## 3 Applications of Sports Wearables  
Wearable technology has been extensively studied in relation to improving sports performance. There are a variety of marginal gains that can be achieved using wearable technology, including the following:  
* Training intensity: Wearable technologies can be used to track training intensity, which can help athletes to train at the right level and avoid overtraining [31]. For example, wireless heart rate monitoring has been used by cyclists for several years and is very useful for detecting early overtraining, as well as providing insight into training intensity and cardiac drift [32; 33]. Wearable devices, such as heart rate monitors (HR) and power meters (PM), offer similar benefits for athletes' performance. A study on recreational cyclists found that both HR- and PM-based training significantly improved lactate threshold power and 20 km time trial completion times. Both groups increased their power by 17 watts and reduced their time by nearly three and a half minutes. No significant differences were found between the two training methods in improving aerobic capacity (VO2 max), indicating that both HR monitors and PMs are equally effective for performance enhancement [34]. * Recovery: Wearable technologies can be used to track sleep quality and other factors that affect recovery. This information can be used to optimize recovery strategies, such as those involving sleep [35] and breathing [36], to ensure athletes are ready  
Figure 2: Keyword distribution across the review. to perform at their best. For example, athletes who used wearable devices to track their sleep quality were more likely to report feeling recovered after training [37]. Wearable devices for monitoring sleep and recovery offer several potential advantages for athletes, even though these benefits are not yet fully validated [38]. Nutrition: In addition to tracking calorie intake and expenditure, wearable technologies can automate certain aspects of diet logging, such as detecting moments of dietary intake and estimating meal composition with chemical sensors [39]. This information can be used to ensure that athletes are meeting their nutritional needs and to minimize errors. For instance, studies have shown that traditional self-report methods, such as 24 h recalls and food frequency questionnaires, can be up to 50% inaccurate compared to actual food intake [40]. For example, non-invasive wearable and mobile electrochemical sensors, capable of monitoring temporal chemical variations upon the intake of food, vitamins, and supplements, are excellent candidates for bridging the gap between digital and biochemical analyses for a successful personalized nutrition approach [41; 42; 43; 44; 45] Technique: Wearable technologies can be used to track movement patterns and identify areas for improvement [46]. This information can be used to improve technique and efficiency. For example, there is evidence supporting the use of wearables to improve running performance, track global training loads applied to the runner, and provide real-time feedback on running speed and run cadence [47]. In Australian football, GPS devices have allowed for detailed analysis of player workload and energy expenditure, providing insight previously unavailable through heart rate monitors alone. In American football, sensors integrated into helmets and mouthguards have detected over 95% of impacts, which is crucial for monitoring and preventing concussions. Studies on baseball have shown that wearable sensors can accurately measure elbow torque and shoulder movement, providing data essential for injury prevention. These devices enable real-time feedback and detailed biomechanical analysis, enhancing training and performance while reducing injury risks [45]. The general concept of wearable devices describes electronic devices that are equipped with built-in sensors that can receive information about the wearer or the environment around them. These devices operate wirelessly or by integration with other devices, such as smartphones and tablets.