Effects Of Different Types Of High Intensity Intermittent And Moderate Intensity Continuous Exercise On QTc Of Young Women And Training Adaptation

Background:High intensity interval training?HIT?has become a popular way of fitness exercise.However,given the high intensity of their exercise,the risk to the heart is worrying.The QT interval of ECG represents the time course of ventricular action potential,and its change reflects the change of the time course of ventricular repolarization.Prolongation of QT interval reflects the decreased stability of ventricular electrophysiological environment,which increases the risk of malignant arrhythmia and sudden cardiac death.At present,it is not clear that the effects of different types of high-intensity intermittent and moderate intensity continuous training on QT interval and training adaptation.Understanding the QT interval changes caused by exercise will help to assess the heart risk of different types of acute exercise.Objective:This study observed the QT interval of ECG before,during and after five times of acute exercise in three kinds of common high-intensity interval training and one kind of moderate intensity continuous training during the four weeks training,so as to understand the change of ventricular repolarization time.Methods:90 young women without sports training experience were randomly divided into five groups?age:21�2;BMI:25�3?,including High-intensity Interval Training?HIT?,Sprint-interval Training?SIT?,Repeated-sprint Training?RST?,moderate-intensity training?MCT?and control group?CON?.HIT was repeated exercise with 90%V?O_2max intensity for4 minutes and rest intermittently for 3 minutes,SIT was repeated exercise with 120%V?O_2maxmax intensity for 1 minute and rest intermittently for 1.5 minutes,RST was full sprint for 6seconds,rest for 9 seconds and repeat for 40 groups,while MCT was continuous exercise with 60%V?O_2max intensity.Each group was trained three times a week for four weeks.The1st to the 6th training,HIT,SIT and MCT groups moved until each group overcame 100KJ mechanical work each time,In the 7th to the 12th training,HIT,SIT and MCT groups moved until each group overcame 200KJ mechanical work each time,and in the 13th training each group overcame 100KJ mechanical work,then retest the V?O_2max,then in the 14th training three groups completed 200kJ mechanical work movement with new power.In RST group,1-6 times of training overcame the initial load of 1kg,7-12 times of training overcame the initial load of 1.5kg,the 13th training overcame the initial load of 1kg,the 14th training overcame the initial load of 2kg.During the four week training of 14 training in total,the 1st training,the 2nd training,the 6th training,the 13th training and the 14th training?after updating to high load?collected the quiet state before exercise,during exercise?each exercise was divided into four segments averagely according to the overcame mechanical work or exercise time,and the part with the highest heart rate in each segment was selected as the 4 observation points in exercise according to the time sequence?and within 30 minutes after exercise?5 minutes 30 seconds after exercise?9 minutes 30 seconds after exercise?15minutes 30 seconds after exercise?19 minutes 30 seconds after exercise?25 minutes 30seconds after exercise?29 minutes 30 seconds after exercise are selected as the 6 observation points of post exercise recovery period?then ECG signals were taken offline to extract ventricular repolarization time data,the original value of QT interval was corrected by Hodges formula to get the heart rate-corrected QT interval?QTc?.Results:1.Compared with that before exercise,QTc was significantly prolonged in acute exercise?P<0.05?,but the lowest in MCT exercise?P<0.05?.QTc did not recover to the pre exercise level 30 minutes after sit exercise?P<0.05?,while QTc recovered completely within 30minutes after other exercise programs.2.There was no significant difference in QTc between the second exercise and the first exercise before,during and after exercise?P>0.05?.Compared with the 1st and 2nd exercise,the recovery QTc of MCT and RST for the 6th exercise was significantly shortened before and after exercise?P<0.05?.There was no significant difference in QTc before,during and after the 6th exercise of SIT and HIT compared with the 1st and 2nd exercise?P>0.05?.3.Compared with the first and second exercises,the recovery QTc of the 13th exercise of MCT and RST was significantly shortened?P<0.05?,but there was no significant difference with the 6th exercise?P>0.05?.Compared with the 1st,2nd and 6th exercise,the recovery period QTc of the 13th exercise of SIT and HIT was significantly shortened?P<0.05?.4.Compared with the 13th exercise,QTc was significantly prolonged during and within15 minutes after the 14th exercise of MCT?P<0.05?.Compared with the 1st,2nd and 6th times of exercise,the QTc recovery period during and after the 14th time of SIT exercise was significantly shortened?P<0.05?.Compared with the 1st,2nd and 6th movements,QTc of the14th movement of HIT was significantly shortened?P<0.05?.Conclusion:1.During acute exercise,ventricular repolarization time is prolonged and recovery after exercise is delayed.Compared with the four training programs,MCT had the lowest extension range,while SIT had the slowest recovery.2.One-time exercise of MCT and RST is not enough,but five times exercise can produce exercise pre adaptation,which can shorten the time of ventricular repolarization in quiet and recovery period after exercise.However,the two programs did not significantly improve the adaptation level by extending the training to four weeks.3.Four weeks SIT shortened the time of ventricular repolarization during exercise and after exercise,but four weeks HIT only shortened the time of ventricular repolarization after exercise.4.Put the training into practice,MCT should be the first choice among the four programs from the perspective of heart risk in sports.In addition,this study also suggests that different training programs can reduce the risk of heart in acute exercise,such as MCT and RST adapt quickly,while SIT can reduce the risk in exercise.In addition,we should also be alert to the decrease of training benefit caused by the increase of load in the training process,especially MCT.