Physical Activity Assessment Methods And Dose-response Effects On Health In Children And Adolescents With Obesity

PurposesThe purpose of this study was to determine the characteristics of physical activity energy expenditure of obese adolescents and to construct the evaluation methods of physical activity of obese adolescents.To provide a methodological reference for accurate monitoring of physical activity of obese adolescents and elucidating the dose-response relationship between physical activity and physical health improvement to obese children and adolescents.MethodsA total of 160 obese children and adolescents aged 10?17 years old were recruited.Indirect calorimetry was conducted to test resting energy expenditure,and the energy expenditure of 3?7 km/h walking and running in the field,ActiGraph GT3X+triaxial accelerometer and Polar heart rate meter were worn to collect accelerometer data(VM3)and heart rate during the test.Metabolic equivalents(METs)was calculated according to resting oxygen consumption and exercise oxygen consumption;energy consumption(EE)and physical activity energy consumption(PAEE)were calculated according to O2 and CO2 measured by indirect calorimetry.A random forest algorithm was used to determine the key features that affect EE,PAEE and METs.Artificial Neural Networks(ANNs),multiple linear regression,and Logistic regression were used to establish the prediction models of EE,PAEE and METs and the diagnostic model of physical activity intensity.Using the receiver operating characteristic curve determines the appropriate cut-off point of physical activity intensity.Root mean square error(Root Mean Square Error,RMSE),Kendall coefficient and weighted Kappa value test the accuracy and consistency of the model.The physical activity assessment method was used to evaluate the physical activity of 96 obese adolescents during a physical activity intervention program.According to the quartile of physical activity levels,96 obese adolescents were divided into different groups(Q1?Q4 group),and the changes of body weight,body composition and cardiovascular metabolic risk(CMR)were observed,and linear regression and logistics regression were used to explore the dose-response relationship between physical activity and physical health improvement.Results(1)The 1 METs to the obese adolescents were 4.35 mL/kg/min(boys:4.51 mL/kg/min,girls 4.19 mL/kg/min).Boys were significantly higher than girls and tended to decrease with sexual maturation development.The METs of 3 km/h(strolling)is 2.82,the METs of 4 km/h(slow walking)is 3.31,the METs of 5 km/h(normal walking)is 4.1,the METs of 6 km/h(jogging)is 6.43,The METs 7 km/h(running)is 7.17.Boys also performed higher EE(kcal/min)and PAEE(kcal/min)in the same items than girls,and after-puberty and late puberty were significantly higher than mid puberty in both boys and girls.(2)Random forest results showed that heart rate reserve(HRR),VM3,weight/age had the greatest contribution to EE,PAEE and METs.The R2 of the EE prediction model established by "HRR?VM3?weight","HRR(%)?weight" and "VM3?weight" were 0.820,0.759,0.706,and the RMSE was 1.45,1.77,1.98,respectively.The R2 of the PAEE prediction model established by "HRR?VM3?weight","HRR(%)?weight","VM3?weight" is 0.823,0.767,0.700,and the RMSE is 1.49,1.54,2.04,respectively.The R2 of METs prediction model established by "HRR(%)?VM3?Age","HRR?Age",and "VM3?Age" is 0.780,0.755,0.608,and the RMSE is 1.05,1.13,and 1.47,respectively.The RMSE of the ANNs prediction model of EE,PAEE,and METs is 1.34,1.31,and 0.78,respectively.(3)The cut-off points for VM3 of 3 METs and 6 METs were 3687 counts/min and 5247 counts/min;the cut-off points of HRR were 41.66%and 63.05%;The multi-index joint diagnosis model is established by "VM3+HRR(%)+age".The multi-index joint diagnostic model of light to moderate intensity is:Y=10.666-0.097*HRR(%)-0.001*VM3(counts/min)-0.290*Age,the cut-off points for the predicted probability of 3 METs is 0.315.The multi-index joint diagnostic model of moderate to vigorous intensity is:y=-1.534+1.274*HRR(%)+6.316*VM3(counts/min)+1.760*Age,the cut-off points for the predicted probability of 6 METs is 0.248.The diagnostic value of "VM3+HRR(%)+Age" prediction probability was significantly higher than that of VM3,HRR(%),the accuracy of cutoff points for VM3?HRR(%)?"VM3+HRR+Age"and the ANNs diagnostic model was 64.81%,74.69%,79.62%and 83.95%,respectively.And the weighted Kappa values were 0.471,0.626,0.686,0.741,respectively.(4)Compared with the Q1 group,the Q4 group had more significant changes in body weight,BMI,body composition,circumference and blood pressure.The total METs,moderate-to-vigorous-intensity physical activity(MVPA),and light-intensity physical activity(LPA)are associated with body composition improvement.There was no relationship were reserved between LPA and the decrease of the circumference and cardiometabolic risk(p>0.05).Compared with Q1 group,Q4 group improved CMR-Z score(OR=8.33)and CMR factor aggregation(OR=8.25).With each increase of 1METs-h/days,the improvement rate of CMR-Z score and CMR factor aggregation increased by 13%(OR=1.13,p<0.05)and 25%(OR=1.25,p<0.05),respectively.With each increase of 10 kcal/days of MVPA,the improvement rate of CMR-Z score and CMR factor aggregation increased by 5%(OR=1.05,p<0.05)and 5%(OR =1.05,p<0.05),respectively.Conclusion(1)The resting oxygen consumption of obese children and adolescents is higher than the agreed value of 3.5 mL/kg/min for adults.for obese children and adolescents,3 km/h exercise is light-intensity physical activity,4?5 km/h exercise is moderate-intensity physical activity,and 6?7 km/h exercise is vigorous-intensity physical activity.(2)The linear regression prediction models of EE,PAEE established by weight combined with VM3 or HRR(%)and the linear regression prediction model established by age combined with VM3 or HRR(%)are valid.The prediction accuracy of EE,PAEE and METs models established by weight or age combined with VM3 and HRR(%)is higher,and the accuracy of EE,PAEE and METs prediction models can be further improved by using ANNs modeling.(3)The criteria of VM3 for diagnosing physical activity intensity as follows:light-intensity physical activity<3687(counts/min),3687(counts/min)?moderate-intensity physical activity<5247(counts/min),5247(counts/minute)?vigorous-intensity physical activity;The criteria of HRR(%)for diagnosing physical activity intensity as follows:light-intensity physical activity<41.66%,41.66%?moderate-intensity physical activity<63.05%,63.05%?vigorous-intensity physical activity.The predictive probability criteria of "VM3,HRR(%),age" for diagnosing light-intensity physical activity is>0.315,and the predictive probability criteria for diagnosing high intensity physical activity is ?0.248.The diagnostic value of a combination of multiple indicators established with "VM3,HRR(%),age" is higher than that of a single indicator The diagnosis of physical activity intensity established by ANNs is more accurate.(4)There is a dose-response relationship between physical activity and cardiometabolic health in children and adolescents with obesity,the improvement rate of CMR-Z score and CMR factor aggregation increased by 13%and 25%with each increase of 1METs-h/days.There was a dose-response relationship between MVPA and cardiometabolic health,with each increase of 10 kcal/days of MVPA,the improvement rate of CMR-Z score and CMR factor aggregation increased by 5%and 5%,respectively.LPA was not associated with cardiometabolic health in children and adolescents with obesity.