many problems occur while we are trying to improve the quality of life and material wealth 
 by the development of modern society . among them
, air pollution is a serious problem in 
 western and developing countries . long - term exposure to air pollution has a high correlation 
 with the incidence of cardiovascular disease , respiratory diseases , and diabetes1,2,3 , threatening health . in particular , air 
 pollution is a major cause of respiratory diseases such as asthma and allergic diseases4 , 5 and 
 it has a negative effect on the healthy growth and development of growing children and 
 adolescents .
another problem caused by the development of modern society is the reduction in physical 
 activity across all generations throughout the world .
the time spent in physical activity by 
 children has decreased significantly compared to before6 , 7 .
the time spent using 
 visual media and watching tv has increased8 , 9 , and physical inactivity due to excessive 
 academic pressure and the influence of parents10 , has increased obesity , incorrect posture , and muscle weakness . in 
 addition , energy consumption has increased due to environmental , metabolic , and genetic 
 factors11 .
thus , children living in 
 modern society are showing gradually decreasing physical fitness . the change in the environment due to
the development of modern society is a threat to the 
 health of growing children . according to the korea education development institute , 

respiratory system abnormalities have been much higher than those other systems over the 
 last three years . reduced basic physical fitness and reduced pulmonary functions are 
 seriously threating the physical development of korean elementary , middle , and high school 
 students .
although the physical fitness and lung health of growing children and adolescents is 
 threatened , some studies have reported a relationship between air pollution and pulmonary 
 function12 , 13 .
however , there has been insufficient research on the relationship 
 between exercise and lung function .
most studies on exercise have only suggested lung 
 function is improved by regular exercise14 , 15 .
the present study is to our knowledge the 
 first to investigate the relationship between basic physical fitness and lung function .
the purpose of the present study was to determine the relationship between basic physical 
 fitness and pulmonary function in healthy korean school students to enable us to present an 
 alternative method for improving their pulmonary function .
a total 240 healthy children and adolescents aged 617  years who lived in busan in korea 
 were recruited for the present study .
the participants had a body mass index ( bmi ) < 
 25  kg / m , and no respiratory system abnormalities .
the sample comprised 20 
 healthy students ( 10 boys and 10 girls ) of each age from 6 to 17 .
the participants who did 
 not meet the bmi criteria or who showed significantly low pulmonary test values were 
 excluded , and replacements were recruited in order to conduct the analysis with the same 
 numbers of subjects .
the participants were divided into the early period of elementary 
 school ( 68 y ) , the late period of elementary school ( 911 y ) , the period of middle school 
 ( 1214 y ) , and the period of high school ( 1517 y ) in order to investigate the rapid changes 
 in body composition and basic physical fitness with growth .
all participants gave their 
 informed consent and the experimental protocol was approved by the ethical committee of 
 dong - a university .
body composition including height , weight , bmi , and body fat ( % ) was measured using a body 
 composition analyzer venus 5.5 ( jawon medical , korea ) while subjects were fully relaxed . 

muscle strength , muscle power , flexibility , and balance were measured to evaluate basic 
 physical fitness .
all participants were given a full explanation about the correct posture 
 and procedure of each measurement .
hand - grip strength was evaluated using a grip - d grip strength dynamometer 
 ( takei , japan ) with 0.1  kg accuracy of both the right and left hands .
flexibility was 
 evaluated by measuring sit and reach using a helmas iii trunk forward flexion instrument 
 ( o2run , korea ) with 0.1  cm accuracy .
muscle power was evaluated by measuring the sargent 
 jump height using a helmas iii sargent jump instrument ( o2run , korea ) with 0.1  cm accuracy . 

