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Occupational whole-body vibration and low back pain : strategies to reduce exposure
Tiemessen, I.J.H.
Publication date 2008
Document Version Final published version
Link to publication
Citation for published version (APA):
Tiemessen, I. J. H. (2008). Occupational whole-body vibration and low back pain : strategies to reduce exposure.
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Download date:06 Oct 2022
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Chapter 1
________________________________________________________________________ 10 External load
(WBV) exposure - Magnitude - Duration
Internal load (‘strain’)
-Physiological effects (non-specific) -Biomechanical effects (frequency-dependent)
Effects on lumbar spine Acute:
- Muscle fatigue - LBP
Permanent/recurrent:
- LBP
- Acceleration of degenerative process of vertebral column - Herniated lumbar disc - Individual susceptibility
-Individual risk factors -Work-related risk factors -Psychosocial risk factors
Behavioural change
Attitude (A)
Social Influence (S)
Self -Efficacy (E)
Knowledge
- Education and individual health surveillance Motivation
- Intention to change
behavioural change are that: (1) the expected effects will be long-lasting (2) possible WBV exposure reduction can be realised without high costs (3) the employers have a specific role in changing their behaviour and the behaviour of their drivers as well (4) it will provide in an active approach towards implementing preventative measures. Actively implementing preventative measures is an important facet of the success of an intervention programme.28
Model 1: The interaction between WBV (exposure) and LBP and behavioural changes
1.2.1. WBV exposure assessment
WBV exposure is a product of the WBV magnitude and WBV duration (the time the driver is operating the vehicle). This WBV exposure can be expressed in different daily and cumulative dose measures. The daily dose measures represent exposure on an average working day (eight hours), while the cumulative dose measures represent the lifetime WBV exposure. An example of a daily dose measure is the action value or exposure limit
formulated in the EU-directive (the current root mean square (r.m.s.) value based on an eight- hour working day). An example of a cumulative dose measure is the lifetime total hours of exposure to WBV. The dose measures will be calculated by both the calculation of the r.m.s.
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SJTLGBDUPST PUIFSUIBOĨēħFYQPTVSFDPNQBSFEXJUIBTTFTTJOHUIFTFXPSLSFMBUFESJTL
GBDUPSTCZNFBOTPGTFMGBENJOJTUFSFERVFTUJPOOBJSFT
P "SFESJWFSTXIPBSFFYQPTFEUPIJHIMFWFMTPGĨēħNPSFBUSJTLPGEFWFMPQJOHĝēġUIBO
ESJWFSTXIPBSFMFTTFYQPTFE
P 8IBU FĊFDUJWF QSFWFOUBUJWF TUSBUFHJFT JO UIF MJUFSBUVSF BSF LOPXO UP SFEVDF Ĩēħ
FYQPTVSF
P *TUIFJNQMFNFOUBUJPOPGB OFXEFWFMPQFEJOUFSWFOUJPOQSPHSBNNFBJNJOHUPSFEVDF
