ssireum is a traditional korean sport in which two athletes hold on to a satba ( a 
 cloth - sash tied around the waist and the thigh of the right leg ) and use strength and 
 various skills to throw their opponent to the ground1 .
the weight classifications depend on the level of ssireum such as 
 gyungjang , sojang , chungjang , yongjang , yongsa , yeoksa , and jangsa1 .
many previous studies have suggested that different sports 
 require athletes to have different physical characteristics according to the way in which 
 the sport is played2,3,4,5 .
for example , judo athletes have a robust skeleton ( that is , strong 
 bone density ) and well - developed muscles to enable them to withstand and transmit the forces 
 applied during the fight6 .
likewise , 
 ssireum athletes have special physical characteristics such as higher weight , muscle mass , 
 and body fat in order to enhance their physical performance1 . in recent years
, an isokinetic muscle test has begun to be used in 
 sports science for the assessment of muscle performance and injury prevention in 
 athletes7,8,9 .
athletes may develop significant 
 muscle imbalance that is specific to the style of the sport they play .
muscle strength 
 imbalance is assessed by comparing the strength of the right muscle group with that of the 
 left muscle group , as well as by determining the agonistic and antagonistic balance 
 relationship .
muscle strength imbalance as it relates to injuries in athletes has been 
 studied , and bilateral imbalance of muscle strength has been suggested as a risk factor for 
 injury in many sports10,11,12,13 .
many previous studies about injury in athletes have shown that imbalance in the 
 hamstring - to - quadriceps peak torque ratio ( h : q ratio ) is correlated with a greater incidence 
 of lower extremity injury7 , 14 , 15 .
overall muscle 
 imbalance can be estimated through not only muscle strength but also through muscle 
 architecture .
a previous study suggested that bilateral structural imbalance of the muscles 
 is related to lower extremity injuries in professional basketball players16 .
muscle structure imbalance can be 
 estimated through the use of a body composition analyzer , which can analyze lean body mass 
 ( lbm ) , fat - free mass ( ffm ) , fat mass ( fm ) , body fat ( bf ) , and lean mass of each limb4 .
although many studies on muscle imbalance 
 in different types of sports activities have been conducted , research on ssireum athletes 
 has rarely been performed .
therefore , our study provides information regarding the muscle 
 conditions of ssireum athletes for the purpose of informing decisions related to training 
 and rehabilitation .
the present study enrolled 25 elite ssireum athletes with no physical or psychological 
 conditions who provided voluntary written informed consent to participate in this study .
the 
 seven weight categories were as follows : gyungjang ( up to 75  kg ) , sojang ( up to 80  kg ) , 
 chungjang ( up to 85  kg ) , yongjang ( up to 90  kg ) , yongsa ( up to 95  kg ) , yeoksa ( up to 
 110  kg ) , and jangsa ( up to 150  kg)1 .
the 
 subjects were asked to complete a questionnaire administered by individual in - depth 
 interviews that took about 30  min per person .
the protocol for the study was approved by the 
 committee of ethics in research of the university of yongin , in accordance with the terms of 
 resolution 5 - 1 - 20 , december 2006 . in the present study , the modified somatotype method for 