balance was evaluated by measuring the eyes - closed single - leg standing time using a helmas 
 iii blind single - leg stand instrument ( o2run , korea ) with 0.1 sec accuracy , and the 
 participants performed the test using their preferred leg .
pulmonary function tests were conducted under standard laboratory conditions ( temperature : 
 2225  c , relative humidity : 5560% ) .
all spirometric tests were conducted by the same 
 technician to reduce inter - observer variability and to prevent the failure of the 
 measurement due to the young age of the subjects .
the participants were given sufficient 
 explanation about the method and instrument use , and the tests were performed in a sitting 
 position while wearing a nose clip . the forced vital capacity ( fvc ) and the forced 
 expiratory volume in one second ( fev1 ) were measured using a quark pft ( cosmed , italy ) .
all 
 of the pulmonary tests were conducted following the standards presented by the american 
 thoracic society / european respiratory society16 .
the data were analyzed using the statistical package for the social sciences ( spss version 
 22.00 ) and the results are presented as the mean  standard deviation .
the significance of 
 differences between boys and girls were examined using the independent t - test .
the relationships between body composition and pulmonary 
 function , and basic physical fitness and pulmonary function were analyzed using simple 
 linear regression analysis .
table 1table 1.the differences in body composition between groups ( gender and age ) and within 
 group ( n=240)groupsage ( yrs)height ( cm)weight ( kg)bmi ( kg / m)body fat ( % ) malefemalemalefemalemalefemalemalefemaleperiod of early elementary school6123.7 4.43121.6 4.9624.8 4.5622.9 3.4816.1 2.0415.4 1.748.9 3.0113.0 5.067127.7 4.66126.2 3.9728.8 4.3726.2 5.0717.6 2.2016.4 2.619.6 4.4216.5 3.618133.0 4.57133.9 5.4631.7 6.6730.8 5.4117.8 2.9117.2 2.4310.5 6.1717.9 3.461,2<3**1<2<3***1<3 * 1,2<3**period of late elementary school9137.3 4.62139.6 5.7135.9 7.7634.8 6.7718.9 3.1817.6 2.2313.1 5.9617.8 4.5110143.9 5.80147.1 9.4245.2 11.9236.8 10.1121.6 4.1216.7 2.8818.2 7.8017.0 4.7611155.5 6.65154.5 2.8648.2 11.5946.8 6.1419.9 3.9919.6 2.2014.7 3.8221.4 5.171<2<3***1<2<3***1<3 * 1,2<3**period of middle school12164.9 6.43158.3 4.9149.3 10.8347.4 6.9519.5 2.9718.9 2.5913.1 8.4720.4 4.0813165.9 3.41159.1 3.3055.1 11.1250.8 6.4520.0 3.9320.3 2.1612.8 7.6021.0 5.8114169.6 5.17158.0 3.0864.9 10.9153.2 5.4421.7 1.7921.3 2.0716.8 3.9721.1 6.401,2<3*period of high school15176.5 7.30164.1 3.8160.3 7.9258.6 2.2419.3 1.4921.8 1.5311.5 4.8126.1 2.9416174.3 5.63162.5 5.8057.6 3.5453.1 5.8720.6 0.5720.0 1.4514.7 3.0024.2 2.3617172.8 4.01163.1 5.0162.4 8.1857.0 5.3220.9 2.3821.4 1.5715.5 5.8326.1 2.06values represent means  sd .
bmi : body mass index . * : significant difference within 
 group ( * p<0.05 , * * p<0.01 , * * * p<0.001 ) shows the differences in body composition between groups ( gender and age ) and 
 within groups .
height was significantly different in the early period of elementary school 
 ( boys : p<0.01 , girls : p<0.001 ) and the late period of elementary school ( p<0.001 
 for both boys and girls ) .
weight was significantly different in the periods of early and 
 late elementary and middle school for boys ( p<0.05 ) , and in the periods of early and late 
 elementary school for girls ( p<0.01 ) .