UIFĨēħFYQPTVSFFĊFDUJWF
0VUMJOFPGUIFUIFTJT
$IBQUFSTIPXTUIFSFTVMUTPGBNFUIPEPMPHJDBMTUVEZJOXIJDIĨēħFYQPTVSFJTBTTFTTFE
TJNVMUBOFPVTMZ XJUI UIF BTTFTTNFOU PG PUIFS QIZTJDBM XPSL EFNBOET $IBQUFST USJFT UP mOE
BEEJUJPOBMFWJEFODFGPSUIFSFMBUJPOCFUXFFOĨēħFYQPTVSFBOEĝēġCZFNQIBTJ[JOHBQPTTJCMF
EPTF SFTQPOTF SFMBUJPOTIJQ CFUXFFO Ĩēħ FYQPTVSF BOE EJĊFSFOU ĝēġ PVUDPNFT NFBTVSFT ɨF
GPMMPXJOHUXPDIBQUFST DIBQUFSBOEDIBQUFSGPDVTPOUIFEFWFMPQNFOUBOEFWBMVBUJPOPGBO
JOUFSWFOUJPOQSPHSBNBJNJOHPOBSFEVDUJPOPGFYQPTVSFUPĨēħ$IBQUFSSFWJFXTUIFMJUFSBUVSF
POTUSBUFHJFTUPSFEVDFFYQPTVSFJOĨēħTJUVBUJPOTɨJTXJMMSFWFBMFWJEFODFCBTFETUSBUFHJFTBOE
NBKPSEFUFSNJOBOUTPGĨēħFYQPTVSFJOPSEFSUPEFWFMPQBOFXJOUFSWFOUJPOQSPHSBNNF XIJDI
XJMMCFEFTDSJCFEJO$IBQUFS'JOBMMZ UIFJNQMFNFOUBUJPOBOEFWBMVBUJPOPGUIJTJOUFSWFOUJPO
QSPHSBNNFBSFEFTDSJCFEJO$IBQUFSɨFDPODMVEJOH$IBQUFSDPOUBJOTBHFOFSBMEJTDVTTJPO
POUIFNBJODPODMVTJPOTPGUIFEJĊFSFOUTUVEJFT4PNFNFUIPEPMPHJDBMQSPCMFNTBSFEJTDVTTFE
BOESFDPNNFOEBUJPOTGPSGVUVSFSFTFBSDIBSFQSFTFOUFE
#HAPTER
#HAPTER
4WO PHYSICAL MEASURING VIBRATION
*OURNAL
5XPXBZBTTFTTNFOUPGPUIFSQIZTJDBMXPSLEFNBOETXIJMFNFBTVSJOHUIFXIPMFCPEZ
WJCSBUJPONBHOJUVEF
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%JSFDUPCTFSWBUJPO JOTUFBEPGVTJOHTFMGBENJOJTUFSFERVFTUJPOOBJSFTNJHIUHJWFNPSF
SFMJBCMFBOETQFDJmDJOGPSNBUJPOBCPVUQIZTJDBMXPSLEFNBOETBUUIFXPSLQMBDFɨJTJOGPSNBUJPO
JTPGVTFJOBQPQVMBUJPOBMSFBEZBUSJTLPGEFWFMPQJOHMPXCBDLQBJO ĝēġEVFUPXIPMFCPEZ
WJCSBUJPO ĨēħFYQPTVSFɨFBJNTPGUIJTTUVEZBSFUPBTTFTTUIFĨēħFYQPTVSFJOBOFYQPTFE
QPQVMBUJPOBOEUPBTTFTTPUIFSQIZTJDBMXPSLEFNBOETJOUXPXBZT CZEJSFDUPCTFSWBUJPOBOE
XJUIUIFVTFPGBTFMGBENJOJTUFSFERVFTUJPOOBJSF8FUIFSFGPSFBTTFTTFEUIFĨēħNBHOJUVEFBOE
ĨēħSFMBUFE QIZTJDBM XPSL EFNBOET CZ VTJOH UIF 1BMN5SBD TZTUFN BOE B TFMGBENJOJTUFSFE
RVFTUJPOOBJSF JO B HSPVQ PG ESJWFST / ɨF NBJO mOEJOHT BSF PVU PG UFO ESJWFST BSF
FYDFFEJOH UIF ĖĦ BDUJPO WBMVF PG UIF ESJWFST VOEFSFTUJNBUFE UIF UJNF ACFOEJOH
UIF UJNF AXBMLJOH TUBOEJOH BOE PWFSFTUJNBUFE UIF UJNF XIFO AMJGUJOH8F DPODMVEFE
UIBU ESJWFST GSPN UIJT HSPVQ BSF BU SJTL PG EFWFMPQJOH ĝēġ BOE TVCTUBOUJBM EJĊFSFODFT FYJTUT
GPS UIF QIZTJDBM XPSL EFNBOET DPNQBSJOH UIF 1BMN5SBD NFUIPE XJUI UIF RVFTUJPOOBJSF
%JSFDUPCTFSWBUJPOBMBTTFTTNFOUJOĨēħNFBTVSFNFOUTZJFMEFYUSBJOGPSNBUJPOɨJTJTVTFGVMGPS
QSFWFOUJWFBDUJWJUJFTOFDFTTBSZBTESJWFSTBSFFYDFFEJOHUIFĖĦBDUJPOWBMVF
,FZ XPSET QIZTJDBM XPSL EFNBOET XIPMF CPEZ WJCSBUJPO BTTFTTNFOU PCTFSWBUJPO TFMG
BENJOJTUFSFERVFTUJPOOBJSF
*OUSPEVDUJPO
*OXFTUFSODPVOUSJFT BOFTUJNBUFEGPVSUPTFWFOQFSDFOUPGBMMFNQMPZFFTBSFFYQPTFEUP
QPUFOUJBMMZIBSNGVMXIPMFCPEZWJCSBUJPO Ĩēħ 4FWFSBMTZTUFNBUJDPSDSJUJDBMSFWJFXTDPODMVEF
UIBUUIFSFJTTUSPOHFQJEFNJPMPHJDBMFWJEFODFGPSBSFMBUJPOTIJQCFUXFFOPDDVQBUJPOBMFYQPTVSFUP
Ĩēħ MPXCBDLQBJO ĝēġBOECBDLEJTPSEFST#PWFO[JBOE)VMTIPGQFSGPSNFEBNFUBBOBMZTJT
PG NFUIPEPMPHJDBMMZ TPVOE TUVEJFT BOE DBMDVMBUFE BO PEET SBUJP PG $* GPS
ĝēġJOBOFYQPTFEQPQVMBUJPOUPĨēħ BTDPNQBSFEUPBOVOFYQPTFEQPQVMBUJPO"NPSFSFDFOU
