R e s e a r c h A r t i c l e A b d o m i n a l B elts f o r M a n u a l H a n d l i n g IN INDUSTRY! The evidence fo r and against BY RS BRIDGERSUMMARY The p a p e r review s research on the use o f a b d o m in a l b e lts f o r in d u strial b a ck injury p re v e n tio n p ro g ra m m e s. The evid en ce f o r biom ech an ica l, p h y s io lo g ic a l a n d p s y c h o p h y sic a l effects o f b e lt use is p re se n te d , f o llo w in g a b r ie f th e o re tic a l discu ssion . A lthough there is som e la b o ra to ry evid en ce th at a b d o m in a l b e lts p r o te c t the spine when lifting, the fin d in g s o f f ie l d stu dies are equ ivoca l. P re v io u sly in ju red w o rkers seem to ben efit the m o si both fro m "back school" train in g c o m b in ed w ith w e a r ­ ing a b d o m in a l b e lts a t work. H ow ever, f a r fro m bein g the solu tion to in d u strial m an u al h an dlin g p ro b le m s, a b d o m i­ n al b e lts h ave on ly a sm a ll p a r t to p la y in com prehen sive risk m an ag em en t p ro g ra m m es a im e d a t redu cing b a ck p r o b ­ lem s in the w o rkplace. K E Y W O R D S: A B D O M IN A L BELTS, OC CU PATIO N AL B A C K PAIN, P REV E N TIO N INTRODUCTION “E rg o g e n ic c o rse ts” , “b a c k b e lts” o r “ ab d o m in al b e lts” are c u rren tly b ein g ev a lu a te d as a fo rm o f p ro te c tio n a g ain st lo w -b a c k in ju ry fo r u se in in d u stria l m a n u al h a n d lin g o p eratio n s (M ag n u sso n et a l', S o h et a l2). U n lik e o th e r p ro d u cts d e s ig n e d to s a fe g u a rd th e h e a lth o f in d u strial w o rk ers, th e effec tiv en ess o f th e s e d e v ic e s re m a in s u n p ro v e d (R a b in o w itz et aP). In th e p re se n t paper, th e resu lts o f a m a n u al sea rch o f th e lit­ e ra tu re o n e rg o n o m ic s an d in d u s tria l safety w as c a rrie d out. T h e ev id e n c e for an d ag ain st the p re scrip tio n o f ab d o m in al b elts in in d u stry is rev iew ed . U sin g an an alo g y w ith o th e r m e d ical p ro d u cts, if b elts are to be accep ted as a fo rm o f p ro ­ te c tio n ag ain st in d u strial injury, a b od y o f ev id e n c e fro m lab o rato ry and clin ical (in d u strial field ) trials is n eed ed w h ich d em o n strates • T h a t the u se o f the b elts co n fers som e k in d o f b io m ec h an ical ad v a n tag e w h ic h w ill p ro te c t the sp ine fro m in ju ry in the w o rk p la ce • T h a t the o c c u p atio n al u se o f the d ev ice s d o es n o t have u n w an ted o r u n e x ­ p e c te d side effects w h ich im p act n e g a ­ tiv ely o n th e h ealth o f th e w o rk er THEORETICAL BACKGROUND T h e p ra c tic e o f w rap p in g m a te ria ls aro u n d th e w aist w ith the aim o f im p ro v - C O R R E S P O N D E N C E B y R S B rid g e r P h.D . H ea d E rg o n o m ics G ro u p , D ep artm e n t o f B io m ed ic al E n g in ee rin g , U C T M ed ic al S ch o o l, O b serv ato ry 7 925, 021 4 06 -6541 (bus) 021 6 86 2 82 0 (resid en ce), e-m ail b rid g e r@ a n at.u ct.a c.za ing p o stu re an d p o ise is fo u n d th ro u g h o u t h isto ry an d acro ss cu ltu res. S h a h 4 fo r ex am p le, rep o rts th a t in N ep al, m o st p e o ­ p le w h o lift an d carry h eav y w eig hts w rap a 5 m e tre le n g th o f clo th (called a “ P a tu k a ” ) a ro u n d the w a ist b e fo re w ork. A n ecd o tally , it is th o u g h t to re d u ce the p re v a le n c e o f o c c u p a tio