A Comparative Study Of Different Methods For The Measurement Of Metabolic Flexibility In Male College Students

Purpose The purpose of this study is to evaluate the metabolic flexibility of sedentary and active people by using glucose tolerance test and incremental exercise blood lactate test,and to compare the consistency of different measurement methods in evaluating the metabolic flexibility.MethodsA total of 32 male subjects were included in this study,including 10 normal weight active subjects(age: 21.24 ± 1.85 years,BMI: 22.04 ± 1.42 kg/m2),10 normal weight sedentary subjects(age: 21.14 ± 2.36 years,BMI: 21.91 ± 1.29 kg/m2),12overweight/obesity sedentary subjects(age: 22.16 ± 2.80 years,BMI: 26.25 ± 1.94kg/m2).OGTT and incremental exercise blood lactate test were used to evaluate metabolic flexibility in all groups.During the OGTT period,venous blood was collected at baseline,30 min,60min,120 min and 180 min to analyze blood glucose(GLU),insulin(INS),free fatty acid(NEFA)and other indexes.Trueone 2400 metabolic test system was worn throughout the test to analyze respiratory quotient(RQ),variation of respiratory quotient(△RQ),area under the curve(t AUC),incremental area under the curve(i AUC),coefficient of variation of respiratory quotient and coefficient of variation of insulin.Carbohydrate oxidation(CHOox)and fat oxidation(FATox)were calculated by Frayn equation.In the incremental exercise blood lactate test,the lactate values under different loads were collected,and wearing breathing mask the whole process for gas analysis.ResultsOGTT results showed that INS in 60 th 120th minute in overweight/obesity sedentary group were significantly higher than those of normal weight active group and normal weight sedentary group(all P < 0.05),NEFA in 30 th and 60 th minute were significantly higher than those of normal weight active group and normal weight sedentary group(all P < 0.05).The t AUC and i AUC of overweight/obesity sedentary group were significantly higher than those of normal weight active group(P = 0.019,P = 0.028).RQ,Δ RQ,RQ t AUC and RQ i AUC of normal weight active group were significantly higher than those of normal weight sedentary group and overweight/obesity sedentary group during OGTT(all P < 0.05).There was statistical difference only in RQ i AUC between the two sedentary groups.RQ,ΔRQ,RQ t AUC and RQ i AUC of normal weight sedentary group were significantly higher than those of overweight/obesity sedentary group P=0.045).In addition,the normal weight active group showed high respiratory quotient variance and low insulin coefficient of variation,while the overweight/obesity sedentary group showed the opposite.The above indexes showed that the metabolic flexibility of the normal weight active group was better than that of the two sedentary groups,and there was no significant difference between the two sedentary groups.The results of incremental load exercise blood lactate test showed that there was no significant difference in CHOox and FATox among the three groups.The blood lactate concentration showed difference only at 135 w.The overweight/obesity sedentary group was significantly higher than the normal weight active group(P = 0.036).With the increase of exercise load,lactate concentration and FATox are showing a significant negative correlation,and the crossover in normal weight active group was later than the normal weight sedentary group and overweight obese sedentary group.Similarly,there was a significant negative correlation between CHOox and FATox among the three groups.The crossover energy supply of CHOox and FATox appeared a longer latency in the active group.Conclusion1.The incremental load exercise blood lactate test is consistent with the traditional OGTT in the evaluation of metabolic flexibility,but for the people with similar metabolic capacity,its distinguishing effect is weaker than the OGTT evaluation method.2.The sedentary male college students showed slightly lower metabolic flexibility than active male college students,indicating that sedentary behavior may be a risk factor for metabolic flexibility.3.In this study,there was no significant difference in metabolic flexibility between normal weight sedentary group and overweight obese sedentary group.The effect of obesity on metabolic flexibility needs to be further studied.