The Effectiveness of Seat Cushion for Reducing Whole Body Vibration and Low Back Pain among Truck Drivers in an Earth Moving Dump Contracting Company, Rayong Province

Abstract

Whole-body vibration (WBV) from driving trucks on rough roads often exceeds the ISO 2631 standard and is a major risk factor contributing to low back pain. The objective of this study was to evaluate the effectiveness of two types of seat cushions: Cushion type 1, made from Ethylene-Propylene-Diene Monomer (EPDM) foam, and Cushion type 2, made from a combination of EPDM foam and natural rubber (NR) foam, in reducing WBV and low back pain. This quasi-experimental research was conducted among 15 dump truck drivers. Data were collected using a triaxial vibration meter (X, Y, and Z axes) and the Nordic Musculoskeletal Questionnaire for low back pain. Data were analyzed using the Wilcoxon signed-rank test.The results showed that before using the seat cushions, the overall mean WBV was 1.120 m/s². After using Cushion type 1, the mean overall WBV decreased to 0.876 m/s², representing an average reduction of 15.74%. This cushion effectively reduced WBV at frequencies of 3.15, 4, 5, 8, 10, 12.5, 16, 25, 50, 63, and 80 Hz. After using Cushion type 2, the mean overall WBV decreased to 0.797 m/s², representing an average reduction of 22.81%. This cushion effectively reduced WBV across a wider frequency range: 1.25, 1.6, 2, 2.5, 3.15, 4, 5, 6.3, 8, 10, 12.5, 16, 20, 25, 31.5, 40, 50, 63, and 80 Hz. Both cushion types significantly reduced low back pain scores at the 0.05 level of statistical significance. Regarding satisfaction, participants indicated a greater willingness to continue using Cushion type 2 compared to Cushion type 1. In conclusion, it is recommended that truck drivers at risk of WBV exposure should consider using cushions made from natural rubber foam combined with EPDM foam, as this material combination covers a wider frequency range of vibration reduction and provides greater health benefits than using EPDM foam alone.