n a l lo w b a c k pain. It w as K e ith 5 w h o first p ro p o se d that in tra-a b d o m in al p re ssu re (IA P ) re su ltin g fro m co n tra c tio n o f th e a b d o m in al m u s­ cles d u rin g liftin g acts to re d u ce the load on the spine. M o rris et a l u se d a b io m e ­ ch an ic al ap p ro ach to su p p o rt th e arg u ­ m e n t th a t IA P red u ce s sp in al co m p re s­ sio n d irectly, by the u p w ard h y d ra u lic actio n o n th e d ia p h rag m , an d by ex ertin g a n e x te n s o r m o m e n t ab o u t th e sp ine (F ig u re 1). T h e e x te n s o r m o m e n t thus p ro d u c e d , w as th o u g h t to assist the b ack ex tensors. F o r a g iv e n lo ad , IA P a ssistan c e w o uld re d u c e the b ack m u sc le e x te n s o r force re q u ire d an d th e re fo re th e c o m p ressiv e lo a d in g o n the spine. I f IA P d oes lo w e r sp in al co m p ressio n by e x e rtin g a h y d ra u lic te n sile fo rc e on th e d ia p h ra g m an d a sp in al e x te n s o r m o m en t, th e n a b d o m in al b elts w o u ld be h y p o th e sise d to a u g m e n t th is effec t by assistin g the a b d o m in al m u scles in g e n ­ e ratin g IAP. F u rth e rm o re , sin ce IA P is g e n e ra te d by ab d o m in al m u sc le c o n tra c ­ tio n a n d s in c e a b d o m in a l m u sc le co n tra c tio n is a ss o c i­ ated w ith an in c re a se in the f le x io n m o m e n t a b o u t th e sp ine (M cG ill an d N o rm a n 7), a b d o m in al b elts w o u ld fa c ili­ tate in c re a se d IA P an d a lo w ­ e re d flex io n m o m en t. A ltern ativ ely , IA P m ay p ro ­ te c t the lo a d ed lu m b a r sp ine ind irectly. C o n tra c tio n o f the ab d o m in a l m u s c u la tu re sets up lateral fo rc es w h ic h act on th e s p in e v ia th e p e lv is , rib c a g e an d lu m b o d o rs a l facia, actin g like guy ro p es w h ich stab ilise a m a st in sid e a n ow , rig id , c y lin d e r. T h is a rg u m e n t w a s e c h o e d by A sp d e n 8, u sin g a n o v e l b io ­ m e ch a n ical a p p ro a c h (based o n th e m e c h a n ic s o f m a so n ry arch es). A sp d e n arg u ed that th e m o re an arch (i.e. th e lu m ­ b ar sp ine, in th is case) is c o m ­ 12 SA J o u r n a l o f Ph y sio t h e r a p y 1997 V o l 54 No 2 R ep ro du ce d by S ab in et G at ew ay u nd er li ce nc e gr an te d by th e P ub lis he r (d at ed 2 01 3. ) mailto:bridger@anat.uct.ac.za p re ssed , th e stiffer an d m o re resista n t to b u c k lin g it b eco m es. IA P m a y th e refo re help to m a in ta in the alig n m e n t o f the m o tio n seg m e n ts an d p re v e n t in ju ry d ue to sm all d isp lace m en ts o f stru c tu res at the lev el o f the face t jo in ts an d interv er- teb ral discs. T ab le 1 su m m arises the p o ssib le b e n e ­ fits an d p o ssib le n eg a tiv e side effec ts o f o c c u p a tio n a l w ea rin g o f ab d o m in al b elts in industry. DOES IAP REDUCE SPINAL COMPRESSION WHEN LIFTING? M cG ill an d N o rm an 7 used b io m e c h a n ­ ical m o d e ls to c alc u late th e L 4/L 5 re a c ­ tio n fo rc e an d th e IA P an d ab d o m in al flex io n m o m e n t in a liftin g task . T he fo rc e s and th e m o m e n t crea te d by the in c re a se d IA P w e re n o t su ffic ien t to o v e rc o m e the flex io n m o m e n t an d re su lt­ ing lu m b a r co m p ressio n ca u se d by the in c re a s e d a b d o m in a l m u sc le activ ity . G re a te r lev els o f IA P co u ld only b e c re ­ ated