falls during daily activities are a concern in stroke patients who have central nervous 
 system damage . falling stems from the inability to lift the ankle ( dorsiflexion ) triggered 
 by the failure of central nervous system mechanisms caused by stroke .
previously , duncan1 reported that a 
 stimulus input in the plantar calcaneal region in an individual with central nervous system 
 damage induced a dorsiflexion reflex as a neurophysiological action .
this mechanism is known 
 as  heel - gait - cast - treatment2  .
later 
 research included studies such as one by charles et al.3 on electromyographic analysis of the effects of a calcaneal region 
 stimulus in individuals with post - stroke hemiplegia on activation of dorsiflexion muscle 
 activity .
it has also been reported that in stroke patients , posture and gait4 , 5 were affected by 
 stimulating6 , 7 the peroneal nerves within an ankle foot orthosis ( afo ) . 

additionally , there have been some reports in which dynamic motion data were changed by 
 neurological intervention in this manner . however , there are few studies on the effect of 
 afo on gait with a focus on energy , which is an indication of the total efficiency .
haruna 
 and his co - workers8 reported that the 
 continuous use of a gait solution afo developed by yamamoto9 , 10 increased the rate of 
 mutual exchange between kinetic energy and potential energy in the gait of a hemiplegic 
 patient .
this change showed that use of the gait solution afo improved the energy conversion 
 efficiency of the body s center of gravity using the so - called inverted pendulum .
we 
 investigated the effects of 27 different shapes and sizes of heel pads on gait using a 
 plantar flexion resistive afo in healthy subjects11 .
this study showed that heel pads fixed to an afo retained the 
 center of pressure ( cop ) at the heel and increased the lever arm of the ground reaction 
 force vector to the ankle related to the dorsiflexion moment .
however , there is a relative lack of research 
 describing the effect of a heel pad on gait in hemiplegic patients .
further studies are 
 therefore required to elucidate the effect of a heel pad on hemiplegic gait .
the simplest method of calculating energy by using positional information on cog is to use 
 the energy conversion efficiency calculation reported by cavana et al12 .
cavana13 integrated the force component ( acceleration component ) obtained 
 from a force plate to calculate the kinetic energy and potential energy , and they calculated 
 the energy conversion efficiency from a physics standpoint .
this enabled us to focus on the 
 conversion of potential energy and kinetic energy obtained from the movement of the cog . 

this study aimed to analyze the effect of heel pads in ankle - foot orthoses on dynamic motion 
 aspects of gait in stroke patients from the viewpoint of energy conversion efficiency .
fourteen chronic stroke patients ( 9 males and 5 females ; age , 5910  years ) who were 
 ambulatory and had lower extremity motor function categorized as brunnstrom20 stage iv participated in the study .
their 
 characteristics are shown in table 1table 1.subject characteristicsevaluation parametersa1a2a3a4a5a6a7a8a9a10a11a12a13a14age ( y)6544367059495263646668695758gender ( m : male , f : female)mffmmfmmmmmfmfparetic sideleftleftrightleftrightleftleftrightrightrightrightrightleftrightbrunnstrom stage ( lower limb)ivivivivivivivivivivivivivivrom ( paretic ankle):plantarflexion  dorsiflexsion405405452045204020400451545204074010401535204504010foot clonus++++++type of everyday use orthosisplsplsplsplsjafoplsjafoplsplsplsplsplsjafoplsaverage walking speed ( m / min)50.433.642.0 48.0 45.344.441.852.342.745.649.539.540.538.8pls : plastic leaf spring afo , jafo : joint afo . selection criteria included subjects who could follow verbal instruction , did 
 not have any orthopedic disease , used an afo routinely on a daily basis , and were able to 
 walk independently .
the selected subjects in this study were able to walk forward by means 
 of a heel strike when using an afo .
there was no restriction regarding cane use , or lack 
 thereof , in the interest of ensuring an adequate number of subjects .
pls : plastic leaf spring afo , jafo : joint afo this study was conducted after obtaining approval from the ethics committee of hokkaido 
 university of science .
the content of the study was explained to cooperating research 
 facilities and the participants in order to obtain their consent , and written informed 
 consent has been obtained from each subject .
the afo9 , 10 used for the study was a joint afo ( jafo , gait - solution - design , 
 pacific supply , japan ) , as shown in fig .
