The Pattern of Gripping Force During Bus Driving
János Pórszász, József Tasnádi, István
Bereczki and József Varga
National Institute of Occupational Health, Division of Occupational Physiology
Corresponding author:
János Pórszász, M.D., Ph.D.
National Institute of Occupational Health
Budapest IX. Nagyvárad tér 2.
1450. P.O.Box 22
Hungary
Tel: (+36) 1-215-7890
FAX: (+36) 1-215-6891
E-mail: 100324.2440@CompuServe.com
CEJOEM 1997, 3:67-80
Key words: Carpal tunnel syndrome, integrated surface
electromyogram, gripping force, bus driving
Abbreviations:
CTS: carpal tunnel syndrome
iEMG: integrated surface electromyogram
Abstract: The calculated gripping force, based on the integrated
surface electromyogram (iEMG) of the long forearm flexors has been measured
on four experienced bus drivers while driving the IKARUS 415 type vehicle
equipped with a power steering system. Surface electrodes were secured
above the capita of long finger flexors and the iEMG was recorded. The
iEMG was recorded under different experimental setups. These included:
moving the steering wheel at different angles on stopped vehicle with running
engine to insure that the power steering system was operating; slalom driving;
driving on an ‘8’-shape; driving on a model path that was constructed on
the basis of ergonomical observations and driving in real traffic situation.
The gripping force changes followed an impulsive pattern with peak values
less than the ergonomically allowed long-term limit for gripping force
and with an average duration of less than 4 to 6 seconds, depending upon
the task performed. The average calculated gripping force did not exceed
the high-risk limit of 4 kp in either task. In real traffic situation the
cycle time was about 19 seconds, but the time spent beyond 4 kp did not
exceed 5% of the total driving time. According to these results it is concluded
that driving the IKARUS 415 type vehicle even under heavy traffic conditions
does not represent high enough strain of the finger flexors that could
provoke the signs and symptoms of carpal tunnel syndrome.
Received: 10 January 1997
Accepted: 14 February 1997
Posted: 14 December 1998 |
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