by fu rth er ab d o m in al co m p ressio n a c c o rd in g to M c G ills m o d e l, lead in g to th e co n c lu sio n th a t IA P m a y n o t allev iate sp in al co m p ressio n at all. R a th e r th a n re d u c in g sp in al c o m p re s­ sio n, it seem s m o re likely, as su g g ested b y C h affin 9, th a t ab d o m in al m u sc le a c tiv ­ ity in liftin g task s is p art o f a co m p lex p ro cess o f co -c o n tra c tio n o f m a n y d iffe r­ en t m u scles w h ich act to stab ilise the trun k. A lth o u g h rese arch ers o fte n ch o o se to m o d e l liftin g task s tw o -d im en sio n ally (the u b iq u ito u s sag ittal p la n e lift), in reality the tru n k is a three d im en sio n al s tru c tu re d e s ig n e d to m o v e in th re e d im en sio n s. O b liq u e /tran sv erse m u scle co c o n tra c tio n d u rin g sag ittal liftin g m ay ju s t b e th e n atu ral resp o n se o f the three- d im en sio n al tru n k co n tro l an d stab ilisa­ tio n system . I f this v iew is co rrect, in c reased IA P d u rin g liftin g m a y b e n o m o re th a n a side effec t o f the o p eratio n o f this system . DO ABDOMINAL BELTS INCREASE IAP WHEN W ORN? M cG ill et al'° m e a su re d b ack ex ten so r E M G an d IA P w h e n s u b je c ts lifte d w eig hts w ea rin g a c o m p e titio n w eig h t lifter's belt. A lth o u g h IA P d id in c rease w h en the b e lt w as w o rn (fro m 9 9 m m H g to 120 m m H g ) th e re w as n o co rre sp o n d ­ ing red u ctio n in b ack ex te n s o r activity. W h e n su bjects h eld th e ir b re a th w h en liftin g , in c re a s e s in IA P w e re a lso o b s e rv e d an d w e re a c c o m p a n ie d by red u ctio n s in b ack ex ten so r E M G - irre ­ sp ectiv e o f w h e th e r a b e lt w as w orn. A lth o u g h there is n o d ire ct e v id en ce o ne w ay o r the other, in c reased IA P acc o m p an y in g b elt use m a y in c rease the risk o f tru n k in ju ry (su ch as u m b ilical h ern iatio n ) o r in c rease load on the c a r­ d io v a sc u la r sy stem b y im p ed in g v eno us retu rn to the heart. DOES WEARING AN ABDOMINAL BELT REDUCE BACK MUSCLE FATIGUE WHEN LIFTING? C iriello an d S n o o k 11 m e a su re d fatig u e o f the b ack ex ten so rs in 13 m a le in d u s tri­ al w o rk ers w h o lifte d a v erag e loads o f 28.1 kg, 4.3 tim es p er m in u te fo r fo u r h o u rs a day. A b elt w as w o rn on tw o o f the d ays. M a x im u m iso k in e tic en d u ran c e d ecreased b y 9 to 11% a fte r fo u r h o u rs o f liftin g. T h is ch a n g e w as n o t sig n ifican tly d iffere n t w h en a b elt w as w o rn, n eith er w ere there d iffere n ce s in the p o w er sp ec­ tru m o f the E M G sig n al as in d icated by m e d ia n fre q u en cy a n a ly sis (D e L u c a 12) S u b je c tiv e ra tin g s o f effo rt w ere n o t in flu en c ed b y b ack b e lt w earin g. DOES WEARING AN ABDOMINAL BELT HAVE AN OVERALL PROTECTIVE EFFECT? R e illy a n d D a v ie s 13 e v a lu a te d a w eig h tlifters b elt b y h av in g su b jec ts lift a 30 k g w eig h t fo r e ig h t sets o f tw en ty re p ­ etition s. S pin al sh rin k ag e as a re su lt o f the ta sk -in d u c e d lo a d in g (u sin g stadiom - etry, E k lu n d an d C o rle tt14) w as red uced by 4 9 % w h en the b e lt w as w o rn (from 4 .08 m m to 2.08 m m .) S pin al sh rin k ag e is m e asu red b y reco rd in g re d u c tio n s in statu re o v e r a p erio d o f liftin g . T h e red u ctio n s are ca u se d by the