An Empirical Study On The Prevention Of Exercise-induced Cardiovascular Events In Obese Senior High School Students

In recent years,adverse cardiovascular events,such as sudden cardiac death,occur frequently when students participate in school sports.In addition to cardiovascular pathology,obesity is considered to be a common cause.The physical condition of the students in our country is decreasing year by year,and the proportion of obese students is increasing.At the same time,in the daily teaching and physical testing of school physical education,endurance development and evaluation are mostly carried out in the form of middle and long distance running.When high school carries out sports activities,sometimes it ignores the individual differences of students'physique,resulting in obese students bearing higher exercise load than normal weight students,which brings higher exercise risk.To avoid this risk through the realization of reasonable intervention strategies is an urgent problem to be solved in the current stage.Recent studies have shown that intermittent high-intensity running can temporarily produce the effect of exercise preconditioning（EP）.Aiming at the subsequent high-load physical activity process,it can improve cardiopulmonary health and reduce the probability of adverse cardiovascular events.Through the correct understanding of sports risks,physical education teachers can help to improve the safety of physical education curriculum and guarantee the healthy development of school teenagers.Objective:This paper analyzes the influencing factors of high risk cardiovascular events in school physical education,and explores the acceptability of sprint interval training（SIT）and moderate intensity continuous training（MICT）as EP means in high school physical education.At the same time,aiming at the obese students,we verify the protective effect of short-term EP exercise pre adaptation,in order to reduce the risk of subsequent exercise-induced cardiopulmonary overload,and solve the practical problems faced by obese students in high school physical education.Methods:The subjects of the experiment were high school students.The experiment was carried out in four classes of a high school.Four classes were randomly divided into two groups,sit experimental class and mict experimental class.The training program was:sit experimental class ran for 1 min with a 3 M/s turn back sprint,then jogged and relaxed for 1 min,and repeated 6 times.Mict group ran at 1.7m/s for 16 minutes.According to the sensitivity of sit intervention of obese boys in the teaching experiment,40 obese boys in senior high school were supplemented through other channels,and further experiments of gender limitation were carried out.The age of subjects was 18±1 years.The subjects were randomly divided into two groups:control group and experimental group.After two days'rest,EP group received sit training for seven days a week,while Ctrl group kept normal life and rest.On the eighth day after the training and the eighth day after the interval between the two groups,EP group was evaluated systematically again,and gradient load resistance car was used to test and blood collection.The data of real-time blood pressure,oxygen uptake,ECG（ST segment,QTc,PR interval）and blood heart damage were obtained.Results:（1）There was no significant difference in heart rate and RPE between the two experimental classes after completing the same exercise amount of sit training and mict;from the PAEs value of physical activity fun,on the second,third and fourth days of the five-day intervention,the PAEs value of the sit group was significantly higher than that of the mict group by 6.17%,4.56%and 2.4%respectively;the PAEs value of the lean boys in the mict group was significantly higher than that of the girls in the same posture by 11.71%（P<0.05）;obese girls were 22.01%（P<0.05）higher than that of boys in the same body state;there was no significant difference between boys and girls in other body states;lean,normal and obese boys in sit group were significantly higher than that of girls in the same body state（P<0.05）,17.06%,10.61%and 18.74%higher respectively.（2）After short-term EP,VO₂max was significantly increased by 8.52%（P<0.05）after intervention,and 26.2%,25.17%,13.14%and 13.20%（P<0.05）when Mets was50%,60%,70%and 80%of HRmax.（3）In terms of blood pressure,after short-term EP,the static systolic blood pressure（SBP）of the subjects decreased significantly（P<0.05）,about 5.74%,and there was no significant difference in the static SBP of the control group（P>0.05）.According to the dynamic data,SBP in EP experimental group was significantly lower than that before intervention（P<0.05）at 50%HRmax,60%HRmax,70%HRmax and80%HRmax（4.97%,4.33%,4.02%and 3.91%respectively）;DBP in EP experimental group was significantly lower than that before intervention at 50%HRmax,60%HRmax,70%HRmax and 80%HRmax（P<0.05）,There was no significant difference in 90%HRmax（P>0.05）.（4）In ECG,after short-term EP,there was no significant difference between obese subjects before and after PR interval intervention at 50%HRmax and 70%HRmax（P>0.05）,but at 60%HRmax,80%HRmax and 90%HRmax decreased significantly（P<0.05）,12.21%,13.71%and 20.34%respectively;ST segment elevation decreased significantly（P<0.05）,18.33%,25%,32.79%,55.56%and 47.67%respectively;The QTc of heart rate correction decreased significantly at 50%,60%,70%and 90%of the maximum heart rate（P<0.05）,6.03%,5.48%,3.06%and 3.2%respectively.There was no significant difference at 80%of the maximum heart rate（P>0.05）.（5）CTnT in three indexes of myocardial infarction increased significantly（P<0.05）after 7 days of sit training as EP method.After intervention,cTnT increased by186.62%in 11.78±4.27,but it was still within the reference range of safety standard.There was no significant difference between myoglobin（MB）and creatine kinase isoenzyme（CK-MB）（P>0.05）.Conclusions:（1）Sit is an EP method which is suitable to replace mict to improve students'cardiopulmonary function and reduce cardiovascular risk in high school physical education.（2）Through short-term EP intervention,the aerobic tolerance of the subjects can be enhanced and the resistance of peripheral circulation can be reduced.（3）Through short-term EP intervention,it can reduce QTc and PR interval of ECG,reduce the elevation of ST segment,enhance the sensitivity of ECG conduction,and reduce the risk of arrhythmia and sudden exercise death.（4）Sit itself will not cause significant heart damage,short-term sit is safe for obese adolescents.（5）When carrying out physical education in schools,we should pay attention to the protection of students with special physique,especially the obese group.In the early stage of teaching,we should do a good job in the screening of related high-risk diseases.In the design of teaching plan,we should also increase EP means to reduce the cardiovascular risk of sports,strictly control the safety of teaching,and guard against the occurrence of high-risk cardiovascular events in sports teaching.