Extended Abstract
1.    Introduction
From a biomechanical point of view, the lower limb is a functional unit whose purpose is to ‎maintain body weight and create leverage to move forward while running (1). It can also be ‎said that the lower limb is the only part of the body that comes into contact with external ‎surfaces while moving and plays a very important role in maintaining balance while running ‎‎(2). Running is one of the most common leisure activities among people in society, so that ‎only in a country like the United States, approximately 30 million people run for the ‎purpose of competition and training (3). During physical activities, especially running, in ‎the support phase, the lower limb is always affected by loads and forces from the ground, ‎and in this phase of running, due to the placement of the lower limb in a closed chain and ‎joint connections, the movement of one limb affects the movement of the adjacent limb (4). ‎In fact, when the adjacent organs are active in a closed chain, they have a coupled ‎movement, coupling, and some kind of special coordination (5). It can be said that running ‎is an activity in a closed chain and the most basic debatable movement and movement ‎pattern that is required in most sports (6). The running speed of people is determined based ‎on the length and frequency of steps (7). Among the kinetic variables, the torque of the ‎joints of the lower limbs can also be mentioned, and it can be said that the greater the ‎strength of the muscles, the more internal torque they can exert on the joint and thereby ‎absorb the forces exerted on the body and during activities such as running  there must be ‎balance between the force on the joint and the muscle strength so that the joint can maintain ‎its stability. So, the greater the external force on the body, the more muscle effort must be ‎done to prevent the joint from rotating due to the external torque. For this reason the ‎analysis of joint torque is very important in the study of body movements (8)‎.

2.    Methods
The statistical population of this study consisted of healthy people and regular runners. A ‎group of 28 healthy male subjects, who were among the runners who ran more than 20 ‎kilometers per week, were selected as the research sample using the convenience sampling ‎method. They were also familiar with running on a treadmill. Three-dimensional kinetic ‎parameters of the lower limb joints for the hip, knee, and ankle joints [torque] and the kinetic ratio of the minimum, maximum ‎and average values of these joints at three different speeds: 2/5,3/5 and 4/5 were measured ‎by two important tools: camera and force plate. Shapiro-wilks test was used to check the ‎normality of data distribution, and data analysis was done using the analysis of variance test ‎with repeated measurements through SPSS software, version 22‎.

3.    Results
Descriptive statistics were used to introduce the mean and standard deviation to evaluate the ‎normality of data distribution. In order to analyze the data inferentially and to investigate ‎the effect of increasing the running speed on the chain and the kinetic ratio of the lower ‎limb joints, the repeated measure test (variance analysis with repeated measurements) and ‎the Bonferroni post hoc test were also used to investigate the difference between the groups. ‎In table 1, 2/5 speed was marked with *, 3/5 speed with ≠ and 4/5 speed with Ω. It should ‎also be noted that the significance level was considered  to be p<=0.05 in all cases and the ‎results in table 1 showed that the amount of torque in the ratio of the joints of the lower ‎limbs, which includes the ratio of the joint thigh to knee, thigh to ankle and knee to ankle in ‎all three planes and three anatomical axes (X, Y, Z) including frontal, transverse and ‎sagittal planes in all three speeds 5.2, 5.3 and 5.4/m/s did not show a significant (+) ‎difference in the stance phase. ‎

4.    Conclusion
According to the obtained results, it can be said that it is possible that the amount of ‎torque of the lower limb joints will be affected by increasing the running speed, ‎which should be taken into consideration in the design of training programs, ‎especially for runners. Also, in this study, it seems that practical solutions can be ‎provided to reduce the amount of damage caused to these 3 joints while running, ‎especially on the treadmill, with the knowledge of the moment changes of the joints ‎of the lower limbs.

Ethical Considerations
Compliance with ethical guidelines
All ethical principles were considered in this article. The participants were informed about the purpose of the research and its implementation stages; they were also assured about the confidentiality of their information; Moreover, they were allowed to leave the study when-ever they wish, and if desired, the results of the research would be available to them.
Funding
This research did not receive any grant from funding agencies in the public, commercial, or non-profit sectors.
Authors' contributions
All authors equally contributed to preparing article.
Conflicts of interest
The authors declared no conflict of interest.