eg ress o f flu id fro m th e in terv erteb ral d iscs d u e to the loading . S pin al sh rin k ag e is u sed as an in d ex o f the cu m u la tiv e co m p ressiv e lo ad in g o n th e sp ine d u rin g th e p e rfo r­ m a n ce o f a task. P e rc e iv e d e x e rtio n w as also lo w e r w ith the b e l t . M a g n u sso n et al' co m p ared lift­ in g w ith and w ith o u t a b elt w h en su bjects lifted 10 kg. fro m flo o r to d e sk h e ig h t tw ice p e r m in u te fo r 5 m in u tes. S pinal sh rin k ag e w as lo w e r w h en th e b e lt w as u sed as w as b a c k m u sc le E M G (n o r­ m a lise d w ith re sp e c t to eac h su bject's m a x im u m v o lu n tary co ntractio n). DOES WEARING AN ABDOMINAL BELT GIVE LIFTERS AN INCREASED SENSE OF STABILITY AND SECURITY? B o th M cG ill et al'", R ed d e ll et a l15 and M a g n u sso n et al' re p o rt th a t w e a rin g eith e r c o m p etitiv e w eig h tlifter's b elts o r ab d o m in al b e lts fo r in d u strial w o rk ers in c reases the sen se o f security. M cC o y et a l'6 fo u n d th a t s u b je c ts s e lf-s e le c te d w eig h ts w h ic h w e re 19% h ea v ie r w h en th e y w ere w e a rin g belts. T h is fin d in g is in ag reem en t w ith the p re d ic tio n s o f “ R is k H o e m o e s ta s is T h e o ry ” w h ic h p re d icts th a t the safe r w e p erceiv e o u rselv es to b e, the m o re d a n ­ g e ro u sly w ill w e b eh a v e. It has b een d e m o n stra te d , fo r ex am p le, th a t d riv ers o f cars e q u ip p e d w ith air b ag s driv e m o re a g gressively , o ffsettin g the effec t o f the air b ag fo r the safe ty o f th e d riv e r and in c re a sin g th e risk o f d eath to o th er road u sers an d p ed e stria n s (P eterso n et a l'1). T h e th e o ry p re d icts th a t ab d o m in al b elts w ill cau se u sers to lift in a m o re d a n g e r­ o u s w ay o r attem p t to lift h ea v ie r loads. A b e tte r w ay to im p ro v e in d u strial safety is to m a k e p eo p le m o re aw a re o f the d a n ­ g ers in h eren t in m a n u al h a n d lin g o f loads an d to m in im ise the d a n g e r b y m e c h a n is­ ing the task o r re d u cin g the load to be lifted. DO ABDOMINAL BELTS PROTECT INDUSTRIAL WORKERS IN PRACTICE? W alsh an d S c h w a rtz 18 d iv id e d 9 0 g ro ­ c e ry w a re h o u s e w o rk e rs in to th re e g ro u p s in a six m o n th in v e stig a tio n . G ro u p 1 (co n tro l) rec e iv e d no in terv en ­ tion . G ro u p 2 rece iv ed a 1 h o u r train in g sessio n on b ack p ain p re v en tio n . G ro u p 3 re c e iv e d th e tra in in g an d a m o u ld e d sp in al o rth o tic b ra ce to b e w o rn a t w ork. T h e re w ere n o sig n ifican t d iffere n ce s in in ju ry rates o r p ro d u c tiv ity b etw een the th re e g ro u p s o v e r th e stu dy p eriod . L o st tim e w as sig n ifican tly lo w e r in G ro u p 3, h o w e v e r (2.5 d ays low er, on av erag e). T h e g ro u p s w ere fu rth e r d iv id e d into h ig h an d a low risk w o rk ers. H ig h risk w o rk ers in G ro u p 3 h ad sig n ifican tly fe w e r in ju ries an d lo st tim e su g g estin g th a t p re v io u sly in ju red w o rk ers will b e n ­ e fit the m o st fro m this fo rm o f in te rv e n ­ tion. R ed d e ll et a l'5 ev a lu a te d an ab d o m in al b e lt an d b ack p ro g ra m m e a m o n g st a g ro u p o f a irlin e b ag g ag e h an d lers. L o st w o rk d ay s an d b ack in ju ries w ere n ot red u ce d , b u t b ack in ju rie s in c re a se