physiotherapy, A u g u s t 1986, vol 42 no 3 85 A re Y ou R ea lly S ittin g C o m fo rta b ly ? A F ield S tu d y o f a F o r w a r d S lo p in g C h a ir a n d S e d e n ta ry L o w B a ck P a in S u ffe re rs R. S. BRIDGER AN D G. G. JAR O S SUMMARY A number of authors have suggested that office chairs designed to encourage users to sit with an "o p e n " trun k-thig h angle (approximately 110-120 degrees) will be more comfortable than conventional chairs and will have benefi­ cial consequences for sedentary low back pain sufferers. This assertion was investigated in a 4 month trial in which 35 sedentary workers were given a forward sloping chair to use. Ratings of perceived back pain and postural comfort when using the chair were compared with ratings obtained when conventional chairs were used. Additionally, users' comments on both chair types were obtained. I For the sample as a whole, significantly less lower back pain was reported on those occa­ sions when the forward sloping chair was used. However, a number of participants reported no change or more back pain when using the ; forward sloping chair. Users’ comments on the chair highlighted a number of practical advan- j tages and disadvantages which relate to its suitability for use in office settings. ! Although the majority of users preferred the forward sloping chair to their usual chairs, the \ available data do not permit the differential response to the chair to be explained on either personal, o ccu p a tio n a l, a n th ro p o m e tric or ergonomic grounds. A more clinically orientated investigation would seem to be required. R. S. B ridger, M .S c. (E rg o n o m ic s) H ead, E rg o n o m ic s G r o u p , D e p t, o f B io m ed ical E n g in e erin g , U niversity o f C a p e T o w n M e d ical S c h o o l a n d G ro o te S c h u u r H ospital G. G. J a ro s , P r. E ng., M .S C . (E n g .), P h .D . Professor, H ea d , D e p t, o f B io m e d ic a l E n g in e e rin g , U n iv ersity o f C ape T o w n M e d ical S ch o o l OPSOMMING Verskeie skrywers het aangedui dat kantoor- stoele met 'n groot rom p-dy hoek (110-120) gemakliker sal wees as die konvensionele kan- toorstoele en dat dit ook voordele kan inhou vir lae-rugpyn lyers. Hierdie stelling is oor ’n tydperk van 4 maande ondersoek. Vyf en dertig (35) kantoor werkers is met stoele met 'n vorentoe helling toegerus, Skattings van rugpyn en gemak is met die skattings vir konvensionele stoele ver- gelyk. Die gebruikers se kommentaar oor die gebruik van hierdie stoeltipes is ook verkry. 'n Beduidende afname in lae-rugpyn het voorgekom met die gebruik van die stoele met vorentoe hellings. 'n Paar gebruikers het geen veranderings of meer rugpyn ondervind nie. Kommentaar van die gebruikers het 'n paar praktiese voordele en nadele vir die gebruik van hierdie stoele in kantore na vore laat kom. Alhoewel die meeste deelnemers die stoele met vorentoe hellings bo hul gewone stoele verkies het, is die beskikbare gegewens nie genoeg om die verskil in reaksie op grond van die persoon, beroep, antropometrie of ergo- nomie te verduidelik nie. 