the analysis of body type was used1 , 5 , 17,18,19,20 . to confirm body composition ,
lbm , ffm , fm , bf , and lean mass of both limbs 
 of participants were measured using a precision body composition analyzer ( inbody 720 ; 
 biospace , korea ) .
measurements were taken with the participants wearing only ssireum pants 
 in a standing position with slight abduction of both arms1 . to measure the isokinetic peak torque of the elbow and knee 
 flexion / extension on both sides
, we used an isokinetic muscle strength dynamometer ( isomed 
 2000 ; isomed , germany ) . for elbow joint testing ,
participants were positioned sitting on the 
 dynamometer chair and stabilized using straps across the chest and pelvis .
the shoulder 
 joint was positioned in 45 abduction with 30 flexion , and the forearm was supine .
the 
 mechanical rotation axis of the dynamometer was aligned with the lateral humeral epicondyle 
 and the established range of motion was 20 to 110. for examination of the knee joint , the 
 participants were positioned sitting on the dynamometer chair and stabilized by straps 
 across the chest and pelvis and femoral region .
the mechanical axis of rotation of the 
 dynamometer was aligned to the femoral lateral epicondyle .
resistance was applied 
 immediately above the ankle joint , and the established range of motion was 20 to 90 of 
 knee flexion .
tests were performed in the reciprocal concentric mode and composed of three 
 repetitions at 60/s velocity to measure peak torque .
prior to testing , the subjects 
 performed three sub - maximal contractions for familiarization .
the examiner verbally 
 encouraged the subjects during the test to help bring forth maximal efforts .
statistical 
 analyses were conducted using pasw statistics version 18.0 ( spss / ibm ; armonk , ny , usa ) to 
 calculate averages and standard deviations .
the significance level was set to =0.05 when performing a paired 
 t - test .
table 1table 1.general characteristics of the korean ssireum athletes included in the 
 studyvariablemean  standarderror / n ( % ) age ( yrs)21.6  0.7gendermale ( % ) /female ( % ) 25 ( 100.0)/ - ( -)height ( cm)/weight ( kg)178.0  1.0/98.1  4.1bmi ( kg / m)30.5  1.1weight divisiongyungjang 5 ( 20.0)sojang 3 ( 12.0)chungjang 4 ( 16.0)yongjang 3 ( 12.0)yongsa 3 ( 12.0)yeoksa 3 ( 12.0)jangsa 4 ( 16.0)career ( yr)10.4  0.5dominant sideupper limbright / left24 ( 96.0)/1 ( 4.0)lower limbright / left24 ( 96.0)/1 ( 4.0)body compositionlbm ( kg)/ffm ( kg)40.6  2.6/74.3  2.2fm ( kg)/bf ( % ) 21.6  3.8/20.7  2.3somatotypeendomorphy -mesomorphy 23 ( 92.0)ectomorphy2 ( 8.0)central -endo .
c0.7  0.1bmi : body mass index ; lbm : lean body mass ; ffm : fat - free mass ; fm : fat mass ; bf : body 
 fat ; endo .
c : 
 ectomorphic component shows the general characteristics and somatotypes of the korean ssireum 
 athletes .
the lbm of the left upper limb was significantly higher than that of the right 
 upper limb .
however , the lbm of the left lower limb was significantly lower than that of the 
 right lower limb ( table 
 2table 2.differences in the lean mass of the limbs on both sides in the korean ssireum 
 athletesvariablelimb sideright sideleft sideupper limb ( kg)4.4  0.24.6  0.2lower limb ( kg)11.0  0.310.9  0.2all data are presented as the mean  standard error . * * p < 0.01 . ) .
the peak torque for left elbow flexion was significantly 
 higher than that for right elbow flexion .
conversely , the peak torque for left elbow 
 extension was significantly lower than that for right elbow extension . furthermore , the peak 
 torque for the left knee was significantly lower than that for the right knee for both 
 flexion and extension ( table 3table 3.difference in the isokinetic muscle strength of the limbs on both sides in the 
 korean ssireum athletesvariablelimb sideright sideleft sideelbowpt - flex ( nm)68.4  3.073.7  3.5pt - ext ( nm)67.2  2.858.0  3.0pt / bw - flex ( % ) 74.6  3.678.7 4.2pt / bw - ext ( % ) 71.8  3.462.3  3.4kneept - flex ( nm)139.2  7.4126.2  6.7pt - ext ( nm)224.7  13.7205.7  10.5pt / bw - flex ( % ) 150.0  7.4133.4  5.7pt / bw - ext ( % ) 236.4  11.8211.7  7.4h : q ratio ( % ) 63.4  2.162.0 
1.9all data are presented as the mean  standard error . * p < 0.05 , * * p < 0.01 . 

pt - flex : peak torque of flexion ; pt - ext : peak torque of extension ; pt / bw - flex : peak 
 torque / body weight of flexion ; pt / bw - ext : peak torque / body weight of extension ; h : q 
 ratio : hamstring - quadriceps ratio ) . the peak torque / body weight ( pt / bw ) ratio for both , elbows and knees showed 
 a similar pattern to the respective peak torques ( table 
 3 ) . however , the h : q ratio was not significantly different between the knee joints 
 ( table 3 ) .
bmi : body mass index ; lbm : lean body mass ; ffm : fat - free mass ; fm : fat mass ; bf : body 
 fat ; endo .
c : 
 ectomorphic component all data are presented as the mean  standard error . * * p < 0.01 .
all data are presented as the mean  standard error . * p < 0.05 , * * p < 0.01 . 

