Study On The Evaluation Methods And Characteristics Of Cardiorespiratory Fitness In Children And Adolescents

As the core element of those components of physical health,cardiorespiratory fitness（CRF）is an independent health determinant in an individual’s life,and it is closely related to academic performance,brain structure and function and cardiovascular disease in children and adolescents.Scientific monitoring of CRF in children and adolescents will help to improve the health status of the current and future population.At present,the national student physical health standard（revised in2014）adopts 50 m×8 back and forth running and 1000/800 m running to evaluate CRF of students.Many studies have confirmed that there is controversy on the validity of 50 m×8 back and forth running and 1000/800 m running in assessing CRF of children and adolescents.Most countries in the world adopt 20 meter shuttle run test（20m SRT）to evaluate CRF of children and adolescents.20m SRT has a high test validity in evaluating CRF of children and adolescents in many foreign countries,but the validity of the test in Chinese children and adolescents has not yet been effectively verified.VO_2maxshould be calculated by formula after 20m SRT.In the domestic studies on the calculation formula of VO_2max,the subjects are limited to selected only from a certain region and a certain school period（college students or junior high school students）,and the coefficients of each factor in the formula also need to be discussed.Studies have confirmed that CRF is affected by factors such as region,nutritional status and personal living habits.In terms of geography,China has a vast territory,numerous ethnic groups and huge differences in geographical environment.Children and adolescents are in the immature stage of physical and mental development,their nutritional status and living habits show a trend of continuous development and change.In this context,it is particularly urgent to scientifically assess the impact of the above factors on the CRF of children and adolescents in China.It is worth emphasizing that,CRF is an important indicator that reflects the overall healthy development of children and adolescents,and to a certain extent is also one of the important indicators of national competitiveness.Researchers should not only pay attention to the development status of CRF of Chinese children and adolescents,but also compare the development status of CRF of Chinese children and adolescents with that of international children and adolescents.As a neighbor of our country,Japan is one of the countries where the physical fitness monitoring of children and adolescents has been carried out well in the world.The comparison of CRF between Chinese and Japanese children and adolescents is of great practical significance to promote the healthy growth of Chinese children and adolescents.Therefore,the present study compared the test validity of 50 m×8 back and forth running,1000/800 m running and 20m SRT,developed the VO_2maxequation of 20m SRT for Chinese children and adolescents,evaluate the characteristics of CRF of Chinese children and adolescents,compare the differences of CRF between Chinese and Japanese children adolescents,so as to provide evidence for promoting the healthy growth of children and adolescents in China.The present study analyzed and discussed assessment methods and characteristics of CRF in children and adolescents from the following four studies,and obtained the following results:Research 1:Study on the evaluation methods of cardiorespiratory fitness in children and adolescentsObjective:To analyze the validity of different test methods for assessing CRF in children and adolescents.Methods:A total of 801 children and adolescents were randomly selected from 16 age groups of children and adolescents aged 7-22 years in Shanghai,Guangdong,Shaanxi,Shanxi and Jiangxi provinces,and VO_2maxwas evaluated by 50 m×8 back and forth running,1000/800 m running,20m SRT and treadmill experimental test.Correlation analysis,intraclass ICC correlation coefficient and Bland-Altman method were used to analyze the data;Results:（1）The correlation coefficients of the value of VO_2maxbetween 50 m×8 back and forth running and treadmill experimental test in boys and girls were 0.539 and 0.486,respectively（P<0.01）;The correlation coefficients of the value of VO_2maxbetween 800 m running test and treadmill experimental test was 0.430,0.568 and 0.475 for middle school girls,university girls and 13-22-year-old girls,respectively（P<0.01）.The correlation coefficients between VO_2maxin 1000 m running test and VO_2maxin treadmill experimental test was 0.476,0.418 and 0.433 for middle school boys,university boys and 13-22 year old boys,respectively（P<0.01）;Correlation coefficient between the values of VO_2maxof the 20m SRT test and treadmill experimental test among primary school boys,middle school boys,university boys,and general boys was 0.617,0.592,0.692 and 0.625,respectively;For girls,it was0.600,0.736,0.632 and 0.695,respectively（P<0.01）;（2）The consistency ICC value of VO_2maxbetween 50 m×8 back and forth running test and treadmill experimental test for boys and girls was 0.486 and 0.445,respectively;The ICC value between VO_2maxof 20m SRT test and treadmill experimental test in primary school male pupils,middle school male students,university male students and overall male students was 0.569,0.566,0.694 and 0.607,respectively;For girls,it was 0.597,0.737,0.631 and 0.695,respectively;The ICC value of VO_2maxbetween 800 m running test and treadmill experimental test in middle school female students,university female students and 13-22-year-old female students was 0.377,0.317 and0.381,respectively;The ICC value of VO_2maxbetween 1000 m running test and treadmill experimental test in middle school male students,university male students and 13-22-year-old male students was 0.457,0.303 and 0.391,respectively;（3）The Bland-Altman consistency of the 20m SRT test and treadmill experimental test in evaluating the VO_2maxin each school segment and the overall male and female students was higher than 50 m×8 back and forth running test and 1000/800 m running test.Summary:（1）The correlation between the VO_2maxof children and adolescents tested by 20m SRT was higher than that tested by running 1000/800 m running;（2）When evaluating the VO_2maxof Chinese children and adolescents,the validity of 20m SRT test was higher than that of 50 m×8 back and forth running test and 1000/800 m running test.Research 