| At present,due to the characteristics of middle and long distance running events,the physiological characteristics of young female athletes and long-term high intensity of sports training,it is easy to cause joint and muscle tissue injury.Instability Resistance Training（IRT）can enhance muscle strength and improve body balance and stability.It can also enhance the muscle activity of the trunk and limbs,reduce the joint torque caused by the load,thus reducing the pressure on the joint system,and play a protective role in the joint.Purpose: This study aims to conduct 8-week intervention training for adolescent female middle-distance runners through IRT,and explore the influence of IRT on the characteristics of lower limb muscle strength and plantar pressure of adolescent female middle-distance runners,so as to provide theoretical basis for scientific training and prevention of lower limb sports injury of adolescent female middle-distance runners.Methods:In this study,literature review method,experimental test method,mathematical statistics method and other research methods were adopted.Subjects selected adolescent female middle-distance runners from Jilin Province Sports School,and IRT was used for 8 weeks of intervention training.Before and after the experiment,the German isometric strength training test System（ISOMED2000）and the Italian Lor An MPS plantar pressure test plate analysis system were used to measure the relevant indicators.The paired sample T test was used to compare and analyze the data before and after the experiment.Results: 1 Before / after the experiment,the hip,knee and ankle muscle strength and standing balance ability of adolescent female athletes were effectively improved（P <0.05）,and there were significant differences in knee H / Q value,ipsilateral homonymous muscle ratio of hip,knee and ankle muscle groups and pressure distribution indexes in various areas of plantar（P < 0.05）.2.In isokinetic muscle strength test,there was highly significant difference in ankle muscle strength of athletes（P < 0.01）,and the difference of muscle strength ratio of the same name on the opposite side of each joint flexor and extensor group was no more than 10%.3.Before the experiment,the H / Q ratio of hip joint,knee joint and ankle joint were 0.64,0.58 and 2.89 respectively;Before the experiment,the H / Q ratio of hip joint,knee joint and ankle joint were 0.66,0.68 and2.71 respectively;After the experiment,the H / Q ratio of hip joint,knee joint and ankle joint were 0.63,0.65 and 3.34 respectively.After the experiment,the H / Q ratio of hip joint,knee joint and ankle joint were 0.67,0.71 and 2.79 respectively.4.In the plantar pressure test,there was a significant difference in the peak pressure of young athletes standing on both feet before / after the experiment（P < 0.05）,but there was no significant difference in the effect on plantar contact area and average pressure（P > 0.05）;Compared with before the experiment,there was no significant difference in the peak pressure between the left and right sides after the experiment（P > 0.05）.The peak pressure point moved forward,and the functionality of T1 area,M1 and 2 area was improved.Conclusion:（1）IRT intervention training can play a positive role in the lower limb muscle strength and balance ability of juvenile athletes.（2）In the isokinetic muscle strength test,after IRT intervention training,the ankle muscle strength of young female athletes is significantly improved,so as to minimize the probability of injury in training.（3）In the plantar pressure test,IRT intervention training can make the foot turnover mode of young female athletes more normal,improve the function of forefoot area,and play a vital role in the pedaling and stretching force and lower limb stability during running. |
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