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Lower-limb influence on sitting balance while reaching forward
730
Lower-limb Influence on Sitting Balance While Reaching Forward Vinjamuri
R. Chari, MD, R. Lee Kirby, MD
Division of PM&R,
Dalhousie
Univer.si&. Haiifus,
Nova Scotia, Canada B3H 4K4
ABSTRACT. Chari VR, Kirby RL: Lower-limb influence on sitting balance while reaching forward. Arch Phys Med Rehabil 67:730-733, 1986. l To test the hypothesis that the lower limbs contribute to sitting balance when a person reaches forward, we measured the limits of forward reach in 20 healthy volunteers. While sitting on the buttocks alone (ischial support) or with the thighs also supported and with both feet on, one foot off, or both feet off the floor (in a balanced order), each subject reached as far forward as possible at table height at 0, 15, 30, and 45” to the sagittal plane. With full thigh support the reaches at all angles were greatest with both feet on the floor, and decreased progressively with one foot off (when reaching toward the foot off the floor) and both feet off. Thigh support permitted significantly greater reach than ischial support at all angles with both feet off the ground, but not in other settings. These results have implications for seat design and when considering prostheses for patients unlikely to walk. KEY WORDS: Amputees;
Biomechanics;
Leg
For patients with lower-limb amputations who cannot walk, prostheses are usually considered cosmetic.‘.” as aids in transferring from one position to another, or as passive counterweights for wheelchair balance. ’ ’ 1I2 However. a wheelchair basketball player with bilateral above-knee amputations pointed out to us that his prostheses allowed him to lean farther forward when retrieving the ball or while rapidly propelling his wheelchair. This observation led us to speculate that the lower limbs or their prosthetic replacements might contribute to sitting balance in other forward-leaning tasks. Such a contribution to stability could be explained as an enlargement of the base of support9 The only reports we could find that have looked at the impairment of sitting balance of amputees have been in patients with paraplegia, in whom the amputations were performed for pressure sores or to eliminate the “cumbersome lower extremities.“* Most groups have noted at least some adverse effects of amputations on function, although all such reports have been anecdotal.7.3.7.x.‘6 The object of this study was to test the hypothesis that the lower limbs contribute to sitting balance when a person reaches forward, and to determine the extent of the contribution of one or both legs, in the presence or absence of thigh support.
METHODS Subjects. We studied 20 healthy volunteers.
IO men and IO women, with a mean ( t SD) age of 32.7( + 11.2) years, height of 167.3( ?6.8)cm and weight of 66.6( 2 15.9)kg. The single arm span, measured from the sternal notch to the tip of the long finger, was 85.3( ~3.8)cm. Subject positioning. We measured forward reach at table height as an important and representative situation with which all subjects would be familiar. Table-height reach has been the subject of earlier investigations by those interested in ergonomics’ ~10~14~1x and in the abilities of spinal-cord-injured patients.“,6 The seat height was 42.5cm’4.‘X and the table height Arch Phys Med Rehabil Vol 67, October 1966
Fig l-Setup for forward-reach testing. The two seating positions are shown, thigh and ischial support to 7.5 and 25cm behind the knees, respectively.
69cm.J,s,‘3,‘5 A constant foot angle of 13” and an interheel distance of 15cm were used, based upon a preliminary study on all subjects, which established that while sitting comfortably the mean angle of each foot with the sagittal plane was 1I .7(-t 9)” and the mean distance between the heels was 17.2( _t3.5)cm. The zero point for forward-reaching distance was in the midline and 30cm behind the heels at a point which approximated the pubic symphysis. Each subject sat barefoot with the lower legs vertical, and in each of two sitting positions-with 7.5cm4.r3.” and 25cm from the back of the knees to the edge of the seat, the thigh-support and ischial-support positions, respectively (fig 1). Procedure. In both thigh- and ischial-support positions we tested subjects with both feet on the floor, one foot off the floor (both left and right were studied in each subject), and both feet off the floor, in a balanced order. Each subject used a vertically held marking pen to mark the outer limits of reach Presented at the combined annual meetmgs of the American Academy Medicine and Rehabilitation and the American Congress of Rehabilitation Kansas City. MO. September 30. 1985.
of Phvwal Medkine.
