Psychophysical scaling of human response to whole-body vertical vibration

Within 30 Hz, the discomfort caused by whole-body vibration in rotational direction is higher than vertical vibration at similar equivalent magnitude. Roll vibration, in particular, produces greater discomfort comparing with pitch and yaw vibrations. It is critical to understand the biodynamic characteristics of seated human body under roll vibration for both comfort assessment and vibration control. Experiments are carried out to obtain the biodynamic response of seated human body under random roll vibrations at four r.m.s. magnitude levels. It is found that the principal resonance in the roll apparent inertia is about 1 Hz, but varied from 0.7 to 1.5 Hz depending on the magnitude of vibration (0.5 to 2.0 rad/s2), and the secondary resonance locates around 3 Hz with a much lower modulus. It is noted that the human response to roll vibration has some features in common with that in the lateral direction. Two lumped parameter models are developed and calibrated to study the correlation between the two excitation axials. The equivalent relationships of magnitude and phase between roll and lateral vibrations are obtained on condition that they produce similar rotational responses of the upper human body. It suggests an equivalence approach between translational and rotational vibrations that can benefit the comfort assessment when exposed to multiaxial excitations.

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A MODAL ANALYSIS OF WHOLE-BODY VERTICAL VIBRATION, USING A FINITE ELEMENT MODEL OF THE HUMAN BODY

Journal of Sound and Vibration ◽

10.1006/jsvi.1996.0674 ◽

1997 ◽

Vol 200 (1) ◽

pp. 83-103 ◽

Cited By ~ 127

Author(s):

S. Kitazaki ◽

M.J. Griffin

Keyword(s):

Finite Element ◽

Finite Element Model ◽

Modal Analysis ◽

Human Body ◽

Element Model ◽

Vertical Vibration ◽

Whole Body

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HUMAN RESPONSE TO VERTICAL VIBRATION

10.4271/460038 ◽

1946 ◽

Cited By ~ 1

Author(s):

Stanley Lippert

Keyword(s):

Vertical Vibration ◽

Human Response

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Physiological Responses and Subjective Discomfort of Simulated Whole-Body Vibration from a Mobile Underground Mining Machine

Proceedings of the Human Factors Society Annual Meeting ◽

10.1518/107118188786762559 ◽

1988 ◽

Vol 32 (11) ◽

pp. 719-723 ◽

Cited By ~ 1

Author(s):

Thomas G. Bobick ◽

Richard L. Unger ◽

Sean Gallagher ◽

Diane M. Doyle-Coombs

Keyword(s):

Underground Mining ◽

Whole Body Vibration ◽

Vertical Vibration ◽

Whole Body ◽

Mining Machine ◽

Body Vibration ◽

Vibration Data ◽

Computer Controlled ◽

Selected Effects ◽

Subjective Discomfort

The U.S. Bureau of Mines has developed an in-house facility to evaluate selected effects of whole-body vibration (WBV) levels experienced by underground mobile equipment operators. Vertical vibration data were collected from a coal haulage vehicle via a uniaxial accelerometer attached to the machine frame under the operator's seat. Data were analyzed and processed so a computer-controlled platform could approximate the vibration signals. Eight men (35.5 yr ± 6.5 SD) participated in a pilot study to evaluate the effects of shock and WBV on heart rate (HR), blood pressure (BP), and subjective discomfort. Subjects were exposed to vibration for 30-min periods while seated in a typical seat (backrest angle at 90° or 130°) that was plain steel or modified with 2 in foam padding. Subjects repeated the same protocol on a separate day, without the vibration. Results indicated the vibration significantly increased the HR (p < 0.01), systolic BP, mean BP, the number of times subjects reported discomfort, and overall subjective discomfort rating (p < 0.05). When seated in the steel seat, the overall discomfort rating (p < 0.001) and the number of times discomfort was reported (p < 0.05) increased significantly. Seatback angle had no significant effect on any of the dependent measures.

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Comparison of the Apparent Mass during Exposure to Whole-Body Vertical Vibration between Japanese Subjects and ISO 5982 Standard

Industrial Health ◽

10.2486/indhealth.43.436 ◽

2005 ◽

Vol 43 (3) ◽

pp. 436-440 ◽

Cited By ~ 10

Author(s):

Setsuo MAEDA ◽

Neil J. MANSFIELD

Keyword(s):

Vertical Vibration ◽

Whole Body ◽

Apparent Mass ◽

Japanese Subjects

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Low-magnitude vertical vibration enhances myotube formation in C2C12 myoblasts

Journal of Applied Physiology ◽

10.1152/japplphysiol.00115.2010 ◽

2010 ◽

Vol 109 (3) ◽

pp. 840-848 ◽

Cited By ~ 20

Author(s):

Chau-Zen Wang ◽

Gwo-Jaw Wang ◽

Mei-Ling Ho ◽

Yan-Hsiung Wang ◽

Ming-Long Yeh ◽

...

Keyword(s):

Molecular Mechanisms ◽

Type I Collagen ◽

Vertical Vibration ◽

Whole Body ◽

Type I ◽

Dependent Manner ◽

C2c12 Myoblasts ◽

Myotube Formation ◽

Ecm Proteins ◽

Whole Body Vibration Training

Whole body vibration training is widely used in rehabilitation and sports activities to improve muscle strength, balance, and flexibility. However, the molecular mechanisms of vertical vibration (VV) training and their effect on the myogenesis of myoblasts remain undefined. This study was undertaken to address the hypothesis that VV can enhance the expression of ECM proteins and myogenic regulatory factors (MRFs) in myoblasts and, in turn, increase myotube formation. Using real-time PCR, Western blot analysis, and immunofluorescence studies, we examined the effect of VV treatment with frequencies of 5, 8, or 10 Hz on the expression of ECM proteins and MRFs as well as myotube formation in C2C12 myoblasts. We showed that VV stimulation is safe and effective at stimulating myogenesis in C2C12 myoblasts. The levels of expression of the ECM proteins type I collagen and decorin were the highest after VV treatment at frequencies of 8 and 10 Hz. Expression of the MRFs MyoD and myogenin increased after VV stimulation in a time- and dose-dependent manner. The total number of myotubes formed, as well as the length and the average area of myotubes, were substantially increased following VV treatment at frequencies of 8 to 10 Hz. In conclusion, VV treatment at frequencies of 8 to 10 Hz can stimulate the expression of ECM proteins and MRFs in myoblasts and, in turn, increase myotube formation.

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