pt - flex : peak torque of flexion ; pt - ext : peak torque of extension ; pt / bw - flex : peak 
 torque / body weight of flexion ; pt /
bw - ext : peak torque / body weight of extension ; h : q 
 ratio : hamstring - quadriceps ratio
in the present study , body composition results showed that the lean mass of the upper limbs 
 was higher on the left side than on the right ; for the lower limbs , lean mass was higher on 
 the right side .
unexpectedly , peak torque and the pt / bw ratio for elbow extension was higher on the left 
 side than on the right .
many previous studies have suggested that muscle strength would be 
 higher on the dominant side than on the non - dominant side in athletes irrespective of 
 whether the upper or lower limbs were evaluated7 , 
 10,11,12 , 21 , 22 . according to previous studies , brazilian 
 national handball players have significantly stronger throwing - side shoulders than 
 non - dominant - side shoulders , and elite karate athletes have greater elbow strength on the 
 dominant side21 , 22 .
however , even though almost all participants in our study were 
 right - handed , body lean mass and peak flexor torque were higher for the left upper limb . 

this can probably be explained by the nature of ssireum . during a ssireum match ,
athletes 
 face their right shoulders ; they grab the  close waist s  satba with the right hand and the 
 far leg s satba with the left hand . using this position
this technique of ssireum may result in superior left elbow compared to right 
 elbow flexor strength , possibly because the left hands are farther from what they are 
 reaching for during this pulling motion .
the risk of bilateral muscle imbalance is greater 
 in the lower limbs than in the upper limbs7 , 10,11,12 .
bilateral muscle imbalance of the lower 
 limbs was suggested as a risk factor for hamstring and anterior cruciate ligament injuries . 

a previous study suggested that there is an increased rate of injury in cases of a 
 difference of 15% or more in knee flexor or hip extensor strength in collegiate 
 athletes14 .
in addition , an imbalance 
 in the h : q ratio was shown to correlate with a higher incidence of lower extremity injury . 

the typical h : q ratio of a healthy knee ranges from 50 to 80% ; it is commonly accepted that 
 an h : q ratio of 60% or higher is desirable in rehabilitation8 , 15 , 23 . in this study ,
ssireum athletes experienced no issues with respect 
 to h : q ratios in their knee joints .
the bilateral muscle strength of the lower 
 limbs in ssireum athletes was imbalanced ; thus , ssireum athletes have a potential risk of 
 knee injuries . according to our previous study on injuries in combat sports ,
although other factors are definitely 
 contributory , this result may be evidence of muscle strength imbalance leading to knee joint 
 injuries in ssireum athletes24 .
balance 
 training exercises , which may involve the use of resistance or unstable surfaces , can 
 decrease lower limb asymmetry with the aim of reducing the risk of injury25 .
we suggest that ssireum athletes 
 undertake balance training exercise to reduce the risk of injury to their knees . in 
 conclusion
, this study revealed a bilateral imbalance in muscle condition in ssireum 
 athletes , suggesting that more studies are needed to assist in proper training , injury 
 prevention , and rehabilitation .
 [ purpose ] the purpose of the present study was to elucidate the muscle conditions such as 
 the isokinetic muscle of korean ssireum athletes . [ subjects and methods ] this study 
 enrolled 25 elite ssireum athletes . 
 we measured body composition and peak torque at an 
 angular speed at 60/s using an isokinetic muscle strength dynamometer . 
 [ results ] the lean 
 body mass of the left upper limb was significantly higher than that of the right upper 
 limb . however , the lean body mass of the left lower limb was significantly lower than that 
 of the right lower limb . 
 the peak torque for left elbow flexion was significantly higher 
 than that for right elbow flexion . 
 conversely , the peak torque for left elbow extension 
 was significantly lower than that for right elbow extension . furthermore , the peak torque 
 for the left knee was significantly lower than that for the right knee for both flexion 
 and extension . 
 [ conclusion ] the data from this study elucidate in part the muscle 
 conditions of korean ssireum athletes , which can be used to establish a reference for the 
 scientific study of sports physiotherapy . 
INTRODUCTION
SUBJECTS AND METHODS
RESULTS
DISCUSSION