1.joint afo used in this study , and measurements were begun after the angle and resistance of the orthose the 
 afo9 , 10 used for the study was a joint afo ( jafo , gait - solution - design ) , as 
 shown in fig . 1 , and measurements were begun after 
 the angle and resistance of the orthoses were adjusted to match each subject s condition 
 over a three - month trial period .
joint afo used in this study the study design was an a - b - a single - system design ( fig . 

. 2.study protocol ) . as a baseline , only jafos tailored for each subject were used for one trial month 
 ( a1 to a2 ) .
next , the jafos were fitted with 3-mm - thick rubber heel pads with 60 degrees of 
 hardness at the plantar calcaneal region of the jafos , as shown in fig . 3fig .
3.heel pad , in order to examine the effect of the press - in force on the calcaneal region ; these 
 heel pads were used for one month ( b1 to b2 ) .
finally , the heel pads were removed , and only 
 the jafos were used for one month ( a3 to a4 ) .
measurements were taken at a1 to a4 , and were implemented on the same days for a2 and b1 
 and for b2 and a3 , falling under the timings for the heel pad intervention .
this was to 
 examine the following : stability of the baseline by comparing a1 to a2 ; immediate effects of 
 the heel pads by comparing a2 to b1 ; impact of the long - term effects of the heel pad 
 intervention by comparing a2 to b2 ; and the carry - over effects by comparing b2 to a4 .
gait was measured using a three - dimensional ( 3d ) motion analysis system vicon - mx ( with six 
 cameras , manufactured by vicon , oxford , uk ) and five force plates ( amti ) .
the sampling frequency for each 
 measuring instrument was 240  hz for infrared cameras and 960  hz for floor reaction 
 force - based measurements .
the measurement path surface was 9.5 m , with three force plates 
 arranged in the middle on the left side and two on the right side . for 3d motion 

measurement , reflective markers with a 14-mm diameter were applied to 21 points on the body . 

the application positions were the forehead , the right shoulder blade , both acromions , the 
 lateral epicondyles of both humeri , both radial styloid processes , both anterior superior 
 iliac spines , both posterior superior iliac spines , both hip joints ( the distal 1/3 point 
 connecting the anterior superior iliac spine and great trochanter ) , both knee joints ( the 
 anteroposterior radius 1/2 point , 1/3 point , and midpoint ) , both ankle joints ( the lateral 
 malleolus center for the healthy side and the orthosis axis center for the orthosis side ) , 
 both calcaneal regions and both fifth metatarsal heads .
the point of interest during 
 measurement on the walking path was data acquisition for 10 trials where one foot was placed 
 on a force plate .
the data obtained from the 3d motion analysis system were used to create middle markers 
 between markers with the vicon s body builder ( example : midpoints between the knee joint and 
 ankle joint markers ) .
thereafter , the walking speed , stance - phase maximum height of the cog , dorsiflexion moment 
 ( maximum value of the loading response ) , and floor reaction force action point ( cop ) were 
 found from the  plug - in - gait model  .
the cop retention rate : the cop of the traveling direction component during heel rocker was 
 extracted , and a secondary function was calculated as per the dotted line in fig .
this quadratic function represents the progression of cop . for instance , a greater 
 quadratic function shows that the plantar cop is advancing quickly forward , which is an 
 index for examining the effects of the heel pad .
calculation of the second - order coefficient of cop the energy conversion efficiency : using the research methods of cavagna et al.12,13,14,15,16,17,18,19 
 makes it possible to calculate the energy conversion efficiency from the cog obtained from 
 the 3d motion data .
this is done by applying a reverse pendulum theory using the force of 
 gravity to calculate the energy conversion efficiency during walking from the kinetic and 
 potential energies during walking .
gait was divided into the paretic stance and the non - paretic stance using cog displacement 
 in the vertical direction , as per fig . 5fig .
