## 1 Introduction  
In professional soccer, assessing the player work load (WL) imposed during training sessions and competitive matches is recognized as a fundamental aspect of the daily tasks of coaching staff, assuming that the process of monitoring and quantifying the load should assist coaches and physical trainers in decision making to enhance both individual and collective team performance while minimising the risk of injuries [1]. Load is typically represented by indicators and variables of external load (EL) and internal load (IL), which are, respectively, defined as the work performed by the athlete and the physiological response associated with it [2]. In this sense, the assessment of load in soccer encompasses various aspects, such as duration, intensity, frequency, and type of activities performed during training sessions and matches [3]. Moreover, advancements in technology, particularly the utilisation of GPS tracking devices and wearable sensors, have provided unprecedented opportunities for the real-time monitoring and analysis of player work load, enabling more precise and individualised training programs tailored to meet the specific needs of each player and optimise performance outcomes [4]. Furthermore, the integration of load monitoring data with other performance metrics such as physiological, biomechanical, and psychological parameters offer a comprehensive understanding of the demands placed on players during soccer activities, facilitating informed decision making by coaching staff to maximise team performance while minimising the risk of injuries [5]. A review of the literature reveals that traditionally, the design of soccer training sessions and drills predominantly focuses on technical load (TL) values, aiming to replicate real game scenarios, alongside physical conditioning [6; 7]. It is widely known that professional soccer teams use methods such as GPS technology for monitoring and quantifying physical load (PL) throughout the season [8; 9; 10]. For this reason, the individual and specific use of the chronic workload ratio has been criticised as a means to control the load and reduce injury risk [11]. However, to the best of our knowledge, there are not many studies exclusively investigating technical load (TL) in soccer [12]. Given these circumstances, the development of new technological devices, such as inertial measurement units (IMUs), could help assess TL more effectively [13]. IMUs, by providing detailed movement analysis, offer a promising tool for capturing the intricacies of technical skills in soccer, which are not adequately captured by traditional PL monitoring methods. In fact, recent studies have revealed a high capability for assessing, monitoring, and controlling both TL and PL in different professional teams in England [14; 15] and Spain [13]. The precise measurement of TL through these advanced devices not only aids in improving performance but also holds clinical relevance. Accurate TL assessment can help in understanding the impact of technical demands on players' musculoskeletal health, thus aiding in the development of targeted interventions to prevent injuries and optimise recovery strategies. Overall, the integration of IMUs in soccer training and performance analysis represents a significant advancement, bridging the gap between physical and technical load management and enhancing our ability to safeguard player health and performance. Considering the previous statement, it can be inferred that PL, which has been extensively studied, could be enhanced from a holistic perspective by incorporating TL. In fact, scientific literature reflects that identifying differences in TL and PL between the first and second halves reveals patterns of fatigue and tactical adjustments as the game progresses [14; 15]. Additionally, understanding how different positions experience and manage loads informs position-specific training and recovery strategies. Therefore, further research is necessary to understand TL and PL by individual profiles.