Enhanced Reaction Time Measurement System Based on 3D Accelerometer in Athletics

Abstract

first_pageDownload PDFsettingsOrder Article Reprints Open AccessArticle Enhanced Reaction Time Measurement System Based on 3D Accelerometer in Athletics by Antonio Pousibet-Garrido 1ORCID,Juan A. Moreno-Pérez 1ORCID,Pablo Escobedo 1ORCID,Israel Caraballo 2ORCID,José V. Gutiérrez-Manzanedo 2ORCID,José L. González-Montesinos 2ORCID andMiguel A. Carvajal 1,*ORCID 1 PRIMELab, ECsens, Sport and Health University Research Institute (iMUDS), Department of Electronics and Computer Technology, Research Centre for Information and Communications Technologies (CITIC), University of Granada, 18071 Granada, Spain 2 Department of Physical Education, Faculty of Education Sciences, University of Cádiz, 11519 Cádiz, Spain * Author to whom correspondence should be addressed. Sensors 2025, 25(21), 6730; https://doi.org/10.3390/s25216730 Submission received: 24 September 2025 / Revised: 27 October 2025 / Accepted: 30 October 2025 / Published: 3 November 2025 (This article belongs to the Special Issue Feature Papers in Physical Sensors 2025) Downloadkeyboard_arrow_down Browse Figures Versions Notes Highlights What are the main findings? A portable system for measuring reaction time at athletic starts was designed and developed using an Inertial Measurement Unit (IMU). Validation tests demonstrated good agreement with the high-speed camera, used as the gold-standard reference system. What is the implication of the main finding? The proposed portable, low-cost system provides reliable reaction time measurements in athletics, offering valuable support for athletes and coaches. Abstract Reaction time (RT) is a key measure of neuromuscular and cognitive performance, but most existing methods rely on laboratory equipment or focus on localized actions such as finger taps or foot lifts, limiting their relevance for whole-body movements. In this work, we present a portable inertial measurement unit (IMU)-based system specifically designed to measure RT during sprint starts. The device integrates a triaxial accelerometer (ICM-20948, ±16 g) and an ESP32 microcontroller, which generates an auditory stimulus, acquires acceleration data at 1 kHz, and computes movement onset in real time. A fixed acceleration threshold, determined from calibration against a high-speed camera reference, was used to detect the first voluntary movement. Both desktop and smartphone applications were implemented to control the system, provide feedback, and store test data. Validation experiments showed good agreement with the high-speed camera used as a reference (R2 = 0.9391), with a mean bias of –1.35 ms and 95% limits of agreement within ±25 ms. The proposed system combines high temporal resolution, portability, and straightforward deployment, enabling reliable assessment of whole-body RT in realistic sports and research environments.