human posture is determined and maintained by muscle coordination , proprioception , 
 equilibrioception , and the position and function of the joints1 .
the ankle strategy that is applied to the ankle joints is an 
 important2 component of maintaining 
 postural adjustment and includes the proper use of hip joint muscles attached to the ankle 
 joints and appropriate stepping strategies3 . in terms of mechanics ,
the maintenance of a 
 sufficient range of motion , strength , and proprioception is crucial in providing shock 
 absorption and balance control of movements in the lower extremities while walking , which 
 are the primary functions of the ankle joints5 .
functional balance is the ability to maintain a position and adjust 
 posture while moving from one postural position to a different position or a functional 
 motion , such as movement from a certain position to another position6 .
the ankle joints are adjusted by the ground reaction force 
 generated by the contractions of the gastrocnemius , peroneus longus , and tibialis anterior 
 muscles7 .
small changes to adjustments 
 in balance are accomplished by the action of the muscles associated with the ankle joints ; 
 the body movement around the ankle , acting like an inverted pendulum , corrects the position 
 of the center of gravity2 .
isometric , isotonic , and isokinetic exercises are used in resistance training for 
 increasing muscle strength .
isotonic exercises are auxotonic contractions in which , despite 
 changes in muscle length , tension in the muscles remains constant and improves muscle 
 strength8 .
isokinetic exercises allow 
 muscles to exert maximum strength within the range of all joint movements at a constant 
 speed ; various exercise methods can be used to improve muscle strength9 .
isometric exercises are popular and have been performed 
 successfully by physiotherapists for rehabilitation . in particular , they can be adjusted for 
 patients whose range of joint movements is limited , and they are useful when performed in a 
 safe training environment10 .
muscle 
 fatigue , which is a hindrance factor during exercise , is defined as a condition that brings 
 about a reduction in maximum voluntary force or power generated by a muscle or muscle group ; 
 the muscle fatigue mechanism is a complex phenomenon in which the central and peripheral 
 nervous systems generally work together11 . in order to evaluate the mechanisms of muscular strength production
muscle movement begins 
 with an electrical activity , and this signal is recorded by electromyography ( emg)8 . determining the level of muscle activity is 
 a non - invasive method of studying the electrical and mechanical events of a single muscle 
 excitation - contraction combination ; recording
the electrical activity of muscles has been 
 widely used in studies on muscle coordination , muscle contraction characteristics , motor 
 unit recruitment , and the muscle firing rate12 . in previous studies of patients with knee osteoarthritis that compared isometric and 
 isokinetic exercises , it was found that isokinetic exercises were much more effective than 
 isometric exercises for improving muscle strength13 .
yang and hwang14 reported that a six - week treatment of neurological physical therapy 
 with afferent knee joint isokinetic exercises in patients with acute stroke and hemiplegia 
 improved balance control and muscle strength in the lower extremities .
in addition , an 
 analysis of the muscle activities of volleyball players who received isometric training for 
 six weeks found that there were significant differences in the improvement of muscle 
 strength8 .
after isokinetic exercises 
 were performed for four weeks on the ankle joints of adults in their 20s , the subjects were 
 asked to complete a one - leg stance on the same leg , and it was reported that the ankle 
 muscle training helped to improve balance control .
the plantar flexor of the ankle joint is considered to be the key regulator in 
 standing15 , and it plays an important 
 role16 in walking efficiency17 .
in the current study , isotonic , 
 isokinetic , and isometric exercises were performed on ankle joints to assess their effects 
 on the muscle activity and balance control of the tibialis anterior , peroneus longus , and 
 gastrocnemius muscles .
the 30 participants in this study were students at a university in cheonan , republic of 
 korea .
the procedures of the experiment were explained to the students , who did not have any 
 problems with the experiment and voluntarily agreed to participate .
exclusion criteria 
 included musculoskeletal or neurological diseases ; muscle strength training during the past 
 six months18 ; joint or bone disorders or 
 ankle sprains ; and tendon , fascia , or ligament inflammation19 .
the exercises were divided into isotonic , isokinetic , and 
 isometric exercises , and 10 students were randomly assigned to each of the three types of 
 exercise groups . a body composition analyzer ( inbody720 , biospace o. ltd . ,
seoul , republic of korea ) was 
 used to determine the general characteristics of the subjects . a functional rehab system 
 ( primus rs , bte tech .
