# Review on Wearable Technology in Sports: Concepts, Challenges and Opportunities
## 2 Bibliographic Analysis of WT in Sports  
In the bibliographic study, a search was conducted on the Web of Science (WoS) using the keywords \"wearable\" or \"wearables\" and \"sport\" or \"sports.\" The search query was refined to include articles published between 2015 and 2023, in English, and indexed in either the Social Sciences Citation Index (SSCI) or the Science Citation Index Expanded (SCI-E), with the article type limited to papers. As a result, 2568 papers were found. Query criteria are limited, and only certain keywords and publication dates are used. Therefore, some relevant studies may have been overlooked during the screening process. The journals in which studies on sports and wearables are published are presented in Figure 1. Accordingly, the magazine with the most publications is Sensors with 287 publications. The number of publications per year is presented in Figure 2, showing an increasing trend over the years. Since this paper was submitted before the completion of 2023, the 165 articles from that year are excluded from the graph. In the context of academic inquiry utilizing the Web of Science (WoS) database, an examination of research areas pertaining to wearables and sports reveals key insights, as illustrated in Figure 3. This figure presents a ranked list of the top twenty research fields along with their corresponding article counts, arranged in descending order. According to Figure 3, the foremost four research areas, in terms of publication frequency, encompass engineering (34.93%), chemistry (21.46%), instrumentation (16.75%), and sport science (16.75%). The realm of research concerning WT predominantly operates within a framework comprising three fundamental dimensions: conceptual design, usage experimentation, and performance analysis. Within the domain of conceptual design, investigations are centered on factors such as sensor utilization, sensor placement, and overarching design considerations. These inquiries are primarily conducted within the domain of engineering studies. In contrast, endeavors related to usage experimentation involve the systematic evaluation of fully developed conceptual designs within meticulously selected and well-defined user cohorts. This category of research assumes an interdisciplinary character,  
Figure 1: Number of Article by Journals. Figure 2: Number of Articles by Year. drawing expertise from diverse domains, including physical education, engineering, and health sciences. Performance studies, conversely, are primarily characterized by investigations carried out using wearables that have attained a level of commercial maturity. In the context of these inquiries, the central focus is directed toward the assessment of athlete performance, with coaching emerging as a prominent field where experts in physical education make substantial contributions. Within the purview of these studies, the engineering component primarily finds application in specialized domains, notably computer science and data analysis. When classifying the countries publishing articles on wearables and sports, the ranking shown in Figure 4 was obtained. The top four countries are Japan (23.48%), the People's Republic of China (20.00%), the United States (17.25%), and Australia (9.07%). When the keywords \"wearable\" and \"sports\" are excluded from the obtained articles' keywords, and a network is created using the VOSviewer program, the resulting graph is shown in Figure 5. According to this graph, the main keywords are the Inertial Measurement Unit (IMU) and its sub-component accelerometer. Machine learning and physical activity keywords follow. The area highlighted in red primarily focuses on athlete performance. The green cluster is primarily related to athlete health and nutrition. The blue region represents the concentration of machine learning-based studies on wearables and athletes. The yellow color encompasses studies in advanced topics such as electronic, flexible wearables, and robotics. Figure 3: Number of Articles by Research Areas. Figure 4: Number of Articles by Country.