Kim D-K1, Hwang J1, You J(H1
1Yonsei University, Physical Therapy, Wonju, Korea (South)
Background: An optimal ergonomic design for motor vehicle seats and pedals is important for comfortable, safe, and mechanical impairment-free driving. It has been theorized that inadequate motor vehicle seats and pedals are associated with lower back pain. Despite advancements in automobile technology and sophisticated design development, there is little research regarding the optimal ergonomic design of motor vehicle seats and pedals that directly consider knee joint angle.
Purpose: The purpose of the present study was to compare the effects of pedal positions and the associated knee joint angles of the Sedan and Sport Utility Vehicle (SUV) automobile types on the back extensor and lower extremity muscles in healthy subjects.
Methods: Twenty-five volunteers (females = 8, males = 17, mean age = 34.6 years) who have at least one year of driving experience underwent electromyography (EMG). A surface EMG system was used to record muscle activity of the erector spinae, rectus femoris, tibialis anterior, soleus, gastrocnemius, and biceps femoris on the dominant side in two types of seating positions: Sedan (low) and SUV (high). An automobile seat position system was custom-built such that the seating height, knee joint, and ankle position were adjustable[A1] , using a knee flexion of 40° for the Sedan (low) and 70° for the SUV (high) seat conditions. The reference EMG data were acquired from a submaximal voluntary isomeric contraction (% sMVIC). A paired t-test was used to compare the differences in EMG activity recordings at p 0.05. The institutional review board (IRB) of Yonsei University Wonju approved the study(approval number: 1041849-2017-BM-062-02). Informed consent obtained from all participants.
Results: EMG activities while pressing the SUV pedal were significantly less than EMG activities while pressing the Sedan pedal for the left erector spinae (p 0.001), right erector spinae (p 0.001), right tibialis anterior (p 0.005), right soleus (p 0.001), right gastrocnemius (p 0.001), and right biceps femoris muscles (p 0.05).
Conclusion(s): The present study provides novel evidence that trunk and lower extremity muscle activities were different depending on the type of car model: Sedan or SUV. SUV pedal position with knee flexion of 70° resulted in lesser activation of the erector spinae and lower extremity muscles compared to that with Sedan pedal position. This outcome indicates that SUV pedal position prevents low back pain, considering that hyperactivity of the erector spinal is a major risk factor for back pain. Therefore, SUV pedal position may help to avoid lower extremity fatigue while driving.
Implications: SUV pedal position has several advantages because 70° of knee flexion allows the lower leg to remain closer to perpendicular position, compared to 40° of knee flexion in sedan pedal position. This is because SUV pedal position enables pressure from the lower leg on the pedal with the assistance of gravity, compared to that in Sedan position. These findings suggest that motor vehicle seat and pedal positions should be considered when designing an optimal ergonomic car.
Keywords: automobile pedal, electromyography, muscle activities
Funding acknowledgements: None of the authors received any funding for this study.
Purpose: The purpose of the present study was to compare the effects of pedal positions and the associated knee joint angles of the Sedan and Sport Utility Vehicle (SUV) automobile types on the back extensor and lower extremity muscles in healthy subjects.
Methods: Twenty-five volunteers (females = 8, males = 17, mean age = 34.6 years) who have at least one year of driving experience underwent electromyography (EMG). A surface EMG system was used to record muscle activity of the erector spinae, rectus femoris, tibialis anterior, soleus, gastrocnemius, and biceps femoris on the dominant side in two types of seating positions: Sedan (low) and SUV (high). An automobile seat position system was custom-built such that the seating height, knee joint, and ankle position were adjustable[A1] , using a knee flexion of 40° for the Sedan (low) and 70° for the SUV (high) seat conditions. The reference EMG data were acquired from a submaximal voluntary isomeric contraction (% sMVIC). A paired t-test was used to compare the differences in EMG activity recordings at p 0.05. The institutional review board (IRB) of Yonsei University Wonju approved the study(approval number: 1041849-2017-BM-062-02). Informed consent obtained from all participants.
Results: EMG activities while pressing the SUV pedal were significantly less than EMG activities while pressing the Sedan pedal for the left erector spinae (p 0.001), right erector spinae (p 0.001), right tibialis anterior (p 0.005), right soleus (p 0.001), right gastrocnemius (p 0.001), and right biceps femoris muscles (p 0.05).
Conclusion(s): The present study provides novel evidence that trunk and lower extremity muscle activities were different depending on the type of car model: Sedan or SUV. SUV pedal position with knee flexion of 70° resulted in lesser activation of the erector spinae and lower extremity muscles compared to that with Sedan pedal position. This outcome indicates that SUV pedal position prevents low back pain, considering that hyperactivity of the erector spinal is a major risk factor for back pain. Therefore, SUV pedal position may help to avoid lower extremity fatigue while driving.
Implications: SUV pedal position has several advantages because 70° of knee flexion allows the lower leg to remain closer to perpendicular position, compared to 40° of knee flexion in sedan pedal position. This is because SUV pedal position enables pressure from the lower leg on the pedal with the assistance of gravity, compared to that in Sedan position. These findings suggest that motor vehicle seat and pedal positions should be considered when designing an optimal ergonomic car.
Keywords: automobile pedal, electromyography, muscle activities
Funding acknowledgements: None of the authors received any funding for this study.
Topic: Occupational health & ergonomics; Human movement analysis; Musculoskeletal: lower limb
Ethics approval required: Yes
Institution: Yonsei University Wonju
Ethics committee: Yonsei University Wonju Institutional Review Board
Ethics number: 1041849-2017-BM-062-02
All authors, affiliations and abstracts have been published as submitted.