DSPTTTFDUJPOBMTUVEZGSPN#PWFO[JFUBMTIPXTBOPEETSBUJPPG GPSĝēġGPSBMPX
FYQPTVSF NFBO NTQPQVMBUJPOJODPNQBSJTPOUPBOVOFYQPTFEDPOUSPMHSPVQɨFPEET
SBUJPGPSUIFIJHIFYQPTVSFQPQVMBUJPO NFBONT
*O TFWFSBM &VSPQFBO DPVOUSJFT JU XBT EFDJEFE UP SFDPHOJ[F BOE DPNQFOTBUF ĝēġ BOE
DFSUBJOTQJOBMEJTPSEFSTBTĨēħSFMBUFEPDDVQBUJPOBMEJTFBTFT BTMPOHBTUIFZNFFUDFSUBJODSJUFSJB
"GUFS NBOZ ZFBST PG EFCBUF BOE QSFQBSBUJPO B OFX &VSPQFBO %JSFDUJWF PO UIF QSPUFDUJPO PG
XPSLFSTBHBJOTUUIFSJTLTPGWJCSBUJPOXBTQVCMJTIFEJOBOEJNQMFNFOUFEJOUIFOBUJPOBM
#HAPTER
MFHJTMBUJPOPGUIFĖĦNFNCFSTUBUFTJOɨJT%JSFDUJWFFTUBCMJTIFTNJOJNVNSFRVJSFNFOUT
GPSUIFQSPUFDUJPOPGXPSLFSTGSPNSJTLTUPUIFJSIFBMUIBOETBGFUZUIBUBSJTFGSPNFYQPTVSFUP
NFDIBOJDBMWJCSBUJPOɨF%JSFDUJWFTQFDJmFTTFWFSBMPCMJHBUJPOTGPSFNQMPZFSTUIFEFUFSNJOBUJPO
BOEBTTFTTNFOUPGSJTLT UIFBEPQUJPOPGNFBTVSFTGPSBWPJEJOHPSSFEVDJOHFYQPTVSF BOEUIF
QSPWJTJPOPGXPSLFSJOGPSNBUJPOBOEUSBJOJOH"DUJPOWBMVFTBOEFYQPTVSFMJNJUTXFSFGPSNVMBUFE
JOUIJTSFHBSEɨFTFWBMVFT XIJDIBSFCBTFEPOBSFHVMBSFJHIUIPVSXPSLJOHEBZ BSFNTBOE
NT SFTQFDUJWFMZ JOUIFEPNJOBOUBYJT*OBEEJUJPOUPUIJT BQQSPQSJBUFIFBMUITVSWFJMMBODF
GPSFYQPTFEXPSLFSTJTPCMJHFE
*OMJOFXJUIUIJT&VSPQFBO%JSFDUJWF BNVMUJDFOUSFQSPKFDUPOUIFSJTLTPGPDDVQBUJPOBM
WJCSBUJPO JOKVSJFT ħĚēģĚĤĜĤ XBT DPOEVDUFE XJUI mOBODJOH GSPN UIF &VSPQFBO $PNNJTTJPO
ɨFUISFFPCKFDUJWFTPGUIJT&VSPQFBONVMUJDFOUSFTUVEZBSFUPJNQSPWF LOPXMFEHFPGUIF
FYQPTVSFSFTQPOTF SFMBUJPOTIJQ CFUXFFO Ĩēħ BOE UIF EFWFMPQNFOU PS SFDVSSFODF PG EJTPSEFST VOEFSTUBOEJOH PG UIF GBDUPST UIBU UPHFUIFS DPOUSJCVUF UP UIF EFWFMPQNFOU PS QSPHSFTTJPO
VOEFSTUBOEJOHPGUIFCFOFmUTPGIFBMUITVSWFJMMBODFBOEPUIFSJOUFSWFOUJPONFBTVSFTɨFSFTVMUT
PGUIJTQBQFSBSFSFMBUFEUPPCKFDUJWF
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JOUIJTTUVEZEFmOFEBTUIFNBJOUBTLT BDUJWJUJFT XJUIJOBDUJWJUJFTBOEQPTUVSFTXIJMFBUXPSL
4JUUJOHJOBDPOTUSBJOFEQPTUVSFPSQFSGPSNJOHNBOVBMNBUFSJBMIBOEMJOHUBTLT GPSJOTUBODF BSF
BTTPDJBUFEXJUIBIJHIFSSJTLPGĝēġ*OTFWFSBMTUVEJFT POUIFSFMBUJPOTIJQCFUXFFOFYQPTVSF
UPĨēħBOEĝēġ BEKVTUNFOUGPSUIFTFDPOUSJCVUJOHQIZTJDBMXPSLEFNBOETXBTNBEF"MUIPVHI
TFMGBENJOJTUFSFERVFTUJPOOBJSFTBSFUIFVTVBMNFUIPEPGHBUIFSJOHJOGPSNBUJPOBCPVUQIZTJDBM
XPSLEFNBOET QSFWJPVTSFTFBSDIIBTDPODMVEFEUIBUUIFVTFPGRVFTUJPOOBJSFTUPBTTFTTUIF
QIZTJDBMXPSLEFNBOETEPFTOPUBMXBZTZJFMESFMJBCMFSFTVMUT)BOTTPOFUBMTVHHFTUFEUIBUEJSFDU
PCTFSWBUJPOBMUFDIOJDBMNFBTVSFNFOUTNJHIUCFQSFGFSBCMF
4FWFSBM PCTFSWBUJPOBM NFUIPET IBWF CFFO EFWFMPQFE GPS BOBMZTJOH QIZTJDBM XPSL
EFNBOETBUUIFXPSLQMBDF0OFPGUIFTFNFUIPETJTUIF1BMN5SBD 5BTL3FDPSEJOHBOE"OBMZTJT
PO$PNQVUFSTZTUFN1BMN5SBDJTBSFMJBCMF WBMJEPCTFSWBUJPOBMNFUIPEGPSBTTFTTJOHQIZTJDBM
XPSL EFNBOET ɨF TUVEJFT GSPN %PVXFT %VMM BOE GSPN -PP[F FU BM TIPXFE UIBU
UIFWBMJEJUZPGWJTVBMPCTFSWBUJPOJTEFQFOEFOUPOUIFEZOBNJDDIBSBDUFSJTUJDTPGUIFXPSL"
QSFWJPVTTUVEZCZWBOEFS#FFLFUBMEFUFSNJOFEUIFJOUFSPCTFSWFSSFMJBCJMJUZPGUIF1BMN5SBD
TZTUFN ɨF JOUFSPCTFSWFS SFMJBCJMJUZ BT NFBTVSFE CZ UIF QFSDFOUBHF PG BHSFFNFOU PG WBSJPVT