'n Meer kliniese georienteerde ondersoek blyk nodig te wees. I N T R O D U C T I O N I n a p r e v io u s a r ti c l e ' s o m e p r e li m in a r y d a t a w e re p r e s e n te d c o n c e r n in g t h e a c c e p ta b ility o f a f o r w a r d s lo p i n g c h a i r w h e n u s e d by s e d e n ta r y w o r k e r s w ith a h i s t o r y o f lo w e r b a c k p a in . T h e p r e s e n t a r tic l e s u m ­ m a ris e s d a t a f r o m th e c o m p le te d tria l. T h e r a ti o n a l e f o r th e u se o f f o r w a r d in g s lo p in g c h a irs h a s b e e n d is c u s s e d e ls e w h e r e .1 H o w e v e r, th e a s s e r tio n t h a t s u c h c h a ir s m a y h a v e b e n e fic ia l c o n s e q u e n c e s fo r s u f f e r e r s f r o m lo w e r b a c k p a in e n g a g e d in s e d e n ta r y o c c u p a tio n s , h a s re c e iv e d little e m p ir ic a l s u p p o r t . A d d i- 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. ) 86 Fisioterapie, A u g u s tu s 1986, deeI 42 no 3 AKRON Therapy products from Medical Distributors (Pty) Ltd 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. ) Physiotherapy, A u g u s t 1986, vol 42 no 3 87 Fig. F o rw a r d slo p in g chair u se d in th e stu d y . t i o n a l l y t h e s u i t a b i l i t y o f s u c h c h a i r s f o r d a i l y u s e is n o t wel l d o c u m e n t e d . T h e p u r p o s e o f t h e p r e s e n t i n v e s t i g a t i o n w a s t o t e s t t h e h y p o t h e s i s t h a t u s e o f s u c h c h a i r s w o u l d l e a d t o r e d u c t i o n i n l o w e r b a c k d i s c o m f o r t a n d t o d o c u m e n t u s e r s ’ p e r c e p t i o n s o f t h e c h a i r in t h e c o n t e x t o f t h e i r d a i l y w o r k i n g a c t i v i t i e s . M E T H O D T h e g e n e r a l a p p r o a c h w a s d e s c r i b e d b y B r i d g e r . ' A d d i t i o n a l p o i n t s t o b e n o t e d a r e a s f o l l o w s : 1. E a c h p a r t i c i p a n t i n t h e t r i a l s a t o n t h e f o r w a r d s l o p i n g c h a i r f o r t w o p e r i o d s o f I m o n t h , i n t e r s p e r s e d w i t h t w o m o n t h l y p e r i o d s o f s i t t i n g o n t h e i r u s u a l c h a i r s . I n t e r v i e w s w e r e h e l d a t e a c h c h a n g e o v e r p e r i o d a n d a t t h e b e g i n n i n g o f t h e t r i a l — a t o t a l o f 5 i n t e r v i e w s w e r e h e l d w i t h e a c h p a r t i c i p a n t . 2. A t o t a l o f 35 o f f i c e w o r k e r s p a r t i c i p a t e d i n t h e e v a l u a t i o n . T a b l e l s u m m a r i s e s t h e i r p e r s o n a l c h a r a c t e r i s t i c s . T h e e s t i m a t e d d u r a t i o n o f b a c k p a i n r a n g e d f r o m 3 m o n t h s t o 25 y r s ( m e a n = 9 , 7 y e a r s ) . 7 7 % o f t h e s a m p l e h a d s o u g h t t r e a t m e n t f r o m d o c t o r s , s u r g e o n s o r p h y s i o t h e r a p i s t s . T h e n u m b e r o f v i s i t s T a b le I. P e rso n a l C h a ra c te ris tic s o f th e sa m p le o f lo w er back p a in su ffe re rs M a les F em ales Age yrs mean 4 1,9 43,0 s.d. 14,3 11,2 S t a t u re cms mean 176,6 163,0 s.d. 7,3 7,6 Weight kgs mea n 73,9 58,5 s.d. 10,6 11,0 N u m b e r of subjects 7 28 PELVIC TILT CHAIR • Three m odels for d iffe re n t w ork heights, from office desk to drawing board to bank counter. • Maintains healthy posture. • Reduces fatigue in standing o c c u ­ pations, e.g. tellers, draughtsmen. • Provides com fortable seating posi­ tion whilst working. R. J. Projects, P.O. Box 33803, Jeppestown, 2043, Johannesburg. (011) 839-2009 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. ) 88 Fisioterapie, A u g u s tu s 1986, dee! 42 no 3 r a n g e d f r o m I to 30 ( m e d i a n = 5). A l t h o u g h d e ta ile d d i a g n o s ti c d a t a w e re n o t o b ta in e d , th e r e a p p e a r e d to b e t h r e e g e n e r a l g r o u p s . G r o u p 1 (5 s u b je c t s ) h a d h a d se v e re p r o b le m s t r e a t e d b y s u rg e ry . G r o u p 2 (14 s u b ­ je c ts ) h a d s im ila r p r o b le m s (e.g . l u m b a r d is c d e g e n e r a ­ tio n , c h r o n ic p a in a fte r c a r a c c id e n ts ) w h ic h w e re t r e a te d b y n o n - s u r g i c a l m e a n s . G r o u p 3 (1 6 s u b je c ts ) w e re la rg e ly u n d i a g n o s e d a n d h a d s o u g h t a n d re c e iv e d little o r n o t r e a tm e n t. P roced u re T h e s a m p le w a s d iv id e d in to 3 m a in g r o u p s — a m a n a g e r i a l g r o u p ( f o r e x a m p l e , p r o f e s s o r , n u r s i n g a d m i n i s t r a t o r , m e d ic a l s u p e r in te n d e n t ) , a s e c r e ta r ia l/ c le ric a l g r o u p ( f o r e x a m p le , s e c re ta r y , ty p is t, c le rk ) a n d a p r o f e s s i o n a l / t e c h n i c a l g r o u p (f o r e x a m p le , c y to lo g is t, c o m p u t e r p r o g r a m m e r , p a th o lo g is t) . A t th e b e g in n i n g o f th e in v e s ti g a ti o n , p a r ti c i p a n ts w e re a s k e d to e s tim a te th e n u m b e r o f h o u r s th e y s p e n t s i ttin g in a t y p ic a l w o r k in g d a y . A t e a c h s u b s e q u e n t in te rv ie w , th e y w e re a s k e d to m a k e a s im ila r e s tim a te o f th e a m o u n t o f tim e th e y h a d s p e n t s i ttin g o n th e c h a i r in q u e s tio n o v e r th e p re v io u s m o n th . A s w ell as in d ic a ti n g c h a i r u s a g e , th is q u e s t io n w a s a s k e d in o r d e r t o o b t a i n d a t a o n a n y c h a n g e s in w o r k r o u t in e w h ic h m a y h a v e s y s te m a tic a lly i n flu e n c e d b a c k d i s c o m f o r t. R E S U L T S T h e m e a n v a lu e s o f e s tim a te d d u r a t i o n o f s ittin g w e re as fo llo w s: 1. M a n a g e r ia l/ A d m in is tr a t iv e w o rk e rs : 5,6 h r s / d a y 2. S e c r e t a r i a l/ C l e r i c a l w o rk e rs : 6,6 h r s / d a y 3. P r o f e s s io n a l /t e c h n i c a l w o rk e rs : 5,2 h r s / d a y T h e d iffe re n c e in e s tim a te d s ittin g d u r a t i o n w e re s ta tis tic a lly s ig n if ic a n t a c r o s s g r o u p s ( K r u s k a l- W a llis s ta tis tic = 7,31 p < 0 ,05). G r o u p I p a r t i c i p a n ts w e re re la tiv e ly u n c o n s t r a i n e d , e n g a g in g in a v a r ie ty o f d e s k - b o u n d a c tiv itie s ( r e a d in g , w ritin g , c o n v e r s a tio n ) , th o s e in G r o u p 2 w e re m o re c o n s t r a in e d , s p e n d in g m o s t o f th e ir tim e d o i n g a lim ite d n u m b e r o f s p e c ifie d ta s k s (ty p in g , r e p e titiv e c le ric a l o p e r a tio n s ) a n d t h o s e in G r o u p 3 w e re ty p ic a lly e n g a g e d in ta s k s in v o lv in g a h ig h d e g re e o f p o s t u r a l a n d v is u a l c o n s t r a i n t ( f o r e x a m p le , u s in g a m ic r o s c o p e o r v is u a l d is p la y u n it). T h r o u g h o u t th e e v a lu a tio n p e r io d , th e e s tim a te s o f d a ily s ittin g tim e d id n o t c h a n g e s ig n ific a n tly . T h e m e a n e s tim a te s ( o v e r a ll g r o u p s ) w e re 5 ,4 a n d 5,1 h o u r s / d a y f o r t h e f i r s t a n d s e c o n d m o n th s o f u s in g th e f o r w a r d s lo p in g c h a i r a n d 5,0 a n d 5 ,2 h o u r s / d a y f o r th e u s u a l c h a ir s ( F r i e d m a n c h i- s q u a r e = 2 ,1 9 , p > 0 ,0 5 ). L o w b ack p ain D a t a w e re o b ta i n e d f r o m th e p a i n / d i s c o m f o r t ra tin g s p l a c e d b y p a r t i c i p a n ts in th e l u m b a r a n d s a c ro - ilia c re g io n s o f th e b o d y d ia g r a m s (T a b le 2). R a ti n g s w ere r e c o r d e d , a t in te rv ie w , a f te r e a c h m o n th ly p e r io d o f s ittin g , y ie ld in g a t o ta l o f 4 b a c k p a i n / d i s c o m f o r t d a ta se ts, 2 f o r e a c h ty p e o f