non - straight steps 
 that change the direction of movement account for 3550% of all steps when walking 
 indoors1 . patients with stroke fall not 
 only during walking but also during standing turn or transfer between bed and 
 wheelchair2 , 3 . therefore , the ability to take multidirectional steps is important 
 for patients with stroke . there are many clinical tests that evaluate the temporal aspects of stepping4,5,6,7 , but 
 there are few that evaluate the spatial aspects . the maximum step length ( msl ) test is a 
 clinical test of stepping distance in which participants step to the front , side , and back 
 as far as possible with one leg , before returning to the starting position8 , 9 . msl values correlate significantly with clinical measures of balance in community - dwelling 
 older adults8 . in addition , 
 community - dwelling older adults showed no significant differences in step distance between 
 the front , side , and back directions8 . however , differences in step distance in the three directions have not been investigated in 
 patients with stroke . in addition , the reliability of the msl test has been investigated 
 only in the front direction and has not been investigated in the side and back 
 directions10 . stroke causes motor 
 dysfunction , loss of coordination , and weakness of the muscles , which affect standing 
 balance and walking11 . these features 
 would also affect step distance , and step distance would be expected to vary between limbs 
 ( paretic vs. non - paretic ) and the direction of stepping ( front , side , and back ) . step 
 training in various directions improves balance and gait12,13,14 , and it is important for the step training to evaluate the 
 characteristics of stepping according to step direction and stepping limb . the purposes of this study were to determine the reliability of the msl test for the side 
 and back directions , the effect of the stepping limb and step direction on step distance , 
 and the associations of step distance and stepping laterality in step distance with walking 
 ability and motor dysfunction . we hypothesized that step distance would vary across step 
 directions and stepping limbs , and that the stepping laterality in step distance would be 
 associated with motor dysfunction and walking ability . thirty - nine patients with chronic hemiparesis as a result of stroke sustained at least 6 
 months previously were recruited from an outpatient rehabilitation center to participate in 
 this study . inclusion criteria were the ability to walk at least 10  m with or without a 
 walking aid or ankle - foot orthosis and the ability to follow commands . individuals were 
 excluded if they had disturbed consciousness , dementia , or musculoskeletal conditions that 
 affect the performance of walking . the institutional review board of the geriatrics research 
 institute and hospital approved this study and all the subjects provided their written 
 informed consent to participation . step distances were measured for the paretic and the non - paretic limbs using the msl 
 test8 , 9 . the subjects stepped out maximally with one leg , maintaining the 
 stance leg in the initial position , and then returned to their initial stance position in 
 one step . participants were instructed to step out with the paretic leg and the non - paretic 
 leg in each direction , and therefore performed six stepping actions : to the front with the 
 paretic limb , to the side with the paretic limb , to the back with the paretic limb , to the 
 front with the non - paretic limb , to the side with the non - paretic limb , and to the back with 
 the non - paretic limb . the subjects were allowed to use their 
 usual ankle - foot orthosis during the msl test . physical impairments that might affect walking ability were evaluated using the stroke 
 impairment assessment set15,16,17 . the motor 
 functions were assessed through hip flexion , knee extension , and foot pat ( rapid foot 
 tapping ) . motor function was evaluated in stages from 0 to 5 , with higher scores indicating 
 better function . this treatment - oriented 
 measure includes two static sitting balance items and eight dynamic sitting balance items . the static sitting balance items assess the ability to maintain the sitting position with 
 and without upper limb support . the dynamic sitting balance items assess the ability to : 
