. the plantar muscles and 
 tendons function as a shock absorber and influence gait efficiency1 .
mla is categorized into three types : flat feet , regular 
 feet , and cavus feet2 .
the causes of flat 
 feet are numerous , and include the weakness of the abductor hallucis , which is an intrinsic 
 muscle of the plantar surface of the foot3
. foot exercise is used to reinforce the arch of the foot and 
 strengthen the plantar muscles .
there are many exercises for strengthening the abductor 
 hallucis muscle , which is one of the intrinsic muscle supporting the mla , for example : toe 
 curls exercise , toe spread exercise , shin curls , and picking up objects4 .
it is performed by 
 shortening the foot in the anterior - posterior direction with the forefoot and heel touch the 
 floor without toe flexion3 .
it was noted 
 that after the short foot exercise was conducted , it was noted that there was an increase in 
 the mla angle3 , and a reduction of center 
 of pressure5 .
therefore , it has been 
 assumed to be an effective method for mla treatment and for strengthening the abductor 
 hallucis muscle .
myers ( 2008 ) described how the plantar fascia and the short toe flexors are 
 connected with the triceps surae ( gastrocnemius ) on the superficial back line6 .
according to the passive length - tension 
 relationship , passive tension in a stretched healthy muscle produces elastic forces7 . an inclined ankle with an elongated the 
 triceps surae also generates larger intrinsic foot muscle tension .
therefore , the purpose of 
 this study was to measure the effect of an inclined ankle on abductor hallucis muscle 
 activation during the short foot exercise .
individuals were excluded if they had 
 arthritis , or had undergone an operation on , or amputation of the foot or ankle in the past 
 6 months .
they were also excluded if they suffered from hallux valgus , hammer toe , or claw 
 toe deformities .
all selected subjects showed values the normal range ( 59 mm ) in the 
 navicular drop test8 and ankle range of 
 motion ( rom ) .
ethical approval was obtained from inje university faculty of health science 
 human ethics committee , and all the subjects signed an informed consent form prior to their 
 participation .
the participants mean age was 24.715.12  years , their mean height was 166.218.96  cm , and 
 their mean body mass was 58.219.42  kg .
the surface emg activities of the abductor hallucis 
 were recorded by a mp150wsw data acquisition system ( biopac systems , santa barbara , ca , 
 usa ) .
all the emg signals were amplified , bandpass - filtered ( 20  hz to 500  hz ) , and sampled 
 at 1,000  hz using acqknoledge software , version 3.9.1 .
the emg data were normalized to peak 
 maximal voluntary isometric contraction ( peak % mvic)9 .
the subjects were instructed to keep an upright sitting posture on the chair , and performed 
 two types of short foot exercises .
one was the general type of short foot exercise performed 
 on a flat floor ( neutral sf ) , and the other the short foot exercise was performed with 30 
 passive ankle dorsiflexion provided by a tilting board for stretching the triceps surae 
 ( inclined sf ) .
the short foot exercise was performed so that the metatarsal was drawn 
 towards the heel without any toe flexion .
the 
 paired t - test was performed to determine significant differences in the activities of the 
 abductor hallucis during the short foot exercises .
the % mvic activations of the abductor hallucis during the short foot exercises were 
 59.1813.00% for the inclined short foot exercise , and 49.3113.27% for the neutral short 
 foot exercise ( table 1table 1.%mvic of the abductor hallucis during the neutral and inclined short foot 
 exercises ( n=14)neutral sfinclined sfmean ( sd)mean ( sd)abductor hallucis49.31 ( 13.27)59.18 ( 13.00 ) * sf : short foot exercise , sd : standard deviation . *
the inclined short foot exercise showed a significantly larger activation 
 than that of the neutral short foot exercise ( p<0.05 ) . sf : short foot exercise , sd : standard deviation .
many previous studies have reported that the short foot exercise is an effective exercise 
 for strengthening the mla of the foot .
thus , this study investigated the effectiveness of an 
 inclined ankle short foot exercise for strengthening the abductor hallucis , when compared to 
 a general short foot exercise .
the abductor hallucis is an intrinsic muscle within the mla 
 supporting muscles , and its electromyographic signal is easy to measure because of its 
 superficial position .
we had a hypothesized that the length - tension relationship would exert an influence on the 
 intrinsic muscle of the foot .
therefore , we performed an inclined short foot exercise with 
 30 passive ankle dorsiflexion to elongate the ticeps surae .
( 2000 ) reported 
 the angle of maximum passive ankle dorsiflexion was about 31 degrees10 , and we set the passive dorsiflexion angle set to 30 
 degrees .
our results show that the inclined short foot exercise showed a higher activation 
 than that of the general short foot exercise .
( 2005 ) found a new method of non - invasively measuring the passive 
 length - tension properties of the human gastrocnemius muscle in vivo11 .
it was the first in vivo study , but the foot plantar 
 muscles were neglected .
also , research related to the foot arch has reported methods for 
 strengthening the abductor hallucis3,4,5 . 
 however , that research used the neutral foot position , and did not consider the passive 
 length - tension relationship of the ankle .
thus , our present suggests a more effective 
 exercise method for abductor hallucis strengthening than passive ankle dorsiflexion for 
 intensifying the foot intrinsic muscle activation .
the sample size was too small , so our results can not be 
 generalized to all subjects .
also , the abductor hallucis is a small muscle , so the emg 
 signal may contain cross talk .
finally , the abductor hallucis does not represent all of the 
 foot arch muscles , which consist of many other small intrinsic muscles .
   [ purpose ] the purpose of this study was to identify the effects of an inclined ankle on 
 the activation of the abductor hallucis muscle during short foot exercises . 
 [ subjects ] we 
 recruited 14 healthy volunteers who were free of pain , and did not suffer from arthritis 
 or osteomuscular problems related to the foot or ankle . [ methods ] the subjects performed 
 short foot exercises and short inclined foot exercises with 30 passive ankle 
 dorsiflexion . [ results ] 
 the exercise with an inclined foot showed a significantly larger 
 activation of the abductor hallucis than that shown during the neutral short foot 
 exercises . 
 [ conclusion ] these results suggest that passive ankle dorsiflexion during short 
 foot exercise for strengthening the abductor hallucis is a more effective clinical 
 treatment exercise . 
INTRODUCTION
SUBJECTS AND METHODS
RESULTS
DISCUSSION