Effects Related to Random Whole-Body Vibration and Posture on a Suspended Seatwith and Without Backrest

Hinz, Barbara; Seidel, Helmut; Menzel, Gerhard; Blüthner, Ralph

doi:10.1006/jsvi.2001.4259

Cited by 51 publications

(31 citation statements)

References 12 publications

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“…Recent studies have attempted to categorize the possible mechanisms of injury related to WBV [6][7][8][9][10][11] and develop models that could optimize preventive measures [12][13][14][15]. Although none of these investigators addresses the effects of WBV on wheelchair users, their conclusions may be used to improve wheelchair design and research.…”

Section: Introductionmentioning

confidence: 99%

Curb descent testing of suspension manual wheelchairs

Kwarciak

Cooper²,

Fitzgerald³

2008

JRRD

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Abstract-Manual wheelchair users are subjected to wholebody vibrations (WBV) on a regular basis as they traverse obstacles and uneven surfaces. One way users could protect themselves from secondary injuries related to WBV is by using a suspension manual wheelchair. This study investigated the ability of suspension manual wheelchairs to reduce seat accelerations during curb descents of various heights (5, 10, and 15 cm). Sixteen manual wheelchairs (four suspension, four folding, four rigid, and four rigid titanium) were tested. Suspension wheelchairs transmitted significantly lower peak seat accelerations than folding wheelchairs during the 5 cm curb descents (p = 0.048) and significantly lower frequencyweighted peak seat accelerations during the 5 and 10 cm curb descents (p = 0.03 for both heights). However, when the suspension wheelchair Quickie XTR (Sunrise Medical; Carlsbad, California) was removed from the analysis, the suspension wheelchairs were not significantly different from the nonsuspension wheelchairs. When weight was considered, the suspension wheelchairs had significantly lower peak seat accelerations than the lighter rigid wheelchairs during 5 cm curb descents (p = 0.047). While suspension manual wheelchairs offer some reduction in WBV during curb descents, their limitations should be considered when a wheelchair is selected for everyday use.

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Section: Introductionmentioning

confidence: 99%

Curb descent testing of suspension manual wheelchairs

Kwarciak

Cooper²,

Fitzgerald³

2008

JRRD

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“…According to Gellerstedt (2002), 4,000 control inputs per hour have to be carried out by the operator, due to the lack of automatic functions of the boom and harvester head. Despite the ergonomic design of the cabs, the operators of mobile machinery are exposed mainly to noise (Hansson 1990;Axelsson 1998;Marsili et al 1998;Nieuwenhuis, Lyons 2002;Messingerová et al 2005;Sümer 2006;Beuk et al 2007;Gerasimov, Sokolov 2009;Aybek et al 2010;Bilski 2013), whole-body vibrations (Boileau, Rakheja 1990;Burdorf, Swuste 1993;Magnusson et al 1993;Hansson 1995;Huston et al 1999;Hinz et al 2002;Paddan, Griffin 2002;Hostens, Ramon 2003;Chen et al 2003;Sherwin et al 2004a,b;Deprez et al 2005;Kolich et al 2005;Tiemessen et al 2007;Li et al 2008;Gerasimov, Sokolov 2009), microclimatic conditions -mostly temperature, and airflow velocity inside the cab (Gao, Niu 2004;Kaynakli, Kilic 2005;Huang et al 2006;Mezrhab, Bouzidi 2006;Cengiz, Babalik 2007;Farzaneh, Tootoonchi 2008;Kim et al 2009;Zhang et al 2009a,b;Alahmer et al 2011), and severe mental and sensory load (Axelsson, Pontén 1990;Poschen 1993;…”

mentioning

confidence: 99%

Objective and subjective assessment of selected factors of the work environment of forest harvesters and forwarders