, hanover , md , usa ) was employed to carry out the isotonic , isokinetic , 
 and isometric exercises . a free emg system ( free emg , bts inc . ,
milan , italy ) measure the 
 muscle activity of the subjects , and a computerized balance platform ( bt4 , hur labs oy . , 

tampere , finland ) was used to determine balance control . after being informed about the study and understanding the purpose and content of the 
 experiment , each of the 30 participants signed a consent form . after measuring their 
 physical characteristics ,
ten students were randomly assigned to each of the three exercise 
 groups : isotonic , isokinetic , and isometric . before conducting the experiment ,
the dominant 
 limb was identified by having the subjects kick a ball that had been placed in front of 
 them .
the limb that was used to kick the ball was identified as the dominant side20 in order to apply the exercise to the 
 non - dominant side ; surface electrodes were then attached to the tibialis anterior , peroneus 
 longus , and gastrocnemius muscles .
the subjects were positioned in the physical rehabilitation equipment with their knees 
 fully extended21 , and both sides of the 
 hip joints and the knee joints were fixed into a neutral position using a strap .
the 
 exercises were performed after fitting the rotational axis of the equipment along the inner 
 elongation of the anklebone with the foot secured in the isokinetic equipment22 .
the isometric 
 exercises were performed three times to induce muscle fatigue in the subjects for maximal 
 voluntary isometric contraction ( mvic)24 . 

of the three mvics , the one with the highest peak torque was 
 selected as the mvic15 .
then the subjects 
 were given verbal reinforcement to encourage them to exert maximum force during the 
 isometric contractions24 .
to familiarize 
 the subjects with the experiment before performing the isotonic , isometric , or isokinetic 
 exercises , submaximal contractions were performed five times as a pre - exercise that involved 
 isokinetic exercises26 .
there was a 
 five - minute rest period after the pre - exercise to prevent the fatigue effect27 .
the isotonic exercise group performed 
 self - paced exercises28 at 50% resistance 
 of mvic29 .
ten repetitions were performed 
 per set , followed by a rest ; three sets were performed , with a one - minute rest period 
 between the sets to prevent fatigue30 . in 
 the isokinetic exercise group ,
changes in the increase of muscle strength occurred according 
 to isokinetic strength exercise implementation , which depends on the dynamic form of 
 exercise , speed , and muscle contraction .
in particular , low - velocity exercises generally 
 increase muscle strength , while high - velocity exercises are mainly used for the recovery of 
 muscle endurance . among the most frequently implemented angular velocities of 60 , 180 , and 
 300 degrees / sec in isokinetic exercises ,
the angular velocity of 60 degrees / sec was 
 selected ; this velocity is mainly used for improving muscle strength in adults or 
 athletes31 .
the ankle was put in a 
 neutral position32 , and the exercise 
 intensity was set within the range of pain tolerance .
three sets of ten repetitions of 
 plantar flexion and dorsiflexion were performed , followed by a rest33 .
there was a one - minute rest period between sets to 
 prevent the fatigue effect32 .
the 
 isometric strength training group used mvic resistance to perform plantar flexion ; 
 dorsiflexion was performed at 70% of mvic resistance21 .
plantar flexion and dorsiflexion of the ankle were sustained for 
 15 seconds33 per repetition for a total 
 of three repetitions per set , and each set was followed by a five - second rest period30 ; three total sets were performed .
there 
 was a one - minute rest period between each set to prevent fatigue32 . in order to enable maximum performance ,
strong verbal 
 reinforcement was provided during all tests , along with auditory and visual feedback15 . to generate the emg data , electrodes were attached to the surface at the state of standard 
 maximum contraction to avoid technical errors that might affect the tests . to minimize 
 errors caused by skin impedance and to keep the impedance below 5 k , the skin was prepared 
 first by exfoliation with sandpaper to remove dead skin cells and debris and then 
 disinfection with sterile alcohol23 .
all 
 active electrodes ( carbon electrode ; 3 m , ) were attached parallel to the direction of the 
 muscle fiber at 2-cm intervals34 .
a 1-khz 
 sampling rate , 500-hz low - pass filter , and 20-hz high - pass filter were used to measure emg . 

the emg signals of each muscle measured were treated with the value of root mean square . 

