Mechanical impedance of the sitting human body in single-axis compared to multi-axis whole-body vibration exposure

Holmlund, P.; Lundström, Ronnie

doi:10.1016/s0268-0033(00)00102-9

Cited by 33 publications

(20 citation statements)

References 4 publications

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“…For whole-body vibration, important contributions have been made by many, including: Fairley 21,22) , Holmlund 18,[23][24][25][26] , Mansfield 16,19,[27][28][29][30][31][32] , Matsumoto 33,34) , Miwa 35) , Nawayseh 36,37) , Rakheja [38][39][40][41][42] , and Smith 43,44) . Although contributions have been made by many individuals, example data presented here will be sourced primarily from the author's own work due to availability of raw data and knowledge of all experimental conditions.…”

Section: Example Impedance Data From the Literaturementioning

confidence: 99%

Impedance Methods (Apparent Mass, Driving Point Mechanical Impedance and Absorbed Power) for Assessment of the Biomechanical Response of the Seated Person to Whole-body Vibration

Mansfield

2005

Ind Health

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Exposure to whole-body vibration is a risk factor for the development of low back pain. In order to develop a fuller understanding of the response of the seated person to vibration, experiments have been conducted in the laboratory investigating the biomechanics of the seated person. Some of these methods are based on the driving force and acceleration at the seat and are reported in the literature as apparent mass, driving point mechanical impedance or absorbed power. This paper introduces the background behind such impedance methods, the theory and application of the methods. It presents example data showing typical responses of the seated human to wholebody vibration in the vertical, fore-and-aft and lateral directions. It also highlights problems that researchers might encounter in performing, analysing and interpreting human impedance data.

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Section: Example Impedance Data From the Literaturementioning

confidence: 99%

Impedance Methods (Apparent Mass, Driving Point Mechanical Impedance and Absorbed Power) for Assessment of the Biomechanical Response of the Seated Person to Whole-body Vibration

Mansfield

2005

Ind Health

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“…Other studies of apparent mass have used sinusoidal vibration as the stimulus. For example, Holmlund and co-workers [12][13][14] measured absorbed power and mechanical impedance (from which apparent mass can be calculated) in the vertical and horizontal directions using sinusoidal vibration over a wide range of frequencies. They also showed a peak in biomechanical response at 4 to 5 Hz with a non-linearity such that the resonance frequency decreased with increased magnitudes of vibration.…”

Section: M(f) = F(f) A(f) Where M(f) Is the Apparent Mass F(f) Is Thmentioning

confidence: 99%

Comparison of the Apparent Mass of the Seated Human Measured Using Random and Sinusoidal Vibration

Mansfield

Maeda

2005

Ind Health

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Exposure to whole-body vibration is generally accepted as being a risk factor for low back pain and therefore exposure to vibration should be minimised. The results of previous laboratory based research investigating the biomechanical response of the seated human to vibration has been used to develop models that can be used within tools that are capable of predicting the response of seats. Several studies in the literature have reported apparent masses of seated human subjects whilst exposed to either random or sinusoidal vibration. Although these studies have shown similar trends, there have been no systematic comparisons of apparent mass for the same subjects exposed to random and sinusoidal vibration. This paper reports a study where twelve male subjects were exposed to random whole-body vibration at 1.0 m/s 2 r.m.s. and to sinusoidal vibration at 1, 2, 4, 8, 16 and 32 Hz. The modulus of the apparent masses were nominally identical when measured using random or sinusoidal vibration. The phase of the apparent masses were similar at 1, 2 and 4 Hz, when measured using random or sinusoidal vibration, but showed consistent differences at 8, 16 and 32 Hz. As the results between experiments using different waveforms are similar, models derived from experimental work based on one type of stimulus could be applied in scenarios involving the other type of stimulus.

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“…Time-and frequency-domain analyses have been performed to understand the relationship between the vibration exposures and effects on human health, comfort, and performance. Techniques for assessing vibration include seat-to-head transmissibility analysis [4,20], apparent mass analysis [17,21], root-mean-square analysis [6], absorbed power analysis [22][23], modal analysis [18], transfer function analysis [3], and mechanical impedance analysis [24][25]. Assessment of seating comfort level is generally predicted with psychophysical techniques that combine subjective measures [26] with stiffness and vibration characteristics [14].…”

Section: Introductionmentioning

confidence: 99%

Effect of rear suspension and speed on seat forces and head accelerations experienced by manual wheelchair riders with spinal cord injury

Requejo

Kerdanyan²,

Minkel³

et al. 2008

JRRD

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Abstract-Whole-body shocks and vibrations experienced during manual wheelchair use can decrease an individual's comfort, increase the rate of fatigue, result in injury, and consequently limit mobility and community participation. We used a wheelchairvibration simulator to examine whether the seat reaction forces experienced by wheelchair users were differentially influenced by wheelchair suspension, trunk-muscle innervations, and ground speed. We used wheelchairs instrumented with load cells and accelerometers to determine the forces transmitted from the seat frame and the head accelerations experienced by riders. We determined that self-selected speed, seat force, and head accelerations differed between subjects with and without trunk-muscle innervations and between rigid and suspension wheelchairs. Seat force and head accelerations were greatest in the rigid-frame wheelchair and lowest in the spring-type suspension-frame wheelchairs. Those participants without trunk-muscle innervations preferred slower speeds than those with trunk-muscle innervations. Forward head accelerations were greater in those without than with trunk-muscle innervations. Wheelchair rear-suspension systems may improve wheelchair mobility function in terms of comfort at higher velocity by minimizing the seat forces and head accelerations experienced by the riders, especially those with higher level spinal cord injury and diminished postural control.

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Mechanical impedance of the sitting human body in single-axis compared to multi-axis whole-body vibration exposure

Cited by 33 publications

References 4 publications

Impedance Methods (Apparent Mass, Driving Point Mechanical Impedance and Absorbed Power) for Assessment of the Biomechanical Response of the Seated Person to Whole-body Vibration

Impedance Methods (Apparent Mass, Driving Point Mechanical Impedance and Absorbed Power) for Assessment of the Biomechanical Response of the Seated Person to Whole-body Vibration

Comparison of the Apparent Mass of the Seated Human Measured Using Random and Sinusoidal Vibration

Effect of rear suspension and speed on seat forces and head accelerations experienced by manual wheelchair riders with spinal cord injury

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