respiratory physiotherapy is an important way to potentially improve lung function in 
 patients including athletes with respiratory dysfunction caused by genetically determined 
 neuropathy , chronic obstructive pulmonary disease , asthma , or sports injury of the 
 chest1,2,3,4 . in 
 particular ,
sports injury in coastal areas is directly or indirectly related to maintenance 
 of athletes performance5,6,7,8 .
korean wrestling , also called ssireum , is unique to the traditional 
 culture and folklore of korean spectator sports9,10,11 . 

the rules for matches are simple , and the outcome is clear to young and old observers alike . 

a korean wrestling match is a gentlemanly sport focused on manners in which the participants 
 do not hit each other9,10,11 .
male athletes are 
 categorized into seven divisions according to body weight , while female athletes compete in 
 two weight divisions .
the objective of korean wrestling is to overcome the opponent by 
 utilizing the muscles of the whole body based on fitness and skill9,10,11 .
therefore , participation in korean wrestling results in 
 balanced development of the whole body . in korean wrestling , the participants hold onto each 
 other s belt ( satba ) and try to cause part of their opponent s body above the knee to touch 
 the ground9,10,11 . ultimately , the body 
 movements used in the attempt to knock over opponents cause development of muscle strength 
 and endurance9,10,11 .
in contrast , pulmonary function testing provides a quantitative 
 assessment of lung function , which is important for estimating an individual s health15 .
respiratory function is influenced by 
 exercise and training15 , 16 . as a result ,
lung function may change depending on the 
 frequency of the sport activity17 , 18 . to date , however , no study has analyzed 
 the respiratory function of korean wrestling athletes .
therefore , the objectives of this 
 research were to analyze and compare the respiratory function of korean wrestling athletes 
 and nonathletes for the study of sports rehabilitation .
one hundred and eleven 
 volunteers who had no abnormal physical or psychological conditions provided written 
 informed consent to participation in this study9 .
participants were asked to complete a questionnaire via individual 
 in - depth interviews , which took 30 minutes per person9 .
there were seven weight categories : gyungjang ( less than 75  kg ) , 
 sojang ( less than 80  kg ) , chungjang ( less than 85  kg ) , yongjang ( less than 90  kg ) , yongsa 
 ( less than 95  kg ) , yeoksa ( less than 110  kg ) , and jangsa ( less than 150  kg)9 , 10 . 

the criteria for the inclusion of participants in the study were as follows : ( 1 ) 2023  years 
 of age , ( 2 ) male , ( 3 ) history of respiratory disease , ( 4 ) experience of stress during 
 exercise , ( 5 ) psychological factors , ( 6 ) history of injuries , and ( 7 ) primary technology 
 used . before measurement
chest circumference was measured at the height of the axilla , and 
 abdominal circumference was measured at the height of the navel .
the participants were measured by lung function testing using the 
 schiller sp-260 spirometer ( schiller ag , baar , switzerland ) .
spirometric parameters , 
 including forced vital capacity ( fvc ) , forced expiratory volume in 1 second ( fev1 ) , 
 fev1/fvc , peak expiratory flow ( pef ) , peak inspiratory flow ( pif ) , slow vital capacity 
 ( svc ) , inspiratory reserve volume ( irv ) , expiratory reserve volume ( erv ) , tidal volume ( tv ) , 
 maximum voluntary ventilation ( mvv ) , minute or expired ventilation ( mv ) , and respiratory 
 rate ( rr ) were recorded and analyzed by methods of resting breathing and forced breathing . 
 measurement was focused on the fvc graph , which was divided into the expiratory area ( exa ) 
 and the inspiratory area ( insa)2 .
analogously , the insa was divided into c and d sections based on 
 the pif .
each a , b , c , and d section was further subdivided to four areas ( fig .
1.differences in fvc and 
 respirogram phase between the korean wrestling athletes and nonathletes2 , 9 , 10area and slope of the fvc and respiratory parameters were determined , as described in 
 the subjects and methods section .
