Study On The Protective Effect Of Different Training Duration Exercise Preconditioning Schemes On Heart Injury In Exhausted Rats

Objective:In this study,we established a rat model of preconditioning exhaustion with different training durations of moderate intensity.By observing the exercise capacity,myocardial morphology,myocardial injury markers,electrocardiogram,cardiac function,and mitochondrial respiratory function,we explored different training duration The effect of exercise preconditioning on cardioprotection in exhausted rats is of great significance in guiding soldiers and athletes to implement scientific and effective training programs,and it also provides new theoretical basis and experimental reference for the study of cardioprotective effects of exercise preconditioning.Method:1.Grouping and models of experimental animals72 male SD rats were randomly divided into 6 groups(n=12),namely: control group(Con group),exhaustion group(EE group),exercise pre-adaptation 20 minutes group(EP+EE20 min),exercise pre-adaptation 40 minutes group(EP+EE40 min),exercise pre-adaptation 60 minutes group(EP+EE60 min),exercise pre-adaptation 80 minutes group(EP+EE80 min).Refer to Lennon and Domenech’s running standards.The exercise pre-adaptation group had a runway with a slope of 5 ° and a speed of 26 m/min.They exercised for 20 minutes,40 minutes,60 minutes,and 80 minutes(15 minutes for each exercise and 5 minutes for rest),exercised for 5 days a week,and took 2 breaks a day.After 3 weeks,all groups except the control group performed a single exhaustive exercise with a slope of 10 ° and a speed of 30-40 m/min.2.Animal treadmill was used to record the changes of exercise ability of rats in each group.3.Optical microscope was used to detect the microstructure of rat myocardium.4.Elisa was used to detect cTnI and NT-pro BNP levels in serum,assess the degree of heart damage.5.The electrocardiogram was recorded with a physiological recorder,and the electrocardiogram parameters of each group of rats were recorded.6.Use Millar pressure volume guide wire to observe the changes of cardiac function in rats,record hemodynamic parameters and observe changes in cardiac function.7.Oxygraph-2K was used to detect the ratio of respiratory rate and RCR respiratory rate of mitochondrial respiratory complexes I,II,IV in each group of rats.Results:(1)Compared with the EE group,the exhaustion distance and time of the rats in the EP + EE groups were significantly longer.(P(27)0.05).(2)Compared with the EE group,the EP + EE groups had different degrees of improvement,and the degree of improvement after 60 minutes of exercise preconditioning was the most obvious.(3)Compared with the Con group,the myocardial microstructure and ultrastructural damage of the EE group and EP + EE groups were significantly changed;compared with the EE group,the EP + EE group myocardial damage was different Alleviated;the 60 minute and 80 minute groups of EP + EE had mild myocardial damage.(4)Compared with the Con group,the serum cTnI and NT-pro BNP levels in the EE group and the EP + EE groups were increased(P(27)0.05);Compared with the EE group,except for the EP + EE20 min group,the other EP + EE groups had different degrees of reduction(P(27)0.05);the serum cTnI and NT-pro BNP levels of the EP+EE60 min group were lower than those of other EP+EE groups(P(27)0.05).(5)Compared with the Con group,the heart rate of the rats in the EE group and the EP+EE groups were increased,the QRS interval was prolonged,and the ST segment was elevated(P(27)0.05).Compared with the EE group,the EP+EE60 min group and EP+EE 80 min group were significantly larger HR slowed,QRS interval shortened,ST segment elevation decreased in rats(P(27)0.05),QRS interval shortened and ST segment elevation decreased in EP+EE 40 min group(P(27)0.05);EP+EE 40 min There were no significant differences in ECG between the three groups,EP+EE 60 min group and EP+EE80 min group(P(29)0.05).(6)Compared with the Con group,the systolic and diastolic functions of the heart were reduced to varying degrees in the EE group and the EP + EE group(P(27)0.05);compared with the EE group,the systolic and diastolic functions of the heart in the EP + EE group were different The improvement was the most significant after 60 minutes of preconditioning(P(27)0.05).(7)Compared with the Con group,the respiratory rate of myocardial mitochondrial complex I,II,IV and the RCR of complex I in the EE group and EP+EE group were reduced(P(27)0.05);compared with the EE group,except EP+EE 20 min group,the respiratory rate of myocardial mitochondrial complex I,II,and IV in other pre-adapted groups increased to varying degrees(P(27)0.05);the respiratory rate of mitochondrial respiratory system complex I,II,IV increased in EP+EE 60 min group and EP+EE 80 min group compared with other pre-adapted groups(P(27)0.05).Conclusion:1.Exercise preconditioning can improve the damage of myocardial morphology and mitochondrial respiratory function caused by exhaustive exercise,and can improve the contractile and diastolic function of the heart.2.There are differences in the degree of cardioprotection of different training durations of EP after exhaustive exercise in rats.When the exercise reaches a certain training duration and intensity,it will trigger more obvious adaptive protection.3.At moderate intensity,when exercise pre-adaptation training exceeds 40 minutes,the exercise capacity,myocardial morphology,cardiac function,and mitochondrial respiratory function of exhausted rats can be improved and enhanced,and corresponding protective effects can be produced,but when EP after more than 80 minutes,the risk trend of myocardial injury increased with the length of exercise.