data for the emg measurements were obtained by eliminating the beginning and end of the emg 
 interval . to test the subjects balance ability , a one - leg stance with eyes open
was performed using 
 a computerized balance platform . while standing barefoot with both arms comfortably at their 
 sides35
, the subjects were asked to 
 bend one leg along the anterior - posterior axis of the balance platform at 30 and stand on 
 the opposite leg , to maintain as stable a stance as possible36 with their eyes open for 30 seconds37 , and to gaze at a point on a monitor 65  cm away35 .
an oral countdown from 4 seconds to 1 
 second was given to start , and the word 
data were obtained by taking the mean value of the measurements , 
 which were repeated twice .
the kolmogorov - smirnov test was used to 
 demonstrate a normal distribution , and the levene f - test was used to verify the homogeneity 
 of the subjects .
multivariate analysis of variance ( manova ) was used to compare the 
 difference in muscle activity and balance control in the tibialis anterior , medial 
 gastrocnemius , and peroneus longus , depending on the group ( isotonic , isokinetic , or 
 isometric exercise group ) and time ( pre- or post - exercise ) . when there was a significant 
 difference ,
this study was approved by the institutional review board of 
 namseoul university ( cheonan , korea , nsu-140528 - 1 ) .
fifteen of the subjects were 
 male , and 15 were female ; 28 of the subjects were right - side dominant , and two were 
 left - side dominant .
information regarding the subjects , such as age , height , weight , and 
 body mass index , is provided in table 
 1table 1.subject characteristicsgroupnage ( years)height ( cm)weight ( kg)bmi ( kg / m)msdmsdmsdmsdisotonic1020.31.7170.29.970.014.623.92.6isokinetic1020.21.8165.59.965.820.223.64.8isometric1020.11.4166.911.568.518.224.13.9msd : means  standard deviation ; bmi : body mass index .
msd : means  standard deviation ; bmi : body mass index the changes in muscle activity before and after the tests are shown in table 2table 2.comparison of pre- and post - test muscle electromyography ( mv)variablegrouppre - testpost - testmsdmsdnon - ta * ( support by non-)isotonic0.350.300.330.14isokinetic1.471.521.180.83isometric0.520.530.420.18non - gcm * ( support by non-)isotonic1.211.371.862.17isokinetic2.132.312.812.40isometric0.760.540.732.17non - pl * ( support by non-)isotonic0.831.010.940.86isokinetic1.591.261.781.76isometric0.760.540.730.52dom - gcm * ( support by dom-)isotonic 0.570.591.372.14isokinetic2.351.622.422.25isometric0.610.370.760.50dom - pl ( support by dom-)isotonic 0.620.581.010.83isokinetic1.400.901.871.23isometric0.820.751.040.69*p<0.05 ; isotonic ; isokinetic ; isometric ; 
 non- : non - dominant side ; dom- : dominant side ; ta : tibialis anterior ; gcm : 
 gastrocnemius ; pl : peroneus longus .
the statistical analysis indicated that no interaction between group and time 
 could be observed in any of the subjects .
the main effects according to group could be observed in the non - dominant tibialis anterior , 
 gastrocnemius , and peroneus longus muscles when the non - dominant limb was weight bearing , 
 and in the peroneus longus and gastrocnemius muscles when the dominant limb was weight 
 bearing .
a multiple comparison analysis showed that there were significant differences among 
 the isokinetic , isotonic , and isometric exercise groups in the non - dominant tibialis 
 anterior and between the isokinetic and isometric exercise groups in the non - dominant 
 gastrocnemius and peroneus longus .
in addition , there were significant differences among the 
 isokinetic , isotonic , and isometric exercise groups in the dominant gastrocnemius and 
 peroneus longus .
* p<0.05 ; isotonic ; isokinetic ; isometric ; 
 non- : non - dominant side ; dom- : dominant side ; ta : tibialis anterior ; gcm : 
 gastrocnemius ; pl : peroneus longus the changes in balance control according to group both before and after the tests are shown 
 in table 3table 3.comparison of pre- and post - test balancevariablegrouppre - testpost - testmsdmsdarea ( mm ) ( support by non-)isotonic435.0139.1615.1244.1isokinetic389.3215.6515.6277.7isometric292.6138.1491.5280.5area ( mm ) ( support by dom-)isotonic399.1151.5495.0229.2isokinetic353.5119.8453.4161.6isometric349.2149.4470.2295.8velocity ( mm / s ) ( support by non-)isotonic11.54.012.23.0isokinetic12.33.713.43.6isometric11.42.816.313.8velocity ( mm / s ) ( support by dom-)isotonic11.73.211.12.6isokinetic12.32.814.46.2isometric12.03.514.78.5*p < 0.05 ; < 0.05 : compared with post - test ; non- : non - dominant 
 side ; dom- : dominant side .
no main 
 effect according to group was observed , and the main effect of time on surface area was 
 present only when the non - dominant and dominant sides were weight bearing .
multiple 
 comparison analysis of the significant differences in surface area showed that when the 
 non - dominant side was weight bearing , there were significant differences in all three 
 exercise groups ; when the dominant side was weight bearing , there were only significant 
 differences in the isokinetic exercise group .