SITTING BALANCE, Chari
731
Thigq Support &1
60-
40-
zo-
450
0
/i-
(4 /' .'/ /'/ *i/ / .'// / ,.;/ // /s; 00
ANGLE OF REACH Fig
Ix hial Smport
150 ANGLE OF REACH
I!----Forward-reach values (8+ ISD): left. with both feet on the ground and right, with both feet off lthe ground.
w
j’ Reach toward the tc;ot 1M s OI Reach toward the foot th,lt‘s ot’
1
_
Ti
I
!
/
‘/--
/’ /
+I/
I,?, / /’ / / /’ / / // / // , , ’ / /’
’
150 ANGLE .-Forward-reach
values (x+
I’ /
,’
/‘/, ’ /’
/
/
,’
‘/
,
,
I’
/’
’ i
/’
/’ , , / /
‘/
/
,,’
300 OF REACH
’
/’ ,/ 1
/’/ / , f/,,’
/’
/’
/’
///,
/
/i
,/ /
,/;,,
‘/
/’ /
,’ ,’
,/
I’
/
_
‘/’
,
i 450
I /‘/
,’
,,’/ /’ >’ I’
I
/,‘,,
Fig
’ /’
i
I
s’ .f
,’
*’ /
7
I /
,
//
T
~
I
I
T
A
I.50 ANGLE
,’
I / ,’ , ,I’
300
OF REACH
LSD) when one foot was off the ground: left. with thigh support and right, with ischial support.
Arch Phys Med Rehabil
Vol67,
October 1966
SITTING BALANCE, Chari
732
RESULTS
Forward Reach While Sitting* Reach angle, degrees Both feet on R hand
L hand
SD
Mean
SD
99. I 101.8 103.0 103.2 98.7 100.9 103.4 103.3
12.3 11.9 II.1 10.0 11.4 12.3 II.6 II.5
97.0 99.7 101.4 101.6 96.9 98.6 100.8 101.1
I I.2 II.0 10.9 9.7 I I .4 II.3 10.9 9.5
30 45
97.1 99.2 99.4 99.5 95.3 98.5 101.7 102.7
I I.9 Il.3 IO.1 8.8 I I .6 12.0 Il.4 10.9
91.9 99.3 98.2 96.7 94.0 98.2 101.5 102.7
II.1 10.3 8.3 7.0 IO. I Il.1 10.3 9.1
0 15 30 45 0 15 30 45
91.2 100.2 102.0 102.4 91.6 99.0 100.3 100.5
IO.8 10.6 9.8 9.3 10.7 10.8 10.3 8.9
96.9 IO0.X 103.5 104.7 98.2 99.4 98.8 97.3
10.2 IO.1 10.0 9.2 I I.4 IO.4 9.3 7.9
0 15 30 45 0 15 30 45
88.1 90.7 93.1 95.4 87.6 89.6 93.5 95.5
7.9 7.5 1.4 7.6 8.3 x.2 x.3 8.4
69.7 71.6 75.7 80.6 68.3 70.4 75.5 80.9
14.0 13.0 12.6 9.5 I I.5 I I.8 II.8 9.4
I.5 30 45 0
0 15 30 45
L hand 15
L foot off R hand
L hand
Both feet off R hand
L hand
Ischial support
Mean
0
15 30 45 R foot off R hand
Thigh support
*Values. in cm. measured from a zero point 30cm behind the heels, at a point approximating the pubic symphysis.
