# Impact of Acceleration and Acceleration-Initial Speed Profiles on Team Success in LaLiga
## 1 Introduction  
Soccer is an intermittent sport characterized by the prevalence of long periods of low-intensity activity with short periods of high-intensity efforts, such as sprints and accelerations [1]. These high-intensity efforts are typically associated with neuromuscular fatigue and risk of injury [2] and represent approximately 1-11% of total distance covered in a match [3], increasing the importance of preparing soccer players to perform high-intensity actions. Physical performance is a key factor for the team's success in competition, due to the increase in high-intensity actions in competition in recent years [4]. Previous studies showed that physical performance is not related to team success at the end of the season in La Liga, Premier League, and Italian Serie A for variables associated with total distance and distance covered per speed zone [5, 6, 7]. Players from the highest-ranked teams covered less total distance > 19.8 km\(\cdot\)h\({}^{-1}\) and total distance > 19.8 km\(\cdot\)h\({}^{-1}\) without ball possession than players from less successful teams [6]. However, the highest-ranked teams covered higher distances above >14 km\(\cdot\)h\({}^{-1}\), >19 km\(\cdot\)h\({}^{-1}\), and >24 km\(\cdot\)h\({}^{-1}\) with ball possessionthan soccer players from less successful teams [5, 7]. [PERSON] et al. (2020) [8] analyzed the maximum capacities of soccer teams in LALIGA and showed that successful and less successful teams had similar high maximum running speeds. However, maximal or near-maximum running speeds occur in critical action during the game, and the average duration of each sprint was between \(\sim\)4.9 s and 9 s, with an average distance covered between \(\sim\)30 and 55 m [9], while the highest intensity actions occurred with less than 20 m distance covered, and the average duration of each action was between \(\sim\)2 s and 4 s [10]. Hence, the maximal running speed values are difficult to achieve in soccer matches [8]. Moreover, short, intense actions are associated with high metabolic demands such as low and moderate velocity [11]. For this reason, short-intensity actions such as accelerations, decelerations, and changing directions are important to evaluate. However, although accelerations are key actions in soccer and [12] is one of the most commonly used variables of external load quantification [13], studies have only analyzed the relationship between external load and team success through variables related to the distances covered per speed zone. Currently, accelerations are quantified by absolute thresholds, considering high-intensity accelerations those that exceed the threshold of 2.5-4 m\(\cdot\)s\({}^{-2}\)[14]. However, the increase in speed causes a decrease in the acceleration capacity, with the highest peak of acceleration at the beginning of the running phase. As such, external load quantification by absolute thresholds underestimates accelerations with high initial running speed for the descent of the capacity of acceleration and overestimates acceleration with low initial running speed [15]. In recent years, studies have examined the relationship between acceleration and running speed to evaluate and quantify high-intensity actions. [PERSON] et al. (2016) [15] introduced a new methodological approach to assess high-intensity accelerations relative to the percentage of maximum acceleration at a specific running speed, measured through a sprint test. According to this method, accelerations exceeding 75% of the maximum acceleration in each speed zone are classified as high-intensity accelerations [15], revealing differences in the number of maximum accelerations performed at various initial running speeds depending on positional roles [16, 17]. More recently, a novel methodology has been proposed to classify acceleration and deceleration intensity based on the individual percentage intensity method developed by [PERSON] et al. (2016) [15].