fvc , forced vital capacity ; as13 , first , second , 
 and third slopes of the a area ; bs13 , first , second , and third slopes of the b area ; 
 cs13 , first , second , and third slopes of the c area ; ds13 , first , second , and third 
 slopes of the d area ; exa , expiratory area ; insa , inspiratory area weight classes of 
 korean wrestling athletes : gj , gyungjang ; sj , sojang ; cj , chungjang ; yj , yongjang ; ys , 
 yongsa ; yes , yeoksa ) . from left to right , the connections between each of the divided points of the a 
 area were designated as the first slope ( as1 ) , the second slope ( as2 ) , and the third slope 
 ( as3 ) . correspondingly , from left to right , the first , second , and third slopes defining the 
 b area were designated bs1 , bs2 , and bs3 , respectively ; the first , second , and third slopes 
 defining the c area were designated cs1 , cs2 , and cs3 , respectively ; and the first , second , 
 and third slopes defining the d area were designated ds1 , ds2 , and ds3 , respectively ( fig .
the angle of each point and the respiratory area of the fvc were each 
 measured in triplicate at each measurement time , and the mean values were calculated2 , 19 . 

the formula for the tangent is given in equation 1 , where r is the radius of a circle 
 composed of the coordinates of the x and y axes .
the cos  is the value obtained by dividing 
 x by r ; sin  is the value obtained by dividing y by r. the tan  is equivalent to the ratio 
 of the sin  to the cos 2 , 20 .
( 1 ) differences in fvc and 
 respirogram phase between the korean wrestling athletes and nonathletes2 , 9 , 10 area and slope of the fvc and respiratory parameters were determined , as described in 
 the subjects and methods section .
fvc , forced vital capacity ; as13 , first , second , 
 and third slopes of the a area ; bs13 , first , second , and third slopes of the b area ; 
 cs13 , first , second , and third slopes of the c area ; ds13 , first , second , and third 
 slopes of the d area ; exa , expiratory area ; insa , inspiratory area weight classes of 
 korean wrestling athletes : gj , gyungjang ; sj , sojang ; cj , chungjang ; yj , yongjang ; ys , 
 yongsa ; yes , yeoksa the angle was determined ( equation 2 ) using the arctangent in order to verify the tangent 
 2 , 21 . in equation 2 , x represents the unknown quantity , and i represents 
 an imaginary quantity .
( 2 ) the ibm spss statistics software ( version 22.0 , ibm corp . , armonk , ny , usa ) was used for 
 the statistical analysis .
the significance level was set to =0.05 , and all data are 
 presented as the mean  standard error ( se ) of the measurements .
the protocol for this study was 
 approved by the committee of ethics in research of yong in university in accordance with the 
 terms of resolution 5 - 1 - 20 .
table 1table 1.general characteristics of the participantsnonathleteskorean wrestling athletesage ( yrs)24.9  2.821.3  1.0height ( cm)174.1  4.7178.6  4.3weight ( kg)75.9  10.194.6  12.9bmi ( kg / m)24.9  2.829.6  3.8career ( yrs)-9.5  0.5training frequency-3/day ( 18/week)training time-5.7  0.3 h / day ( 34.2  1.8 h / week)aerobic exercise-2.2  0.2 h / day ( 13.2  1.2 h / week)anaerobic exercise-3.1  0.5 h / day ( 18.6  3.0 h / week)ches cir ( cm)rest96.1  6.3113.1  13.8exp94.0  6.5110.6  16.9insp100.3  6.1115.4  12.1der1.6  1.42.4  3.1dir3.3  2.22.4  1.9abd cir ( cm)rest86.8  7.5101.5  13.9exp84.5  8.098.1  13.6insp89.4  7.9104.1  13.3der2.1  2.03.5  2.0dir2.2  1.82.6  2.4weight category ( % ) gyungjang / sojang-2 ( 12.5)/2 ( 12.5)chungjang / yongjang-3 ( 18.8)/2 ( 12.5)yongsa / yeoksa-4 ( 25.0)/3 ( 18.8)jangsa -- hand technique ( % ) am - c / dm - c-1 ( 6.3)/- ( -)o - c / ym - c-2 ( 12.5)/- ( -)g - d / ds - j-1 ( 6.3)/1 ( 6.3)leg technique ( % ) ad - g / bd - g-8 ( 50.0)/5 ( 31.3)h - g / bb - g-1 ( 6.3)/4 ( 25.0)b - g / c - d-1 ( 6.3)/- ( -)d - g-4 ( 25.0)trunk technique ( % ) j - c / oe - b-6 ( 37.5)/5 ( 31.3)d - b / g - c-14 ( 87.5)/- ( -)mixed technique ( % ) or - d / oe - d-2 ( 12.5)/1 ( 6.3)d - d-1 ( 6.3)all data are presented as the meanse
. bmi : body mass index ; ches cir : chest 
 circumference ; abd cir : abdominal circumference ; exp : expiration ; insp : inspiration ; 
 der : differences between expiration and rest ; dir : differences between inspiration and 
 rest ; am - c : ap mureup - chigi ; dm - c : dwit mureup - chigi ; o - c : oguem - chaegi ; ym - c : yeop 
 mureup - chigi ; g - d : ggok - dwijypgi ; ds - j : deung satba - jabachaegi ; ad - g : ahn dari - geolgi ; 
 bd - g : bat dari - geolgi ; h - g : homi - geoli ; bb - g : balmok bitjang - geoli ; b - g : 
 baldeung - geoli ; c - d : cha - dolrigi ; d - g : deot - geoli ; j - c : jab - chaegi ; oe - b : oen - baejigi ; 
 d - b : deul - baejigi ; g - c : ggatdan - chigi ; or - d : oreun - dwijypgi ; oe - d : oen - dwijypgi ; d - d : 
 dwiro - dwijypgi . * significantly different from nonathletes , p < 0.05 shows the general characteristics of the korean wrestling athletes compared 
 with those of the nonathletes .