* p < 0.05 ; < 0.05 : compared with post - test ; non- : non - dominant 
 side ; dom- : dominant side
the ankle strategy requires a normal operating range and muscle strength , and it is used to 
 maintain balance . if the range of movement of the ankle joints becomes constrained , the 
 postural adjustment provided by the ankle joints becomes constrained as well5 .
postural adjustments require integration of 
 body segment movement navigation and the information sent through the central nervous system 
 through the proprioception , tactile , visual , and afferent systems ; muscle fatigue influences 
 one or more regulatory systems , such as postural adjustment , and it is typically associated 
 with changes in movement and sensory systems39 . in this study ,
the subjects were young , healthy adults who performed isotonic , isokinetic , 
 and isometric exercises of the ankle joints ; this study analyzed the effects these exercise 
 methods have on the muscle activity and balance control of the tibialis anterior , 
 gastrocnemius , and peroneus longus muscles . in the case of muscular activity
, there were 
 significant differences in the non - dominant tibialis anterior , gastrocnemius , and peroneus 
 muscles when the non - dominant side was weight bearing ; when the dominant - side was weight 
 bearing , there were significant differences in the dominant gastrocnemius and peroneus 
 longus muscles . in the case of balance , there were significant differences in surface area , 
 depending on time when both the non - dominant side and the dominant side were weight bearing ; 
 however , no significant difference in velocity was observed .
significant differences were noted in the emg of the non - dominant tibialis anterior when 
 the non - dominant limb was weight bearing .
these results are consistent with previous 
 research on the bilateral effects of muscle fatigue of one leg and muscle emg , where it was 
 found that the tibialis anterior muscle of the limb on which the exercise was performed 
 experienced a decline in emg .
it was reported that this decline was related to resistance to 
 stretching of the fatigued muscles , as fatigued muscle activity is usually associated with 
 increased passive tension39 .
38 analyzed the muscular activity of 
 the plantar flexor and dorsiflexor muscles in elderly and young adult patients by having 
 them perform a one - leg stance with their eyes closed , and they found that the emg of the 
 tibialis anterior was higher than that of the gastrocnemius in both groups . when a one - leg 
 stance with eyes open was performed , emg was higher in the tibialis anterior of the elderly 
 group and higher in the gastrocnemius of the young adult group .
the findings were similar in 
 the current study , in which adults in their 20s were the subjects ; in addition , the emg of 
 the non - dominant gastrocnemius was higher than the non - dominant emg of the tibialis anterior 
 when the non - dominant limb was weight bearing .
these results indicate that due to the muscle 
 fatigue induced by the three exercises , the emg activity of the tibialis anterior declined 
 in relation to the resistance to muscle activity by the muscle that had been fatigued by the 
 one - leg stance with eyes open . in a study regarding the effects of fatigue during isometric contractions of both the 
 dominant and non - dominant quadriceps muscles
, it was found that initial recovery from the 
 combined effect of the fatigue mechanisms that contribute to the maximum decline in power 
 due to sustained isometric contraction was in the dominant leg .
this result occurred even 
 though the combined effect of the peripheral and central fatigue mechanisms that induce the 
 development of muscle fatigue during continuous isometric contraction of one side was not 
 related to the dominant leg40 . in 
 addition , in a study on postural adjustment disturbance of the opposite leg in a one - leg 
 stance brought on by fatigue induced by stimulation and voluntary contraction of the same 
 limb ( the exercised lower extremities ) , it was reported that the cross - over fatigue effect 
 after stimulation and voluntary contraction could interfere with postural adjustment .
the 
 training of one weight - bearing side could also be transferred to the untrained side due to 
 the cross - education effect41 .
thus , in 
 this study , the unexercised , dominant side showed significant differences in the 
 gastrocnemius and peroneus longus when the dominant leg was weight - bearing due to this 
 effect , while the unexercised dominant gastrocnemius and peroneus longus developed tiredness 
 before muscle fatigue .
