# Review on Wearable Technology in Sports: Concepts, Challenges and Opportunities
## 7 Applications of Wearables in Sports  
The integration of WT devices into the fields of sports science and sports medicine is increasing. Nowadays, national and professional sports teams utilize WT devices to achieve general performance optimization in training and competitions [9; 91], obtain quantitative biomechanical [92], and physiological [93; 94; 95] data, and monitor training load [96; 97; 93]. WT devices in sports include other sensors such as GNSS and IMU (accelerometers, gyroscopes, and magnetometers) [98]. These sensors provide real-time intelligent inputs that enable the measurement of various physiological characteristics, the identification of physical performance, and the characterization of biomechanical, thermal, and neuromuscular aspects of metabolic fatigue [80]. Consequently, they are seen as significant feedback mechanisms in the substantial improvement of training methods and injury prevention initiatives [99], as well as in the rehabilitation of injuries. Thus, they facilitate the development of athlete-centered training and treatment protocols, leading to enhanced athlete performance [100]. It has even been claimed that WTs are transforming the rules of sports activities [10]. With recent advancements in wearable technologies, coaches, strength and conditioning personnel, and sports scientists have shown great interest in WT for athlete tracking and performance analysis [48]. These systems allow for tracking of external training load and visualization of internal training load, enabling the application of training with targeted exercise intensity [101]. The recent amendment to World Aquatics (formerly FINA) regulations represents a significant departure from the previous stance on WTs in aquatic competitions. While the previous rules strictly prohibited any devices that could enhance swimmers' performance, the revised regulations now allow the use of technology-driven automated data collection devices, with the sole purpose of gathering data for later analysis. However, these devices are expressly forbidden from transmitting data or aiding swimmers in real-time, emphasizing their role as data-gathering tools rather than performance enhancers [102]. Many WTs are used not only in competitions but also in training, and when equipped with gyroscopes, accelerometers, and magnetometers, they allow for quantification of player load measurements. For these reasons, the use and integration of WT devices in professional sports is rapidly increasing [103]. WT devices have now reached a level of usage in sports competitions and are becoming increasingly popular in various disciplines. Major League Baseball allows the use of WTs in games, enabling analysis of various discomorts (such as specific stresses on pitchers) prevalent among baseball players [104]. The International Federation of Association Football (FIFA) and the International Tennis Federation were among the first sports federations to allow the use of these devices in international matches [69]. FIFA, in particular, announced KINEXON as the world's first \"FIFA Preferred Provider Live Player and Ball Tracking\" device in 2021 [105]. WTs such as CATAPULT and KINEXON are used by some basketball teams to analyze tracking data through the use of GNSS data [106]. From a sporting performance perspective, a significant advantage of wearable systems is their ability to provide real-time feedback to athletes in a real sports environment (their natural surroundings), which is not provided by video analysis [91]. For example, different sensors with the capability of collecting data in various environments are used in sports such as skiing [107], snowboarding [108], and swimming [56]. These devices have also provided tools to measure athletes' movement quantity and quality outside of a biomechanics laboratory [51]. WT devices have become indispensable assistants for coaches working to enhance sports performance [101].