the important functions of shoes include protecting the feet and enabling movement without 
 pain .
shoes influence the stability of posture by accepting feedback from the somatosensory 
 system including changes in friction between the shoes and the soles of the feet1 .
generally speaking , shoes are used as a 
 means of basic transport for human beings during such activities as walking and jogging , and 
 as a means of enhancing physical strength2 .
hemp , straw , wood , and leather have mainly been used as material for 
 shoes in the past , while various other materials , including rubber , cloth , and plastic , are 
 more frequently used today .
the types of shoes currently available are quite diverse and 
 subdivided , including high heels for beauty , slippers for comfort , running shoes for 
 exercise , military boots for physical hardship , and aqua shoes for water activities3 .
electromyography ( emg ) records information on bioelectrical activities related to muscle 
 contraction and muscle control , and can illustrate the relationships between anatomical 
 movements and temporal aspects of the human body , energy generation and emg , and muscle 
 fatigue and emg4 . a previous study on shoes related to falling in the elderly reported that heel height , sole 
 hardness , and tread and heel geometry affected both , balance and walking5 .
another study focusing on basketball 
 players reported no relationship between shoe design and ankle sprain6 .
furthermore , a previous study investigating the effect of 
 high - top versus low - top shoes on ankle inversion kinematics and prelanding emg activation of 
 the ankle evertor muscles during landing on a tilted surface demonstrated that wearing 
 high - top shoes can induce delayed preactivation timing and decreased evertor muscle 
 activity7 . recently , although the aesthetic interest in shoes and the types of shoes that are worn 
 have varied , most previous studies have focused on muscle activity based on shoe type , such 
 as high heels and sneakers . in this study , the rain boots , which have recently become a 
 representative fashion item for females , and the effect of boot shaft length on lower 
 extremity muscle activity while walking were investigated .
among female students aged in their twenties who were attending a college located in 
 cheonan city , south korea , 12 healthy females who had not experienced surgical impairment 
 within the past year and who did not feel pain while walking were selected for inclusion in 
 this study ( table 1table 1.general characteristics of the subjectscharacteristicmean  sdage ( yrs)20.5  0.5height ( cm)159.0  4.9weight  ( kg)51.4  7.2 ) .
they understood the purpose and content of this experiment , and voluntarily 
 provided informed consent before the experiment .
this study was approved by the 
 institutional review board of namseoul university ( no .
three types of rain boots , based on shaft length , were investigated ; heel height was 
 standardized as 3.5  cm ( table 2table 2.general characteristics of the rain bootsbootslength ( cm)weight  ( kg)long40.01.6middle29.01.3short17.00.8 ) . a body composition analyzer ( inbody 720 ; biospace o. ltd . ,
seoul , republic 
 of korea ) was used to measure the physical characteristics of the subjects .
while the 
 subjects walked on a treadmill ( sns care m-400 m ; sns care co. , ltd . , goyang - si , republic of 
 korea ) while wearing rain boots , a wireless surface emg system ( free emg ; bts inc . , milan , 
 italy ) was used to measure lower extremity muscle activity and muscle fatigue . in this single - sample repeated measures experiment ,
the subjects were divided into three 
 groups based on rain boot shaft length : long , middle , and short .
electrodes were attached to 
 the subjects to measure muscle activity before the experiment and immediately after walking 
 on a treadmill at 3.6  km / h constantly8 for 
 30 minutes9 while wearing rain boots . for measurement of muscle activity , 4  3.5  cm surface electrodes ( 3  m red dot 2570 ; 3  m 
 center , st .
the 
 electrodes were attached to the rectus femoris ( rf ) , vastus lateralis ( vl ) , semitendinosus 
 ( st ) , tibialis anterior ( ta ) , peroneus longus ( pl ) , and gastrocnemius ( gm , medial part ) . for 
 the rf , electrodes were attached to the halfway point between the patella anterior to the 
 femur and the anterior iliac spine11 ; for 
 the vl , the point 50 relative to the femoral longitudinal axis and over 5  cm from the 
 superomedial patella toward the vastus medialis12 ; for the st , the middle point between the ischial tuberosity and 
 the tibia , and 3  cm to the inside of the st11 ; for the ta , the point 33% from the tip of the fibula toward the 
 medial malleolus ; for the pl , the point 25% from the fibular head toward the lateral 
 malleolus13 ; and for the gm , the point 
 35% inside and 2  cm over the distal midline of the knee joint . for all cases , the distance 
 between the electrodes was 2  cm11 .
all of 
 the electrodes were attached by the same researchers . in order to avoid errors that might 
 affect the experiment ,
spss version 18.0 for windows ( ibm corporation , armonk , ny , usa ) was used for statistical 
 analysis .
the kolmogorov - smirnov test was used to prove normality , and levene s f test was 
 used to assess the homogeneity of the subjects .
two - way repeated measures analysis of 
 variance was performed to compare the muscle activities of each group before and after 
 walking .
scheff s test was used for post hoc analysis in case of a significant difference . 