d an d w ere m o re sev ere afte r b e lt u se w as d is ­ c o n tin u ed . M itc h ell et a l'9 e x a m in e d b elt use. train in g , b ack in ju ry an d lo st tim e in a U S A ir F o rc e b ase. T h e p re d icto rs o f low b ack in ju ry w e re as e x p e cted - tim e sp ent liftin g an d p re v io u s b ack injury. B ac k train in g p ro g ra m m e s w ere fo u n d to h a v e a sm all p re v e n ta tiv e effec t as did the use o f b a c k b elts. H o w ev er, the costs o f treatin g in ju rie s w h en th e y d id o ccu r w ere fo u n d to be h ig h e r am o n g st b elt w ea rers lead in g the au th o rs to c o n c lu d e th a t b elt use w as n o t in d icated in this typ e o f w ork. SA J o u r n a l o f Ph y sio t h e r a p y 1997 V o l 54 No 2 13 R ep ro du ce d by S ab in et G at ew ay u nd er li ce nc e gr an te d by th e P ub lis he r (d at ed 2 01 3. ) DOES OCCUPATIONAL ABDOMINAL BELT WEARING DE­ CONDITION THE TRUNK MUSCULATURE? T h e e v id en ce su gg ests not. M cG ill et a / 10 n oted th a t e v en th o u g h b elt w ea rin g d o es red u ce a b d o m i­ nal m u sc le E M G d u rin g liftin g, the red u ctio n is n ot large. E v e n w h en liftin g h eav y loads (ab o v e 7 0 kg) w ith o u t a belt, p eak ab do m in al m u scle E M G levels are a sm all p e rc e n ta g e o f th o se o b serv ed w h en su b ­ je c ts e x e rt a m a x im u m v o lu n tary co n trac tio n o f th e ir a b d o m in al m u scles. T h e re fo re, the ab d o m in al train in g effec t o f liftin g is likely to b e sm all (c o m ­ p ared , fo r ex am p le w ith c o u g h in g o r lau g h in g ). W alsh an d S c h w a rtz 18 m e asu red ab d o m in al stren g th b e fo re and after the six m o nth study p erio d and fo u n d no e v id en ce fo r a red u ctio n in ab d o m in al stren g th am o n g st b elt w earers co m p ared w ith c o n ­ trols. Table 1. P o s s ib le B e n e fits a n d P o te n ti a l N e g a tiv e S id e E ffects o f A b d o m in a l B e lts in In d u s tr y . IS ABDOMINAL BELT WEARING HAZARDOUS FOR WORKERS W ITH LATENT CORONARY HEART DISEASE? It is k n o w n th a t both b elt w earin g and b reath h o ld in g w h ile liftin g in c rease IA P a n d in tra-th o rac ic p ressu re. H u n te r et al20 h ad su b jec ts h o ld 4 0 % o f th e ir m a x im u m w eig h t in the dead lift p o stu re for tw o m in u tes. B lo o d p re ssu re an d h eart rate w ere h ig h e r w hen the b elt w as w o rn lead in g to the co n c lu sio n th a t card iac c o m ­ p ro m ise d in d iv id u als are p ro b a b ly a t g re a te r risk w h en e x e r­ cisin g w h ile w earin g b ack su pp orts. It is k n o w n that in c reased in tra-tru n ca l p re ssu re h in d e rs v en o u s retu rn to the h eart an d is P o ssib le B en efits 1. In c rease d IA P and red u ced sp inal c o m p re ssio n w h en liftin g 2 S ta b ilisatio n o f lu m b a r m o tio n seg m e n ts 3. S tiffe n in g o f lu m b a r sp in e d ue to in c re a se d IA P 4. L ifte r "rem in d ed " to av o id lu m b a r flex io n and lift co rrectly 5. "S p lin ting " actio n o f belt. D an g e ro u s m o tio n s su ch as e x cessiv e sagittal flex io n and ax ial ro ta tio n are re stric te d b ecau se the b elt stiffen s the trun k 6. In c rease d sen se o f security an d stab ility P o ssib le H azards 1. In c rease d IA P b u t n o re d u ctio n in sp in al c o m p re ssio n w h en liftin g 2. D e-c o n d itio n in g o f tru n k m u scu latu re th ro u g h lo n g -te rm