ankle sprain is a common injury for athletes who perform cutting maneuvers , landings , or 
 frequent jumps or make contact with other players1 .
approximately 4075% of individuals develop residual symptoms or 
 chronic ankle dysfunction due to lateral ankle sprain2 .
in addition , functional ankle instability may affect the postural 
 control and whole body balance .
ross et al . quantified the time required for stabilization 
 during single - leg jump landing .
they concluded that their functional ankle instability group 
 took significantly longer to stabilize in the sagittal and frontal planes of motion3 .
based on the findings of the abovementioned 
 studies , individuals with functional ankle instability have a greater risk of injury because 
 of their poor postural control , balance , and proprioception .
ankle taping has been proved to reduce impact force and to balance the ankle power4 .
peak dorsiflexion and average eversion 
 moments were significantly reduced in sidestepping tasks after taping5 . proper ankle taping decreases inversion and plantar 
 flexion , which may be related to the most common injury mechanisms6 . some scholars also reported that kinesio tape may improve 
 static restraint without altering dynamic postural control or peak motion7 . to summarize the above reports , taping and 
 bracing have been widely practiced as both preventative and rehabilitative interventions for 
 ankle sprains by providing mechanical support and enhancing proprioception8 .
so far , limited research has been performed in spite of biomechanical evaluation of jump 
 landing with kinesio taping .
the aim of this study was to investigate the effect of the kinesio taping on the 
 ankle functional instability ( fi ) of athletes during the landing phase in three - dimensional 
 ( 3d ) biomechanics analysis . from the hypothesized biomechanical view ,
kinesio taping had a 
 positive effect on peak ankle plantar flexion moment and peak vertical ground reaction 
 forces in the fi group .
ten male athletes with ankle functional instability ( fi ) were recruited in this study from 
 a college volleyball team .
( age , 231.58  years ; height , 172.36.27  cm ; weight , 
 70.29.11  kg ) . the inclusion criteria of the fi group were as follows : ( 1 ) no structural 
 instability or other anatomy structure disorder , ( 2 ) a feeling of giving way in the ankle 
 joint during exercise or daily activities , and ( 3 ) history of ankle sprain , but not in the 
 past six months9 .
subjects were excluded 
 if painful gait or painful range of motion was observed during the data collection 
 procedure . each subject s age , height , weight , and previous injury history were recorded .
a physical 
 therapist applied the anterior drawer test and talar tilt test to exclude subjects with 
 ankle mechanical instability .
each participant was requested to perform two tasks , the countermovement jump and vertical 
 jump with run - up .
each subject rested more than seven days between two conditions ( with and 
 without kinesio tape ) , and performed the countermovement jump and vertical jump with run - up 
 randomly . in the vertical jump with run - up movement ,
the subjects take a stride with their 
 dominant leg and then jump as high as possible . in the countermovement jump ,
the subjects 
 start from an upright standing position and then flex the knees and hips to make a 
 preliminary downward movement .
the subjects were asked to jump as high as possible in both jump 
 movements .
kinesio tape was applied to each participant s ankle by a professional athletic trainer . 

the taping methods used included application of tape in the basketweave pattern with 
 application of horseshoe and reinforcing strips10 .
the tape applied was a 5-cm kinesio tape ( kinesio tex products , 
 nkt-050 , japan ) .
the procedure for ankle taping was as follows : the tibialis anterior was 
 taped with elasticity of 6070% ( fig .
1b ) , 
 and then the area from the medial malleolus to the lateral malleolus was taped ( fig .
finally we applied tape with a basketweave 
 pattern , which was followed by application of heel locks with elasticity of 4050% ( fig .
kinesio taping procedures twenty - one reflective markers were placed on anatomic landmarks of the bilateral lower 
 limbs for each subject .
the selected anatomic landmarks were the sacrum , bilateral anterior 
 superior iliac spine , medial and lateral epicondyles of the femur , lateral thigh , lateral 
 shank , calcaneus , medial and lateral malleolus , and base of the second metatarsal bone11 .
a vicon612 motion analysis system ( oxford 
 metrics group , oxford , uk ) with six cameras was used to collect the trajectories of the 
 markers at 250  hz .
watertown , 
 ma , usa ) was used to record the ground reaction forces and moments at 1,000  hz sampling 
 rates .