spirometry parameters in the athletes group were 
 significantly higher than in the nonathletes , but not erv , irv , and mvv ( table 2table 2.differences in respiratory function between the nonathletes and korean wrestling 
 athletesvariablenonathleteskorean wrestling athletesfvc ( l)4.9  0.55.2  0.4 * fev1.0 ( l)4.1  0.44.6  0.4 * fev1.0/fvc ( % ) 84.1  6.187.8  4.5 * pef ( l / s)9.2  1.410.5  1.4 * pif ( l / s)6.4  1.27.3  1.7 * svc ( l)4.8  0.65.2  0.6 * erv ( l)1.5  0.41.5  0.5irv ( l)2.4  0.62.6  0.5tv ( l)0.7  0.31.2  0.6 * mvv ( l / min)161.5  30.5171.6  33.3rr ( l / min)94.5  17.991.1  32.7tv ( l / min)1.7  0.41.9  0.5mv ( l / min)12.8  6.019.0  6.2 * rr ( l / min)27.1  6.821.6  7.3 * tv ( l / min)0.5  0.30.9  0.3 * all data are presented as the meanse .
fvc : forced vital capacity ; fev1.0 : forced 
 expiratory volume in one second ; fev1.0/fvc : fev1.0/fvc ratio , pef : peak expiratory 
 flow ; pif : peak inspiratory flow ; svc : slow vital capacity ; irv : inspiratory reserve 
 volume ; erv : expiratory reserve volume ; tv : tidal volume ; mvv : maximum voluntary 
 ventilation ; mv : minute ventilation ; rr : respiratory rate * significantly different 
 from nonathletes , p < 0.05 ) .
respirogram phasic analysis revealed that the expiratory ( exa ) and total 
 area ( total ) of the fvc were significantly increased in the athletes compared with the 
 nonathletes ( table 3table 3.differences in respirogram phases of forced vital capacity between the 
 nonathletes and korean wrestling athletesvariablenonathleteskorean wrestling athletesafvcexa20,026.3  2,966.224,429.5  10,269.5insa22,449.5  6,610.425,101.1  16,417.0total42,475.8  8,039.349,530.6  21,591.9sfvcas110.3  3.112.1  4.0as25.6  2.47.1  3.3as31.9  1.02.6  1.4bs11.4  0.81.5  0.8bs21.4  0.61.3  0.4bs31.4  0.51.2  0.4cs12.7  1.72.5  1.0cs20.5  4.41.0  0.4cs30.5  0.40.5  0.3ds10.3  0.30.4  0.3ds20.7  0.50.6  0.4ds31.7  1.11.8  1.0all data are presented as the meanse .
afvc : area of forced vital capacity ; exa : 
 expiratory area ; insa : inspiratory area ; total : total area ; sfvc : slope of forced 
 vital capacity ; as1 : first slope of the a area ; as2 : second slope of the a area ; as3 : 
 third slope of the a area ; bs1 : first slope of the b area ; bs2 : second slope of the b 
 area ; bs3 : third slope of the b area ; cs1 : first slope of the c area ; cs2 : second 
 slope of the c area ; cs3 : third slope of the c area ; ds1 : first slope of the d area ; 
 ds2 : second slope of the d area ; ds3 : third slope of the d area . * significantly 
 different from nonathletes , p < 0.05 and fig .
