Effects of Seat-Integrated Low-Frequency Acoustic Vibration on Muscle Mechanical Properties and Electromyographic Responses During Real-World Driving

Prolonged driving is associated with musculoskeletal loading, muscle fatigue, and discomfort, which may adversely affect driver performance and well-being. This study investigated the effects of seat-integrated low-frequency acoustic vibration on muscle mechanical properties and electromyographic responses during real-world driving. Twenty healthy adults participated in a randomized crossover study and completed two driving sessions under vibration and control conditions. Each driving session lasted approximately 50–60 min on a mixed urban–highway route, and in the vibration condition, low-frequency acoustic vibration was delivered to the lumbar region for 20 min, beginning 20 min after driving onset. Trunk flexibility, lumbar muscle mechanical properties (natural frequency and dynamic stiffness), upper trapezius median frequency, and integrated electromyography (iEMG) were assessed before and after driving. Compared with the control condition, the vibration condition yielded significantly greater improvements in trunk flexibility (p = 0.025), lower lumbar muscle natural frequency (p = 0.004), reduced dynamic stiffness (p = 0.032), increased median frequency (p = 0.001), and decreased iEMG activity (p = 0.008), with moderate-to-large between-condition effect sizes (Cohen’s d = 0.70–1.73). These findings indicate that low-frequency acoustic vibration may attenuate driving-related increases in muscle tone and stiffness. The observed increase in median frequency and decrease in iEMG are consistent with reduced neuromuscular fatigue and muscular activation demands during prolonged driving. Within the constraints of a small, predominantly male sample of healthy adults and a single seat–vehicle configuration, these preliminary findings suggest that seat-integrated low-frequency acoustic vibration may be a potentially useful, non-invasive strategy for supporting musculoskeletal function and neuromuscular efficiency during prolonged driving. Larger and more diverse studies are needed to confirm these effects, optimize vibration parameters, and evaluate long-term responses across different driver populations and vehicle environments.