Post-exercise Stretching Protects Strain of Knee Joint Movement System by Relieving Knee Pain and Iliotibial Band Tension


 Background Studies have reported that exercise stretching therapy has a certain effect on improving knee joint pain and knee joint function.However, few studies have compared the effects of post-exercise stretching and non-stretching on strain of knee joint movement system. The purpose of this study is to observe the influence of whether people have stretched after exercise on knee joint pain and iliotibial band tension,and to compare the difference between the stretched group and the unstretched group after exercise for further discussion.Methods Collecting data analysis of 71 people who love sports in the First People's Hospital of Xiaoshan District from December 2019 to October 2020, including the non-stretching group after exercise (group A, n=40) and post-exercise stretching Group (Group B, n=31), compare the differences in knee pain and iliotibial band tension between the two groups and analyze the relationship between this difference and stretching.Results The incidence of knee pain and iliotibial band tension in group A was significantly higher than that in group B (P<0.05). The risk of knee pain in group A was 2.940 times greater than that in group B. The incidence of iliotibial band tension in group A was 4.190 times higher than that in group B. Conclusions 1. People who do not stretch after exercise are at higher risk of knee pain than those who stretch. 2. People who do not stretch are more likely to develop iliotibial band tension than those who stretch. 3. Stretching after exercise helps to relieve the stiffness of the iliotibial band, maintain the stability of the knee joint, and reduce the occurrence of knee pain.

The incidence of iliotibial band tension in group A was 4.190 times higher than that in group B. Conclusions 1. People who do not stretch after exercise are at higher risk of knee pain than those who stretch. 2. People who do not stretch are more likely to develop iliotibial band tension than those who stretch. 3. Stretching after exercise helps to relieve the stiffness of the iliotibial band, maintain the stability of the knee joint, and reduce the occurrence of knee pain.

Background
Nowadays, people are paying more and more attention to the concept of health. Among them, exercise has an important impact on health [1] .Exercise can not only enhance physical tness, prevent and treat certain diseases [28,29] ,but also improve people's sleep quality and fatigue [27] . Effective stretching can also be used as an exercise therapy to treat body pain and improve physical function [5,24,33] ,but modern people do not pay attention to stretching after exercise and lack relevant knowledge. Research reports that stretching exercises are of great signi cance to range of motion and physical performance [21,26] .
Stretching activities can effectively relieve muscle fatigue and improve muscle exibility [2,25] . Stretching after exercise can not only increase the range of exercise and reduce stiffness, but also help strength recovery and improve delayed muscle soreness [22] . In sports, people who stretch are usually more effective in improving sports performance than people who do not stretch [3,6,34] . Excessive tension of the iliotibial band and knee joint pain are common phenomena in today's society. Continuous tension of the iliotibial band can cause Iliotibial Band Friction Syndrome and cause knee pain. Studies have reported that exercise therapy has a certain effect on knee pain and knee joint function [4,23] . However, there are few studies comparing the effects of stretching and non-stretching after exercise on the improvement of the two. Therefore, it is discussed whether post-exercise stretching can improve the effect and provide a reference for basic research in sports medicine.

Research objects selection
The study collected 71 people who volunteered to participate in the posture study from December 2019 to October 2020 in the First People's Hospital of Xiaoshan District, divided them into 2 groups according to whether there was stretching after exercise. Knee pain and iliotibial band test were investigated, and statistical analysis was performed. The measurement data was completed by the same senior physician.

Inclusion criteria:
1) The survey population has no history of related diseases and operations; 2) There is no statistical difference in age between the two groups; 3) Sign informed consent; 4) People who insist on exercise for a long time; 1.2 Exclusion criteria: 1) Excluding knee joint diseases; 2) Except for the history of related operations such as hip joint and knee joint; 3) Excluding obesity BMI> 28 and pregnant women; 4) Excluding other related factors of disease; 2 Measurement methods: The degree of knee pain was judged by the VAS score scale after the doctor asked the medical history. Inspection method of iliotibial band test: To judge the tension of the iliotibial band through the Thomas test, the hip joint cannot reach 0° indicating that the iliopsoas muscle is tense.
When the hip joint is 0°, the knee joint is greater than 90°, re ecting the tension of the rectus femoris, keeping the hip joint adduction and abduction 0° and let it fall naturally from a high place. If the leg is raised, it means that the iliotibial band is tight.
3 Statistical analysis method SPSS 16.0 statistical software is used for data processing in the data analysis of this study. Mann-Whitney test is used to compare the age of two groups of people.Chi-square test is used to compare the incidence of knee pain, iliotibial band tension, and gender differences. Relevant risk assessment adopts logistic regression analysis. P<0.05 considered the difference to be statistically signi cant.

