## 3 Wireless Sensor Networks (Internet of Things--IoT)  
The IoT paradigm exploits multiple, often small, interconnected devices that work together with a shared job to enable seamless communication and cooperation. Rapid technological development in the wearable IoT industry has occurred in recent years. Some forecasts show a speedy increase in the budget and number of connected wearable devices worldwide in the following years (e.g., according to some market research, the market for wearable technology sensors will reach USD 6.1 billion in 2026 in the United States only) [31; 32]. At the same time, because of this wide availability of low-cost, low-power, and lightweight devices, it has experienced an acceleration in the growth of an even more increasing number of IoT-based applications implementing not obstructive wearable sensors for both professional and recreational athletes [33; 34]. As a result, many wirelessly connected sensors integrated into apparel and sports equipment have emerged. In this framework, two technologies are mainly used: Radio Frequency Identification (RFID) and wireless sensor networks (WSNs) [35]. For this purpose, specific studies on the features of the antennas (e.g., among the flexible, patch, monopole textile, or fully textile loop antennas) that can be safely used for body-worn wireless devices (e.g., they must present a value of specific absorption rate below the maximum limit allowed by the standards) have been carried out for applications in free space as well as on wireless body area network (WBAN) [35; 36; 37; 38; 39; 40; 41; 42; 43]. Furthermore, especially during the last COVID-19 pandemic, their employment in remote patient monitoring also significantly increased.  
High sports performance requires advanced technologies, as each athlete tries to gain a competitive edge through incremental improvement. DAQ plays a fundamental role in this competitive environment, supplying athletes and coaches with quantitative insights into every performance aspect [36; 37; 38]. Nevertheless, collecting kinematic, dynamic, or physiological data during athletes' physical activities represents a critical issue when you need to avoid any alteration in the measure due to physical or psychological obstruction from applying any measurement system. Thus, IoT technology has brought the birth of several new unobtrusive DAQ systems, overcoming most of the drawbacks mentioned above. Consequently, in the sports community, the interest in this area and the requests to carry out reliable and trustworthy measures are now increasing among the coaches and the athletes themselves [39; 40].  
IoT devices in the sports industry aim to conduct performant devices wearable by the athletes or installed on equipment, such as smart bicycles, medical sensors, and fitness trackers that can acquire biological and biomechanical parameters and wirelessly send them to proper user terminals such as tablets, smartphones, and smartwatches. Variables such as heart rate, blood lactate, or training impulse to prevent injuries or position and trajectory tracking information of a ball, athlete movement pathway in individual games such as ski or team technical footpath such as football defenders are nowadays accessible via IoT technology [25; 26].