c h a ir. T h e ra tin g s w e re c o m b in e d o v e r b o t h m o n th s a n d b a c k p a i n / d i s c o m f o r t w as c o m ­ p a r e d a c c o r d in g to th e c h a i r t y p e u s e d , u s in g th e W il c o x o n m a t c h e d p a ir s , s ig n e d r a n k s te s t. A Z v a lu e o f 4 ,0 4 (p < 0 ,0 1 , 2 -ta ile d ) in d ic a te d t h a t th e ra tin g s w e re lo w e r o n th o s e o c c a s io n s w h e n th e f o r w a r d s lo p in g c h a i r w as u se d . A s i m ila r a n a ly s is o f th e r a ti n g s o f b a c k d is c o m f o r t o u ts id e o f w o r k in g h o u r s y ie ld e d a Z v a lu e o f 2 ,1 0 (p < 0 ,0 5 , 2 - ta ile d ) , a g a in i n d ic a ti n g less p a i n / d i s c o m f o r t in th e m o n th s w h e n th e f o r w a r d s lo p in g c h a i r w a s u se d . R e f e r e n c e to T a b l e 2 in d ic a te s t h a t r a tin g s w e re lo w e r in t h e s e c o n d m o n t h o f u s e in th e c a s e o f b o t h c h a ir s . A n a n a ly s is w as u n d e r ta k e n to t e s t th e s ig n ifi­ c a n c e o f th is . N o n - s ig n if ic a n t re s u lts w e re o b t a i n e d f o r b o t h c h a i r t y p e s f o r b a c k p a in d u r i n g a n d o u ts id e w o r k in g h o u r s . T h e r a ti n g sc a le ra n g e d f r o m 1 to 7 ( s lig h t d i s c o m f o r t to u n b e a r a b le p a in ) . A ll o f th e m e a n r a tin g s in T a b le 2 a re v e ry lo w a n d th e d iffe re n c e s b e tw e e n th e m e a n s a re n o t la r g e in te r m s o f th e r a ti n g s c a le . F u r t h e r a n a ly s is re v e a le d t h a t , o f t h e 35 p a r t i c i ­ p a n t s , 20 r e p o r t e d a r e d u c t i o n in lo w e r b a c k p a i n / d i s ­ c o m f o r t in o n e o r b o t h o f th e m o n th s w h e n th e f o r w a r d s lo p in g c h a i r w a s u s e d . In 8 c a s e s n o d iffe re n c e s w e re r e p o r t e d a n d in t h e r e m a in in g c a s e s , lo w e r b a c k p a in / d is c o m f o r t w a s m o r e se v e re w h e n th e f o r w a r d s lo p in g c h a i r w a s u se d . F u r t h e r a n a ly s is w a s u n d e r ta k e n in T a b le 2. M e a n levels o f b a c k p a in /d is c o m f o r t o v e r th e e v a lu a tio n p e rio d F o rw a r d s lo p in g ch a ir U sual chair F irst m o n th S e c o n d m o n th F irst m o n th S e c o n d m o n th S ittin g a t w o rk 0,51 0,40 1,60 1,11 O u tsid e o f w o rk 0,92 0,78 1,44 1,08 T a b le 3. A n a ly sis o f p a r tic ip a n ts ’ ra tin g s o f lo w e r b a c k d isc o m fo rt w h en s ittin g ( ra tin g s a v e ra g e d o v e r b o th m o n th ly sittin g p e rio d s o n e ach c h a ir). D a ta w ere a n a ly se d by o c c u p a tio n a n d th e n by b a c k h isto ry A n a ly s is b y F o rw a r d S lo p in g U sual N u m b e r o f O ccu p a tio n C hair C hair su b je c ts Sig n ific a n c e G ro u p 1 0,6 1,6 16 p < 0,025 G ro u p 2 0,3 1,2 13 p < 0 , 0 1 G ro u p 3 0,3 1,8 6 p < 0,025 A nalysis by b ack h isto ry G ro u p 1 1,3 2,6 5 p > 0,05 G ro u p 2 0,6 1,3 14 p < 0,025 G ro u p 3 0,4 1,7 16 p < 0 , 0 1 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. ) Physiotherapy, A u g u s t 1986, vol 42 no 3 89 o r d e r to d e te r m in e w h e t h e r th e s e d if f e r e n t r e s p o n s e s w e re a s s o c ia t e d w ith o c c u p a ti o n o r b a c k h i s t o r y . T a b le 3 s u m m a ris e s th e re s u lts . In a ll g r o u p s , r a tin g s w ere lo w e r s u b s e q u e n t t o th e f o r w a r d s lo p in g c h a i r h a v in g b e e n u se d . In a ll b u t o n e in s ta n c e , th is w a s s ta tis tic a lly sig n ific a n t. R a ti n g