Martin¹,

Messingerová²,

Ferenčík³

et al. 2016

J. For. Sci.

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This article was aimed at assessment of selected factors of the work environment, which influenced the operators of harvesters and forwarders. The selection of the work environment factors was based on a thorough literature survey. From the survey exposure to whole-body vibrations, noise (equivalent and peak), microclimatic conditions and mental load were selected for detailed observations. The measurements were conducted according to international standards and assessed according to European or national legislation. Subjective assessment of the effects of the work environment was conducted through a structured interview. The exposure to whole-body vibrations was 0.5 m·s -2 . The equivalent noise exposure was 78 dB, peak noise exposure was 130 dB. The average temperature inside the machine cabs was 17.9°C and average airflow velocity was 0.06 m·s -2 . Mental load was high according to the Meister questionnaire, three operators considered the load inadequate, two considered it adequate. Subjective assessment showed that operators considered other factors to be light or no load.Keywords: noise exposure; whole-body vibrations; microclimate; mental load Work environment is a set of all conditions in which workers carry out their work. It consists of all workers and factors present at the workplace, or of those who have to do with the work and influence the health or comfort of workers. The worker is exposed to many harmful factors which interact and their joint effect can be synergistic or complementary (Schwartz et al. 2013).Operators of multi-operational machinery carry out their tasks in ergonomically designed cabs capable of partial attenuation of noise and vibrations caused by the machine movement, driving gear, and working parts of the machine. Cabs are also equipped with air conditioning and glare reducing windows. Some factors (e.g. electromagnetic, ionising radiation, various chemical factors, or energy expenditure) do not apply to the jobs of multioperational machinery operators. Their assessment would only consume time with no significant effect on the overall outcome of the assessment. The nature of work in mechanized logging partially shifted from physical to mental after employment of multi-operational machinery. The need for muscular activity decreased and the need to stay concentrated and alert through long periods grew in importance. Harvester operators have to be able to process a lot of information, react quickly, and retain their concentration in monotonous, repetitive operations (Axelsson, Pontén 1990;Poschen 1993;Gellerstedt 1997;Gellestedt et al. 1999;Tsioras 2012). Operating the machines is quite demanding. According to Gellerstedt (2002), 4,000 control inputs per hour have to be carried out by the operator, due to the lack of automatic functions of the boom and harvester head. Despite the ergonomic design of the cabs, the operators of mobile machinery are exposed mainly to noise (Hans-

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“…The disregard of a bent forward posture can cause a significant underestimation of the static internal forces contributing to the health risk 9,20) . The use of the backrest can reduce the load on the spine 15,34) . In general, differences between subjects have been largely neglected, although selection phenomena suggest they may be of major importance.…”

Section: Relationship Associated With Epidemiological Studiesmentioning

confidence: 99%

“…The verification of the human interaction with the seat was done using data from measurements 87) . Hinz et al 15,34) used this model for the prediction of the internal spinal load by considering individual vibration inputs to the buttocks and to the back on a suspended seat. The peak transmissibilities between the accelerations at the seat base and the compressive forces at L5/S1 were highest for the seat without the backrest during a forward bending posture.…”

Section: Relationship Associated With Model Predictionsmentioning

confidence: 99%

“…The WBV-exposure causes an acceleration of the human body with related dynamic forces acting on the spine. The significant effects of posture and backrest contact on the transmissibility of WBV to the head 15) suggest the interaction between the subject and the seat to have an effect on the associated dynamic internal forces. Further dynamic internal forces arise from the muscle response with alternating increased and decreased activity [16][17][18][19] .…”

Section: Introductionmentioning

confidence: 99%

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On the Relationship between Whole-body Vibration Exposure and Spinal Health Risk

Seidel

2005

Ind Health

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A conceptual framework provides the possibility to identify factors determining the effects of whole-body vibration (WBV) on the spine and the internal stress-strain relationships. Epidemiological studies were critically evaluated with respect to their significance for the derivation of quantitative exposure-effect relationships. The approach of deriving such relationships from a comparison with self-generated accelerations during daily activities was considered as unsuited. Trunk muscle activity and control with apparently identical accelerations of body parts during selfgenerated and forced motions differ widely. Simple biodynamic models coupled with experimental in vivo and in vitro data permitted a preliminary deduction of quantitative relationships between WBV and spinal health with the consideration of individual factors and exposure conditions. Examples of anatomy-based verified finite element models and their application are provided. Such models are considered as a very promising instrument. They can be used to assess quantitatively preventive measures and design. Future research needs concern the examination of (1) the nonlinearity of biodynamics, (2) the effects of WBV in x-and y-axes, (3) the strength of the spine for shear, (4) the contact parameters between the seat and man, (5) the significance of postures and muscle activity, and (6) material properties of spinal structures.

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Effects Related to Random Whole-Body Vibration and Posture on a Suspended Seatwith and Without Backrest

Cited by 51 publications

References 12 publications

Curb descent testing of suspension manual wheelchairs

Curb descent testing of suspension manual wheelchairs

Objective and subjective assessment of selected factors of the work environment of forest harvesters and forwarders

On the Relationship between Whole-body Vibration Exposure and Spinal Health Risk

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