Research On Adaptability And Mechanism Of Cardiac Morphology And Function Of Exercise-induced Weight Loss In Obese Adolescents

Objective: Health problems of obese adolescents is not ignored now. Aggregate incidence ofobese adolescents’ cardiovascular risk factors is increasing the the developed countries. Therate of adolescents obesity in our country has close to that of developed countries, earlyprevention and control has become one of major health problems. Based on the changes ofheart rate, blood pressure, echocardiographic parameters, the myocardial enzymes, etcmolecular markers level of different degree of obesity, this paper compared the difference ineffects of different degree of obesity on adolescents’ cardiac structure and function of theeffect, explored adaptability and mechanism of cadiac structure and function of obeseadolescents under long-term and low-intensity exercise intervention, and provide thetheorical basis of effects of exercise induced weight loss on obese adolescents’ health, earlyprevetion and cure.Methods:A total of33obese adolescents-smaller-class and the VIP members, including16men with an average age of19.63±3.03years and17Women with an average age of19.71±3.96years old, Aeeording to body fat percentage(BFP),underwent exercise-inducedweight loss interventions in Dianfeng Co. LTD, Shanghai Universtiy of sports. The subjectswere divided into moderately-to-severely obese group(15,mean age20.09士3.71,meanBFP=39.07士4.76)and severely obese group(18,mean age19.36士3.36,mean BFP=52.64士7.65). Before experiment, on the basis of health status and exercise stress testing, exerciseintensity was determined, individual exercise prescription and3-month fully-closed nutritionand exercise-induced weight loss interventions were formulated. Somatotype indicators (bodyheight, body weight, BMI, body fat ratio (BF%), waist and hip circumference, etc), bloodbiochemical indicators (fasting blood glucose, four blood lipid items, insulin and hs-CRP),cardiac molecular markers (myocardial enzyme, cTnI and NT-proBNP) were measured,cardiac structure and function parameters were also measured by Color DopplerEchocardiography, and as well as resting blood pressure and pre-exercise, post-exerciseinstantly and resting for a while heart rate in the first day, the day before the four weeks andthe day before leaving.Results：1Effects of exercise-induced weight loss on somatotype, lipid, insulin and hs-CRP of obeseadolescentsCompared with pre-trainning, body weight, BMI, body fat ratio, waist circumference,hip circumference of different gender obese adolescents are significantly decreased after1month and3months exercise training(P<0.01).FBG,TC, LDL-C, TG, FINS and HOMA-IR level of obese teenageers and adolescentsare notably declined(P<0.01); HDL-C has no statistically significant compared withpre-training (P>0.05).There is a significant positive correlation between serum hs-CRP and body fat rate, hipcircumference, waist circumference, body fat mass, fasting blood glucose, insulinresistance(P<0.05), and negatively related to high-density lipoprotein cholesterol (P<0.05).2Effects of exercise-induced weight loss on heart rate and BP of obese adolescentsBasal heart rate and resting heart rate, heart rate instantly after exercise load and heartrate recovery after resting1min decrease significantly after1month and3months compared with pre-training(P<0.01), slope between obese adolescents’ heart rate and load intensitysignificantly lowered, intercept also decreased. Compared with pre-training, both obeseadolescents’ systolic and diastolic pressure significantly decreased after1month and3months (P<0.01).3Effects of exercise-induced weight loss on NT-proBNP and biomarker of myocardialdamage of obese adolescents24h after quantitative exercise load test in pre-training,1-and3-month end,serumcardiac troponin calcium protein T(cTnT) has no significant difference (P>0.05),24hafter quantitative exercise load test, serum resting cTnT had no significant differences inpre-training, the last day of1month and3months, and value also in normal range.After1-and3-months, obese adolescents’ serum resting NT-proBNP levels droppedsignificantly than pre-training (P<0.05). NT-proBNP level of1month and3-month traininghad no significant difference (P>0.05).Compared with pre-training, NT-proBNP level after immediately quantitative load testwas significantly higher than resting value(P<0.05). NT-proBNP had no significantlydifference in the same quantitative load test after1month and3months (P>0.05).Compared with pre-training, NT-proBNP level after the same-grade quantitative loadtest immediately had no significant difference (P>0.05), after3months, NT-proBNP levelinstantly after quantitative load significantly decreased (P<0.05).4Effects of exercise-induced weight loss on cardiac structure and function of obeseadolescentsBefore pre-training, extremely severe obese adolescents cardiac structure index such asventricular septal thickness, left ventricular wall thickness