on the table top at 0, 15, 30. and 4.5” to either side of the sagittal plane, using the hand on that side. The reach was recorded to the nearest O.lcm. An audible signalling device was used to detect when contact between the buttocks and the seat was broken-if this occurred we repeated the test. Subjects were not permitted to lean with their arms on the table, the seat, or their knees. With 10 of the subjects. 5 men and 5 women, we measured the reach at 0” twice with an interval of about 15 minutes. The test-retest reliability of the measure was high (r>0.841. JKO.01). Statistical analysis. After a preliminary determination that there was no consistent and significant difference between reach with the left and right hands, we used an average of left and right values for statistical comparisons when the foot support was symmetrical. When one foot was off the ground we combined the data to provide average values for reach toward the foot off the ground (right foot off, right hand reach and left foot off, left hand reach) and reach toward the foot on the ground (right foot off, left hand reach and left foot off, right hand reach). We used matched-pairs f-tests to compare the reach values of the different sitting and foot support positions. The level of statistical significance was defined as pCO.05. Arch Phys Med Rehabil Vol67,
October 1966
The forward-reaching values are shown in the table. With both feet on the ground (fig 2, left), there was a slight increase in reaching distance from 0 to 45” tp
DISCUSSION The results of our study indicate that the lower limbs contribute to sitting balance during forward reach. The loss of forward reach is greatest with both feet off the ground, particularly when the thighs are unsupported. The magnitude of the contribution of the lower limbs is substantial, amounting to about 30cm difference between both feet on, with thigh support, in comparison with both feet off and ischial support. With one foot off the ground there is a slight diminution of reach, particularly in the direction of the unsupported foot.
AT Oc
BOTH
ONE FOOT ONE FOOT
FEET
OFF
ON
(toward thefoot
OFF
BOTH FEET
(towarc OFF theloot
that15on) lhaiIS011)
Fig 4-Forward-reach values (x+ 1SD) with both feet on, one foot off, and both feet off the ground at 0, 15, 30 and 45”.
SITTING BALANCE, Chari
l‘hc limilationa of thih study were the use of only the table height reacblng ketting. and the small number and normality of the subjects studied. Nevertheless, the forward-reaching values of our subjec~ts approximated those of earlier studies.5.h,‘J.‘X although the te\tin:; circumstances were not directly comparahle Although confirmation ot’ our findings by testmg specific patient populations will be necessary before firm recommendations can be ,lustified. our findings may have some implications for patient :arc. For instance, prosthetic replacement of amputated lower limbs in patients not expected to stand or walk may enhance \itting forward-reach activities. Modifica-tion of the sitting surface to permit better support through the residual limb\ or the use of a seat belt across the lap may be equally effective. This study also suggests the importance ot properly adjusted fbotrests on wheelchairs. not always an easy task for patients such as those with meningomyclocele and ma,lor disproportion in size between the upper and lower body. Our finding’\ may also have significance for the field of ergonomics and seat design at home and at work.“,”
733
3. Conway
H. Stat& RB. Wereter JC‘ (;;Lrcta FA Kavanaugh JI). Complicatmns of decubitus ulcers in prticnts with paraple@;l Plsjt Rcconstr Surp 7: 117 - 130. 1Y.i; I
4. Diffrient N. Tilley .4R. Bardagjy Jc‘. IHumansalr 1!2/3: Poll. folio of Information. Cambridge, MA. hllT Press. 1973
5. Floyd WF. Guttmann
L, Noble CU. of wheelL,hair
of space requirements IY6hi67
0. Goldsmtth S: Dcl\ipning Publications Ltd. 1976
Farkcs KR. Ward J: Stud! u XI \
for the Di!,;tb,:,.I
Par.tpkgia
kd .3 London.
7 Cirundv DJ. Silver JR: M~JUI- amputatloll trapIs&
patients.
Int J Rchabil
in paraplegtc Mcd 6 if>?-162. 1983
and Research. Ed 2. Oxford. 1976. pp 512-542
9 Haye\ KC: Biomechanics Rev 10:%X-39
Blacbwr
of postural
I Ycientit‘ic :clnttol.
