# A Systematic Review of Insole Sensor Technology: Recent Studies and Future Directions
## 1 Introduction  
The use of sensor technology in wearable devices, specifically in the field of footwear, has attracted considerable interest in both the improvement of performance and the rehabilitation of individuals [1; 2; 3]. Insoles integrated with sensors serve as a vital convergence of biomechanics, data science, and sports science, providing a distinctive platform for real-time monitoring of biomechanical factors and physiological responses. These devices are crucial for athletes seeking to enhance performance and avoid injuries [4], as well as those in rehabilitation, as they offer valuable information that informs therapeutic actions [5].  
Accurate numerical information about the movement and forces involved in foot mechanics is crucial in multiple areas of scientific investigation. Therefore, assessing plantar forces is an essential technique for examining human body movement [6]. In general, the trade-off between the flexibility of wearable devices and the precision of fixed systems must be considered. Force plates are widely recognized as the most reliable way for precisely identifying gait events. Nevertheless, force plates are mostly utilized in controlled laboratory environments, and the limited availability of these plates restricts the numberof steps that may be accurately measured. On the other hand, sensor insoles provide a convenient method for gathering data in both controlled and real-world settings, with few limitations on their use. They offer exceptional efficiency, adaptability, and portability [6].  
Advancements in technology have resulted in a rise in sensor technologies that may be integrated into insoles, with each sensor providing distinct data types and valuable information. These include pressure sensors that measure weight distribution and gait patterns, as well as accelerometers and gyroscopes that detect movement dynamics and orientation. The wide range of sensor technologies accessible offers a vast array of possibilities for investigation, but it also creates difficulty in identifying which sensors provide the most dependable and valuable data for specific applications. Exploring alternative combinations and types of sensors is necessary due to the crucial considerations of the number, location, and applicability of sensors in the insole.  
This systematic review seeks to synthesize and gather existing information on this issue, offering a complete study of the many types of sensors used in insoles to improve sports performance and aid in rehabilitation. Hence, this research aims to methodically identify and assess the many types of sensors presently utilized in insoles, evaluating their applications, efficacy, and the data quality they offer. The primary inquiry is as follows: \"What types of sensors are employed in insoles to enhance performance and facilitate rehabilitation?\" This inquiry seeks to clarify the predominant sensor technologies, emphasizing their advantages and limitations in these two important situations. This comprehensive analysis aims to provide organized and informed perspectives that aid in choosing the most suitable sensor technology for specific requirements.