the arches of the feet , i.e. , the medial longitudinal , lateral longitudinal , and transverse 
 arch , are important structures that act as shock absorbers for body weight , and preserve 
 stability during both walking and standing1 .
individuals with flatfeet show 
 not only imperfect foot load transfer3 but 
 also hip joint , knee joint , and lumbar region imperfections4 .
the foot structure is involved in load bearing , leverage , shock absorption , balance , and 
 protection5 .
if the foot structure is 
 destroyed , as in flatfeet , surgical treatment6 and conservative treatment , e.g. , physical therapy , exercise , and 
 orthoses , are available .
although it is reported that the foot orthosis reduces the instability of the center of 
 gravity9,10,11 , there are a variety of 
 foot orthoses available .
bmz insoles ( bmz , japan ) are reported to support the arch and 
 improve drifting to the center of gravity . unlike existing foot orthoses , bmz insoles ( fig.1fig .
the superfeet insole supports the medial 
 longitudinal arch , the bmz insole supports the cuboid . )
insoles are said to support not only the medial longitudinal arch but also the 
 lateral longitudinal arch and transverse arch by supporting the cuboid to balance mobility 
 with stability .  
the superfeet insole supports the medial 
 longitudinal arch , the bmz insole supports the cuboid .
furthermore , 
 no study has yet been performed to investigate whether the bmz insole or an existing foot 
 orthosis ( the superfeet insole ) is more effective .
therefore , the purpose of the present 
 study was to examine whether the two types foot orthosis were effective for flatfeet on the 
 basis of measurement of the center of gravity and whether standing balance was influenced by 
 normal feet and flatfeet .
twenty subjects with flatfeet ( 10 female , 10 male ) and 20 subjects with normal feet ( 10 
 female , 10 male ) were included in this study which was not case contolled .
the mean age was 
 20.1  years ( range , 1923 years ) , mean height was 164.4  cm ( standard deviation ( sd ) , 9.2 cm ) , 
 mean weight was 56.8 kg ( sd , 7.9 kg ) and mean shoe size was 25.2  cm ( sd , 1.1 cm ) .
the ethics 
 committee of hokkaido bunkyo university approved all study protocols , and each participant 
 provided written informed consent prior to enrollment .
the medial longitudinal arch height was evaluated using the bony arch index12 ( bai ) .
the bai was calculated from the 
 navicular height ( h ) divided by the foot length ( l ) ( bai = h / l ) .
a low arch was defined as a 
 bai of less than 0.21 during a weight - bearing activity , a normal arch was regarded as a bai 
 between 0.21 and 0.27 , and a high arch was regarded as a bai greater than 0.27 .
body sway was evaluated based on the center of pressure ( cop ) while the subjects stood on 
 level ground with their open .
body sway was measured during upright standing with the feet 
 10  cm apart for 30 seconds .
the total locus length ( tll ) and the area of body sway ( abs ) 
 were measured using a zebris fdm - sx system ( zebris medical gmbh , isny , 
 germany ) .
measurements were taken under three sets of conditions : using bmz insoles , which supported 
 the cuboid ; using superfeet insoles ( impact trading , yokohama , japan ) , which supported the 
 medial longitudinal arch ; and with no insoles .
measurements were taken three times for each condition , and mean values were used for 
 analysis .
statistical 
 analysis was performed by three - way repeated measures anova , and differences among the 
 parameters were checked using the bonferroni test .
iccs increased to above 0.8 ( p<0.05 ) . the tll values with no insoles , with superfeet 
 insoles , and with bmz insoles were 353.252.2  mm , 342.461.6  mm and 346.662.1  mm , 
 respectively , in subjects with normal feet . in subjects with flatfeet ,
they were 
 456.055.5  mm , 428.153.5  mm , and 436.271.3  mm , respectively ( table 1table 1 . total locus length ( mm)categoryno insolesuperfeetbmznormal - arched feet group*353.252.2342.461.6346.662.1flat - footed group456.055.5428.153.5436.271.3values are expressed as means  sd . * p < 0.05 ( category ) , p < 0.05 
 ( type of insole ) ) .
