## 1 Introduction  
Radar guns have emerged as invaluable tools in assessing throwing and ball-kicking movements across various sports and testing scenarios [1]. Leveraging the principles of Doppler radar technology, these devices accurately measure the velocity of an object in motion by analyzing the frequency shift of reflected radio waves [2]. In sports such as baseball, cricket, volleyball, or tennis, radar guns provide coaches and athletes with real-time feedback on the speed of pitches, throws, and serves, enabling precise performance evaluation and targeted training interventions [3]. Similarly, in soccer or rugby, radar guns offer insights into the power of kicks, aiding in the refinement of technique and the optimization of player performance [4]. Moreover, radar guns facilitate objective comparisons between athletes in different tests and serve as objective metrics for a battery of tests for talent identification or motor competence assessment [5]. Their non-invasive nature and portability make them versatile instruments suitable for use in training sessions, competitions, and scientific research, contributing to advancements in sports biomechanics and performance analysis [6]. Recent developments in sports performance monitoring are increasingly incorporating wearable sensors, video analysis systems, and other advanced tracking technologies [7]. Wearable sensors, for example, provide continuous and detailed data on metrics such as acceleration, impact, and heart rate, offering a greater view of an athlete's physiological responses and movement patterns during play [8]. Video-based systems, particularly those using markerless motion capture, allow for detailed kinematic analysis and can be combined with radar guns to create a fuller picture of athletic performance [9]. These innovations complement radar-based speed measurements and are increasingly used in both training and competition to refine performance and mitigate injury risks [7]. This convergence of technologies is revolutionizing sports monitoring, allowing coaches and researchers to tailor interventions based on a more comprehensive set of data. However, radar guns remain a practical and accessible tool for specific tasks, such as measuring throwing and kicking speeds, particularly when budget-friendly solutions are available. These tools are increasingly used in sports settings where resources may be limited, such as in youth coaching, community sports programs, and even in rehabilitation centers where objective performance data can inform programmed recovery plans [10]. For example, in real-world coaching, tools such as the Bushnell radar gun allow practitioners to monitor throwing or kicking speeds in various field environments, providing instantaneous data that can be used to refine techniques and prevent overuse injuries [11]. In rehabilitation contexts, low-cost monitoring tools can support patient progress tracking, enabling therapists to measure specific movement speeds or forces in exercises as patients advance through recovery stages, particularly for return-to-sport decisions [12]. Testing concurrent validity and agreement between instruments is paramount in scientific and practical contexts to ensure the interchangeability and quality of data collection [9]. Concurrent validity assessments involve comparing the results obtained from the instrument under study with those from a reference standard or established measure [13]. This process is essential for verifying that the new instrument measures what it intends to measure, validating its efficacy for the intended purpose [13]. Additionally, evaluating agreement between instruments ensures consistency and reliability in measurement outcomes [14]. By testing concurrent validity and agreement, researchers and practitioners can confidently select appropriate measurement tools, establish data comparability, and make informed decisions based on reliable and valid data.