2:Study on the regression equation of estimating VO_2maxin children and adolescents from 20 meter shuttle run testObjective:To develop the VO_2maxestimation equation suitable for the characteristics of CRF among children and adolescents in China.Methods:801children and adolescents in Study 1 were selected as the participants.Correlation analysis,multiple stepwise linear regression and Bland-Altman method were used to analyze the data.Results:（1）Linear regression analysis to calculate VO_2maxshowed that the adjusted R²of regression models ranged from 0.265 to 0.518,and the adjusted R²of model 4 was 0.518.In the total sample,the correlation coefficient among VO_2maxcalculated by regression models in the present study,foreign formulas and treadmill experimental test was from 0.480 to 0.662,among which model 4 had the highest correlation coefficient（r=0.662,P<0.05）;（2）Bland-Altman analysis of the VO_2maxof treadmill experimental test and VO_2maxof the total samples calculated by each model showed that the test validity of model 4 was the highest,in which 4.87%（39/801）of the scattered points were outside the 95%consistency limit,with a mean difference of-0.1 and a difference of 95%CI of-13.8～14.0.Summary:Compared with other models,the VO_2maxcalculated by model 4:VO_2max=62.103+（0.302×laps）-（0.877×BMI）-（4.874×sex）-（0.465×age）（male=0,female=1）was in higher consistency with the VO_2max（gold standard）calculated by treadmill experimental test.Research 3:Characteristics of cardiorespiratory fitness in children and adolescentsObjective:Using the calculation equation of VO_2maxdeveloped in study 2,the present study explored the differences and characteristics of CRF of children and adolescents in different age,gender,nutritional status,sleep status and latitudes.Methods:A total of 9,892 children aged 7-22 from East China,South China,Central China,North China,Northeast China,Northwest China,and Southwest China were selected as the participants by stratified cluster random sampling.LMS method,one-way ANOVA and linear regression model were used to analyze the data.Results:（1）In China,the 20m SRT laps,number of completed stages/minutes,speed at the last complete stage and VO_2maxof boys were higher than those of girls,and the gaps between boys and girls had gradually increased from the age of 10 to 11,with the largest gap between the ages of 17 and 20;（2）Regardless of gender,20m SRT laps,number of completed stages/minutes,speed at the last complete stage and VO_2maxof normal weight children were higher than those of overweight and obese children（P<0.05）;（3）In general,VO_2maxof boys and girls with adequate sleep was higher than that of boys and girls with insufficient sleep by 1.16 m L/kg/min and 1.32 m L/kg/min,respectively;The laps,number of completed stages/minutes,speed at the last complete stage and VO_2maxin P₃,P₅₀and P₉₇of students with adequate sleep after 12years old were higher than those of students with insufficient sleep,and the difference increased with age;（4）In general,the VO_2maxof boys in low latitudes,mid-latitudes and high latitudes was 51.43,50.04,49.92 m L/kg/min,respectively;for girls,it was43.36,42.67,41.99 m L/kg/min,respectively.Summary:（1）In China,CRF of boys was higher than that of girls,CRF of normal weight students was higher than that of overweight and obese students;（2）In general,CRF of the students with adequate sleep was higher than that of the students with insufficient sleep.After 12 years old,CRF of students with adequate sleep was higher than that of students with insufficient sleep,and the difference gradually increased with the increase of age;（3）In general,CRF of students in high latitude was lower than that of students in low and middle latitude.Research 4:Comparison of cardiorespiratory fitness between Chinese and Japanese children and adolescentsObjective:The calculation equation of VO_2maxdeveloped in study 2 was used to compare the differences between Chinese and Jpanese children and adolescents in20m SRT laps,speed at the last complete stage,completed stages per minutes and VO_2max.Methods:Using stratified cluster random sampling method,6922 children and adolescents aged 7-17 years were selected from Japan,and 6951 Chinese children and adolescents aged 7-17 years were selected in Study 3.T-test and LMS method were used to analyze the data.Results:（1）In general,the 20m SRT laps,completed stages/minutes,speed at the last complete stage and VO_2maxof Chinese boys was lower than that of Japanese boys by 34.37 laps,3.35 stages,1.68 km/h,and10.84 m L/kg/min,respectively.For girls,it was 20.01 laps,2.09 stages,1.04 km/h and 5.91 m L/kg/min,respectively;The 20m SRT laps,number of completed stages/minutes,speed at the last complete stage and VO_2maxof P₁₀,P₅₀and P₉₀of Chinese children and adolescents were lower than those of Japanese children and adolescents,and the gap increased with age;（2）The P₁₀,P₅₀and P₉₀VO_2maxvalues of Chinese children and adolescents were basically flat or decreased with age.The P₁₀,P₅₀and P₉₀VO_2maxvalues of Japanese boys increased gradually with age.The P₁₀,P₅₀and P₉₀VO_2maxvalues of Japanese girls increased significantly from 7 to 12 years old,and remained flat after 13 years old.Summary:The CRF of Chinese children and adolescents was lower than that of Japanese children and adolescents,and the gap increased with age.The conclusions of the present study were as follows:Conclusions:（1）Taking the VO_2maxof treadmill experimental test as the gold standard,the test validity of the 20m SRT was higher than 50 m×8 back and forth running,1000 m running and 800 m running in children and adolescents.（2）Model:VO_2max=62.103+（0.302×laps）-（0.877×BMI）-（4.874×sex）-（0.465×age）（male=0,female=1,R²=0.522）were recommended as the equation for estimating CRF of 20m SRT in Chinese children and adolescents.（3）The CRF of boys in my country was higher than that of girls,and the gap between boys and girls had gradually increased from the age of 10 to 11,with the largest gap between the ages of 17 and 20;CRF of normal weight children and adolescents was higher than that of overweight and obese children and adolescents;CRF of children and adolescents with adequate sleep was higher than that of children and adolescents with insufficient sleep.In general,CRF of children and adolescents in high latitude was lower than that of children and adolescents in low and middle latitude.（4）The CRF of Chinese children and adolescents was lower than that of Japanese children and adolescents,and the gap increased with age.