## 1 Introduction  
Wearable measuring devices have the ability to gather objective, real-time data on a range of physiological and biomechanical characteristics, offering insightful information on a person's general health, fitness, and well-being. They can also wirelessly sync with other devices and programs to deliver information in the form of text notifications and data visualization, which users can then use for their self-assessment [1]. Oftentimes, they are utilized as tools for monitoring and evaluating exercise regimens and athletic training. Wearable technology has remained the top trend in fitness since it was first identified in the poll in 2016, except for 2018 and 2021 when it fell to third and second place, respectively [2] which shows their popularity and increased use in recreational use. Several reviews were conducted in the last five years focusing on the effectiveness of wearable devices, especially smart watches and their use in medicine or health monitoring. [PERSON] and [PERSON] [3] in their review showed that the use of smartwatches has several limitations and their widespread adoption in health care has barriers. Another systematic review on smartwatches focused on their interaction using gesture recognition presenting several methods and applications that use the continuous recognition of gestures [4]. Furthermore, authors found positive outcomes in predicting the disease with the use of smartwatch and advocate for their continuous use in health care [5]. The potential of smartwatches in monitoring various health parameters and detecting diseases and the evolution of smartwatches in the biomedical sector was confirmed in another recent review [6]. The COVID-19 pandemic brought extensive research on activities and sedentary behavior, which was largely conducted using monitoring devices, that are acceptable in the socially distant world. [PERSON] and [PERSON] [7] authored a scoping review regarding the impact of wearables on physical health during the pandemic and concluded that wearables are a growing tool in improving physical activity and reducing sedentary behavior. Wearable devices have emerged as invaluable tools in the battle against the COVID-19 pandemic by promoting and enhancing individual health. These smart gadgets, ranging from fitness trackers to smartwatches, have played a pivotal role in monitoring vital health metrics, including heart rate, sleep patterns, and physical activity, thereby enabling individuals to proactively manage their well-being during these challenging times. Furthermore, the real-time data and alerts provided by these wearables have helped individuals detect potential symptoms early, facilitating timely medical intervention and reducing the risk of disease transmission. By fostering a sense of self-awareness and accountability in maintaining a healthy lifestyle, wearable devices have proven to be indispensable companions in the quest for optimal health amidst the ongoing global health crisis [8]. In this paper, we will cover recent developments on the subject of wearable technologies in sport in order to provide a summary of the current state of knowledge on this subject and to help to obtain a better understanding of it. Considering that \"wearable technologies\" are becoming an increasingly common way to monitor short-term and long-term training effects, the authors believe that the need for such papers is significant. The need for this type of research becomes particularly important during the pandemic, when a large number of recreational and elite athletes were forced to train individually, leading to a lack of coach assessment of training effects. This method of training monitoring enables coaches to obtain credible effects of the programmed training plan, which they have conveyed to their athletes in various ways. Overall, there has not been an open access, indexed systematic review in the Web of Science or Scopus about the use of these devices in sport or physical activity in recent years.