and left ventricular mass weresignificantly higher than moderate obese adolescents (P<0.05), left ventricular end-diastolicdiameter has no significant difference; Systolic function index such as EDV/BSA, CI, SIsignificantly lower than moderate obese adolescents (P <0.05), cardiac output higher thanmoderate-to severe-obesity groups, but has no significance. Diastolic function index such aspeak flow velocity late diastole mitral valve A, mitral valve ring late diastole peak flowvelocity in the Va significantly higher than moderately-to severely-obese group, E/A, andVe/Va significantly lower than moderate obese adolescents (P <0.05).Compared with pre-training, after a month, IVSd, LVPWd, LVM and standardizedLVMI in moderate-to severe-and severely obese patients and RWT in severely obese groupsignificantly reduced (P <0.05). After3months, IVSd, IVSs AOD, LVPWd, RWT, LVMand standardized LVMI in moderate-to severe-and severely obese patients are verysignificant decline (P<0.01), LVPWs in extremely severe obesity group significantly reduced(P<0.05), LVDd before and after reducing weight had no significant difference (P>0.05).After3months, AOD, compared with that of moderate to severe group, IVSd, LVPWd,LVM and standardized LVM is significant in of severely obese group(P <0.05).Compared with pre-training, after a month, SI and EDV/BSA in moderate-to severe-and severely obese patients and SV in the latter increased significantly (P <0.05); after3months, SI and EDV/BSA increase significantly (P <0.01), SV and ET in moderately-toseverely-obese group significantly increased, CO reduced significantly (P <0.05), SI andEDV/BSA in severely obese group were lower than those of moderately-to severe-obeselygroup (P <0.05). Compared with pre-training, after a month, E/A and Ve/Va in moderately-to severely-obese group and severely obese patients were significantly increased. After3months, E, Ve,E/A and Ve/Va in different obese group increased significantly, and A and Va declinedobviously (P <0.05); Compared with moderately-to severely-obese patients, there issignificant difference in Va, Ve/Va in severely obese group (P <0.05).Before reducing weight,46%of obese adolescents were LVH, of which12%was28%for remodeling and6%for eccentric hypertrophy. After three months, only6%obeseadolescents still existed LVH,and eccentric hypertrophy recovered to the normalconfiguration, normal cardiac geometric alteration ratio were from54%to94%; Afterreducing weight, it appeared that normal left ventricular configuration did not develop to leftventricular hypertrophy.Compared with pre-training, after a month, LVM, LVMI, LVPWd, RWT and IVSd inLVH subjects significantly reduced, and SI, E, E/A and Ve/Va increase obviously (P <0.05).After Three months, RWT, LVM, IVSd, LVMI, LVPWd very significantly decreased. SI,mVcf and EDV/BSA increase significantly (P <0.05). E and Ve increase significantly, A andVa significantly reduced,(P <0.05), E/A notably increased (P <0.01).The correlation analysis shows that the cardiac structural index such as standardizedLVM and body somatotype(BMI, PBF and WC), HOMA-IR, E/Va and NT-proBNP had asignificant positive correlation(P <0.05). EF was significant negative correlated with CRP (P<0.05). E/A and PBF, WC and DBP had a significant positive correlation(P <0.05); Ve/Vais very significant negative correlated with BMI and PBF(P <0.01). E/Va were significantlycorrelated to PBF and LVMI (P <0.05).Conclusion:1Three months and low-intensity aerobic exercise can reduce obese adolescents’ weight andbody fat percentage, improve somatotype, lipid metabolism status and IR, reduce serumhs-CRP levels significantly, hve the importance to prevent, reduce the occurrence anddevelopment of cardiovascular disease, and promote the obese adolescents health.2Exercise-induced weight loss can significantly lowered basal heart rate, resting heart rateand the immediate heart rate at each level exercise load and1-min recovery heart rate ofobese adolescents, enhance heart rate reserve, reduce myocardial oxygen consumption, andimprove cardiac function.3Obese adolescents had cardiac hypertrophy obviously, the concentric remodeling is themain form of the conformational changes of the left heart.3month low-intensity aerobicexercise can reverse obese adolescents left ventricular remodeling.4Low-intensity aerobic exercise can reverse the cardiac structure including left ventricularmass, left ventricular posterior wall and interventricular septal thickness, significantlyimproved systolic and diastolic function of obese adolescents. Very severely obese patientsmay be more severe than moderately-to severely-obese group needed reducing more weightand longer exercise time to fully recover their diastolic function.5After exercise training, the resting and exercise immediately serum NT-proBNP levelsreduced in obese adolescents, long-term and low-intensity aerobic exercise can improveseverely obese subjects with cardiac capacity overload and improve cardiac function.