moreover , the lack of significant differences in the dominant 
 tibialis anterior muscle when the dominant side was weight - bearing might be due to the 
 morphological characteristics of the muscles : the plantar flexor , which is composed of 
 cooperative muscles , has a high compensation potential , but the muscle fatigue recovery rate 
 is slow , while the dorsiflexor has relatively low compensation potential but a fast fatigue 
 recovery rate . in this study , the results of balance ability both before and after exercise in the 
 respective exercise groups showed that there were significant differences in the dominant 
 and non - dominant weight - bearing sides in terms of area . in a previous study ,
in which young 
 adults performed a 30-second one - leg stance on their dominant leg after inducing isokinetic 
 fatigue in the ankle and hip joints , there was no significant difference in the area of the 
 ankle joint , even though the area tended to increase after the fatigue rather than before 
 the fatigue42 . in a study on changes in 
 balance orientation of healthy elderly women after knee and ankle fatigue , it was found that 
 acute muscle fatigue reduced balance adjustment43 and localized dorsiflexor fatigue from the midsagittal plane was a 
 leading factor in precipitating postural adjustment disturbance ; this was found to produce a 
 higher average disturbance threshold during posture correction than the plantar flexor in a 
 non - fatigued state44 .
the analysis of the 
 effects of ankle muscle fatigue on one - leg stance posture control and recovery in adult male 
 and female subjects showed that there were no gender differences ; the fatigue effect 
 appeared in the right and left factors both before and after fatigue in both the male and 
 female groups45 . in a study in which 
 young adults performed a one - leg stance with their eyes open after isokinetic fatigue
had 
 been induced in the ankle , knee , and hip joints , it was found that from the coronal plane , 
 knee and hip joint fatigue brought about disturbances to posture adjustment ; however , 
 midsagittally , the fatigue of the three joints produced posture adjustment disturbances46 .
similarly , as in previous studies , the 
 lower extremity fatigue induced by the three exercise methods implemented in this study 
 affected the posture adjusting mechanisms .
even the non - dominant side , which did not perform the exercises , 
 was affected before the fatigue ; thus , the transferred fatigue caused postural sway to 
 increase significantly .
this outcome shows the direct effect of plantar flexor and 
 dorsiflexor fatigue of the ankle joints . in this study , there were no significant differences in velocity before or after the 
 exercises depending upon the group .
according to a study on the effects of ankle and hip 
 joint muscle fatigue on postural sway in a one - leg stance , muscle fatigue of the plantar 
 flexor and dorsiflexor of the ankle joints did not increase the sway velocity compared with 
 the muscle fatigue in the flexion and extensor muscles of the hip joints ; muscles that are 
 proximal ( hip and knee ) exert a greater influence on posture adjustment than muscles that 
 are distal ( ankle ) .
the use of the hip joint strategy increases according to the difficulty 
 of the tasks  however , the ankle strategy is primarily used when standing .
thus , the one - leg 
 stance is adjusted by a combination of hip and ankle joints .
when the ankle joints are 
 fatigued , decreased ankle joint control ( due to a damaged ankle proprioceptive sense ) can be 
 compensated for by increased dependency on the hip strategy42 . a study analyzing
the effects of vision on postural control and 
 muscle fatigue in triceps surae muscles47 
 reported that vision can bring about postural deficiency related to fatigue in the plantar 
 flexor .
in addition , in a study of postural sway during one - leg stance , lower body angle and 
 postural strategy , and the effects of plantar flexor and dorsiflexor fatigue , it was found 
 that visual senses compensated for compromised postural adjustment .
a proprioceptive sensory 
 deficit strengthened the role of vision and subsequently reduced the amount of 
 proprioceptive sensory information necessary to stand on one leg , particularly when the 
 support surface decreased37 . in a study 
 of healthy athletes and athletes with functional ankle instability that investigated the 
 effects of fatigue due to treadmill running and sensorimotor control ,
it was found that 
 fatigue due to treadmill running had negative effects on static and dynamic posture control 
 assessment in all groups .
