Experimental Study On The Effects Of Physical Exercise On Diastolic Function Of Left Cardiac Ventricle

Object:To investigate the amount threshold of an acute exercise that can affect the left cardiac ventricular diastolic function,and investigate the dynamic changing regulation of five weeks' aerobic exercise on diastolic function of left cardiac ventricle.Methods: Adopting the MCA-3C synthetic tester of cardiac information to record and analyze the apex cardiogram(ACG),electrocardiogram(ECG)and phonocardiogram(PCG)in resting state,during exercise and after exercise respectively.The machine was produced by Jiali electronic company of Xi' an electronic technological college.At first the subjects take a rest about 5-10 minutes in bed,and then clean their skin with alcohol cotton ball.Place the electrode and transducer correctly,recordⅡelectrocardiograms and phonocardiogram in turn.The subjects lie on their back when record the apex cardiograms.Determinate the most powerful spot of apex beat by palpation and auscultation,then put the top of arterial pulse transducer on the center of the spot of apex beat,fix it by adhesive bandage and perpendicularity with chest wall.Setting up the switch of the machine panel on[measure,normal,two,time domain], holding breath then sampling five waves in eight seconds or more,the frequency of sampling is 500Hz.We adopt supine position to tread on the power bike of Monark Egomedic 881E which produced by Sweden in the acute aerobic exercise scheme.The distance between table top and the lowest of the pedal is 15cm.The rotation speed is 50rpm.In the research of intensity threshold,the subjects take exercise for 15min using the intensity of 0W.25W.50W and 75W,the interval between two exercises depend on the subjects' heart rate,it must return to the resting value. Record the ACG,ECG and PCG after exercise immediately in turn.In the research of time threshold,the subjects take exercise using 50W for 30min at constant speed,and then recording ACG,ECG and PCG at the time point of 5.10.15.20.25 and 30min during exercise.In the research of five weeks aerobic exercise scheme,we adopt Monark Egomedic 839E power bike produced by Sweden.The subjects take exercise for 15min one time on erect position,three times per week,the intensity of exercise is 125W and the rotation speed is 50rpm.We adopting ACG,ECG and PCG in dorsal position before and after exercise(immediately postexercise about 1—5min)twice weekly.We choose the values of cardiac cycle(rr).heart rate(hr).rapid filling time(rft).slow filling time(sft).the ratios of sft and rft(sft/rft).isometric relaxation phase(irp)and the ratios of diastolic time and systolic time(lvdt/c-s2)to evaluate the diastolic function of left cardiac ventricular.Analyzing the values with SPSS11.5 statistical treatment,and the significance test of difference adopting paired-samples T test.analysis of variance and multiple comparison of equal variances.Results:①Along with the raise of exercise intensity,hr are increasing,the indexes of duration and ratio are cutting down.The value of rr.hr.sft.rft.sft/rft.irp and lvdt/c-s2 are change significantly(p＜0.05)in 50W exercise intensity comparing with that before exercise.②In the experiment of time threshold in 50W exercise intensity,along with the lengthen of movement time,hr are increasing,the indexes of duration and ratio are cutting down.The values of hr(p＜0.05).irp(p＜0.05).rr(p＜0.01).sft(p＜0.01), rft(p＜0.01).sft/rft(p＜0.01).and lvdt/c-s2(p＜0.01)are change significantly in 10min comparing with that before exercise.③At the effect of five weeks' aerobic exercise,the change tendency of heart rates(hr)both before and after exercise are descending,the values of interval and ratios are ascending.All values in third week are change significantly(p＜0.05)comparing with that in first week except irp. Conclusion:①The 50W is the lowest intensity threshold that can affect the left ventricular diastolic function significantly in 15min aerobic exercise.②In the aerobic exercise of the intensity of 50W,10min is the minimum time threshold which can affect the left ventricular diastolic function significantly.③Long-term(≥three weeks)aerobic exercise can elevate the level of left ventricular function.