these two devices were initiated with a trigger , and the synchronization was 
 recorded .
the study protocols were approved by the ethics committee of national taiwan 
 college of physical education ( no . 98002 ) .
all participants signed an informed consent form 
 and agreed to participate in the test . nf1 and
nf2 were defined as the first and second peak vertical ground reaction forces 
 normalized by each subject s body weight .
t1 and t2 were defined as the times to the first 
 and second peak vertical ground reaction forces after landing11 . for smoothing the trajectories of the markers ,
a generalized cross - validation spline 
 smoothing routine at a cutoff frequency of 6  hz was used in this study12 .
programs custom made with the matlab computer language 
 ( the mathworks , inc , natick , ma , usa ) were used to calculate the joint moments of the lower 
 limbs using the inverse dynamic method and the parameters of ground reaction forces .
the independent t test 
 was used to compare the differences between the countermovement jump and vertical jump with 
 run - up .
ninety - five percent confidence intervals ( 95% ci ) were calculated for the difference 
 between groups and conditions .
a statistical significant difference was observed only in the vertical jump with run - up 
 group ( p=0.02 , table 1table 1.the first ( nf1 ) and second ( nf2 ) peak vertical ground reaction forces normalized 
 by each subject s body weightunit = n / kgcountermovement jumpvertical jump with run - upnf1nf2nf1nf2non - taped1.560.23 4.030.761.720.515.311.00taped1.370.183.640.681.750.494.550.72significance#significant difference with and without taping ( p<0.05 ) ) . to further investigate the effect of kinesio taping on the vertical ground 
 reaction force , the first ( nf1 ) and second ( nf2 ) peak vertical ground reaction forces
we found that the nf2 in the 
 vertical jump with run - up decreased significantly after application of kinesio tape . 

we 
 then compared the types of jump , and the results showed that larger values were observed for 
 the vertical jump with run - up than the countermovement jump .
significant difference with and without taping ( p<0.05 ) regarding the peak ankle inversion moment , the moment decreased after taping , but no 
 statistical difference was revealed .
in addition , there was no significant difference 
 between the two types of jump .
furthermore , a larger plantar flexion moment was measured in 
 the vertical jump with run - up than the countermovement jump during landing ( table 2table 2.the peak moment of ankle plantar flexionunit = nm / kgcountermovementjumpvertical jumpwith run - upsignificancenon - taped0.090.040.170.06*taped0.060.020.120.05significance##significant difference with and without taping ( p<0.05 ) . *
significant 
 difference between tasks ( p<0.05 ) the times to the first ( t1 ) and second ( t2 ) peak vertical ground reaction forces after 
 landing are shown in table 
 3table 3.the times to the first ( t1 ) and second ( t2 ) peak vertical ground reaction 
 forces after landingunit = mscountermovement jump vertical jump with run - upt1t2t1t2non - taped11.362.91 62.778.3410.413.8953.0115.75taped13.293.6066.826.9710.633.5953.0513.8 .
no significant difference was observed for the effect of taping 
 on the times to the first ( t1 ) and second ( t2 ) peak vertical ground reaction forces .
a positive effect was observed on the peak vertical ground reaction forces and peak ankle 
 plantar flexion moment in the vertical jump with kinesio taping with run - up .
these 
 experimental results provide useful information for attenuating the risk of both jump 
 movements in athletes with ankle functional instability .
ankle sprains that occur during landing may result from uncertain factors , such as uneven 
 stance and exertion of excessive force .
large ground reaction forces at landing have been 
 reported , and the same results were obtained in this study13 . in the vertical jump with run - up , there was a significant difference in nf2 after taping . 

it seems that taping has an important effect on the vertical jump with run - up .
the findings 
 for the instability group may due to distinct recruitment of muscle fibers of the skeletal 
 muscle during the jump exercise . in the study of simon et al .