Publicattnn\
Excrc
Sport SKI
IO Institute for Consumer Ergonomtch:
Se;& anthropometry: proh Iem5 involved in large scale sune! of dl~\~hled md elderly pco pk. Ergonomics 24:X31-8-1.5. 1981
II
I3 IJ
Loane TD. Kirby RL: Static rear Ltablltty of c.mventtonal Itghtweipht vsriable-3xle-position w.hecIt:hairs Arch Phy\ Rehabil 66: 17&l 76. 1985
Pheasant ST: Anthmpometric Eryonomica 2599% IO01 .
whct’lch:ttr\.
;\rch
anti Mecc
to improve Phy> Me<+
estimates tnr Britistr civilian
adult\.
I982
Roberts DF: Functional anthropoml:tc g~tnomic\ 3:32l-377. I960
1.s Shahnavaz H: Lighting condition, VDII-operators. Ergonomics 25:
1
;md tc
I. I982
\tatic re;u stability of occupied Rrhabil 67:263-266. 1986
1.
RlBn
x Guttmann L: Spinal Cord Injuries: l:‘~miprehrns~vc Managrment
11 Loanc TD. Kirby RL: Lou anterior counterweiqhtb
References Barlila D: t\timation of body measurements ot‘ British population in relation to seat &sign. Ergonomics 4:123-132. IY61 Chabc RA. White WL: Bikral amputation in rehabilitation oi paraplegic\ f’l;t\t Reconstr Surg 24:445455 ( 19W
4:?1-37,
(1’ tide1 I> women.
and workplaci,
Er-
dimension3
ot
I 165.. I 173. 19b2
Ih
Spira M. Hardy SB: Our experiences with high thigh amputations in paraplegics. Plast Rcconstr Sure .31..:~+&353. 1963
17
Van de Ven CMC: Pilot survcv of eldrrl\, bilat-ral amputees. Physiotherapy 59:3 I k311 I. 1%3
IX
Ward JS. Kirk NS: Anthropomctv nomic\ 10: I7-‘7-I. 1967
o* elderly
lower-limb
women.
Arch Phys Med Rohehil Vol 67. October
Ergo-
1986
Lower-limb Influence on Sitting Balance While Reaching Forward Vinjamuri
R. Chari, MD, R. Lee Kirby, MD
Division of PM&R,
Dalhousie
Univer.si&. Haiifus,
Nova Scotia, Canada B3H 4K4
ABSTRACT. Chari VR, Kirby RL: Lower-limb influence on sitting balance while reaching forward. Arch Phys Med Rehabil 67:730-733, 1986. l To test the hypothesis that the lower limbs contribute to sitting balance when a person reaches forward, we measured the limits of forward reach in 20 healthy volunteers. While sitting on the buttocks alone (ischial support) or with the thighs also supported and with both feet on, one foot off, or both feet off the floor (in a balanced order), each subject reached as far forward as possible at table height at 0, 15, 30, and 45” to the sagittal plane. With full thigh support the reaches at all angles were greatest with both feet on the floor, and decreased progressively with one foot off (when reaching toward the foot off the floor) and both feet off. Thigh support permitted significantly greater reach than ischial support at all angles with both feet off the ground, but not in other settings. These results have implications for seat design and when considering prostheses for patients unlikely to walk. KEY WORDS: Amputees;
Biomechanics;
Leg
For patients with lower-limb amputations who cannot walk, prostheses are usually considered cosmetic.‘.” as aids in transferring from one position to another, or as passive counterweights for wheelchair balance. ’ ’ 1I2 However. a wheelchair basketball player with bilateral above-knee amputations pointed out to us that his prostheses allowed him to lean farther forward when retrieving the ball or while rapidly propelling his wheelchair. This observation led us to speculate that the lower limbs or their prosthetic replacements might contribute to sitting balance in other forward-leaning tasks. Such a contribution to stability could be explained as an enlargement of the base of support9 The only reports we could find that have looked at the impairment of sitting balance of amputees have been in patients with paraplegia, in whom the amputations were performed for pressure sores or to eliminate the “cumbersome lower extremities.“* Most groups have noted at least some adverse effects of amputations on function, although all such reports have been anecdotal.7.3.7.x.‘6 The object of this study was to test the hypothesis that the lower limbs contribute to sitting balance when a person reaches forward, and to determine the extent of the contribution of one or both legs, in the presence or absence of thigh support.