use 3. R aise d b lo o d p re ssu re in c reases risk o f b la ck o u ts, stro k e o r h eart attack 4. In c re a se d risk o f u m b ilical o r h ia tu s h ern ia 5. In c re a se d sen se o f security an d stab ility cau ses w o rk ers to tak e u n n ec­ essary risks 6. M an a g em en ts issu e b elts to "p rotect" w o rk ers in ste ad o f re d e sig n in g or m e ch a n isin g h a zard o u s o p eratio n s • PH Y SIO TH ER A PISTS A R E V O U C O N S I D E R I N G W O R K I N G I N T H E U K ? Then talk to the company with years of experience of bringing satisfied health professionals to the UK. We have superb opportunities for physiotherapists and the best benefits package available within the N H S and private sector. Talk to us now to find out how we can help you in your career. Benefits include: A ssista n ce with and paym ent of C P S M fees A ssistan ce with visas and work permits* Excellent bonus p ackag e Meet and greet at the airport Induction p ack Accom m o datio n provided Excellent locum pay rates Locum and perm anent positions ^ S u b je c t to a p p lica b le conditions Simply com m it to work for us for 16 w< cks an d w<. will do We rely on your com m itm ent to us, not lengthy legakcti'ntracfs fo llo w e d by a ru s h u p o n p re ssu re release w h ich can cau se u n c o n ­ scio u sn ess in ex tre m e cases. M cG ill et a lm sp ecu late th a t this m ay ex p la in the h ig h in c id en ce o f h e a rt attack s am o n g st u nfit p eo p le c a rry in g o u t cy clic liftin g activ ities su ch as sn o w sh o v el­ ling. LIMITATIONS OF THE STUDIES M any o f the fu n d a m e n ta l stu d ies cited are o f in tere st b ecau se they e lu cid ate the m e ch a n ism s u n d erly in g in ju ry an d p ro tectio n ag ain st injury. T h e m a in d ra w b a c k s are that they are ca rrie d o ut on sm all n u m b ers o f y o u n g su b jects, o fte n stu d en ts, w h o are n ot rep re se n ta tiv e o f likely in d u strial users. A m a jo r w ea k n ess o f th o se stu d ies w h ich h av e fo u n d m o d e st b en e fits fro m ab do m in al b elt u sage is that p o stu re w as n o t m e asu red . It is p o ssib le that b elt w earin g altered su b je c ts ’ p o stu re w h en liftin g an d that the b e n e fit w as, in d irect, d ue to the ch a n g e in p o stu re ra th e r than a p ro te c tiv e effec t o f the b elt itself. CONCLUSIONS AND RECOMMENDATIONS 1. A lth o u g h the m e ch a n ism is u nclear, b elts do seem to p ro v id e so m e typ e o f p ro tectio n in lig h t task s su ch as g ro cery selectio n (w h ere the lo a d s are n o rm a lly lig h t b u t the liftin g an d b en d in g freq u en cy is g re at). P rev io u sly in ju red w o rk ers b e n e fit the m ost. 2. W ith h eav y task s, the e v id e n c e is less c le a r an d there are real c o n c e rn s ab o u t w h e th e r b elts cre a te a fa lse sen se o f sec u rity and e n co u rag e w o rk ers to lift h e a v ie r w eig hts. 3. T h e re are real c o n c e rn s ab o u t p o ssib le side effec ts o f o c c u ­ p atio n a l b elt use. A lth o u g h th e re is no ev id e n c e fo r d e c o n d itio n ­ ing o f the trun k m u scles, c h ro n ically in c reased IA P in the w o rk ­ p la ce m ay b rin g w ith it ca rd io v a sc u la r an d o th er risks. C learly, these d ev ices sh o u ld n e v e r b e issu ed as q u ick fixes to “ so lv e ” m anu al h a n d lin g p ro b le m s in industry. A p ro p e r a ss e ss­ m e n t o f the w o rk e n v iro