PCTFSWBUJPOTWBSJFECFUXFFOBOE EFQFOEJOHPOUIFCPEZSFHJPOUIBUXBTPCTFSWFE5P
PVSLOPXMFEHF OPQSFWJPVTTUVEJFTIBWFSFQPSUFEPOUIFTJNVMUBOFPVTNFBTVSFNFOUPGĨēħJO
mFMEQSBDUJDFTBOEUIFBTTFTTNFOUPGPUIFSQIZTJDBMXPSLEFNBOETCZBOPCTFSWBUJPOBMNFUIPE
ɨFBJNTPGUIJTTUVEZBSFUPBTTFTTUIFĨēħFYQPTVSFJOBOFYQPTFEQPQVMBUJPOBOEUP
BTTFTTPUIFSQIZTJDBMXPSLEFNBOETJOUXPXBZT CZEJSFDUPCTFSWBUJPOBOEXJUIUIFVTFPGBTFMG
#HAPTER
BENJOJTUFSFERVFTUJPOOBJSF*UJTIZQPUIFTJ[FEUIBUUIJTEJSFDUPCTFSWBUJPOBMNFUIPEUPHFUIFSXJUI
ĨēħNFBTVSFNFOUTVOEFSBDUVBMXPSLJOHDJSDVNTUBODFTZJFMETNPSFSFMJBCMFJOGPSNBUJPOBCPVU
UIFTFQIZTJDBMXPSLEFNBOETUIBOXIFOVTJOHUIFTFMGBENJOJTUFSFERVFTUJPOOBJSFPOMZ
.FUIPET 1PQVMBUJPO
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GSPNUIFQPQVMBUJPOPGUIFQSFWJPVTMZNFOUJPOFEħĚēģĚĤĜĤTUVEZɨFTFUFOESJWFSTXFSFTFMFDUFE
CFDBVTFPGUISFFSFBTPOT'JSTU XFFYQFDUFEEJĊFSFODFTJOUIFMFWFMPGĨēħFYQPTVSFNBHOJUVEF
XJUIJOUIJTHSPVQPGESJWFST4FDPOE XFFYQFDUFEEJĊFSFODFTUIFUPUBMUJNFPGFYQPTVSFUPQIZTJDBM
XPSLEFNBOETXJUIJOUIJTHSPVQPGESJWFST"OEUIJSE UIJTHSPVQPGESJWFSTBSFFYQPTFEUPĨēħ
GPSBUMFBTUGPSUZIPVSTBXFFLɨFESJWFSTUIBUXFSFJODMVEFEJOUIJTTUVEZXPSLFEGPSTFWFO
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UIFJOUFSOBUJPOBMĚĤĠTUBOEBSEĨēħXBTNFBTVSFEBUUIFESJWFSTFBUJOUFSGBDFVTJOHB
USJBYJBMTFBUBDDFMFSPNFUFS JODMVEJOHĕĚğNJDSPEPU$BCMFĨĝɨFBYJTSFDPSEFETJHOBMT
XFSF BNQMJmFE DPOWFSUFE UP WPMUBHF BOE mMUFSFE XJUI UZQF #SǂFM ,KBFS DIBOOFM
IVNBOWJCSBUJPOGSPOUFOE XJUIPOFDIBOOFMDPOOFDUFEUPB*PCTFSWFSNPEVMBSQSFDJTJPO
Y
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1IZTJDBMXPSLEFNBOET
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JO UIJT TUVEZ XFSF BTTFTTFE JO UXP EJĊFSFOU XBZT XJUI B TFMGBENJOJTUFSFE RVFTUJPOOBJSF
EFWFMPQFECZ-VOETUSÚNFUBMBOE XJUIUIF1BMN5SBDTZTUFN<>EVSJOHPCTFSWBUJPOBUUIF
XPSLQMBDF
1BMN5SBDTZTUFN
ɨF 1BMN5SBD TZTUFN JT BO JOFYQFOTJWF FBTZ UP MFBSO BOE RVJDL UP VTF EJSFDU
PCTFSWBUJPOBMNFUIPEɨF5SBDPCTFSWBUJPOBMNFUIPEXBTPSJHJOBMMZEFWFMPQFEBUUIF3PCFOT
*OTUJUVUF 6OJWFSTJUZ PG 4VSSFZ 6, BOE GVSUIFS BEBQUFE CZ UIF 4UVEZ $FOUSF PO 8PSL BOE
)FBMUI&3(0DBSF "DBEFNJD .FEJDBM $FOUSF 6OJWFSTJUZ PG "NTUFSEBN 7SJKF 6OJWFSTJUFJU
"NTUFSEBN UIF/FUIFSMBOET
#HAPTER
ɨFĥģĒĔTZTUFNXBTDPOWFSUFEUP1BMN5SBDCZUIF$PSPOFM*OTUJUVUFGPS0DDVQBUJPOBM
BOE &OWJSPONFOUBM )FBMUI ĒĞĔ "NTUFSEBN JO DPPQFSBUJPO XJUI ĖĩġSFT 7SJKF 6OJWFSTJUFJU
OFXNPSFVTFSGSJFOEMZġĕĒDPNQVUFS BTPQQPTFEUPUIF1TJPO0SHBOJ[FSQPDLFUDPNQVUFSBOE
1BMN5SBD
'JHVSFTIPXTUIFWBSJPVTGFBUVSFTPGUIF1BMN5SBDTZTUFN4UFQJOWPMWFTPCTFSWBUJPO
PGUIFQPQVMBUJPOPGJOUFSFTUBUUIFXPSLQMBDF VTJOHBWJEFPDBNFSBɨFUBTLT BDUJWJUJFT XJUIJO
BDUJWJUJFT QPTUVSFTBOEFYUSBJOGPSNBUJPOPGUIFNPTUJNQPSUBOU SFQSFTFOUBUJWFXPSLDZDMFTTIPVME
CFBTTFTTFEEVSJOHUIJTPCTFSWBUJPO BMPOHXJUIUIFJSSFQFUJUJPOT4UFQESBXTPOUIFBOBMZTJTPG
UIFWJEFPUPBSSBOHFUIFUBTLT BDUJWJUJFT XJUIJOBDUJWJUJFT QPTUVSFTBOEFYUSBJOGPSNBUJPOJOUP
BUSFFEJBHSBN UIFMJCSBSZɨFBDDVSBUFEFmOJUJPOPGFBDIPGUIFTFFMFNFOUTJTBOJNQPSUBOU
