and neck muscles raising
his chin. If it is too high the driver has to bow his head, what leads
to the fatigue of the shoulder muscles and hampers the process of breathing.
With the right angle of the seat cushion the efforts to control the pedals
can be reduced by 15-20%. The distance from the edge of the seat to the
driver's knees should be at least 15% of the length of the thigh.
Decreasing this distance may cause dysfunction of the foot as a result
of blood vessels and nerves compression in the hip area. The higher the
seat, the smaller the angle should a cushion have. Sometimes, trying to
make it more comfortable the depth of the cushions is enhanced what results
in limited freedom of movement of the driver's feet.
The back of the seat should be vertical; it should have a certain inclination
so that the body weight is distributed more favorably on the seat and back,
and the hip muscles are relaxed. However, the excessive back angle of the
driver's seat makes it uncomfortable to drive the car.
In this case, even though his back has certain support, the lower part
of the backbone, muscles, neck and arms have excessive strain. The leg
muscles are overloaded as well, because they don't have enough support.
That's why a seemingly comfortable driving position can make feel tired
very quickly, and the driver's attention is reduced.
The procedure for adjusting the seat is the following: first it is necessary to push it so that it can be easy to reach the pedals with your feet and to place hands comfortably on the steering wheel, and only then to change the angle of the seat.