METHODS Subjects. We studied 20 healthy volunteers.
IO men and IO women, with a mean ( t SD) age of 32.7( + 11.2) years, height of 167.3( ?6.8)cm and weight of 66.6( 2 15.9)kg. The single arm span, measured from the sternal notch to the tip of the long finger, was 85.3( ~3.8)cm. Subject positioning. We measured forward reach at table height as an important and representative situation with which all subjects would be familiar. Table-height reach has been the subject of earlier investigations by those interested in ergonomics’ ~10~14~1x and in the abilities of spinal-cord-injured patients.“,6 The seat height was 42.5cm’4.‘X and the table height Arch Phys Med Rehabil Vol 67, October 1966
Fig l-Setup for forward-reach testing. The two seating positions are shown, thigh and ischial support to 7.5 and 25cm behind the knees, respectively.
69cm.J,s,‘3,‘5 A constant foot angle of 13” and an interheel distance of 15cm were used, based upon a preliminary study on all subjects, which established that while sitting comfortably the mean angle of each foot with the sagittal plane was 1I .7(-t 9)” and the mean distance between the heels was 17.2( _t3.5)cm. The zero point for forward-reaching distance was in the midline and 30cm behind the heels at a point which approximated the pubic symphysis. Each subject sat barefoot with the lower legs vertical, and in each of two sitting positions-with 7.5cm4.r3.” and 25cm from the back of the knees to the edge of the seat, the thigh-support and ischial-support positions, respectively (fig 1). Procedure. In both thigh- and ischial-support positions we tested subjects with both feet on the floor, one foot off the floor (both left and right were studied in each subject), and both feet off the floor, in a balanced order. Each subject used a vertically held marking pen to mark the outer limits of reach Presented at the combined annual meetmgs of the American Academy Medicine and Rehabilitation and the American Congress of Rehabilitation Kansas City. MO. September 30. 1985.
of Phvwal Medkine.
SITTING BALANCE, Chari
731
Thigq Support &1
60-
40-
zo-
450
0
/i-
(4 /' .'/ /'/ *i/ / .'// / ,.;/ // /s; 00
ANGLE OF REACH Fig
Ix hial Smport
150 ANGLE OF REACH
I!----Forward-reach values (8+ ISD): left. with both feet on the ground and right, with both feet off lthe ground.
w
j’ Reach toward the tc;ot 1M s OI Reach toward the foot th,lt‘s ot’
1
_
Ti
I
!
/
‘/--
/’ /
+I/
I,?, / /’ / / /’ / / // / // , , ’ / /’
’
150 ANGLE .-Forward-reach
values (x+
I’ /
,’
/‘/, ’ /’
/
/
,’
‘/
,
,
I’
/’
’ i
/’
/’ , , / /
‘/
/
,,’
300 OF REACH
’
/’ ,/ 1
/’/ / , f/,,’
/’
/’
/’
///,
/
/i
,/ /
,/;,,
‘/
/’ /
,’ ,’
,/
I’
/
_
‘/’
,
i 450
I /‘/
,’
,,’/ /’ >’ I’
I
/,‘,,
Fig
’ /’
i
I
s’ .f
,’
*’ /
7
I /
,
//
T
~
I
I
T
A
I.50 ANGLE
,’
I / ,’ , ,I’
300
OF REACH
LSD) when one foot was off the ground: left. with thigh support and right, with ischial support.
