| Objective:To compare the results of two kinds of advanced methods for measuring the energy system to 400-meters run,namely two Maximal accumulated oxygen deficit methods(MAOD)and three phosphocreatine-lactate-oxygen methods(PCR-LA-O2),and to analyze the correlation between the energy supply ratio and the performance of 400 meters run.Methods:13 male 400-meter runners(age:19.92±1.44 years old,height:177.62±5.03cm,weight:69.85±7.21kg)were recruited to carry out incremental load,constant load(5 levels:50%,60%,70%,80%and 90%VO2max)and tests on 400-meter track and field.When the MAOD is used to calculate the energy supply ratio,there are two calculation methods,namely MAOD1 method,which represents the fixed resting oxygen uptake as the y-intercept(5+Y)in the simulated oxygen uptake-output power equation.MAOD2 method,representing the analog oxygen uptake-output power equation is not fixed resting oxygen uptake as the y-intercept(5-y).When calculating the energy supply ratio by PCr-La-O2 method,there are three calculation methods,respectively,PCr-La-O21 method,which represents the energy supply of oxygen-free and lactic acid part by the product of amplitude and time constant of the fast part of oxygen uptake after exercise.PCr-La-O22 method represents the energy supply of anaerobic and lactic acid free parts,which is calculated by the mass of pyrophosphate-per unit body weight(the percentage of muscle content).The PCr-La-O23 method represents the energy supply of the part without oxygen and lactic acid,which is calculated by the oxygen intake 6 min after exercise.Single factor repeated measurement analysis of variance was used to evaluate the differences of energy supply ratio of 400 meters race measured by 2 categories and 5 methods.Pearson correlation coefficient was used to evaluate the correlation between energy supply ratio and athletic performance,and the statistical significance level was set at 0.05.Results:(1)Aerobic and anaerobic energy supply ratio of 400 meters run measured by different methods:MAOD1 method was 47.12±4.46%and 52.88±4.46%,MAOD2 method was 48.33±5.52%and 51.67±5.52%,PCr-La-O21 method was 36.37±7.61%and 63.63±7.61%,PCr-La-O22 method was 34.38±2.75%and 65.62±2.75%,PCr-La-O23 method was 32.57±3.22%and 67.43±3.22%,respectively.There was no statistically significant difference in the energy supply ratio calculated by MAOD1 and MAOD2(P>0.05),and there was no statistically significant difference in the energy supply ratio calculated by PCr-La-O21,PCr-La-O22 and PCr-La-O23(P>0.05),while there was statistically significant difference in the energy supply ratio calculated by MAOD1 or MAOD2 and PCr-La-O21,PCr-La-O22 or PCr-La-O23(P<0.05).(2)The energy supply ratio of anaerobic lactic acid and non-lactic acid was calculated by different PCr-La-O2 methods.(3)The energy supply ratio calculated by PCr-La-O22 method was correlated with athletic performance(aerobic energy supply ratio:r=0.58,P<0.1;anaerobic energy supply ratio:r=-0.58,P<0.05),and there was no correlation between the percentage of muscle content and athletic performance(r=-0.51,P>0.05).The energy supply ratio of anaerobic lactic acid calculated by PCr-La-O23 method was negatively correlated with athletic performance(r=-0.68,P<0.05).However,there was no statistical significance in the correlation between energy supply ratio and sports performance under other calculation methods(P>0.05).Conclusions:Different measurement methods will affect the measurement results of energy supply ratio in 400-m runs,and affect the correlation between energy supply ratio and athletic performance.Compared with the PCr-La-O2 method,the MAOD method is more accurate in measuring the energy supply ratio and is the most widely used method.However,they are not completely accurate measurement methods.When monitoring the energy supply ratio of athletes for a long time,the measurement method should be fixed. |
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