An experimental study on the neurological effects of hand-arm vibration: considering vibration frequency, ambient temperature, and wrist posture

Hand–arm vibration (HAV) is an occupational hazard associated with neurological and sensory disturbances. This study investigated the effects of vibration frequency, ambient temperature, and wrist posture on tactile sensory threshold and motor nerve conduction velocity (MNCV) following hand-transmitted vibration exposure. In this within-subject study, 25 construction workers completed 12 scenarios combining 10 m/s² acceleration, two vibration frequencies (31.5 and 63 Hz), two ambient temperatures (5 and 25 °C), and three wrist postures (neutral, flexion, and extension). Each scenario involved 30 min of exposure using a hand–arm vibration simulator. Median nerve MNCV was measured before and after exposure, and tactile sensory threshold was assessed using monofilament testing. Changes were analyzed using linear mixed models. All scenarios produced reduced MNCV and increased tactile threshold. The greatest MNCV reduction occurred at 31.5 Hz, 5 °C, and wrist flexion (− 2.780 ± 0.465 m/s), whereas the largest increase in tactile threshold occurred at 63 Hz, 5 °C, with wrist flexion or extension (0.533 ± 0.467 g). For tactile sensory threshold, significant main effects were observed for vibration frequency ( p < 0.001), ambient temperature ( p < 0.001), and wrist posture ( p = 0.010). For MNCV, significant main effects were also found for frequency, temperature, and wrist posture (all p < 0.001). No significant two-way or three-way interactions were observed for either outcome. Temperature had the largest effect on tactile threshold (ηp² = 0.307), while frequency had the largest effect on MNCV (ηp² = 0.606). These findings highlight the importance of vibration frequency, ambient temperature, and wrist posture in HAV risk assessment.