BTQFDUPGUIFDSFBUJPOPGUIJTMJCSBSZɨFFMFNFOUTBSFIJFSBSDIJDBMMZTUSVDUVSFEJOCMPDLT mSTU
CMPDLXJMMCFUIFEFTDSJQUJPOPGUIFUBTLJUTFMG GPSJOTUBODFMBOENPXJOH UIFTFDPOECMPDLXJMM
CFBEFTDSJQUJPOPGUIFBDUJWJUJFTEVSJOHMBOENPXJOH GPSJOTUBODFTJUUJOH XBMLJOH BOESVOOJOH
ɨFSECMPDLXJMMCFXJUIJOBDUJWJUJFT GPSJOTUBODFXJUIXBMLJOHPOFDBOBDUVBMMZCFQVTIJOHPS
MJGUJOHXFJHIUTɨFUICMPDLEFTDSJCFTXIJDICPEZQPTUVSFTUIFXJUIJOBDUJWJUJFTXJUIIFME GPS
JOTUBODFXIJMFXBMLJOHBOEQVTIJOHPOFTSPUBUJOHIJTIJQTEFHSFFT#MPDLHJWFTVTFYUSB
JOGPBCPVUUIFXFJHIUPGUIFPCKFDUXIJDIJTCFJOHQVTIFEBOECMPDLJTBOJOEJDBUJPOBCPVUUIF
EVSBUJPOPGUIFBDUJWJUZBOEUIFXJUIJOBDUJWJUZ"DDVSBUFEFmOJUJPOPGUIFEJĊFSFOUCMPDLTIFMQTUP
FOTVSFIJHIJOUSBPCTFSWFSBOEJOUFSPCTFSWFSSFMJBCJMJUZ"OFYBNQMFPGUIJTBDDVSBUFEFmOJUJPOPG
BUBTLGPSBESJWFSNJHIUCF USBOTQPSU BMMBDUJWJUJFTXJUIUIFHPBMPGNPWJOHMPBE"GSPNQMBDF9
UPQMBDF:4UFQJOWPMWFTUIFUSBOTGFSPGUIFMJCSBSZUPUIF1FSTPOBM%JHJUBM"TTJTUBOU ġĕĒ4UFQ
DPOTJTUTPGUIFBDUVBMXPSLTJUFPCTFSWBUJPO BOEUIFPCTFSWFEEBUBBSFUSBOTGFSSFEUPUIFDPNQVUFS
JO4UFQ4UFQJOWPMWFTUIFmOBMFEJUJOH QSPDFTTJOH MJOLJOHBOEDBMDVMBUJPOPGUIFEVSBUJPO GSFRVFODZBOEJOUFOTJUZPGUIFQIZTJDBMEFNBOETJOUIFBTTFTTFEPCTFSWBUJPOT"GVMMEFTDSJQUJPOPG
UIF5SBDTZTUFNIBTCFFOQVCMJTIFEFBSMJFS
#HAPTER
'JHVSF%JĊFSFOUTUFQTJOWPMWFEJOUIFVTFPGUIF1BMN5SBDTZTUFN
4JNVMUBOFPVTNFBTVSFNFOU
5P FOTVSF UIBU UIF 1BMN5SBD TZTUFN BOE UIF Ĩēħ NFBTVSFNFOU XPVME XPSL
TJNVMUBOFPVTMZ UIF TUBSU PG UIF NFBTVSFNFOU XBT TZODISPOJ[FE " NFBTVSFNFOU PG UIF Ĩēħ
NBHOJUVEFBDDPSEJOHUPUIFSFRVJSFNFOUTPGUIFJOUFSOBUJPOBMĚĤĠTUBOEBSETIPVMEMBTUT
BUNJOJNVNNJOVUFTBOETIPVMESFQSFTFOUBTNVDIBTQPTTJCMFBDPNQMFUFXPSLDZDMFPGUIF
WFIJDMF PG JOUFSFTU ɨF Ĩēħ NFBTVSFNFOUT JO UIJT TUVEZ MBTUFE CFUXFFO BOE NJOVUFT UIF FYBDU NFBTVSFNFOU UJNF EFQFOET PO UIF SFQSFTFOUBUJWF XPSL DZDMF PG UIF TQFDJmD WFIJDMF
0CTFSWBUJPOCZ1BMN5SBDMBTUFEBQQSPYJNBUFMZGPVSIPVST%VFUPQSBDUJDBMNBUUFST UIFFYBDU
UJNFPGUIF1BMN5SBDPCTFSWBUJPOTXJMMWBSZ
4FMGBENJOJTUFSFERVFTUJPOOBJSF
%BUBPOQIZTJDBMXPSLEFNBOETXFSFDPMMFDUFEVTJOHUIFħĚēģĚĤĜĤ8IPMFCPEZWJCSBUJPO
*OJUJBM"TTFTTNFOU 4FMG"ENJOJTUFSFE2VFTUJPOOBJSFɨJTRVFTUJPOOBJSFXBTFMBCPSBUFEGSPNBO
FBSMJFSWFSTJPOUIBUXBTUFTUFEJOTFWFSBMQPQVMBUJPOT "OEXBTVTFEJOUIFCBTFMJOFNFBTVSFNFOU
GSPNUIFħĚēģĚĤĜĤTUVEZ'PSUIJTTUVEZPOMZUIPTFRVFTUJPOTUIBUDPODFSOQIZTJDBMXPSLEFNBOET
4FDUJPOXFSFJODMVEFE4QFDJmDBMMZUIJTDPODFSOTRVFTUJPOB B BOE TFFBQQFOEJY
'JWFQIZTJDBMXPSLEFNBOETXFSFEFmOFEBDDPSEJOHUPUIFRVFTUJPOTBOEJUTRVFTUJPOOBJSF
XFSFHBUIFSFEXJUIUIFTFMGBENJOJTUFSFERVFTUJPOOBJSFXFSFTUPSFEJOB.JDSPTPGU"DDFTT
EBUBCBTF
"OBMZTFTĨēħNFBTVSFNFOU
ɨF Ĩēħ NFBTVSFNFOU EBUB XFSF FYQPSUFE BOE TUPSFE JO BO &YDFM TQSFBETIFFU VTJOH
UIF/PJTF&YQMPSFSUZQFWFSTJPOTPGUXBSF'PSGVSUIFSBOBMZTJT UIFmSTUUXPNJOVUFTPG
UIFUPUBMSFDPSEFEUJNFXFSFEFMFUFE BTJUXBTOFDFTTBSZUPJOTUBMMCPUIUIFFRVJQNFOUBOEUIF
ESJWFSQSPQFSMZ;FSPWBMVFTUIBUNJHIUBQQFBSJOUIFĨēħTJHOBMPGUIFBDUVBMNFBTVSFNFOU EVF
UPWFSZTIPSUMPTUTJHOBM XFSFEFMFUFEBOEFYUSBQPMBUFEɨJTXBTEPOFCZVTJOHUIFBWFSBHFPGUIF
WBMVFTPOFTFDPOECFGPSFBOEPOFTFDPOEBGUFSUIF[FSPWBMVF BTUIFĨēħTJHOBMXBTMPHHFEFWFSZ
