A Quantitative Study On The Aging Characteristics And Exercise Intensity Of SD And Wistar Rats

1 Objective:Using multi-channel energy metabolism system to test the VO₂max direct test program for SD and Wistar rats in different age groups,determine the VO₂max reference range and explore the differences between the two species of rat exercise capacity and VO₂max age-related changes and to calculate VO₂max prediction formula.Test VO₂ of Rats under different exercise intensity and develop exercise intensity reference standards,enrich and improve the exercise intervention program of animal experiment,provide a reasonable experimental basis for the follow-up experiment in the selection of experimental subjects and exercise intensity.2 Methods:Experiment 1:Male SD rats and Wistar rat were divided into three groups according to their ages（one month old）,adult（two-three months old）,and middle age（ten months old）,sixteen rats in each group.Three different incremental load VO₂max test programs were used:Scheme One（P1）:Bedford improvement scheme.Scheme Two（P2）:Speed increasing scheme.Scheme Three（P3）:Increase speed first and then increase slope scheme.)VO₂max tests were performed on each group and record the performance of the rats（degree of cooperation,exhaustion state）,the number of false platform occurrences,the complete time of each protocol,VO₂max and RER values,according to the performance of the exercise and test data compare the advantages and disadvantages of the program.Experiment 2:Twenty male SD rats and twenty male Wistar rats,and twenty male Wistar rats of aged（sixteen months old）in seven groups.The VO₂max test was performed on rats according to the optimal test protocol for each age group obtained from experiment one（the old rat test protocol was revised based on the middle-aged rat test protocol）.The differences in VO₂max between SD and Wistar rats were compared,and methods of rats VO₂max prediction formula was searched.Experiment 3:There are five groups in total.Twenty young male SD rats and twenty male Wistar rats,and twenty Wistar rats in old age.Rats were tested at different slope（0°,5°,10°,15°）and speeds.The VO₂ value under the combined intensity was compared with the corresponding VO₂max value at the beginning of 10 m/min,increment of 5 m/min every 3 min,and increased until the rats were exhausted.The exercise intensity was quantified by VO₂max%.3 Results:Experiment 1:（1）The mean value of VO₂max measured by the P1 protocol of juvenile rats was higher than that of P2 and P3,and there was a significant difference from the test value of P3（p<0.05）.The VO₂max criterion was better than the other two schemes.（2）There was no significant difference in the completion of each scheme among adult rats.Between the test values,the mean value of VO₂max measured by P2was higher than that of P1 and P3,however,only P1 and P3 showed significant difference（p<0.05）.there was no statistical significance between the RERs of each protocol.on the completion time of the protocol,the test time of P3 was significantly less than P1（p<0.05）,P2（p<0.01）.).（3）The VO₂max values and completion time of middle-aged rats had not statistically significant.However,on the completion of the protocol,P3 was significantly better than the other two programs,and the RER value of the P3 program was significantly higher than the test value of the P1 group（p<0.01）,there was no significant difference between P3 and P2.Experiment 2:The reference range of VO₂max for male SD rats in each age group as following:young（6186.59±314.80 ml/kg/hr）.adult（5093.13±174.97 ml/kg/hr）.middle age（3687.82±244.85 ml/kg/hr）.The reference range of VO₂max for male Wistar rats in each age group:young（6338.77±287.32 ml/kg/hr）.adult（5124.88±241.46 ml/kg/hr）.middle age（3735.19±384.20 ml/kg/hr）.（3373.17±148.93ml/kg/hr）.The data showed that there was no significant difference in VO₂max between the same age groups,but the VO₂max age of each rat species had significantly changed（p<0.01）.According to a large number of test values,the VO₂max prediction formula for male SD and Wistar rats is calculated as:VO₂max（ml/kg/hr）=-4.369 x body weight（g）-1.519 x rat age（d）+6951.130 R=0.96.Experiment 3:VO₂ in rats and their corresponding VO₂max%intensities of Male SD rats and Wistar rats in all age groups were at slope 0,5,10,and 15,and the speeds were 10m/min,15m/min,20m/min and other exercise intensity.Among them,the young Wistar rats running at a 0 slope,10m/min intensity,VO₂max of 3385.92±459.86ml/kg/hr,55.05±4.59 VO₂max%was classified as moderate exercise intensity.Tthe intensity of exercise increases with the speed,the intensity can increase to about6482.53±415.34 ml/kg/hr at 55m/min,which is equivalent to 100 VO₂max%intensity.4 Conclusion:（1）The exercise ability of Wistar and SD rats had significant age characteristics.The VO₂max test program for rats of different ages has different selections.The P1 program with increasing intensity is suitable for testing in young rats.the speed increase program（P2）is suitable for adult rat test.middle-aged and old rat test is suitable for selecting increase speed first and then increase slope scheme（P3）,it is recommended to increase the slope after 85%-90%VO₂max.（2）There was a significant changes of the age-related of VO₂max in rats,there was no significant difference in VO₂max between male SD rats and Wistar rats in the same age group,but Wistar rats showed better exercise performance than SD rats.in addition,There is a high correlation between the VO₂max with body weight and age of rats,and the VO₂max estimation can be performed in the later experiments based on the VO₂max prediction formula obtained in this study.（3）There was a clear corresponding relationship between exercise intensity（slope,velocity combination）and VO₂max%in male SD and Wistar rats of different age groups.The results of this study can be used as reference standards for experimental dynamic strength in the later period.