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Effect of non-neutral seated postures on whole-body vibration measurements
Journal article   Peer reviewed

Effect of non-neutral seated postures on whole-body vibration measurements

Salam Rahmatalla, Jonathan DeShaw, Yash Kumar Dhabi, Brian Fiegel, Elizabeth M Ritchie, Tyler Guzowski, Geb Thomas, David G Wilder and Nathan B Fethke
Applied ergonomics, Vol.138, 104868
08/07/2026
DOI: 10.1016/j.apergo.2026.104868
PMID: 42566806

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Abstract

ISO 2631-1 generally treats frequency-weighted acceleration measured at the seat-occupant interface as independent of operator posture, yet this assumption has rarely been examined explicitly. This study evaluates that assumption. Twenty-four participants were exposed to three-dimensional whole-body vibration on a machine operator seat while maintaining forward lean, reclined, and twisted postures. Despite constant base excitation vibrations, the seat-interface frequency-weighted RMS acceleration (FWRMS) differed significantly across postures (F = 0.871, R = 0.765, T = 0.845 m/s ; p < 0.001), with posture explaining 78% of variance. A sandbag surrogate experiment confirmed that body-weight redistribution alone, without neuromuscular involvement, produced an approximately 13% variation in FWRMS, linking postural load shift to altered seat suspension dynamics. When propagated through ISO 2631-1 exposure equations, this corresponds to an approximately 27% difference in allowable daily exposure duration. These findings highlight the need to incorporate posture into whole-body vibration standard 2631-1 and occupational vibration risk assessment.
Measurement Discomfort Whole-body vibration Body-weight shift Health Posture

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