TFDPOE
Chapter 2
________________________________________________________________________ 21
3. Transfer
library to PDA 4. Perform observation
Print 5. Transfer
data to PC 6. Edit Process Link Calculate
2 3 4
5 Save to file
1
1. Observation
by camera 2. Create library
6
repetitions. Step 2 draws on the analysis of the video to arrange the tasks, activities, within activities, postures and extra information into a tree-diagram (the library). The accurate definition of each of these elements is an important aspect of the creation of this library. The elements are hierarchically structured in 6 blocks; first block will be the description of the task it self (for instance land mowing), the second block will be a description of the activities during land mowing (for instance sitting, walking, and running). The 3rd block will be within activities (for instance with walking one can actually be pushing or lifting weights). The 4th block describes which body postures the within activities withheld, (for instance while walking and pushing ones rotating his hips 45 degrees). Block 5 gives us extra info about the weight of the object which is being pushed and block 6 is an indication about the duration of the activity and the within activity. Accurate definition of the different blocks helps to ensure high intra-observer and inter-observer reliability. An example of this accurate definition of a task for a driver might be, transport = all activities with the goal of moving load A from place X to place Y. Step 3 involves the transfer of the library to the Personal Digital Assistant (PDA). Step 4 consists of the actual worksite observation, and the observed data are
transferred to the computer in Step 5. Step 6 involves the final editing, processing, linking and calculation of the duration, frequency and intensity of the physical demands in the assessed observations. A full description of the Trac system has been published earlier.18
Figure 1: Different steps involved in the use of the PalmTrac system
Simultaneous measurement
To ensure that the PalmTrac system and the WBV measurement would work simultaneously, the start of the measurement was synchronized. A measurement of the WBV magnitude according to the requirements of the international ISO standard 2631-1 should lasts at minimum 3 minutes and should represent as much as possible a complete work cycle of the
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Chapter 2
________________________________________________________________________ 22 vehicle of interest. The WBV measurements in this study lasted between 15 and 25 minutes, the exact measurement time depends on the representative work cycle of the specific vehicle.
Observation by PalmTrac lasted approximately four hours. Due to practical matters, the exact time of the PalmTrac observations will vary.
