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Back muscle response of seated individuals to single and superimposed sinusoidal, vertical vibration
Abstract   Open access

Back muscle response of seated individuals to single and superimposed sinusoidal, vertical vibration

David G Wilder, Allison Kaigle, Jean‐Guy Beliveau, Dryver Huston, James Fenwick, James Tranowski and Malcolm Pope
The Journal of the Acoustical Society of America, Vol.88(S1), pp.S63-S63
11/1990
DOI: 10.1121/1.2029095
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https://doi.org/10.1121/1.2029095View
Published (Version of record) Open Access

Abstract

Data exist on the erector spinae muscle activity during steady state and random vibration. The purpose of this study was to determine how the muscles responded to vibration between those limits. This was achieved by measuring the surface electromyographic (EMG) muscle response to single and superimposed vibration signals. Subjects were tested at the following single and combined frequencies: 2, 3,…, 10, 2 + 4, 3 + 6, 4 + 8, 5 + 10, 2 + 4 + 6, 3 + 6 + 9, (All) 2 + 3 + … + 10. The EMG activity for the combined signals was evaluated at each single frequency and the ensemble averaged peak‐to‐peak predicted torques computed [Seroussi et al., J. Biomechanics 22(3), 219–229 (1989)]. For the superimposed signals, the torque was significantly greatest at the following frequency evaluation windows (signals used): 4 Hz (2 + 4, 2 + 4 + 6, All); 6 Hz (3 + 6, 3 + 6 + 9); 8 Hz (4 + 8); and 5 Hz = 10 Hz (5 + 10). The natural frequency of the seated subject has been reported in the 4.5‐ to 6‐Hz range. The maximum EMG response for all but two of the seven superimposed signals occurred at a frequency within this range. The results show that the spinal system is frequency sensitive. Thus vibration attenuation may need to accommodate frequencies outside the natural frequency range of the seated driver.

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