Results
Studies have investigated that approximately 25% of adults in the world often suffer from knee joint pain, which affects the quality of life and limits the function and range of motion of the knee joint [31] .
All study subjects are from people who volunteered to participate in the posture study from December 2019 to October 2020.A total of 112 volunteers are selected for this study. After the inclusion and exclusion criteria, 71 volunteers are nally included to participate in the research survey. Among them, 35 are males and 36 are females. According to whether they stretched after exercise, they are divided into 40 people in group A and 31 people in group B. The age of group A is 42.88±10.05 years old, and the age of group B is 41.42±8.78 years old. Basic information of the two groups are shown in Table 1. Through the analysis of the research results in Table 2 and Table 3, There is no statistical difference in age and gender between the two groups (P>0.05), the incidence of knee pain and iliotibial band tension between the two groups is statistically different (P<0.05). The incidence of knee pain in group A is signi cantly higher than that in group B. The incidence of iliotibial band tension in group A is signi cantly higher than that in group B. Logistic regression analysis is used to analyze the relative risks of various indicators between the two groups. It is concluded that the risk of knee pain in group A is 2.940 times higher than that in group B, and the risk of iliotibial band tension in group A is 4.190 times higher than that in group B.

Discussion
Knee joint damage is a common symptom in strain of movement system.The knee joint is an important joint of the lower limbs, allowing it to move between the femur, tibia and patella.The knee joint is a modi ed hinge joint that participates in a variety of motion functions of the lower limbs [30] .Knee joint pain has become a common clinical symptom that plagues people of all ages in society, and the risk of knee joint pain is mostly related to external environmental damage and own factors [13,14] . For the treatment of knee joint pain, there are various treatment methods such as surgery, medication and physical therapy [24,15,16,35] . The literature reports that exercise therapy can be used as an intervention to treat knee osteoarthritis [7] . This is based on the principle that exercise therapy can increase joint stability and exibility and reduce pain, thereby optimizing functional capacity and independence. Exercise therapy can signi cantly improve pain and function [8] . Stretching after exercise can further provide a bene cial effect on the knee joint and its surrounding tissues [9] .
The iliotibial band is the thickened part surrounding the fascia lata of the thigh. It originates from the iliac crest. The lower end is attached to the lateral tibial condyle, bular head and joint capsule of knee. It has the function of maintaining the stability of the knee joint. When the disease occurs, it can cause related knee joint pain [17,18] .It has been reported in the literature that knee joint pain is related to Iliotibial Band Friction Syndrome.Iliotibial Band Friction Syndrome is one of the many causes of knee pain.Various types of sports can cause it to occur. The incidence of runners and other sports athletes is 1.6-12% [32] .Various factors in the exercise process can cause the iliotibial band to be tight and can cause the pathological changes related to the iliotibial band.Long-term iliotibial band tension can cause Iliotibial Band Friction Syndrome and ultimately lead to the occurrence of knee pain, and relaxation of the iliotibial band through stretching exercises can effectively improve knee joint pain [10,11] . There are usually surgical and non-surgical treatments for the treatment of Iliotibial Band Friction Syndrome, and stretching can also be used as a non-surgical treatment for Iliotibial Band Friction Syndrome [11,12] .The tense iliotibial band can be relaxed by proper stretching method, so as to achieve the purpose of treatment.
This study takes stretching as an important in uencing factor, analyzes the effect of stretching on the knee joints of sports people, and provides a reference for improving the quality of sports and reducing related injuries.Due to limited time and nancial resources, there are some problems as follows. First of all, it is impossible to conduct detailed retrospective interviews and add more testing indicators.Secondly, there is a lack of relevant tests for the correctness and effectiveness of the patient's stretching, so it is impossible to analyze the situation of each patient more comprehensively.In addition, the in uence of psychological factors on exercise [19] and the in uence of different exercise types on knee symptoms should also be considered [20] .Further research is needed in the future to investigate the in uence of these factors on the knee joint.Finally, this study has a lot of room for improvement, and more testing items can be added in the future to analyze the impact of stretching on the sports crowd.

Conclusions
Based on the comparison of the incidence of knee pain and iliotibial band tension and related risk analysis of the above two sets of data, it can be concluded that stretching after exercise is better for knee pain and iliotibial band tension than without stretching after exercise. Stretching after exercise can reduce the risk of knee pain and iliotibial band tension in the crowd. Stretching after exercise can more effectively prevent knee pain and maintain the exibility of the iliotibial band, maintain the function of the iliotibial band, stabilize the knee joint, and reduce related knee pain caused by the disease of the iliotibial band. For those people who insist on physical exercise for a long time, stretching is a very good way to prevent the occurrence of sports injury diseases. Stretching can not only improve athletic ability and promote physical health, but also can effectively relieve muscle fatigue and tension through stretching. At the same time, it also has a certain therapeutic effect on some sports injuries. It is worth popularizing among the sports crowd.

Declarations
Ethics approval and consent to participate All participants read and signed a written informed consent prior to the start of this study. In compliance with relevant Chinese laws and regulations, the trial was conducted in accordance with the Declaration of Availability of data and materials Due to the large amount of personal privacy involved, the data and materials in this study are not disclosed. However, the data are available from the corresponding author on reasonable request.