* : significant difference within 
 group ( * p<0.05 , * * p<0.01 , * * * p<0.001 ) table 2table 2.the differences in basic physical fitness between groups ( gender and age ) and 
 within group ( n=240)groupsage ( yrs)basic physical fitnesspulmonary functionright hand grip ( kg)left hand grip ( kg)sit and reach ( cm)sargent jump ( cm ) single - leg stance ( sec)fvc ( l)fev1 ( l)boysperiod of early elementary school68.42.508.81.954.75.2823.23.808.46.071.360.321.300.20710.62.3610.52.678.05.8326.64.5615.911.371.730.451.540.4089.32.6010.92.594.44.8226.02.5910.97.181.840.351.720.44period of late elementary school912.51.4714.13.325.66.3528.13.6925.819.002.000.381.850.411017.82.7517.02.765.66.7230.15.6544.224.672.550.442.220.321119.14.1018.73.897.99.1738.56.5933.118.672.590.532.390.531<3***1<2,3 * 1,2<3**1<2,3 * 1<3*period of middle school1220.97.5221.89.112.29.6238.55.5226.317.333.430.703.190.621326.64.3029.94.385.27.6141.26.5626.222.533.540.563.530.291436.69.3937.97.137.89.1145.35.7530.813.514.270.493.840.511<2,3**1,2<3**1,2<3*period of high school1531.96.1232.67.117.05.6343.64.4131.425.804.180.654.010.571636.30.3538.50.8512.12.2543.50.5052.56.504.600.724.390.661736.83.0438.32.8611.59.5147.69.8236.422.784.120.703.850.65girlsperiod of early elementary school67.71.878.52.059.43.3122.14.1411.17.901.460.261.230.2178.81.589.21.9510.83.7825.96.0916.315.781.430.271.310.2789.31.829.33.456.13.7525.03.134.32.091.660.281.570.283<1*period of late elementary school910.23.0310.93.226.46.2327.94.4223.917.791.830.411.580.311012.72.6813.84.009.88.5430.04.8329.621.722.040.591.930.531116.83.5317.43.9910.87.4030.48.6735.422.812.540.392.330.341<3***1,2<3**1<3 * 1<3*period of middle school1218.92.5520.01.9313.48.5333.65.8512.65.732.630.442.490.371321.74.8322.64.8310.38.7329.82.5727.820.372.610.322.580.241420.12.7021.73.6311.78.3428.44.0337.422.332.510.572.300.50period of high school1523.62.4225.53.9910.911.3129.87.8023.319.162.780.372.680.371622.23.9324.14.0415.310.6629.64.1330.215.853.010.472.850.371720.23.2323.03.4110.311.7028.95.0524.76.582.920.212.810.16values represent means  sd .
fvc : forced vital capacity , fev1 : forced expiratory 
 volume in 1 second . * : significant difference within group ( * p<0.05 , * * p<0.01 , 
 * * * p<0.001 ) shows the differences in basic physical fitness and pulmonary function between 
 and within groups . for boys , right and left hand - grip strength were significantly different 
 in the late period of elementary school ( right : p<0.001 , left : < 0.05 ) and middle 
 school ( p<0.01 ) .
the sargent jump height was only significantly different in the late 
 period of elementary school ( p<0.01 ) for boys .
in the case of girls , right and left 
 hand - grip strength significantly different in the late period of elementary school 
 ( p<0.01 ) , and the sit and reach distance was significantly different in the early period 
 of elementary school ( p<0.01 ) .
for boys , fvc was significantly different in the late 
 period of elementary school and middle school ( p<0.05 ) , and fev1 was significantly 
 different only in the late period of elementary school ( p<0.05 ) , and for girls , fvc and 
 fev1 were significantly different in the late period of elementary school ( p<0.05 ) .
fvc : forced vital capacity , fev1 : forced expiratory 
 volume in 1 second . * : significant difference within group ( * p<0.05 , * * p<0.01 , 
 * * * p<0.001 ) table 3table 3.the results of simple linear regression analysis between pulmonary function and 
 body compositionfvcfev1rrboysheight0.827***0.758***weight0.677***0.658***bmi0.168***0.144***body fat ( % ) 0.048 * 0.037girlsheight0.756***0.764***weight0.728***0.733***bmi0.455***0.462***body fat ( % ) 0.392***0.400 * * * * p<0.05 , * * p<0.01 , * * * p<0.001 shows the results of the simple linear regression analysis that was performed 
 for fvc and fev1 against height , weight , bmi , and body fat ( % ) . for boys ,
fvc significantly 
 correlated with height ( r=0.827 , p<0.001 ) , weight ( r=0.677 , 
 p<0.001 ) , bmi ( r=0.168 , p<0.001 ) , and percent body fat 
 ( r=0.048 , p<0.05 ) in descending order .