s o f lo w e r b a c k p a i n / d i s c o m f o r t e x p e r ie n c e d w h e n s it tin g a t w o r k a n d a t o t h e r tim e s , w e re lo w e r in th e m o n th s w h e n t h e f o r w a r d s lo p in g c h a i r w a s u se d . H o w e v e r , s o m e o f th e p a r ti c i p a n t s d id n o t e x p e rie n c e th e s e r e d u c t io n s . T h e s e i n d iv id u a ls d id n o t a p p e a r to be d is tr ib u t e d s y s te m a tic a lly in to a n y p a r t i c u l a r o c c u p a ­ tio n a l o r b a c k h is to r y g r o u p . A n a ly s is o f p a r t i c i p a n t s ’ s p o n t a n e o u s c o m m e n ts re v e a le d t h a t 12 in d iv i d u a ls a t t r i b u t e d p e r c e iv e d r e d u c ­ tio n s in lo w e r b a c k p a i n / d i s c o m f o r t d ir e c tly to u se o f th e f o r w a r d s lo p i n g c h a i r a n d t h r e e o f th e s e id e n tifie d th e i r u s u a l c h a i r as a c a u s e o f b a c k p a in . E R G O N O M I C A S P E C T S O F T H E F O R W A R D S L O P IN G C H A I R 1. C o m fo r t 29 s u b je c ts s t a te d t h a t th e f o r w a r d s lo p in g c h a i r w as c o m f o r t a b l e . T a b le 4 s h o w s th e g e n e r a l b o d y a r e a s in w h ic h p a r ti c i p a n t s e x p e r ie n c e d d i s c o m f o r t w h e n s ittin g . F o r th e f o r w a r d s lo p in g c h a ir, d is c o m f o r t w as fre q u e n tly o b s e r v e d in t h e lo w e r l e g s /k n e e s . A p a s t h i s t o r y o f k n e e i n ju r y w a s o f te n m e n ti o n e d in c o n ju n c t io n w ith c o m p l a in t s o f k n e e d i s c o m f o r t. F o r t h e c o n v e n t i o n a l c h a ir s , th e lo w e r b a c k w a s th e site o f m o s t o f th e d is c o m f o r t. A ls o 3 s u b je c ts h a d v a r ic o s e v e in s in th e lo w e r legs a n d f e lt th is t o be a m a j o r d is a d v a n t a g e w h e n u s in g th e f o r w a r d s lo p in g c h a ir. K n e e i n ju r y a n d lo w e r lim b c ir c u la tio n p r o b le m s m a y c o n tr a - in d i c a t e th e g e n e r a l u s e o f th is ty p e o f c h a ir. M o r e d a t a w o u ld a p p e a r to be r e q u ir e d . 2. P o stu r e T h e m o s t f r e q u e n t ly e n c o u n t e r e d c o m m e n t p e r ta in i n g to th e f o r w a r d s lo p in g c h a i r w a s t h a t it e n a b le d u s e rs to sit w ith a n u p r i g h t p o s t u r e . T h e k n e e lin g p o s tu r e w a s c o m m e n te d o n f a v o u r a b l y b y 2 u s e r s a n d 5 u s e rs d is lik e d th e lo w e r lim b c o n s t r a i n t w h ic h a c c o m p a n ie s th e u se o f t h is ty p e o f c h a ir. T a b le 4. P a in /d is c o m f o r t by a n a to m ic a l region* F o r w a r d S lo p in g U sual C hair C hair N e c k /s h o u ld e rs 5 11 U p p e r arm s 0 2 T h o ra c ic spine 4 6 L u m b a r sp in e /s a c ro -ilia c region 19 36 B u tto ck s 2 0 T h ig h s 3 6 K nees 11 0 L o w er legs 3 2 F eet 2 5 3. W o r k sp a ce D e s ig n and A n th r o p o m e tr y In o r d e r t o e v a l u a te th e a r r a n g e m e n t o f th e e x is tin g w o r k p la c e s , th e d iffe re n c e b e tw e e n th e a n th r o p o m e t r i c d i m e n s i o n s o f u s e rs a n d th e c o r r e s p o n d i n g w o r k p la c e d im e n s io n s w e re c a lc u la te d . T h e fo llo w in g c r it e r i a w e re u se d : 1. A d e q u a c y o f f o o t / f l o o r c o n ta c t w h e n s ittin g o n th e c h a ir : P o p l i t e a l h e ig h t (w ith s h o e s ) — s e a t h e ig h t ( P H S ) 2. A d e q u a c y o f b a c k s u p p o r t: B u t to c k - k n e e le n g th — s e a t d e p th (B K S ) 3. D e s k