values are expressed as means  sd . * p < 0.05 ( category ) , p < 0.05 
 ( type of insole ) on level ground , significant differences were found in tll according to insole conditions 
 in both flat - footed and normal - arched subjects , with the tll values for superfeet insoles 
 being significantly lower than those for bmz insoles and no insoles ( p<0.05 ) .
further , 
 the values for the normal - arched feet group were significantly lower than those for the 
 flat - footed group ( p<0.05 ) .
the abs values with no insoles , with superfeet insoles , and with bmz insoles were 72.731.0 
 mm , 71.538.6 mm , and 82.451.1 mm , respectively , in 
 subjects with normal - arched feet . in subjects with flatfeet , they were 103.356.5 
 mm , 91.140.0 mm , and with bmz 99.852.8 mm , 
 respectively ( table 2table 2 .
area of body sway ( mm)categoryno insolesuperfeetbmznormal - arched feet group*72.731.071.538.682.451.1flat - footed group103.356.591.140.099.852.8values are expressed as means sd .
no significant difference in abs value was found for any 
 insole condition between subjects with flatfeet and those with normal - arched feet . however , 
 the values for the normal - arched feet group were significantly lower than those for the 
 flat - footed group ( p<0.05 ) .
we measured tll and abs for subjects with no insoles , superfeet insoles , and bmz insoles on 
 level ground .
the superfeet insoles supported the medial longitudinal arch ; however , the bmz 
 insoles , which are designed to support the cuboid , could provide stability to the lateral 
 part of the foot .
the tll values for subjects with superfeet insoles were significantly lower than those for 
 subjects with bmz insoles and no insoles under all insole conditions .
one previous study 
 reported better postural control in young subjects wearing plastic - textured insoles13 , but another did not observe improvement 
 of balance in male athletes with two different foot orthoses14 .
although there are many types of insole , consensus concerning 
 which insoles are better has not been obtained . in this study ,
two different insoles were 
 compared : the superfeet insoles , which supported the medial longitudinal arch , and bmz 
 insoles , which have a structure designed to support the cuboid . on level ground ,
superfeet insoles were effective in stabilizing standing balance in both 
 flat - footed and normal - arched subjects .
our study suggests that support of the medial 
 longitudinal arch is important when standing .
however , in daily life , individuals encounter 
 not only level ground but also slopes of various degrees of tilt .
further study is needed to 
 clarify the results when standing on uneven ground and while walking .
the reason why the bmz 
 insoles were not effective maybe that bmz insoles provide a rather low amount of support to 
 the medial longitudinal arch .
the medial longitudinal arch seems essential to stabilize 
 postual sway , which standing still .
however instability while standing on the ground might 
 be better for initiation of dynamic motions such as walking or running .
we measured tll and abs under static conditions while 
 the subjects were standing still on the ground .
active condition such as walking or running 
 might be needed to evaluate the effects of bmz insoles .
this is the first evidence concerning bmz insoles in subjects standing still on the ground . 

bmz insoles represent a new concept in insoles in that they support the lateral part of the 
 foot , and investigation of other types of environments such as uneven terrain , walking or 
 running would be needed to determine if this insole is effective .
   [ purpose ] the aim of this study was to determine whether insoles change standing balance 
 on the ground in normal and flat - footed subjects . [ subjects ] twenty subjects with flatfeet 
 and 20 subjects with normal feet were included in this study . 
 [ methods ] body sway was 
 evaluated based on the center of pressure while subjects stood on the ground . 
 body sway 
 was measured during upright standing with the feet 10  cm apart for 30 seconds . the total 
 locus length and the area of body sway 
 were then measured using a zebris system . 
 
 measurements were made under three sets of conditions : using bmz insoles , which supported 
 the cuboid ; using superfeet insoles , which supported the medial longitudinal arch ; and 
 with no insoles . 
 [ results ] the 3 insole conditions were compared . on level ground , 
 the 
 total locus length for the superfeet insole was significantly less than those for the bmz 
 insole and no insole . [ conclusion ] on level ground , superfeet feet 
 insoles were effective 
 in stabilizing standing balance in both flat - footed and normal - footed subjects . 
INTRODUCTION
SUBJECTS AND METHODS
RESULTS
DISCUSSION