 reach with an upper limb , lift the pelvis from a table , move the buttocks in the frontal 
 plane , move the buttocks in the sagittal plane , flex the hips individually , flex the hips 
 together , rotate the upper trunk , and flex the shoulder of the non - paretic upper limb . the 
 maximum score is 20 , with higher scores indicating better trunk function . walking ability in the home was evaluated using the functional ambulation category ( fac ) , 
 which includes walking on uneven terrain and walking up and down stairs19 . walking ability was rated on the following six - point 
 scale : ( 0 ) unable to walk or requires the help of two persons to walk ; ( 1 ) ambulatory with 
 firm continuous contact with one person ; ( 2 ) ambulatory with the intermittent or continuous 
 support of one person ; ( 3 ) ambulatory on level surfaces with verbal supervision or stand - by 
 help from one person without physical contact ; ( 4 ) independent ambulation only on level 
 surfaces ; and ( 5 ) independent ambulation anywhere , including stairs . walking ability was 
 also evaluated using gait speed in the 10-m walk test and the timed up and go ( tug ) 
 time20,21,22 . for the 10-m walk test , 
 participants walked in a straight line at a comfortable speed for 16 m , including 3-m 
 runways at the start and end of a 10-m test walkway . gait speed was calculated from the time 
 required to walk across the 10-m walkway . the tug time was the amount of time required to 
 stand from a seated position , walk forward 3 m , turn around , walk back to the chair , and sit 
 down . the participants completed these tasks at a comfortable speed and used their usual 
 walking aid and ankle - foot orthosis . the test - retest 
 reliability of the two administrations of the msl test was evaluated using the intraclass 
 correlation coefficient , model 1,1 [ icc(1,1)]23 . step distance was compared across limbs and step directions using two - way 
 repeated - measures analysis of variance ( anova ) and the bonferroni post hoc test . for each 
 step direction , the difference in the step distance of the paretic and non - paretic limb was 
 calculated ( paretic limb minus non - paretic limb ) . this stepping laterality was compared 
 across the three directions using one - way repeated - measures anova . pearson correlation 
 coefficients were calculated for all pairwise combinations of step distance in the front , 
 side , and back directions of the two limbs . a conservative estimate of the minimal detectable change at the 95% confidence level 
 ( mdc95 ) is 8.128  cm ( 3.2 inches)10 . therefore , subjects were classified into three groups according to 
 the stepping laterality in step distance to the front : a paretic step distance > 8.128  cm 
 and longer than the non - paretic step distance ( longer paretic step group ) , stepping 
 laterality between 8.128  cm and 8.128  cm ( symmetric group ) , or a paretic step distance 
 > 8.128  cm and shorter than the non - paretic step distance ( longer non - paretic step group ) . one - way anova and tukey s post hoc tests were used to compare walking ability across the 
 three groups . the kruskal - wallis and mann - whitney u tests with bonferroni adjustments were 
 used to compare motor impairment across the three groups . receiver operating characteristic curves were generated to compare the diagnostic validity 
 of step distance to the front to distinguish fac 5 from fac 4 . optimal cut - off points were 
 determined by sensitivity , specificity , positive predictive value , and negative predictive 
 value . table 1table 1.characteristics of the subjectsmean  sdmedian [ first  third quartile]age ( years)69.99.8gender : male / female ( n)23/16duration since stroke onset ( days)1562.41182.0paretic side : right / left ( n)27/12siaship - flexion4 [ 24]knee - extension3 [ 24]foot - pat3 [ 14]fact10 [ 614]gait speed ( m / sec)0.50.3tug ( s)36.124.0fac4 [ 35]fac : functional ambulation category ; fact : functional assessment for control of 
 trunk ; tug : timed up and go test ; sias : stroke impairment assessment set shows the characteristics of the 39 subjects . their mean ( sd ) age was 69.9 
 ( 9.8 ) years , and the duration since stroke onset was 1,562.4 ( 1,182.0 ) days . the mean gait 
 speed in the 10-m walk test was 0.5 ( 0.3 ) m / s , and the tug time was 36.1 ( 24.0 ) s. the msl 