w o r k c a n be c a r r i e d o u t w h e n s it ti n g e re c t w it h o u t f le x in g e lb o w s o r e le v a tin g th e s h o u ld e rs : S it tin g e lb o w h e ig h t — ta b le h e ig h t (S E T ) 4. M in im u m v is u a l d is ta n c e w h e n s it tin g e re c t: S it ­ tin g eye h e ig h t — ta b l e h e ig h t ( S E H ) . T a b l e 5 s u m m a r i s e s th e r e s u lts o f t h is a n a ly s is . In 74 % o f th e c a s e s th e s e a t h e ig h t w a s f o u n d to b e g r e a te r t h a n th e p o p lite a l h e ig h t ( w i th s h o e s ), s u g g e s tin g t h a t th e s e u s e r s w o u ld b e a b le t o r e s t t h e i r f e e t c o m f o r t a b l y o n th e f l o o r o n ly b y e x e r tin g e x c e ss p r e s s u r e o n th e p o s t e r io r a s p e c t o f t h e th ig h o r b y s ittin g o n th e e d g e o f th e s e a t a n d p o in tin g th e t h ig h s d o w n w a r d s . In 3 0 % o f c a s e s, th e s e a t d e p t h w a s g r e a te r t h a n th e b u t to c k - k n e e le n g th m a k i n g a p p r o p r i a te u se o f th e b a c k r e s t d iffic u lt. In 7 1% o f c a s e s , s i ttin g e lb o w h e ig h t w a s less t h a n th e h e ig h t o f th e ta b le . R e f e r e n c e to ty p ic a l e r g o n o m ic s g u id e lin e s f o r f u r n i ­ t u r e d e s ig n in d ic a te d t h a t t h e c o n v e n t io n a l f u r n i tu r e w a s , in g e n e r a l, p o o r ly c o n fig u r e d . T a b le 5. A n aly sis o f disc re p a n c ie s b etw een u se r a n th ro p o m e try a n d c o rre sp o n d in g w o rk sp a c e d im en sio n s* M e a n s.d. ra n g e P H S - 2 ,4 4,7 -1 3 t o + 1 5 B K S 5.6 6.6 - 7 t o + 1 5 S E T -2 ,3 3,9 -11 to + 6 S E H 48,1 5,4 + 3 6 to + 5 6 D a ta in c e n tim e tre s Since all p a r tic ip a n ts sa t o n b o th c h a irs tw ice, th e re w ere 70 p o ssib le p a r tic ip a n t re c o rd in g o c c a s io n s. D a t a a re th e to ta l n u m b e r o f re sp o n se s fo r b o th o ccasio n s. 4. S u b je ctiv e c o m m e n ts c o n c e r n in g e r g o n o m ic s and chair d esig n N o c o n s e n s u s w a s a p p a r e n t in t h e c o m m e n ts a b o u t th e f o r w a r d s lo p in g c h a ir . M o s t o f th e c o m m e n ts w e re p o s itiv e , h o w e v e r. T h e m a jo r ity o f c o m m e n ts c o n c e r n in g th e c o n v e n t i o n a l c h a ir s w e re n e g a tiv e , th e s e a ts b e in g p e rc e iv e d as t o o h ig h a n d t o o d e e p a n d t h e b a c k s u p p o r t i n a d e q u a te . T h is is c o n s is te n t w ith th e r e s u lts o f th e a n a ly s is in th e p re v io u s s e c tio n . 5. U s a b ility T h is c a t e g o r y w a s in t r o d u c e d to in c lu d e c o m m e n ts p e r ta i n i n g t o th e u se o f th e c h a i r in c a r r y in g o u t o ffice ta s k s . T a b le 6 s u m m a r is e s th e in c id e n c e o f th e s e s p o n ­ t a n e o u s c o m m e n ts . A l a r g e r n u m b e r o f p o s it iv e c o m m e n ts w e re m a d e a b o u t th e f o r w a r d s lo p in g c h a ir , th e re v e rs e b e in g tr u e f o r th e c o n v e n t io n a l c h a ir s . F o r th e f o r w a r d s lo p in g c h a i r , th e m o s t f r e q u e n t c o m m e n t c o n c e r n e d m a n o e u v ­ r a b ili ty . P a r t ic i p a n t s w e re g e n e r a lly n e g a tiv e o r in d if ­ f e r e n t t o t h e ir u s u a l c h a irs . 