Ibrahim MS1, Elhafez YM2, Ashour AA3, Elhafez NM4, Elhafez SM1
1Faculty of Physical Therapy, Cairo University, Biomechanics, Giza, Egypt, 2Helwan University, Faculty of Applied Arts, Industrial Design, Giza, Egypt, 3Faculty of Physical Therapy, October 6 University, Biomechanics, Giza, Egypt, 4Faculty of Physical Therapy, Cairo University, Basic Sciences, Giza, Egypt
Background: Driving with a comfortable position and with minimum effort is the main target of every driver as well as product designer who makes products more efficient for users.
Purpose: This study was designed to investigate and measure the most comfortable knee joint angle which has the least electromyography activities of the lower limb muscles and the least vertical ground reaction force (VGRF) magnitude during driving a vehicle by simulating clutch pedal design.
Methods: Thirty normal female volunteers of an average age of 19.4 (±2.7) years, an average height of 159.6 (±4.4) cm and an average mass of 63.3 (±9.3) kg participated in the study. Each participant assume three knee joint flexion angles which were 50°, 60° and 70° by simulating the clutch pedal operation. The clutch pedal was designed by industrial designer in cooperation with ergonomics and biomechanics team to simulate the real clutch pedal operation during driving. The design was constructed to assure the best fit between a driver and the job being done. The GRF data were collected while the clutch pedal was placed on AMTI force platform. The EMG activities of left vastus medialis (VM), vastus lateralis (VL), tibialis anterior (TA) and medial gastrocnemius (MG) muscles were recorded at the same time during the motion. Each participant answered a questionnaire concerning the most and the least comfortable knee joint angle assumed during the experiment.
Results: According to the clutch pedal simulated in this study, the results revealed that the most comfortable knee angle was 60° as reported by 63% of the subjects. About 80% of the participants expressed the angle 50° as the least comfortable angle and about 37% of the subjects reported 70° as the most comfortable angle. The knee joint angle of 50° is associated with higher VGRF magnitude and higher EMG amplitudes of MG muscle. In addition there was a significant correlation (p 0.05) between higher EMG amplitudes and feelings of discomfort by decreasing the angle of knee flexion. The uncomfortable knee angle reported by the participants was the angle of highest VGRF and EMG activities.
Conclusion(s): The best knee joint flexion angle assumed during the clutch pedal operation is suggested to be the angle of 60°while the worst angle is the 50°.
Implications: Product designer has a great sharing role in assessment and improving aspects of product´s function. One can relay on the objective measures, as GRF and EMG, to evaluate the subjective feeling of comfort or discomfort.
Keywords: EMG, Ergonomics, Clutch pedal design
Funding acknowledgements: No fund
Purpose: This study was designed to investigate and measure the most comfortable knee joint angle which has the least electromyography activities of the lower limb muscles and the least vertical ground reaction force (VGRF) magnitude during driving a vehicle by simulating clutch pedal design.
Methods: Thirty normal female volunteers of an average age of 19.4 (±2.7) years, an average height of 159.6 (±4.4) cm and an average mass of 63.3 (±9.3) kg participated in the study. Each participant assume three knee joint flexion angles which were 50°, 60° and 70° by simulating the clutch pedal operation. The clutch pedal was designed by industrial designer in cooperation with ergonomics and biomechanics team to simulate the real clutch pedal operation during driving. The design was constructed to assure the best fit between a driver and the job being done. The GRF data were collected while the clutch pedal was placed on AMTI force platform. The EMG activities of left vastus medialis (VM), vastus lateralis (VL), tibialis anterior (TA) and medial gastrocnemius (MG) muscles were recorded at the same time during the motion. Each participant answered a questionnaire concerning the most and the least comfortable knee joint angle assumed during the experiment.
Results: According to the clutch pedal simulated in this study, the results revealed that the most comfortable knee angle was 60° as reported by 63% of the subjects. About 80% of the participants expressed the angle 50° as the least comfortable angle and about 37% of the subjects reported 70° as the most comfortable angle. The knee joint angle of 50° is associated with higher VGRF magnitude and higher EMG amplitudes of MG muscle. In addition there was a significant correlation (p 0.05) between higher EMG amplitudes and feelings of discomfort by decreasing the angle of knee flexion. The uncomfortable knee angle reported by the participants was the angle of highest VGRF and EMG activities.
Conclusion(s): The best knee joint flexion angle assumed during the clutch pedal operation is suggested to be the angle of 60°while the worst angle is the 50°.
Implications: Product designer has a great sharing role in assessment and improving aspects of product´s function. One can relay on the objective measures, as GRF and EMG, to evaluate the subjective feeling of comfort or discomfort.
Keywords: EMG, Ergonomics, Clutch pedal design
Funding acknowledgements: No fund
Topic: Occupational health & ergonomics; Musculoskeletal: lower limb; Human movement analysis
Ethics approval required: Yes
Institution: Faculty of Physical Therapy, Cairo University, Egypt
Ethics committee: Ethical Committee of Faculty of Physical Therapy
Ethics number: P.T. REC/012/00768
All authors, affiliations and abstracts have been published as submitted.