then , the reverse pendulum motion was separated into a rising section and a falling 
 section from the information on the lowest point and the highest point for the respective 
 cog heights , and the energy conversion efficiency was calculated in each section as follows . 
 to calculate the kinetic energy and potential energy during ambulation ,
the kinetic energy 
 ( ek.y ) in the direction of progress of the body cog was calculated by the formula , 
 ek.y=1/2mvy , the kinetic energy ( ek.z ) in the vertical direction by 
 ek.z=1/2mvz , the potential energy ( ep ) by ep = mgz , the total kinetic energy(ek ) 
 by ek = ek.y+ek.z , and the total energy ( etot ) by etot = ek+ep , where  m is the body mass , g is 
 the acceleration due to gravity ( 9.8 m / s ) , vz is the vertical velocity of cog , 
 and vy is the velocity in the direction of cog progress .
separate phases of mechanical energy of cog the external work for accelerating the cog in the direction of progress was calculated 
 using formula 1 , the external work of raising the cog in the vertical direction against 
 gravity by formula 2 , and the external work generated by the muscles to move the cog was 
 calculated using formula 3.wy=ek.y 
 ( 1),wz= ( ek.z+ep ) 
 ( 2),wext=etot ( 3 ) , where  is the amount of energy increase or decrease , and  is the summation of the data of 
 . conversion efficiency ( % recovery ) was calculated using formula 
 4.%recovery=(|wy|+|wz|-wext )  ( |wy|+|wz| )  100 ( 4 ) analysis methods : for each assessment parameter , data after heel pad intervention were 
 standardized using the mean and standard deviation of the baseline ( a1 ) .
this made it 
 possible to nullify the effects between subjects and the differences in units between 
 assessment parameters to look at the relative growth rate versus the baseline . in the 
 statistical analysis
, data were analyzed using the statistical software , excel - toukei 2008 
 ( social survey research information co. , ltd . ) .
friedman test and steel - dwass - test for 
 multiple comparisons were performed to compare the standardized numerical values .
evaluation parameters standardized by baseline a1 are shown in table 2table 2.evaluation parameters showing the changes from baselinenormalized parametersincrease rate ( % ) no pada2padb1padb2no pada4retention rate of cop0.32.2 10.68.5** 23.515** 12.112**ankle dorsiflexion moment  1.01.213.41652.915**27.337paretic - side cog 0.11.06.82.0 * 9.12.8**8.53.4**non - paretic - side cog  0.21.24.33.27.42.8**7.12.3**paretic - side upward energy conversion 
 efficiency2.02.0 12.01526.012**20.013**paretic - side downward energy conversion 
 efficiency1.22.03.46.7 1.98.08.23.9non - paretic - side upward energy conversion 
 efficiency4.12.98.81221.49.8**22.212**non - paretic - side downward energy conversion 
 efficiency1.44.219.48.8**16.88.8**21.98.8**values are group mean  deviation .
comparisons of a1 to a2 : no heel pad group as a control , b1 : immediate 
 intervention effects of the heel pad , b2 : long intervention effects of the heel pad , and a4 : 
 carry - over effects after removing the heel pad are also shown in table 2 .
significant difference base line 
 a1 . : p<0.01 , : p<0.05 the parameter of retention rate of the cop indicated retention of the cop at the heel as 
 immediate effects ( table 2-b1 ) .
in contrast , 
 there were no immediate effects in the paretic - side cog ( table 2-b1 )
. however , long - term effects were observed in the 
 paretic - side cog ( table 2-b2 ) .
in addition , a 
 significant correlation was shown between retention rates of the cop and paretic - side cog 
 ( table 3table 3.matrix of correlation between parametersretention rate ofcopankle dorsiflexionmoment paretic - sidecognon - paretic - sidecogretention rate of cop-0.620.560.39ankle dorsiflexion moment * * -0.640.44paretic - side cog * * * * -0.72non - paretic - side cog * * * * * * -upper part shows correlation coefficients .
p<0.01 paretic - side upward energy conversion efficiencies at b2 were also significantly increased 
 with long - term effects in the paretic - side cog ( table 
 2-b2 ) .
all parameters of long - term effects ( table 2-b2 ) and carry - over effects ( table 
 2-a4 ) in energy conversion efficiency were significantly increased except the 
 paretic - side downward .
the heel pads fixed the cop at the heel rocker section during walking , and they increased 
 the ankle joint dorsiflexion moment . in this regard , it appears the heel pads fixed the cop at the heel rocker section during 
 walking , and they increased the ankle joint dorsiflexion moment . in this regard , it appears 
 that the phenomenon of cop retention ( fig .