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. ) 90 Fisioterapie, A u g u s tu s 1986, deel 42 no 3 T a b le 6. C o m m e n ts c o n c e rn in g u sa b ility (n — n u m b e r o f p a rtic ip a n ts p e r item ) F o rw a r d S lo p in g C h a ir U sual C hair P o sitiv e N e g a tive P ositive N e g a tive c o m m e n t c o m m e n t c o m m e n t c o m m e n t M a n o e u v ra b le 21 0 1 0 U n m a n o e u v ra b le 1 0 0 4 S av e sp a ce in office* 7 0 0 0 A ccess to desk 7 5 2 1 In g re s s/e g re s s 2 5 2 1 Use o f “d ic ta p h o n e ” pedals** 0 2 0 0 C a n ’t h a n g ja c k e t o n b a c k re st 0 2 0 0 E n h a n c e d reach 2 0 0 0 T o ta l C o m m e n t 40 9 4 12 * C h a ir m a y be sto w e d u n d e r desk w hen n o t in use. ** T y p ists only. 6. P referen ce U s e r s ’ p r e fe r e n c e s in o ffic e s e a tin g a t th e e n d o f th e t r ia l w e re a s f o llo w s : 6 3% o f th e s a m p le p r e fe r r e d th e f o r w a r d s lo p in g c h a ir , a f u r t h e r I l % p r e f e r r e d th e f o r w a r d s lo p in g c h a ir w ith m o d if ic a tio n (ty p ic a lly , a f l a t t e r s e a t a n d / o r a b a c k r e s t ) , 8 % p r e f e r r e d t h e i r e x is tin g c h a ir s , 11% p r e f e r r e d s o m e o t h e r ty p e o f c o n ­ v e n tio n a l c h a ir ( ty p ic a l d e s ire d fe a tu r e s in c lu d e d c a s to r s a n d a s w iv e llin g s e a t w h e re th e s e w e re n o t p r e s e n t ) a n d 7% h a d n o p r e fe re n c e f o r a n y c h a ir . D I S C U S S I O N C a u tio n s h o u ld b e e x e rc is e d in i n te r p r e ti n g th e r e s u lts o f th is t r ia l . C le a r ly , i n a d e q u a c i e s in th e e x is tin g w o r k ­ p la c e s a re lik e ly t o h a v e in flu e n c e d th e re s u lts . A ls o , it is a r g u a b l e t h a t t h o s e u s e rs w h o f o u n d th e c h a ir a c c e p t ­ a b le m a y h a v e a c c e p te d a n in c re a s e in lo w e r lim b d is c o m f o r t b e c a u s e o f th e r e d u c tio n in lo w e r b a c k p a in . I f th is w a s th e c a s e , th e s e c h a ir s m a y b e less a c c e p ta b le to u se rs w h o d o n o t s u ffe r f r o m lo w e r b a c k p a in . H o w e v e r, th e re s u lts o f th e m a in p a r t o f t h e in v e s tig a ­ tio n w o u ld s u g g e s t t h a t th e c h a ir in v e s tig a te d m e rits f u r t h e r a t t e n ti o n r e g a r d i n g its u se in o ffic e s e ttin g s , p a r t i c u l a r l y a m o n g s t s e d e n t a r y u s e r p o p u l a t i o n s in w h ic h lo w e r b a c k p a in is p r e v a le n t. A n u m b e r o f th e u s e r s ’ c o m m e n ts a re w o r th y o f d is c u s s io n . G e n e ra lly , m o re c o m m e n ts w e re m a d e a b o u t th e f o r w a r d s lo p i n g c h a ir t h a n a b o u t t h e c o n v e n tio n a l c h a ir s . P a r t ic i p a n t s w e re o f te n i n d if f e r e n t o r n e g a tiv e w h e n d is c u s s in g th e l a tte r . I n v iew o f th e r e s u lts o f th e e r g o n o m ic a n a ly s is a n d t h e n o v e lty o f th e f o r w a r d s lo p in g c h a ir s , th is is n o t s u rp ris in g . F o u r p a r t i c i p a n t s s t a te d t h a t a b a c k r e s t w a s u n n e c e s ­ s a r y w h e n u s in g t h e f o r w a r d s lo p in g c h a ir , a s o p p o s e d to o n e p a r t i c i p a n t w h o f e lt t h a t it w a s n e c e s s a r y . W h e t h e r o r n o t a b a c k r e s t is o r is n o t r e q u ir e d is b e y o n d th e s c o p e o f th is d is c u s s io n . H o w e v e r , th e p r o v is i o n o f a b a c k r e s t o n a n y c h a ir h a s d e m o n s tr a b l e p o s t u r a l a n d b io m e c h a n i c a l c o n s e q u e n c e s a n d th e r e la ­ tiv e p a u c i ty o f c o m m e n t o n th is m a t t e r is s o m e w h a t s u rp r is in g . T h e r e s u lts o f th e e r g o n o m ic a n a