, it was speculated that an 
  injured  population with an actual proprioceptive deficit would respond differently14 . ankle functional instability is a 
 proprioceptive deficit .
thus , it is likely more effective for sensory input of the skin to 
 modulate muscle performance . in our study ,
the knee angle was not controlled in the subject , 
 and this could be a reason why no significant differences occurred during the 
 countermovement jump .
mcnitt - gray reported an nf2 of 4.16  1.3 n / kg ( jumping height 0.32 m ) . the results of the 
 present study were in agreement with those of the study of mcnitt - gray13 .
however , riemann s study revealed that nf1 and nf2 were 
 significantly higher in a non - taped group than a taped group during a jumping motion15 .
the difference in nf1 might have been due 
 to the various heights that the subjects jumped .
the subjects landed after jumping to a 
 height of 0.59  m in riemann s study , while the subjects landed after jumping to a height of 
 only 0.40  m in this study .
thus , the difference between the studies may be due to use of different 
 subjects .
the ankle plantar flexion moment decreased significantly both in the countermovement jump 
 and vertical jump with run - up after kinesio taping .
they concluded that taping 
 decreased joint position errors in plantar flexion but not inversion . in our results for 
 plantar flexion moment
, it appears that application of kinesio tape may restrict the range 
 of motion of the ankle ( table 2 ) .
postural 
 amendment , decreased inflammation and pain , feelings of comfort , and normalization of joint 
 range of motion after application of elastic taping have been pointed out by many 
 scholars9 . from a biomechanical perspective , using elastic taping would affect the joint reposition 
 sense and proprioception .
application of kinesio tape may support the muscles and ligaments 
 and reduce sudden force concentration during the landing phase , and it may especially 
 decrease the plantar flexion moment . on the other hand , kinesio taping did not improve the 
 ankle sensory sense in the healthy subjects in the study of halseth et al17 . the mechanism for instability group 
 whether same for healthy group need to be further discussed .
mcnitt - gray s study reported a mean value of t2 of about 61  ms for a jump with a height of 
 0.32  m. in our study , the average jumping height was 0.40 m , and the mean t2 value was 
 63.73  ms13 .
nigg mentioned that the duration between muscle contraction for energy absorption and 
 landing was about 5070  ms .
larger ground reaction forces in this period ( 50  ms ) would 
 increase the risk of injury18 . in our 
 study ,
the time of the second ( t2 ) peak vertical ground reaction force was often greater 
 than 50  ms , and this may be a reason for recurrence of ankle sprains in countermovement 
 jumping and vertical jumping .
in retrospect , there is a clear need for further clinical and 
 science research of taping .
the results would help the athletes with ankle functional 
 instability to select appropriate management .
although we made an effort to investigate the effect of kinesio taping , there are many 
 limitations of this study .
this is because 
 very few subjects met the criteria of ankle functional instability . also , potential subjects 
 were worried about the risk of reinjury and rejected our invitation .
we investigated the characteristics of the vertical jump with run - up and 
 countermovement jump in subjects with functional ankle instability .
this study proved the 
 beneficial effect of kinesio taping on the ground reaction force in the sagittal plane and 
 peak ankle plantar flexion moment .
fortunately , ankle kinesio taping plays an important role 
 in reducing the moment of the ankle joint .
these findings may provide some suggestions for 
 avoiding lateral ankle sprain . in terms of clinical application ,
kinesio taping may be 
 applied to individuals with ankle instability and may be considered as alternative 
 intervention in the sports rehabilitation field .
 [ purpose ] limited research has been performed in spite of biomechanical evaluation of 
 jump landing with kinesio taping . 
 therefore , the main objective of this study was to 
 evaluate the effect of kinesio taping applied to athletes . 
 in this study , the authors 
 wished to investigate the effect of kinesio taping during a vertical jump with run - up and 
 countermovement jump on ankle functional instability . 
 [ subjects and methods ] ten male 
 athletes with ankle functional instability ( fi ) were recruited in this study from a 
 college volleyball team . 
 each participant was requested to perform two tasks , the 
 countermovement jump and vertical jump with run - up . 
 infrared high - speed cameras and force 
 plates were used to assess the effect of ankle taping . [ results ] 
 the results showed that 
 the peak ground reaction force in the sagittal plane during a vertical jump with run - up 
 slowed down after kinesio taping and that the peak ankle plantar flexion moment in both 
 types of jump also decreased . 
 [ conclusion ] in conclusion , this study proved the effect of 
 kinesio taping on ankle functional instability , which was evaluated by measuring the 
 vertical ground reaction force and peak plantar flexion moment . 
 its finding may allow us 
 to provide some recommendations for athletes and trainers . 
INTRODUCTION
SUBJECTS AND METHODS
RESULTS
DISCUSSION