fev1 significantly correlated with 
 height ( r=0.758 , p<0.001 ) , weight ( r=0.658 , p<0.001 ) , and bmi 
 ( r=0.144 , p<0.001 ) ; however , there was no significant correlation with 
 percent body fat ( r=0.037 , p=0.077 ) . in the case of girls ,
fvc significantly 
 correlated with height ( r=0.756 , p<0.001 ) , weight ( r=0.728 , 
 p<0.001 ) , bmi ( r=0.455 , p<0.001 ) , and percent body fat 
 ( r=0.392 , p<0.001 ) in descending order .
fev1 significantly correlated with 
 height ( r=0.764 , p<0.001 ) , weight ( r=0.733 , p<0.001 ) , bmi 
 ( r=0.462 , p<0.001 ) , and percent body fat ( r=0.400 , p<0.001 ) 
 in descending order . * p<0.05 , * * p<0.01 , * * * p<0.001 the results of the comparison between boys and girls revealed that height and weight were 
 similarly correlated .
however , bmi ( fvc : 0.455 vs. 0.168 , fev1 : 0.462 vs. 0.144 ) and percent 
 body fat ( fvc : 0.392 vs. 0.048 , fev1 : 0.400 vs. 0.037 ) showed higher correlations with 
 pulmonary function in girls than in boys .
table 4table 4.the results of simple linear regression analysis between pulmonary function and 
 basic physical fitnessvariablefvcfev1rrboysright hand grip strength 0.774***0.794***left hand grip strength 0.747***0.762***sit and reach distance 0.0420.039sargent jump height0.573***0.584***single - leg standing time 0.058 * 0.048*girlsright hand grip strength 0.619***0.652***left hand grip strength 0.607***0.641***sit and reach distance 0.0200.015sargent jump height0.129**0.121**single - leg standing time 0.0180.020 * p<0.05 , * * p<0.01 , * * * p<0.001 shows the results of the simple linear regression analysis that was performed 
 for fvc and fev1 against right hand - grip strength , left hand - grip strength , sit and reach 
 distance , sargent jump height , and single - leg standing time .
for boys , both fvc and fev1 
 showed high correlations with right hand - grip strength ( r=0.774 , 
 r=0.794 , p<0.001 ) , left hand - grip strength ( r=0.747 , 
 r=0.762 , p<0.001 ) , sargent jump height ( r=0.573 , 
 r=0.584 , p<0.001 ) , and single - leg standing time ( r=0.058 , 
 r=0.048 , p<0.05 ) in descending order . in the case of girls , both fvc and 
 fev1 showed high correlations with right hand - grip strength ( r=0.619 , 
 r=0.652 , p<0.001 ) , left hand - grip strength ( r=0.607 , 
 r=0.641 , p<0.001 ) , and sargent jump height ( r=0.129 , 
 r=0.121 , p<0.01 ) in descending order , whereas the sit and reach distance 
 and single - leg standing time showed no significant correlations .
* p<0.05 , * * p<0.01 , * * * p<0.001 the results of boys and girls were similarly in descending order .
however , basic physical 
 fitness parameters were more highly correlated with pulmonary function for boys than for 
 girls , especially the sargent jump height ( fvc : 0.573 vs. 0.129 , fev1 : 0.584 vs. 0.121 ) .
the purpose of this study was to determine the relationship between basic physical fitness 
 and pulmonary function in healthy korean school students , in order to present an alternative 
 method for improving their pulmonary function .
an investigation of the development of korean students was conducted by the ministry of 
 education in 2014 .
the results show that boys grow 56  cm per year from an average height of 121.5  cm 
 in the first grade of elementary school .
the biggest growth was found among 6th grade 
 elementary school students and 1st grade middle school students .
girls grow around 6  cm per year from an average height of 120.3  cm 
 in the first grade of elementary school .
their degree of growth decreases rapidly after 6th 
 grade elementary school compared to boys .
body weight of boys showed the biggest differences 
 between the first and second grades of middle school ( 5.9  kg ) , and between the 5th and 6th 
 grades of elementary school among girls ( 5.5  kg ) .
the results of the present study show that 
 the height of both boys and girls rapidly increased in the elementary school period . 