that finding indicates that damage has occurred to muscle 
 activation patterns and reflex activity ; in the state of fatigue , postural adjustment is 
 affected by complex mechanisms of the sensory , neural - muscular , and central nervous systems ; 
 the central nervous system receives more disturbances than the peripheral mechanisms of 
 proprioception48 . moreover , in a study on posture sway and the effects of incremental difficulties in a 
 standing balance task with visual feedback , as the difficulty of the task increased , the 
 amplitude of the postural sway increased , and the fuzzy entropy of postural sway also 
 increased from the anteroposterior axis in the most unstable condition49 . according to a study on visual compensation in accordance 
 with muscle fatigue and postural adjustment ,
different sensory systems exist in a complex 
 relationship related to postural control . under the condition of muscle fatigue
, vision can 
 compensate for the muscle fatigue generated by the triceps surae muscle by increasing the 
 contributions of the various sensory systems for adjusting posture .
concurrently , in the 
 state of muscle fatigue , the effectiveness of the visual presentation is important for 
 proper adjustment of support47 . 

therefore , the reason there was no significant difference in velocity / speed was because the 
 balance was measured in a one - leg stance with eyes open without constraining the subject s 
 vision .
due to the muscle fatigue , compensation from visual information regarding postural 
 adjustment and dependence on the hip strategy were amplified ; the impairment of the 
 sensorimotor system and proprioception of the ankle joints for maintaining balance were not 
 sufficient to make a significant impact on velocity .
this study analyzed the effects of muscle fatigue on muscle activity and balance control in 
 the lower extremities using three exercise methods .
the ankle joint in which this was 
 implemented was limited ; balance was measured with visual information , and the subjects were 
 confined to healthy students .
for further research , studies regarding the relationship and 
 compensation potential of various joints , such as hip , knee , and ankle joints ; studies on 
 postural and balance control both with and without visual information , as vision and 
 proprioception are closely related50 ; and 
 research focusing on specialized groups , such as patients and athletes with pain or disease 
 in the ankle joint , are needed to expand the scope and variety of the research . in conclusion , in this study , isotonic , isokinetic , and isometric exercises were applied to 
 the ankle joints of healthy adults in their 20s to investigate the effects of these exercise 
 methods on the muscle activity and balance control of the tibialis anterior , inner 
 gastrocnemius , and peroneus longus muscles .
our results indicated that 1 ) there were no 
 significant differences due to the changes of muscle activity before , during , or after the 
 exercise between the interaction of group and time ; however , there were significant 
 differences according to group in the non - dominant tibialis anterior , gastrocnemius , and 
 peroneus longus muscles when the non - dominant side was weight - bearing , as well as in the 
 dominant gastrocnemius and peroneus longus when the dominant side was supported ; 2 ) there 
 were no significant differences before or after exercise in the interaction of group and 
 time due to the change in balance control ; depending on time , there were significant 
 differences in the surface area depending upon whether the non - dominant side or the dominant 
 side was weight - bearing , but there was a significant difference in speed .
accordingly , the 
 muscle fatigue generated by the three exercise methods affected the decline in muscle 
 activity and balance control ; it also influenced the side that did not perform the exercise 
 before fatigue due to this effect .
the finding that visual compensation occurs to maintain 
 postural balance will further aid future treatment and research regarding muscle activity 
 and balance control in the lower extremities .
 [ purpose ] this study analyzed the effects of isotonic , isokinetic , and isometric 
 exercises of ankle joint muscles on lower extremity muscle activity and balance control . 
 
 [ subjects and methods ] the subjects were 30 healthy adults ( 15 males ) in their 20s who 
 were randomly assigned to three different exercise method groups of 10 people each . 
 the 
 isokinetic exercise group performed three sets at an angular velocity of 60/sec , 
 including a single rest period after every set of 10 repetitions . 
 the isometric exercise 
 group performed three sets consisting of three 15 repetitions of a 15-second exercise 
 followed by a 5-second rest . 
 [ results ] multivariate analysis of variance revealed that 
 depending on the exercise method , the non - dominant tibialis anterior , gastrocnemius 
 muscle , and peroneus longus showed significant differences in muscle activity for 
 weight - bearing non - dominant sides ; when the dominant side was weight - bearing , the dominant 
 gastrocnemius and peroneus longus showed significant differences in muscle activity ; and 
 the non - dominant and dominant sides showed significant differences in balance control 
 depending on the duration of support in the area . 
 [ conclusion ] muscle fatigue from the 
 three exercise methods produced a decline in muscle activity and balance control ; due to 
 the fatigue before exercise , the side that did not perform the exercises was affected . 
INTRODUCTION
SUBJECTS AND METHODS
RESULTS
DISCUSSION