 test had excellent test - retest reliability ( icc(1,1 ) = 0.9390.957 ; table 2table 2.reliability and step distance in each directionicc ( 1,1)95% cistep distance ( cm)step limbstep directionlimb  directionpareticfront0.9430.895 , 0.97026.120.4n.s**n.sside0.9390.888 , 0.96820.716.9back0.9570.919 , 0.97719.117.0non - pareticfront0.9510.909 , 0.97425.124.1side0.9540.915 , 0.97620.821.3back0.9460.899 , 0.97119.119.0icc : intraclass correlation coefficients . values are mean  sd . * * significantly 
 different according to anova ( p < 0.01 ) significantly different from 
 the front and side ( p < 0.01 ) significantly different from the side 
 and back ( p < 0.01 ) ) . there was 
 no significant effect of stepping limb on step distance ( f = 0.735 , p = 0.483 ) , but there 
 was a significant effect of step direction ( f = 19.969 , p < 0.01 ) . for the paretic limb , 
 front step distance was significantly longer than those of the side and back step distances 
 ( p < 0.01 ) . for the non - paretic limb , front step distance was significantly longer than 
 those of the side and back step distances ( p < 0.01 ) . step distances were significantly 
 correlated across all pairwise combinations of direction and side ( table 3table 3.correlation between paretic and non - paretic step distances in each 
 directionpareticnon - pareticfrontsidebackfrontsidebackpareticfront0.930**0.946**0.938**0.892**0.941**side0.931**0.896**0.914**0.893**back0.890**0.855**0.931**non - pareticfront0.955**0.966**side0.929**backvalues are pearson correlation coefficients . * * p < 0.01 ) . there was no significant effect of step direction on the stepping laterality 
 in step distance ( f = 0.735 , p = 0.482 ) . the stepping lateralities in the front , side , and 
 back directions were 0.9  8.6 [ 1.9 to 3.8 ] cm , 0.2  9.0 [ 3.1 to 2.8 ] cm , and 0.0  7.0 
 [ 2.3 to 2.2 ] cm , respectively ( mean  sd [ 95% confidence interval ] ) . fac : functional ambulation category ; fact : functional assessment for control of 
 trunk ; tug : timed up and go test ; sias : stroke impairment assessment set icc : intraclass correlation coefficients . values are mean  sd . * * significantly 
 different according to anova ( p < 0.01 ) significantly different from 
 the front and side ( p < 0.01 ) significantly different from the side 
 and back ( p < 0.01 ) values are pearson correlation coefficients . * * p < 0.01 table 4table 4.motor function and gait abilities of the three groupslonger paretic stepgroup ( n=7)symmetricgroup ( n=26)longer non - paretic stepgroup ( n=6)grouphip - flexion3 [ 2.53.5]4 [ 24]4.5 [ 45]knee - extension2 [ 23.5]2.5 [ 24]4.5 [ 45]*foot - pad2 [ 1.52.5]3 [ 24]4.5 [ 45]fact8 [ 5.511]9.5 [ 615]13.5 [ 1114]gait speed ( m / sec)0.23 0.120.46 0.280.86 0.17**tug ( s)51.1 19.836.9 24.715.1 2.8**fac2 [ 23.5]4 [ 35]5 the subjects were classified 
 into three groups according to the stepping laterality front step distance ( longer 
 paretic step group , symmetric group , longer non - paretic step group ) . statistically significant 
 difference between longer paretic step group and longer non - paretic step group ( p < 
 0.05 ) . statistically significant difference between longer paretic step 
 group and symmetric group ( p < 0.05 ) . statistically significant 
 difference between longer non - paretic step group and symmetric group ( p < 0.05 ) shows the motor function and walking ability of the longer paretic step group , 
 symmetric group , and longer non - paretic step group . gait speed , tug time , and fac were 
 better in the longer non - paretic step group than in the symmetric group and the longer 
 paretic step group . the subjects were classified 
 into three groups according to the stepping laterality front step distance ( longer 
 paretic step group , symmetric group , longer non - paretic step group ) . statistically significant 
 difference between longer paretic step group and longer non - paretic step group ( p < 
 0.05 ) . statistically significant difference between longer paretic step 
 group and symmetric group ( p < 0.05 ) . statistically significant 
 difference between longer non - paretic step group and symmetric group ( p < 0.05 ) the cut - off value of the paretic front step distance which distinguished fac 5 from fac 4 
 was 33  cm . the sensitivity , specificity , positive predictive value , and negative predictive 