Arch Phys Med Rehabil
Vol67,
October 1966
SITTING BALANCE, Chari
732
RESULTS
Forward Reach While Sitting* Reach angle, degrees Both feet on R hand
L hand
SD
Mean
SD
99. I 101.8 103.0 103.2 98.7 100.9 103.4 103.3
12.3 11.9 II.1 10.0 11.4 12.3 II.6 II.5
97.0 99.7 101.4 101.6 96.9 98.6 100.8 101.1
I I.2 II.0 10.9 9.7 I I .4 II.3 10.9 9.5
30 45
97.1 99.2 99.4 99.5 95.3 98.5 101.7 102.7
I I.9 Il.3 IO.1 8.8 I I .6 12.0 Il.4 10.9
91.9 99.3 98.2 96.7 94.0 98.2 101.5 102.7
II.1 10.3 8.3 7.0 IO. I Il.1 10.3 9.1
0 15 30 45 0 15 30 45
91.2 100.2 102.0 102.4 91.6 99.0 100.3 100.5
IO.8 10.6 9.8 9.3 10.7 10.8 10.3 8.9
96.9 IO0.X 103.5 104.7 98.2 99.4 98.8 97.3
10.2 IO.1 10.0 9.2 I I.4 IO.4 9.3 7.9
0 15 30 45 0 15 30 45
88.1 90.7 93.1 95.4 87.6 89.6 93.5 95.5
7.9 7.5 1.4 7.6 8.3 x.2 x.3 8.4
69.7 71.6 75.7 80.6 68.3 70.4 75.5 80.9
14.0 13.0 12.6 9.5 I I.5 I I.8 II.8 9.4
I.5 30 45 0
0 15 30 45
L hand 15
L foot off R hand
L hand
Both feet off R hand
L hand
Ischial support
Mean
0
15 30 45 R foot off R hand
Thigh support
*Values. in cm. measured from a zero point 30cm behind the heels, at a point approximating the pubic symphysis.
on the table top at 0, 15, 30. and 4.5” to either side of the sagittal plane, using the hand on that side. The reach was recorded to the nearest O.lcm. An audible signalling device was used to detect when contact between the buttocks and the seat was broken-if this occurred we repeated the test. Subjects were not permitted to lean with their arms on the table, the seat, or their knees. With 10 of the subjects. 5 men and 5 women, we measured the reach at 0” twice with an interval of about 15 minutes. The test-retest reliability of the measure was high (r>0.841. JKO.01). Statistical analysis. After a preliminary determination that there was no consistent and significant difference between reach with the left and right hands, we used an average of left and right values for statistical comparisons when the foot support was symmetrical. When one foot was off the ground we combined the data to provide average values for reach toward the foot off the ground (right foot off, right hand reach and left foot off, left hand reach) and reach toward the foot on the ground (right foot off, left hand reach and left foot off, right hand reach). We used matched-pairs f-tests to compare the reach values of the different sitting and foot support positions. The level of statistical significance was defined as pCO.05. Arch Phys Med Rehabil Vol67,
October 1966
The forward-reaching values are shown in the table. With both feet on the ground (fig 2, left), there was a slight increase in reaching distance from 0 to 45” tp
DISCUSSION The results of our study indicate that the lower limbs contribute to sitting balance during forward reach. The loss of forward reach is greatest with both feet off the ground, particularly when the thighs are unsupported. The magnitude of the contribution of the lower limbs is substantial, amounting to about 30cm difference between both feet on, with thigh support, in comparison with both feet off and ischial support. With one foot off the ground there is a slight diminution of reach, particularly in the direction of the unsupported foot.
AT Oc
BOTH
ONE FOOT ONE FOOT
FEET
OFF
ON
(toward thefoot
OFF
BOTH FEET
(towarc OFF theloot
that15on) lhaiIS011)
Fig 4-Forward-reach values (x+ 1SD) with both feet on, one foot off, and both feet off the ground at 0, 15, 30 and 45”.