when muscle activities based on boot shaft length were compared , there were no significant 
 differences in terms of the interaction between group and time among the six muscles 
 measured in this study .
in addition , no significant differences were found in the main 
 effects of group or time ( table 3table 3.pre- and post test muscle electromyographic results according to rain boot group 
 ( mv)variablegrouppretestposttestmean  sdmean  sdrflong32.0  17.955.1  16.7middle 14.1  16.29.0  8.9short11.2  16.94.1  10.7vllong48.9  50.021.7  32.5middle 65.4  54.157.7  30.3short89.3  50.8153.3  40.6stlong184.5  214.6120.0  151.1middle 221.6  230.2149.4  167.2short199.9  199.4143.2  151.7talong45.2  41.815.1  17.3middle 42.7  40.723.4  19.8short38.4  37.218.9  15.8pllong46.5  42.610.5  18.0middle 36.2  18.338.4  17.7short36.1  15.236.5  17.6gmlong52.7  26.849.8  14.8middle 43.3  23.145.0  22.4short52.4  29.348.8  27.2gm : gastrocnemius ; pl : peroneus longus ; rf : rectus femoris ; st : semitendinosus ; ta : 
 tibialis anterior ; vl : vastus lateralis ) .
gm : gastrocnemius ; pl : peroneus longus ; rf : rectus femoris ; st : semitendinosus ; ta : 
 tibialis anterior ; vl : vastus lateralis
shoes are important for protecting the human body , and those worn during exercise are 
 useful for preventing injury in several joints , including the ankle , by absorbing the impact 
 of landing while walking and running2 . 

shoes have been developed to serve different purposes , and the types of shoes that are worn 
 vary based on an individual s particular interests . in this context , this study investigated 
 lower extremity muscle activity based on rain boot shaft length , since these boots have 
 become a popular fashion item among young females . when muscle activities based on boot shaft length were compared in this study ,
there were 
 no significant differences in the interaction between group and time among the six muscles . 

in addition , no significant differences were found in the main effects of group or time .
a previous study investigating the effect of high - top versus low - top sneakers on ankle 
 inversion reported that the former were more effective in reducing ankle inversion and might 
 be slightly more helpful in preventing ankle sprain based on loading conditions14 .
another study exploring the effect of 
 shoes on achilles tendon loading reported that high - top sneakers were more effective in 
 reducing peak achilles tendon tension15 . 

the effects of shoe collar height on the kinematics and kinetics of the ankle joint in 
 athletic performance during unanticipated maximum - effort side - cutting also have been 
 explored .
it was reported that high - collar shoes reduced ankle inversion and external 
 rotation of the planting leg during initial contact , and showed less ankle joint range in 
 the sagittal and transverse planes .
however , ankle movement and performance indicators , 
 including cutting performance time , ground contact time , and propulsion ground reaction 
 forces and impulses , were not affected by collar height .
such results indicate that 
 high - collar shoes do not have a negative effect on athletic cutting performance , but , 
 instead , transform ankle positioning and restrict ankle joint freedom16 .
contrary to previous studies , no significant differences were found in muscle activities in 
 this study , indicating that rain boot shaft length did not play a critical role in 
 restricting lower extremity movement . unlike the characteristics of the material used in 
 sneakers , rain boots did not restrict joint range , owing to the flexibility of the soles , 
 despite the long shaft .
they also did not affect muscle activity based on shaft length 
 because of the characteristics of the rubber and the large circumference of the shaft .
first , the results would be difficult to generalize 
 because muscle activity was analyzed in a small number of samples .
third , this study analyzed emg only . therefore , 
 further studies involving a larger number of samples including various types of subjects , 
 such as athletes , elderly individuals , and specific patients , are required .
in addition , 
 relative analysis has to be performed for various variables regarding the rain boots , such 
 as joint angle and proprioception . in conclusion , the lower extremity muscle activity based on rain boot shaft length was 
 investigated because these boots are commonly used in the rainy season for practical reasons 
 and have become a fashion item for young females , resulting in no significant differences 
 among the activities of all six muscles measured in this study .
the results of this study 
 may suggest that movement of the lower extremities was not restricted by friction force 
 based on the characteristics of the boot material ( rubber ) or the circumference of the boot 
 shaft .
thus , it may be helpful instead to consider the material of the sole or the weight of 
 the boots when choosing rain boots for practical purposes .
 [ purpose ] this study aimed to determine the extent of lower extremity muscle activity 
 before and after walking based on rain boot shaft length . [ subjects and methods ] 
 the 
 subjects , 12 young and healthy females , were divided into three groups based on rain boot 
 shaft length ( long , middle , and short ) . 
 they walked on a treadmill for 30 minutes . 
 
 activity of the rectus femoris , vastus lateralis , semitendinosus , tibialis anterior , 
 peroneus longus , and gastrocnemius was measured using electromyography before and after 
 walking . 
 two - way repeated measures analysis of variance was performed to compare the 
 muscle activities of each group . 
 [ results ] there were no significant differences in terms 
 of the interactive effects between group and time for all muscles , the main effects of 
 group , or the main effects of time . 
 [ conclusion ] the results of this study may indicate 
 that movement of the lower extremities was not significantly limited by friction force 
 based on the characteristics of the boot material or the circumference of the boot shaft . 
 thus , it may be helpful instead to consider the material of the sole or the weight of the 
 boots when choosing which rain boots to wear . 
INTRODUCTION
SUBJECTS AND METHODS
RESULTS
DISCUSSION