however , weight dramatically increased in the period of elementary school and middle school 
 among boys , and in the period of elementary school among girls .
the growth of children and 
 adolescents who participated in this study seems to be representative of korean children and 
 adolescents since the results appear to be similar to the findings of the ministry of 
 education .
however , bmi was somewhat different since we selected healthy students , excluding 
 obese children as subjects . basic physical fitness is closely related to health .
especially , it has a negative 
 correlation with the prevalence of obesity17 , hypertension18 , 
 and cardiovascular disease19 . in this 
 respect ,
the korean government has implemented the physical activity promotion system ( paps ) 
 in order to systematically measure the physique and fitness , as well as to prescribe 
 physical activity for individuals , highlighting the need of regular exercise . however , 
 accurate measurement , evaluation , and prescription of exercise seem insufficient . in the 
 present study ,
basic physical fitness was measured using the correct postures and methods by 
 a fully trained technician .
muscle strength increased sharply in the late period of 
 elementary and middle school in boys , and in the late period of elementary school in girls . 

in addition , muscle power of boys increased sharply only in the late period of elementary 
 school . pulmonary function
was reported as being correlated with age20 , 21 , in addition , height , 
 weight , area of body surface , percent body fat , smoking status , and residential environment 
 also have effects on spirometry22,23,24,25 .
height is a factor positively influencing 
 lung function at all ages26 , whereas age 
 and body fat mass sometimes have an inverse correlation in accordance with the age of 
 subjects .
the present study revealed that pulmonary function increased with age for subjects 
 during the growth period .
in addition , pulmonary function was influenced by height , weight , 
 bmi , and percent body fat , in descending order .
height , area of 
 body surface , and weight correlate with pulmonary function in descending order27 , a result which is consistent with the 
 results of our present study .
girls showed higher correlation than boys between percent body 
 fat and pulmonary function in the present study .
however , the percent body fat showed slight 
 or no correlation with pulmonary function for boys , a result which differs from those of 
 previous studies .
rossi et al.28 found 
 that body fat and lung function showed an inverse correlation in obese female adults . 

gonzalez - barcala et al.29 conducted a 
 study of children aged 6 to 18  years whose bmi was under 30  kg / m .
they suggested 
 that lung function can be difference depending on individual differences . in the present 
 study , subjects had normal weight and bmi < 25  kg / m .
park et al.30 reported that it was difficult to explain 
 the effects of bmi , percent body fat , and muscle mass on pulmonary function .
therefore , 
 different results of pulmonary function could be occurred depending on the body composition 
 of the individual subjects .
thus , aerobic exercise and resistance 
 exercise are effective ways of improving lung function . besides
the present study 
 revealed that pulmonary function is highly correlated with right hand - grip strength , left 
 hand - grip strength , and sargent jump height in descending order .
therefore , exercises for 
 muscle strength and power could be effective at improving school students pulmonary 
 function . in summary , in order to improve the pulmonary function of growing children and adolescents , 

aerobic exercise and exercise programs to increase muscle strength and power are needed , and 
 they would be especially effective if they were to begin in the late period of elementary 
 school when the muscle strength and power of students are rapidly increasing .
 [ purpose ] the purpose of the present study was to determine whether there was a 
 correlation between basic physical fitness and pulmonary function in korean school 
 students , to present an alternative method for improving their pulmonary function . 
 
 [ subjects and methods ] two hundred forty healthy students aged 617  years performed 
 physical fitness tests of hand - grip strength , sit and reach , sargent jump , single leg 
 stance , and pulmonary function tests of forced vital capacity ( fvc ) and forced expiratory 
 volume in one second ( fev1 ) using a quark pft . 
 [ results ] muscle strength and power of boys 
 improved in the late period of elementary school and middle school 
 . muscle strength of 
 girls improved in the late period of elementary school . 
 analysis of factors affecting 
 pulmonary function revealed that height , weight , bmi , and body fat significantly 
 correlated with spirometric parameters . 
 right hand - grip strength , left hand - grip strength , 
 and sargent jump also significantly correlated with fvc and fev1 . 
 [ conclusion ] in order to 
 improve the pulmonary function of children and adolescents , aerobic exercise and an 
 exercise program to increase muscle strength and power is needed , and it should start in 
 the late period of elementary school when muscle strength and power are rapidly 
 increasing . 
INTRODUCTION
SUBJECTS AND METHODS
RESULTS
DISCUSSION