the slopes of 
 respirogram phases , such as the tangent angles , of the fvc were compared between nonathletes 
 and athletes ( table 3 , fig .
the tangents for athletes at slopes 1 , 2 , and 3 of the a 
 area ( as1 , as2 , and as3 ) were significantly increased ( table 3 , fig .
furthermore , in the 
 correlative analysis , chest and abdominal circumference were not correlated with the area of 
 the fvc ( table 4table 4.correlation coefficients of the circumference and area of forced vital 
 capacityafvcchest circumferenceabdominal circumferencerestexpinspderdirrestexpinspderdirexa0.0380.0380.0730.0840.0660.2560.2450.2610.2420.177insa0.1610.1560.1670.0300.0080.2340.2610.1800.1520.467total0.1150.1110.1030.0150.0240.3110.3290.2690.0070.284afvc : area of forced vital capacity ; exp : expiratory condition ; insp : inspiratory 
 condition ; der : differences between expiration and rest ; dir : differences between 
 inspiration and rest ; exa : expiratory area ; insa : inspiratory area ; total : total 
 area ) .
the correlation coefficients for the chest circumference and tangent are 
 shown in table 5table 5.correlation coefficients of the circumference and slope of forced vital 
 capacitysfvcchest circumferenceabdominal circumferencerestexpinspderdirrestexpinspderdiras10.2470.2620.1920.0800.1560.2290.2120.1970.3010.174as20.0250.0170.0630.2800.2020.0930.0840.1200.1280.297as30.5710.6000.5880.4630.0690.4640.4510.4700.1090.012bs10.0580.0100.1380.3350.4270.1060.0980.0760.1730.143bs20.0810.0420.1370.0590.0710.0640.0350.1130.0840.269bs30.3100.3650.3010.5490.3050.1280.1540.0960.3710.465cs10.0620.0870.0010.0360.0310.0220.0450.0100.0460.125cs20.3130.3340.3170.3050.0750.0810.1140.0620.3330.264cs30.2950.2660.3220.0930.1020.1630.1800.1660.2680.157ds10.0630.0380.0190.5780.1960.1100.1140.1280.0030.175ds20.0140.0510.0200.0160.5160.0800.0820.0810.3280.339ds30.3400.3740.3660.0180.4280.3420.3330.3300.4440.245sfvc : slope of forced vital capacity ; exp : expiration condition ; insp : inspiration 
 condition ; der : differences between expiration and rest ; dir : differences between 
 inspiration and rest ; as13 : first , second , and third slopes of the a area ; bs13 : 
 first , second , and third slopes of the b area ; cs13 : first , second , and third slopes 
 of the c area ; ds13 : first , second , and third slopes of the d area .
* p<0.05 , with slope 3 of the a area ( as3 ) showing significant correlation .
bmi : body mass index ; ches cir : chest 
 circumference ; abd cir : abdominal circumference ; exp : expiration ; insp : inspiration ; 
 der : differences between expiration and rest ; dir : differences between inspiration and 
 rest ; am - c : ap mureup - chigi ; dm - c : dwit mureup - chigi ; o - c : oguem - chaegi ; ym - c : yeop 
 mureup - chigi ; g - d : ggok - dwijypgi ; ds - j : deung satba - jabachaegi ; ad - g : ahn dari - geolgi ; 
 bd - g : bat dari - geolgi ; h - g : homi - geoli ; bb - g : balmok bitjang - geoli ; b - g : 
 baldeung - geoli ; c - d : cha - dolrigi ; d - g : deot - geoli ; j - c : jab - chaegi ; oe - b : oen - baejigi ; 
 d - b : deul - baejigi ; g - c : ggatdan - chigi ; or - d : oreun - dwijypgi ; oe - d : oen - dwijypgi ; d - d : 
 dwiro - dwijypgi . * significantly different from nonathletes , p <
fvc : forced vital capacity ; fev1.0 : forced 
 expiratory volume in one second ; fev1.0/fvc : fev1.0/fvc ratio , pef : peak expiratory 
 flow ; pif : peak inspiratory flow ; svc : slow vital capacity ; irv : inspiratory reserve 
 volume ; erv : expiratory reserve volume ; tv : tidal volume ; mvv : maximum voluntary 
 ventilation ; mv : minute ventilation ; rr : respiratory rate * significantly different 
 from nonathletes , p < 0.05 all data are presented as the meanse .
afvc : area of forced vital capacity ; exa : 
 expiratory area ; insa : inspiratory area ; total : total area ; sfvc : slope of forced 
 vital capacity ; as1 : first slope of the a area ; as2 : second slope of the a area ; as3 : 
 third slope of the a area ; bs1 : first slope of the b area ; bs2 : second slope of the b 
 area ; bs3 : third slope of the b area ; cs1 : first slope of the c area ; cs2 : second 
 slope of the c area ; cs3 : third slope of the c area ; ds1 : first slope of the d area ; 
 ds2 : second slope of the d area ; ds3 : third slope of the d area .