Self-administered questionnaire
Data on physical work demands were collected using the VIBRISKS Whole-body vibration, Initial Assessment, Self-Administered Questionnaire.22 This questionnaire was elaborated from an earlier version that was tested in several populations.8,23 And was used in the baseline measurement from the VIBRISKS study. For this study only those questions that concern physical work demands (Section 2) were included. Specifically this concerns question 8a, 9a,13, 16 and 15 (see appendix 1). Five physical work demands were defined according to the questions and its questionnaire items, respectively: (1) walking + standing, (2) bending over (straight or twisted), (3) sitting- while driving, (4) sitting twisted/ leaning forward- while driving and (5) lifting. The data that were gathered with the self-administered questionnaire were stored in a Microsoft Access (2002) database.
Analyses
WBV measurement
The WBV measurement data were exported and stored in an Excel spreadsheet, using the Noise Explorer type 7815 version 4.7 software. For further analysis, the first two minutes of the total recorded time were deleted, as it was necessary to install both the equipment and the driver properly. Zero values that might appear in the WBV signal of the actual
measurement, due to very short lost signal, were deleted and extrapolated. This was done by using the average of the values one second before and one second after the zero value, as the WBV signal was logged every second.
The vibration vector sum (total value) of the weighted root-mean-square (r.m.s.) accelerations (awv) in m/s2was calculated according to formula 1:
(1)
(whereawx is the frequency weighted r.m.s. for the x-axis, awyis the frequency weighted r.m.s.
for the y-axis, and awz is the frequency weighted r.m.s. for the z-axis). We calculated for each 1.4awx² + 1.4awy² + awz²
awv = Chapter 2
________________________________________________________________________ 23 driver the daily r.m.s. acceleration normalized to an eight hour working day (a(8)). This a(8) was calculated according to formula 2:
(2)
whereT0is the duration of eight hours expressed in seconds, awv2 is the squared vector sum awv, and Tiis the WBV measurement time expressed in seconds.
PalmTrac data
Results from the ten drivers were used for the comparison between the self-reported and the observational assessments of physical work demands. All of the questions in the self- administered questionnaire were related to an entire working day (8 hours). PalmTrac data were recorded for approximately four hours. To standardize the PalmTrac data also to an entire working day, the exact PalmTrac recording time (in minutes) was calculated as a proportion of eight hours (480 minutes). This proportion was multiplied by the total recorded time for each of the five physical work demands.
Self-administered questionnaire data
The self-administered questionnaire included a response item (question 16, see 2.6) with an ordinal (never- seldom- often) scale. The physical work demand that was defined according to this question is ‘sitting twisted/ leaning forward’. To make a comparison possible between the self-reported and observational assessments of physical work demands in total time, we retrospectively defined ‘never’ as 0 minutes, ‘seldom’ as 0-10 minutes, and
‘often’ as time in excess of ten minutes.
Agreement between PalmTrac data and data from the self-administered questionnaire To test the agreement between the total time revealed by the PalmTrac observation and the estimated total time (based on the self-administered questionnaire) the total times were compared. The estimation of the total time for the physical work demands in the questionnaire is based on the chosen response item. Underestimation was assumed when the total time for the physical work demands revealed by PalmTrac (for instance; 12 minutes) was smaller than the time from the chosen response item in the questionnaire (for instance 15-30 minutes).
Agreement was assumed when the total time for the physical work demands revealed by a(8) = T0
1 �awv² Ti
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Chapter 2
________________________________________________________________________ 24 PalmTrac (for instance; 24 minutes) overlaps with the time from the chosen response item in the questionnaire (for instance 15-30 minutes). Overestimation was assumed when the total time for the physical work demands revealed by PalmTrac (for instance; 45 minutes) was greater than the time from the chosen response item in the questionnaire (for instance 15-30 minutes).
Results Drivers
Subject characteristics for the ten drivers (all male) are shown in Table 1. The average age of the group of drivers was 45 years (±11yrs), the average height 179 centimetre (± 8cm) and the average weight 93 kilograms (± 12kg). The workers drove on their vehicles on average for 16.6 years (± 11.3yrs).
Table 1: Age, height, weight and type of vehicle (specifics) for the ten randomly selected drivers Subject Age (yrs) Height (cm) Weight (kg) Type of Vehicle Specifics
12 30
34 185
190 105
105 Lorry
Wheeled loader (Ginaf M3232S EVS) (Ahlmann AZ 150)
3 37 192 100 Lawn-mowing
machine (Toro Groundmaster 40000D)
4 38 182 92 Wheeled loader (Ahlmann AZ 150)
5 48 178 91 Double crane (Fermec 960, 2001)
6 49 176 86 Wheeled loader (Caterpillar 928D)
7 54 175 80 Boat (Corvus: unique,1997)
8 55 178 105 Wheeled loader (Volvo 150C, 1998)
9 56 175 75 Excavator (Leibherr Litronic A900c)
10 58 166 100 Steam roller (Hamm 2411 D)
Mean± Sd 45 ±11 179 ± 8 93 ± 12
WBV measurements
Table 2 presents the vibration magnitude (m/s2) for the ten selected drivers in x-, y- andz direction. The vector sum (av) of the WBV magnitude for the different kinds of vehicles ranged from 0.20 m/s2for the boat to 1.53 m/s2 for a wheeled loader. Seven out of the ten drivers are exceeding the action value of 0.5 m/s2 in the dominant axis assuming that the emission value during the actual measurement is maintained all work day long (8 hours).The dominant axis appeared to be dependent of the vehicle driven; the x-axis is dominant for drivers 4, 9 and 10, the y-axis is dominant for drivers 2, 3, and 5-8, and the z-axis is dominant for driver 1.