6.mechanism of cog rise ) maintained the distance between the floor reaction force acting line and the ankle 
 joint center ( fig .
the increase in the ankle 
 joint dorsiflexion moment also caused the paretic - side cog height to rise .
this is likely 
 because there is a large ankle joint dorsiflexion moment in the paretic - side heel rocker 
 period , and this produces forward rotation of the paretic lower extremity around the heel 
 ( fig .
6 - 4 ) , indirectly causing the paretic - side 
 cog height to rise ( fig . 6 - 5 , 6 )
. mechanism of cog rise in general , the cog height in normal walking peaks at mid - stance , and it has left - right 
 symmetry . during post - stroke walking , however , often a decrease in the support of the 
 paretic side or other factors causes the paretic - side cog height to have a lower maximum 
 value than the non - paretic side20,21,22 , 
 resulting in a loss of symmetry ( fig .
the heel 
 pads , however , caused the maximum value of the paretic - side cog height to rise , which 
 reduced the left 
we do , however , feel that despite the lack of an increase in the dorsiflexion moment , the 
 appearance of raising the paretic - side cog as an immediate effect ( table 2-b1 ) was caused by the higher energy conversion efficiency 
 in the non - paretic - side descent in the direction of travel ( table 2-a4 ) .
this indicates that when the energy conversion 
 efficiency on the non - paretic side increases , the paretic foot can land in a state where 
 kinetic energy is maintained , as in fig .
6 - 1 , and 
 an effect of retaining cop is also obtained , thus yielding a dual effect on increasing the 
 cog height in the paretic stance
it therefore appears that even a slight moment in the dorsiflexion direction 
 contributes to raising the cog .
we also obtained the long term effect on all parameters except for the paretic - side 
 downward energy conversion efficiency .
these results coincided with the results of previous 
 studies21,22,23 , which showed that the 
 continuous use of an afo increased the kinetic energy of non - paretic side descent .
the present study was an experimental investigation of the effect of heel pad intervention 
 on dynamic motion assessment parameters using a single - system a - b - a design in 14 stroke 
 patients .
the results showed that a heel pad attached to the calcaneal region of an afo caused slight 
 retention of the cop at the heel during the heel rocker function along with cog elevation 
 and raised energy conversion efficiency , especially on the non - paretic side .
 [ purpose ] this study aimed to analyze the effect of heel pads in ankle - foot orthoses on 
 dynamic motion aspects of gait in stroke patients from the viewpoint of energy conversion 
 efficiency . 
 [ subjects ] fourteen chronic stroke patients who were ambulatory and had lower 
 extremity motor function categorized as brunnstrom stage iv participated in the study . 
 [ methods ] 
 a three - dimensional motion analysis system was used to assess the effect of heel 
 pad intervention on dynamic motion gait parameters using a single - system a - b - a design . 
 
 [ results ] the results showed that a heel pad attached to the ankle - foot orthosis caused 
 significant retention of the center - of - pressure at the heel during the heel rocker 
 function and significant increase in the dorsiflexion moment and the height of the center 
 of gravity . 
 [ conclusion ] the present study showed that a heel pad attached to the 
 calcaneal region of an ankle - foot orthosis caused slight retention of the 
 center - of - pressure at the heel during the heel rocker function along with center of 
 gravity elevation in the stance phase and improved the energy conversion efficiency , 
 especially on the non - paretic side . 
INTRODUCTION
SUBJECTS AND METHODS
RESULTS
DISCUSSION