* significantly 
 different from nonathletes , p < 0.05 afvc : area of forced vital capacity ; exp : expiratory condition ; insp : inspiratory 
 condition ; der : differences between expiration and rest ;
dir : differences between 
 inspiration and rest ; exa : expiratory area ; insa : inspiratory area ; total : total 
 area sfvc : slope of forced vital capacity ; exp : expiration condition ; insp : inspiration 
 condition ; der : differences between expiration and rest ; dir : differences between 
 inspiration and rest ; as13 : first , second , and third slopes of the a area ; bs13 : 
 first , second , and third slopes of the b area ; cs13 : first , second , and third slopes 
 of the c area ; ds13 : first , second , and third slopes of the d area .
balance is very important in ssireum , 
 which is also called korean wrestling9 , 10 .
therefore , the 
 respiratory function of korean wrestling athletes is better than that of nonathletes , as 
 were other physical parameters such as height , weight , body mass index , chest circumference , 
 and abdominal circumference .
analysis of the fvc graph revealed that the exas of the korean 
 wrestling athletes and the nonathletes were significantly different .
the respiratory muscles of the ssireum athletes 
 were anticipated to be better than those of the nonathletes . according to other studies , 

examination of the reasons for this 
 development in ssireum athletes prompted respiratory analyses in this study .
the primary 
 techniques of the ssireum athletes were considered , including hand techniques , leg 
 techniques , trunk techniques , and mixed techniques9,10,11 .
the preferred technique for ssireum athletes is the 
  deul - baejigione of the trunk techniques .
. muscle strength and respiratory function are 
 closely related to each other , because poor respiratory function is an indicator of muscle 
 weakness24 .
the interaction between 
 respiratory and motor functions can be observed from normal functions , such as simple limb 
 movements and muscle strength25,26,27,28 .
korean wrestling 
 matches also end within less than one minute . therefore , korean wrestling athletes can 
 expect type ii muscle development to be enhanced by anaerobic exercise .
features of the type 
 ii muscles are used to demonstrate instantaneous power rather than endurance28 , 30 .
this can be observed in the as1 , as2 , and as3 sections of the graph . 

therefore , instantaneous power , as opposed to endurance , is relatively weak , because the 
 decrease in the b section of the pef area has the same slope in athletes and nonathletes . 

buh in mongolia , 
 sambo in russia , kara kucak and yagli gures in turkey , das schwingen in switzerland , fang in 
 iceland , and lucha canaria in spain31 . in 
 addition
, these same athletes can anticipate similar development of the type ii muscles as a 
 result of anaerobic exercise31 .
however , 
 further systematic and scientific studies in the area of sports physiotherapy research and 
 therapy , especially for chest injuries related to various sports , are needed32,33,34,35 .
 [ purpose ] respiratory function is important for patients including athletes who require 
 physical therapy for respiratory dysfunction . 
 the purpose of the present study was to 
 analyze the differences in the respirograms between korean wrestling athletes and 
 nonathletes according to phase for the study of sports physiotherapy . 
 [ subjects and 
 methods ] respiratory function was measured using spirometry in both the athletes and 
 nonathletes while they were in a sitting position . 
 [ results ] spirometry parameters in the 
 athletes were significantly higher than in the nonathletes . in respirogram 
 phasic 
 analysis , the expiratory area and total area of forced vital capacity were significantly 
 increased in the athletes compared with the nonathletes . 
 the slopes of the forced vital 
 capacity for athletes at slopes 1 , 2 , and 3 of the a area were significantly increased . in 
 correlative analysis , 
 chest circumference was significantly correlated with slope 3 of the 
 a area of the forced vital capacity . 
 [ conclusion ] the results suggest that the differences 
 in changes in the phases of the respirogram between the korean wrestling athletes and 
 nonathletes may in part contribute to our understanding of respiratory function in sports 
 physiotherapy research . 
INTRODUCTION
SUBJECTS AND METHODS
RESULTS
DISCUSSION