n m e n t sh o u ld first be c a rrie d o u t to d e te rm in e the sco pe fo r am elio ratio n th ro u g h m e ch a n isatio n , red esig n (red u ctio n ) o f the lo a d s o r im p ro v e m e n t o f the w o rk e n v iro n m e n t (see B rid g e r21, fo r ex am p le). T h e c a rd io v a sc u la r an d g en e ra l h e a lth status o f the w o rk fo rc e sh ou ld b e w e ll-u n d e r­ sto o d b efo re c o n sid e rin g b elts. B elts sh o u ld only be issu ed as p art o f a c o m p re h e n siv e p ro g ra m m e o f risk m a n a g e m e n t an d only w o rn fo r sh o rt p erio d s fo r the p e rfo rm a n ce o f sp ecific tasks.M e d a c s , T h e O l d S u r g e r y , 4 9 O t l e y S t r e e t , S k i p t o n , N o r t h Y o r k s h i r e , B D 2 3 1 E T E n g l a n d M e d o c s is t h e U K 's l e a d i n g h e a l t h p r o f e s s i o n a l r e c r u i t m e n t a g e n c y . A m e m b e r o f th e C o rp o ra te S ervices G ro u p pic R ep ro du ce d by S ab in et G at ew ay u nd er li ce nc e gr an te d by th e P ub lis he r (d at ed 2 01 3. ) REFERENCES 1. M agnusson M, Pope MH, Hansson T. Does a back support have a positive biom e­ chanical effect? Applied Ergonomics, 1996; 27(3):2 01-205 2. Soh TN, Parker PL Crumpton LL et al. 1997. An investigation of respiration while wearing back belts. Applied Ergonomics, 1997, 28(3): 189-192. 3. Rabinowitz D, B ridger RS, Lambert M. Lifting technique and abdominal bell usage: a biom echanical, physiological and subjec­ tive investigation. Safety Science (In Press). 4. Shah RK. A pilot survey o f the traditional use o f the patuka round the waist for the pre­ vention o f back pain in Nepal. Applied Ergonomics 1993; 24:337-344. 5. Keith A. M an's posture: its evolution and disorders. Lecture VI: The adaptations of the abdomen and its viscera to the orthograde posture. British M edical Journal 1923; 1:587-590. 6. M orris JM , Lucas DB, Bresler B. R ole of the trunk in the stability o f the spine. Journal o f Bone and Joint Surgeiy 1961; 43A: 327-351. 7. M cGill S, Norman RW. Reassessm ent of the role o f intra-abdominal pressure in spinal com pression. Ergonomics 1987; 30(11): 1565-1588. 8. Aspden RM. The spine as an arch: A new mathematical model. Spine 1989; 14: 266- 274. 9. Chaffin D. Biom echanical m odelling of the low back during load lifting. In D esigning a B etter World, Proceedings of the 1 0th Congress o f the International Ergonomics Association, Sydney, Australia. Ergonomics Society o f Australia Inc, 1988. 10. M cGill S, Norman RW, Sharratt. The effect o f an abdominal belt on trunk muscle activity and intra-abdominal pressure during squat lifts. Ergonomics 1990; 33(2): 146-160. 11. Ciriello VM, Snook SH. The effect of back belts on lum bar m uscle fatigue. Spine 1995;20(11): 1271-1278. 12. DeLuca CJ. M yoelectric manifestations o f localised m uscle fatigue. Critical Reviews o f Biom edical Engineering 1985, 11:251- 279. 13. Reilly T Davies S. Effects o f a weightlifting belt on spinal loading during performance o f the dead lift. In Spo rt, Leisure and Ergonomics, edited by G Atkinson and T Reilly, E and FN Spon, 1995. 14. Eklund JAE, Corlett EN. Shrinkage as a measure o f the effect o f load on the spine. Spine 1984;9:189-194. 15. Reddell CR, Congelton JJ, Huchingson Rd, M ontgomery JF. An evaluation o f a weightlifting belt and back injury protection prevention training class for airline baggage handlers. Applied Ergonomics 1992;23(5):319-329. 