Apparent mass of the human body in the vertical direction: Inter-subject variability
Apparent mass of the human body in the vertical direction: Inter-subject variability
The biodynamic responses of the seated human body to whole-body vibration vary considerably between people, but the reasons for the variability are not well understood. This study was designed to determine how the physical characteristics of people affect their apparent mass and whether inter-subject variability is influenced by the magnitude of vibration and the support of a seat backrest. The vertical apparent masses of 80 seated adults (41 males and 39 females aged 18–65) were measured at frequencies between 0.6 and 20 Hz with four backrest conditions (no backrest, upright rigid backrest, reclined rigid backrest, reclined foam backrest) and with three magnitudes of random vibration (0.5, 1.0 and 1.5 m s-2 rms). Relationships between subject physical characteristics (age, gender, weight, and anthropometry) and subject apparent mass were investigated with multiple regression models. The strongest predictor of the modulus of the vertical apparent mass at 0.6 Hz, at resonance, and at 12 Hz was body weight, with other factors having only a marginal effect. After correction for other variables, the principal resonance frequency was most consistently associated with age and body mass index. As age increased from 18 to 65 years, the resonance frequency increased by up to 1.7 Hz, and when the body mass index was increased from 18 to 34 kg m?2 the resonance frequency decreased by up to 1.7 Hz. These changes were greater than the 0.9-Hz increase in resonance frequency between sitting without a backrest and sitting with a reclined rigid backrest, and greater than the 1.0-Hz reduction in resonance frequency when the magnitude of vibration increased from 0.5 to 1.5 m s?2 rms. It is concluded that the effects of age, body mass index, posture, vibration magnitude, and weight should be taken into account when defining the vertical apparent mass of the seated human body.
827-841
Toward, Martin G.R.
1d10e993-e6ef-449d-bccb-1f8198169bee
Griffin, Michael J.
24112494-9774-40cb-91b7-5b4afe3c41b8
14 February 2011
Toward, Martin G.R.
1d10e993-e6ef-449d-bccb-1f8198169bee
Griffin, Michael J.
24112494-9774-40cb-91b7-5b4afe3c41b8
Toward, Martin G.R. and Griffin, Michael J.
(2011)
Apparent mass of the human body in the vertical direction: Inter-subject variability.
Journal of Sound and Vibration, 330 (4), .
(doi:10.1016/j.jsv.2010.08.041).
Abstract
The biodynamic responses of the seated human body to whole-body vibration vary considerably between people, but the reasons for the variability are not well understood. This study was designed to determine how the physical characteristics of people affect their apparent mass and whether inter-subject variability is influenced by the magnitude of vibration and the support of a seat backrest. The vertical apparent masses of 80 seated adults (41 males and 39 females aged 18–65) were measured at frequencies between 0.6 and 20 Hz with four backrest conditions (no backrest, upright rigid backrest, reclined rigid backrest, reclined foam backrest) and with three magnitudes of random vibration (0.5, 1.0 and 1.5 m s-2 rms). Relationships between subject physical characteristics (age, gender, weight, and anthropometry) and subject apparent mass were investigated with multiple regression models. The strongest predictor of the modulus of the vertical apparent mass at 0.6 Hz, at resonance, and at 12 Hz was body weight, with other factors having only a marginal effect. After correction for other variables, the principal resonance frequency was most consistently associated with age and body mass index. As age increased from 18 to 65 years, the resonance frequency increased by up to 1.7 Hz, and when the body mass index was increased from 18 to 34 kg m?2 the resonance frequency decreased by up to 1.7 Hz. These changes were greater than the 0.9-Hz increase in resonance frequency between sitting without a backrest and sitting with a reclined rigid backrest, and greater than the 1.0-Hz reduction in resonance frequency when the magnitude of vibration increased from 0.5 to 1.5 m s?2 rms. It is concluded that the effects of age, body mass index, posture, vibration magnitude, and weight should be taken into account when defining the vertical apparent mass of the seated human body.
Text
14678 MGRT-MJG 2011 Inter-subject_variability_in_vertical_apparent_mass
- Accepted Manuscript
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Published date: 14 February 2011
Organisations:
Human Sciences Group, Institute of Sound & Vibration Research
Identifiers
Local EPrints ID: 354923
URI: http://eprints.soton.ac.uk/id/eprint/354923
ISSN: 0022-460X
PURE UUID: 11a5768b-ee4c-4c61-8fab-b65a87320422
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Date deposited: 23 Jul 2013 08:55
Last modified: 15 Mar 2024 03:07
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Author:
Martin G.R. Toward
Author:
Michael J. Griffin
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