Changes in steering performance and muscle activity of the upper extremity according to the position of the spinner...

A spinner knob attached to the steering wheel enables one-handed driving. However, changes in steering performance and muscle activity of the upper extremity based on the differences in the position of the knob are unknown.

To quantify changes in steering performance and their muscle activity according to the position of the knob.

Twenty right-handed healthy men with a mean age of 30.9 years participated in the study. Steering operation (reaction time, accuracy, right-left balance and adaptability) as assessed by steering with both hands and left one-handed driving with the spinner knob at three positions (8, 10, and 12 o'clock) were evaluated using a driving simulator. Muscle activities of the left anterior deltoid, biceps brachii and long head of the triceps brachii during the simulated tasks were also recorded using a wireless surface electromyography.

Muscle activity while steering with the knob at 8 o'clock was significantly lower than with the knob at 10 or 12 o'clock, and was equivalent to the steering performance and muscle activity when driving with both hands. On the other hand, muscle activity while driving with the knob at 10 o'clock was significantly higher than with the knob in the other positions.

The present study provides basic data for determining the position of the spinner knob attached to the steering wheel when driving one-handed with the non-dominant left hand. Positioning of the knob at 8 o'clock can be recommended on the basis of steering performance and lower muscle activities.IMPLICATIONS FOR REHABILITATIONThe safe driving of an automobile requires the driver to have an adequate range of motion and advanced voluntary motor control of the upper and lower extremities.When steering with the bilateral hands becomes difficult and driving with one-hand is required, it is necessary to attach a spinner knob on the steering wheel.This study provides objective and valuable information for clinicians and therapists to determine the optimum position of the spinner knob.