 values were 0.81 , 0.91 , 0.87 , and 0.88 , respectively . the cut - off value of the non - paretic 
 front step distance which distinguished fac 5 from fac 4 was also 33  cm . the sensitivity , 
 specificity , positive predictive value , and negative predictive values were 0.93 , 0.91 , 
 0.88 , and 0.95 , respectively . we investigated the reliability of the msl test and the difference in step distance between 
 the paretic and non - paretic limbs for steps to the front , side , and back . pardo reported 
 that the test - retest reliability of the msl test in the front direction was excellent for 
 both the paretic and the non - paretic limbs10 . in this study , test - retest reliability was excellent in each step 
 direction ( icc > 0.900 ) . step distance did nt differ significantly between the paretic 
 and non - paretic limb . this indicates that patients with stroke adapt to motor 
 impairment24 , and can perform similar 
 length steps with the paretic and non - paretic limb . on the other hand , step distances 
 significantly differed between the front , side and back directions . it is possible that poor 
 coordination of limb segments , poor posture in stepping , the effect of visual information , 
 and insufficient experience of stepping to the side and back caused the differences in step 
 distances across directions . we classified participants into three groups according to the stepping laterality in step 
 distance to the front , with reference to a previous study10 . the longer non - paretic step group had better walking ability than 
 the symmetric group and the longer paretic step group . moreover , 
 weight - bearing by the paretic limb improves gait and balance ability26 . the step distance of the non - paretic limb indicates the 
 weight shift ability of the paretic lower limb , and good weight shift ability in the paretic 
 limb is necessary for large step distances by the non - paretic limb . therefore , the longer 
 paretic step group had limited weight - bearing ability for the paretic limb and the longer 
 non - paretic step group had adequate weight - bearing ability for the paretic limb , indicating 
 that step distance of the non - paretic limb is important for walking ability . on the other 
 hand , most measures of motor function of the paretic limb did nt differ among the three 
 groups . functional mobility was nt strongly correlated with impairments of motor function in 
 the paretic - lower limb27 . therefore , it 
 is possible that motor function of the paretic - lower limb does not affect the stepping 
 laterality in step distance between the paretic and non - paretic limbs . however , the number 
 of participants was small , and this limits the generalizability of our results . correlations between step distances in the different directions were high . therefore , we 
 calculated cut - off scores for the paretic front step distance and non - paretic front step 
 distance to distinguish fac 5 from fac 4 . the cut - off score was 33  cm for the paretic front 
 step distance and non - paretic front step distance . fac can discriminate independent walkers , 
 and thus step distance to the front is useful because it can rapidly be evaluated in small 
 spaces . a limitation of this study is that participants had chronic hemiparesis , and most had low 
 walking ability . therefore , our results might not be reflected by stroke patients with good 
 walking ability . in addition , it is possible that the classification of the subjects into 
 three groups using the mdc95 of the msl test may not have been appropriate . the 
 mdc95 of a previous study was too large to usefully classify the participants 
 in our study into three groups10 . subjects of the previous study had high gait ability , a mean gait speed of 0.8 
 m / seconds10 , which is equivalent to 
 that of community walkers21 . to conclude , we investigated the reliability of the msl test and the differences in step 
 distance across stepping limbs and step directions . the test - retest reliability coefficients 
 were excellent for all step directions ( icc = 0.9390.957 ) . in addition , paretic step distance shorter than non - paretic step 
 distance indicated good walking ability . paretic front step distance and non - paretic front 
 step distance may be useful for discriminating independent walkers .