SITTING BALANCE, Chari
l‘hc limilationa of thih study were the use of only the table height reacblng ketting. and the small number and normality of the subjects studied. Nevertheless, the forward-reaching values of our subjec~ts approximated those of earlier studies.5.h,‘J.‘X although the te\tin:; circumstances were not directly comparahle Although confirmation ot’ our findings by testmg specific patient populations will be necessary before firm recommendations can be ,lustified. our findings may have some implications for patient :arc. For instance, prosthetic replacement of amputated lower limbs in patients not expected to stand or walk may enhance \itting forward-reach activities. Modifica-tion of the sitting surface to permit better support through the residual limb\ or the use of a seat belt across the lap may be equally effective. This study also suggests the importance ot properly adjusted fbotrests on wheelchairs. not always an easy task for patients such as those with meningomyclocele and ma,lor disproportion in size between the upper and lower body. Our finding’\ may also have significance for the field of ergonomics and seat design at home and at work.“,”
733
3. Conway
H. Stat& RB. Wereter JC‘ (;;Lrcta FA Kavanaugh JI). Complicatmns of decubitus ulcers in prticnts with paraple@;l Plsjt Rcconstr Surp 7: 117 - 130. 1Y.i; I
4. Diffrient N. Tilley .4R. Bardagjy Jc‘. IHumansalr 1!2/3: Poll. folio of Information. Cambridge, MA. hllT Press. 1973
5. Floyd WF. Guttmann
L, Noble CU. of wheelL,hair
of space requirements IY6hi67
0. Goldsmtth S: Dcl\ipning Publications Ltd. 1976
Farkcs KR. Ward J: Stud! u XI \
for the Di!,;tb,:,.I
Par.tpkgia
kd .3 London.
7 Cirundv DJ. Silver JR: M~JUI- amputatloll trapIs&
patients.
Int J Rchabil
in paraplegtc Mcd 6 if>?-162. 1983
and Research. Ed 2. Oxford. 1976. pp 512-542
9 Haye\ KC: Biomechanics Rev 10:%X-39
Blacbwr
of postural
I Ycientit‘ic :clnttol.
Publicattnn\
Excrc
Sport SKI
IO Institute for Consumer Ergonomtch:
Se;& anthropometry: proh Iem5 involved in large scale sune! of dl~\~hled md elderly pco pk. Ergonomics 24:X31-8-1.5. 1981
II
I3 IJ
Loane TD. Kirby RL: Static rear Ltablltty of c.mventtonal Itghtweipht vsriable-3xle-position w.hecIt:hairs Arch Phy\ Rehabil 66: 17&l 76. 1985
Pheasant ST: Anthmpometric Eryonomica 2599% IO01 .
whct’lch:ttr\.
;\rch
anti Mecc
to improve Phy> Me<+
estimates tnr Britistr civilian
adult\.
I982
Roberts DF: Functional anthropoml:tc g~tnomic\ 3:32l-377. I960
1.s Shahnavaz H: Lighting condition, VDII-operators. Ergonomics 25:
1
;md tc
I. I982
\tatic re;u stability of occupied Rrhabil 67:263-266. 1986
1.
RlBn
x Guttmann L: Spinal Cord Injuries: l:‘~miprehrns~vc Managrment
11 Loanc TD. Kirby RL: Lou anterior counterweiqhtb
References Barlila D: t\timation of body measurements ot‘ British population in relation to seat &sign. Ergonomics 4:123-132. IY61 Chabc RA. White WL: Bikral amputation in rehabilitation oi paraplegic\ f’l;t\t Reconstr Surg 24:445455 ( 19W
4:?1-37,
(1’ tide1 I> women.
and workplaci,
Er-
dimension3
ot
I 165.. I 173. 19b2
Ih
Spira M. Hardy SB: Our experiences with high thigh amputations in paraplegics. Plast Rcconstr Sure .31..:~+&353. 1963
17
Van de Ven CMC: Pilot survcv of eldrrl\, bilat-ral amputees. Physiotherapy 59:3 I k311 I. 1%3
IX
Ward JS. Kirk NS: Anthropomctv nomic\ 10: I7-‘7-I. 1967
o* elderly
lower-limb
women.
Arch Phys Med Rohehil Vol 67. October
Ergo-
1986