## 1 Introduction  
Football is one of the most physically demanding sports, with players frequently exposed to a considerable risk of injuries, particularly in the lower extremities [1]. These injuries not only affect individual performance but also have significant implications for team dynamics and overall game outcomes [2]. Common lower limb injuries in football often result from improper movement patterns or biomechanical errors, such as poor ankle stability, or asymmetrical weight distribution, like dynamic knee valgus, where the knee collapses inward during activity [3, 4]. These biomechanical errors place excessive stress on joints and soft tissues, increasing the likelihood of injuries like anterior cruciate ligament (ACL) tears, ankle sprains, or muscle strains [5]. Biomechanics plays a crucial role in injury prevention by identifying movement inefficiencies and correcting faulty mechanics before they lead to injuries [6], especially during high-impact movements--such as rapid accelerations, decelerations, cutting maneuvers, and landings--are particularly susceptible to these biomechanical errors, making real-time monitoring and correction essential for injury prevention [7]. Several key biomechanical markers indicate injury risks, including joint angles, plantar pressure distribution, and the center of pressure (COP). These parameters provide insights into an athlete's movement quality and highlight areas requiring intervention. For example, an improper COP shift during landing can signal a high risk for ACL injuries, while uneven plantar pressure distribution may contribute to chronic overuse injuries. Identifying these risk factors enables targeted interventions, such as neuromuscular training and movement re-education, to optimize movement efficiency and reduce injury susceptibility [8]. In response to these challenges, injury prevention programs like FIFA 11+ have been developed to improve players' strength, balance, and neuromuscular control. The FIFA 11+ program, developed by the Federation Internationale de Football Association (FIFA), is a comprehensive injury prevention initiative for football players [9; 10]. It consists of warm-up routines, strength training, balance exercises, and agility drills aimed at reducing injury risk, especially for the lower limbs [11]. Despite its success in preventing injuries [9; 10], it lacks personalized, real-time feedback for monitoring and correcting players' movements, leading athletes to perform exercises incorrectly, reducing players' effectiveness and leaving them susceptible to injury [12]. Various devices have been introduced to monitor movement quality [13]. These include wearable sensors and integrated systems within training equipment that offer real-time feedback on performance, allowing for immediate adjustments [14]. Despite these advancements, many current devices suffer from issues such as rigidity [15], discomfort [16], and sensor displacement [17] leading to inaccurate data and limited user acceptance [18; 19]. Smart textiles offer a promising solution to these challenges [20]. Smart textiles, or e-textiles, integrate electronic components directly into fabrics, creating flexible, wearable devices that conform to the body's movements [20; 21]. For instance, smart socks equipped with pressure sensors and inertial measurement units (IMUs) can measure critical parameters such as plantar pressure distribution and ankle joint positioning [22; 23]. These smart socks provide continuous biomechanical monitoring without the discomfort associated with traditional devices [24]. However, applying this technology specifically to youth football players presents new challenges, including adapting the approach to the rigorous training demands of young athletes. Our interdisciplinary research project aims to address these challenges by developing through conceptualization a biofeedback method based on DAid(r) smart socks for youth football players.