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Chapter 2
________________________________________________________________________ 25 Table 2: The measured WBV magnitude (m/s2) in x, y, and z-direction and the vector sum for 10 randomly selected drivers.
Illustration of a simultaneously measurement
Figure 2 shows an example of the added value of the simultaneous assessment of physical work demands and a WBV measurement under actual working circumstances for one specific driver (subject 6). For this three-minute period, the WBV measurement on the seat of the wheeled loader revealed frequency-weighted r.m.s acceleration values of ax= 0.57 m/s2, ay= 0.79 m/s2,az= 0.37m/s2and an acceleration total value (vector sum) of (av)= 1.31 m/s2. Examining the example that is illustrated in Figure 2 more closely, the dominant axis exceeds the action value of 0.5 m/s2 for ‘sitting twisted/ leaning back’, ‘sitting’ and ‘sitting while driving with and without load’ all during the task of ‘leveling off’.
Driver ax
(m/s2) ay
(m/s2) az
(m/s2) av
(m/s2)
1 0.28 0.26 0.29 0.54
2 0.60 0.62 0.53 1.15
3 0.83 0.87 0.56 1.53
4 0.76 0.69 0.49 1.31
5 0.66 0.67 0.52 1.23
6 0.65 0.90 0.43 1.38
7 0.08 0.13 0.08 0.20
8 0.75 0.78 0.69 1.45
9 0.52 0.24 0.30 0.74
10 0.37 0.25 0.34 0.63
Mean± Sd 0.55 ± 0.24 0.54 ± 0.29 0.42 ± 0.17 1.02 ± 0.46
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Chapter 2
________________________________________________________________________ 26 Figure 2: Example of a result of the simultaneous assessment of physical work demands and WBV measurement for one driver
Comparison of physical work demands between PalmTrac and self-administered questionnaire
Results of the comparison in total time between the physical work demands assessed by the self-administered questionnaire and by the PalmTrac system are presented in Figure 3- 7. Each of the physical work demands is presented in a figure. Comparisons are made based on a total duration of a normal eight-hour working day.
Figure 3 shows that for ‘walking + standing’, twenty percent (N=2) of the drivers reported durations that were comparable to the PalmTrac assessments; sixty percent (N=6) underestimated the total time, and twenty percent (N=2) overestimated the total time in which
m/s2 Physical work
Demand ax ay az
Sitting
Leveling-off 0.27 0.42 0.15 Sitting 0.88 1.07 0.54 Sitting twisted/
leaning back 0.96 1.53 0.60 Sitting 0.22 0.36 0.80
Sitting (driving
without load) 0.67 0.97 0.44
Sitting 0.61 0.53 0.37 Transport 0.29 0.38 0.28 Sitting 0.14 0.24 0.28 Sitting (Driving
with load) 0.35 0.47 0.24
Leveling off 0.34 0.18 0.16 Sitting twisted/
leaning back 0.41 0.34 0.21 Sitting (Driving
with load)
0 0,2 0,4 0,6 0
,8 1 1,2 1,4 1,6 1
,8 2 13:43:30
13:43:39 13:43:48 13:43:57 13:44:06 13:44:15 13:44:24 13:44:33 13:44:42 13:44:51 13:45:00 13:45:09 13:45:18 13:45:27 13:45:36 13:45:45 13:45:54 13:46:03 13:46:12 13:46:21
Actual time
accelareation (m/sec2)
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Chapter 2
________________________________________________________________________ 27
4 3
2 1
2,50 2,00 1,50 1,00 0,50 0,00
Total time PalmTrac (hrs) 1
2 3
4 5 6
7 9 8
10
Total time questionnaire, 1= 0 hrs, 2=<1hr, 3=1-3 hrs, 4=>3 hrs (annotation = number of driver)
they were walking and standing during a normal working day. Figure 4 shows that for
‘bending over (straight or twisted)’, eighty percent (N=8) of the drivers reported that they did not perform this activity during a normal working day. PalmTrac, however, showed that half (N=5) of these drivers actually did bend over. Workers apparently tended to underestimate the time that they spent in a bent-over (straight or twisted) posture. The twenty percent (N=2) of the drivers who had reported bending over (straight or twisted) overestimated the total time.
Figure 5 shows that for the time spent in a normal sitting posture, all drivers (N=10) reported durations that were comparable to the PalmTrac assessments. Figure 6 shows that the PalmTrac data revealed that ninety percent (N=9) of the drivers were ‘sitting twisted/ leaning forward’ during their normal work duties. The drivers’ self-reported estimations for this physical work demand varied: thirty percent (N=3) of the drivers underestimated, forty percent (N=4) estimated it correctly and thirty percent (N=3) overestimated. Figure 7 shows that although PalmTrac registered no lifting for ninety percent (N=9) of the drivers, half (N=5) of the drivers estimated that they lift during a normal working day. There is an apparent tendency to over-estimate this physical work demand. One worker (Worker 3) did not provide a response to the question about lifting. As shown in Figures 3- 7, the total time estimated by the self-administered questionnaire differed substantially from the total time that was assessed by PalmTrac for the five recorded physical work demands. Table 3 presents a summary of the agreement between the different physical activities recorded by the PalmTrac system and estimation by the self-administered questionnaire.
Figure 3: Comparison of the total time on a normal working day spend on ‘Walking+ Standing’ between objective (PalmTrac) and subjective (questionnaire) assessment
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