16. M cCoy MA, Congleton JJ, Johnston W L, Jiang BC. The role o f lifting belts in manual lifting. International Journal o f Industrial Ergonom ics 1988; 2: 259-266. 17. Peterson S, Hoffer G, and M illner E. Are drivers o f air-bag-equipped cars more aggressive? A test of the offsetting behaviour hypothesis. 1995. Journal o f Law and Economics, 38: 251-265. 18. Walsh NE Schwartz MS. The influence o f prophylactic orthoses on abdominal strength and low back injury in the work­ place. American Journal o f Physical M edicine and Rehabilitation 1990;69(5):245-250. 19. M itchell RV, Lawler FH, Bowen D, M ote W, Asundi P, Purswell J. Effectiveness and cost effectiveness o f em ployer-issued back belts in areas o f high risk for back injury. Journal o f O ccupational M edicine 1994; 36(l):90-94. 20. Hunter GR, M cGuirk J, M itrano N, Pearm an P, Thomas B, Arrington R. The effects o f a weight training belt on blood pressure during exercise. Journal o f Applied Sports Science Research 1989; 3( 1): 13-18. 21. Bridger RS. Introduction to Ergonomics. New York: M cGraw-Hill. 1995. In o r d e r to g e t th e m o s t o u t o f y o u r w o r k in g h o li d a y in B r ita in , y o u ’ 11 w a n t th e e x p e r t c a r e y o u c a n o n ly g a in f r o m C o r in th . W ith a lm o s t th ir ty y e a r s e x p e r ie n c e w e 'v e g r o w n to b e th e le a d in g s p e c i a l is t E m p lo y m e n t A g e n c y in o u r fie ld b y h e lp in g P h y s io th e r a p is ts fr o m all o v e r th e w o r l d c o m b in e b u s in e s s w ith p le a s u r e : g iv i n g th e m th e o p p o r tu n it y to w o r k w ith th e U K 's l e a d in g h o s p ita ls a n d h e l p i n g th e m ta k e Lime o u t to e n jo y th e d if f e r e n t c u ltu r e s a n d s ig h ts . W h a t 's m o r e , a s w e ll a s to p ra te s o f p a y a n d an e x c e lle n t p a c k a g e o f b e n e f it s , y o u w o n 't b e tie d to a n y b in d in g c o n tr a c ts a n d y o u w o n 't b e c h a r g e d f o r o u r s e r v ic e s . W e 'l l s im p ly o f f e r y o u th e w id e s t s e l e c t i o n o f j o b s a n d s u p p l y f r ie n d ly a n d c o n f i d e n t i a l a d v i c e o n all a s p e c ts o f w o r k in g th r o u g h a n a g e n c y . W a n t u s to p u t y o u in th e p i c t u r e '’ I f so . c o m p le te th e c o u p o n b e lo w a n d s e n d it to o u r R e c r u itm e n t M a n a g e r . D e b i F a u l d e r M C S P S R P a n d s h e w ill s e n d y o u o u r F R E E 'W o r k i n g H o lid a y s in B r i t a i n ’ I n f o r m a t io n P a c k . A lte r n a t i v e l y , y o u c a n c a ll us T O L L - F R E E o n 0 8 0 0 - 9 9 - 8 1 6 8 ( 2 4 h o u r s ) . F O R C O R I N T H M E D I C A L Post to: Corinth Medical 5 Theobald Court, Theobald Street Borehamwood, Hertfordshire WD6 4RN. ENGLAND Tel: 09 44 181 207 0234 Fax: 09 44 181 207 6894 T H E P R O F E S S I O N A L S T A F F I N G A G E N C Y ^Corinth s§k> Medical I 'd lik e t o k n o w m o r e a b o u t C o r in t h M e d ic a l P le a s e s e n d m e y o u r 'W o r k i n g H o lid a y s in B r it a in ' b r o c h u r e Nam e — Address Tel -------------------------------------------------------------------------------------------------------------- A n ticipa ted d a te o f travel _______________ Montn _________ Yeai PTNRSA SA J o u r n a l o f Ph y sio t h e r a p y 1998 V o l 54 No 2 15 R ep ro du ce d by S ab in et G at ew ay u nd er li ce nc e gr an te d by th e P ub lis he r (d at ed 2 01 3. )