ly s is c o m p lic a te th e i n te r p r e t a ti o n o f th e b a c k p a i n / d i s c o m f o r t d a t a , sin c e th e o b s e r v e d r e d u c t io n s in d i s c o m f o r t m ig h t be a t t r i ­ b u te d to im p r o v e m e n t s o f a n e r g o n o m ic n a tu r e d u e to d e s ig n a s p e c ts o f th e f o r w a r d s lo p in g c h a i r o t h e r th a n th e f o r w a r d s lo p in g se a t. I f t h is w e re th e c a s e , it m ig h t b e h y p o th e s iz e d t h a t s im ila r r e d u c tio n s in d i s c o m f o r t m ig h t b e o b t a i n a b le u s in g c o n v e n t io n a l f u r n i tu r e w h ic h a ls o o v e r c o m e th e s e d e fic ie n c ie s . T h is m a t t e r is o p e n to in v e s tig a tio n . S o m e e v id e n c e f o r th e e x is te n c e o f t h e “ a d ju s tm e n t p e r i o d ” r e p o r te d b y D r u r y a n d F r a n c h e r 2 w a s o b t a in e d . A n u m b e r o f u s e rs , w h o e v e n tu a ll y f o u n d th e c h a ir a c c e p ta b le , in itia lly e x p e r ie n c e d a g g r a v a ti o n o f lo w e r b a c k s y m p t o m s a n d lo w e r lim b d is c o m f o r t . T h e d u r a ­ t io n o f th is p e r io d w a s ty p ic a lly o n e t o tw o w e e k s a n d it o n ly o c c u r r e d in th e f ir s t m o n th o f u s in g th e f o r w a r d s lo p i n g c h a ir . T h e p r e s e n t d a t a d o n o t e n a b le th e s e in d iv i d u a ls t o b e d is tin g u is h e d f r o m t h o s e w h o d id n o t e x p e r ie n c e th e a d ju s tm e n t p e r io d . C O N C L U S I O N S T h e f in d in g s o f th e p r e s e n t in v e s tig a tio n s u g g e s t t h a t th e f o r w a r d s lo p i n g c h a i r is lik e ly to b e r e g a r d e d as a c c e p ta b le a n d c o m f o r ta b le by a w id e ra n g e o f s e d e n ta ry w o r k e r s . H o w e v e r, th e d a t a a ls o s u g g e s t t h a t th e r e a re f a c t o r s w h ic h m a y c o n tr a - in d i c a t e th e u se o f t h is ty p e o f c h a i r b y c e r t a i n in d iv i d u a ls . T h e p r e s e n t s a m p le is t o o s m a ll to e n a b l e f ir m c r i t e r i a to b e e s ta b lis h e d , a l t h o u g h th e p re s e n c e o f lo w e r lim b a ilm e n ts w o u ld a p p e a r to be a n i m p o r t a n t c o n s i d e r a tio n . In th is in v e s ti­ g a t i o n , v a r ic o s e v e in s a n d p r e v io u s in ju r y to th e k n e e s w e re a s s o c ia te d w ith p re fe re n c e f o r c o n v e n tio n a l se a tin g . ̂ A d d i tio n a l ly , f o r s o m e u s e rs , th e r e w a s a n a d ju s tm e n t p e r io d o f u p to tw o w e e k s , d u r i n g w h ic h tim e th e s e v e rity o f s y m p to m s in c re a s e d . D e s p ite th e s e o b s e r v a tio n s , th e m a in b o d y o f d a t a in d ic a te s t h a t c h a ir s b a s e d o n th is d e s ig n c o n c e p t w a r ­ r a n t th e a tt e n t i o n o f th o s e c o n c e r n e d w ith th e m a n a g e ­ m e n t o f c h r o n ic s e d e n ta r y lo w b a c k p a in s u ffe re rs . A c k n o w le d g e m e n t T h is w o r k w a s s u p p o r t e d b y th e M e d ic a l R e s e a rc h C o u n c il o f S o u t h A f r ic a a n d D r H y m a n G o ld b e rg . R e fe re n c e s 1. B rid g er R S . A re you sittin g c o m fo rta b ly ? U sers’ percep tio n s o f a P elv ic T ilt C h a ir. S o u th A fr ic a n J o u r n a l o f P h y s io ­ th e r a p y 1985; 41(4): 110-115. 2. D r u ry C G a n d F ra n c h e r M . E v a lu a tio n o f a F o rw a rd S lo p in g C h a ir. A p p lie d E rg o n o m ic s 1985; 16(1): 41-47. 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. )