## 1 Introduction  
Running is one of the most popular forms of physical activity, evidenced by the number of runners worldwide. It is considered that as much as 36% of the population in Europe runs recreationally. Although running is considered a simple motor activity, it requires complex motor integration of all body segments [1]. In addition, high running loads are often associated with injuries such as fatigue fractures of the tibia, plantar fascitis, or patellofemoral pain [2]. It is estimated that each year as many as 80% of runners suffer an injury [3]. To prevent these injuries, understanding the correct running pattern is key [4]. Therefore, the biomechanics of running has been a major interest for researchers in human locomotion sciences due to its uniqueness and complexity [5; 6]. Indeed, analyzing biomechanical variables might provide a better understanding of the runners' motor actions [4; 7]. The dynamics of change and the kinematic structure of running are characterized by a cycle that consists of a support phase and a flight phase [8]. Previous studies report that effective running is characterized by a cycle in which the flight phase is about 65% and the support phase is about 35% [7]. Step length, contact time, flight time, step frequency, or step time are parameters that regulate and optimize the above-mentioned cycle [9; 10]. Appropriate proportions of those variables in the spatiotemporal structure optimize the dynamics of running, increasing its efficiency [7]. The parameters can also be important predictors of injury risk [11]. Step width can cause changes in lower limb biomechanics. It has been observed that an increased step width can lead to decreased hip adduction angle and heel roll or peak knee inversion. Conversely, an increased peak hip adduction angle may be one of the factors that causes patellofemoral pain [12]. In addition, it has been shown that an increased stride frequency can significantly reduce stress on the knee and hip joints, which can result in a lower risk of running injuries [11]. On the other hand, a literature review conducted by [PERSON] et al. [3] found no significant correlations between spatiotemporal parameters and injury history. In contrast, according to other studies, stepping too long caused a disruption in the synchrony of the knee and ankle joint, which increased the load on the entire limb and thus the risk of injury [13]. Examples of the spatiotemporal parameters may include distance and running speed, running stride width and length, or stride frequency. It has been suggested that they may be related to injury risk [3]. Step width can cause changes in lower limb biomechanics. It has been observed that an increased step width can lead to a decreased hip adduction angle and heel roll or peak knee inversion. Conversely, an increased peak hip adduction angle may be one of the factors that causes patellofemoral pain [12]. In addition, it has been shown that an increased stride frequency can significantly reduce stress on the knee and hip joints, which can result in a lower risk of running injuries [11]. On the other hand, a literature review conducted by [PERSON] et al. [3] has not found any significant correlations between spatiotemporal parameters and injury history. According to previous research, maximum speed results from the optimal relationship (combination) between stride length and stride frequency [14]. Similar findings were reported by [PERSON] et al. [15], who characterized several runners based on their stride length and frequency, describing a strong relationship between both parameters. Moreover, several authors reported a curvilinear increase in stride length and cadence with running [15; 16; 17; 18; 19; 20]. In the literature, available reports on this matter also described the negative curvilinear relationship of stance phase with increasing speed [15; 18; 21; 22; 23; 24; 25]. The phase of flight, however, was reported to grow with increasing running speed, although at high speeds, it stabilized at a constant level [15].