RT Journal Article T1 The validity and reliability of a novel mobile app to measure agility performance in the physically active youth population A1 Escobar Álvarez, Juan Antonio A1 Carrasco Zahinos, Rocío A1 Olivares Sánchez-Toledo, Pedro Rufino A1 Feu Molina, Sebastián A1 Ramírez Vélez, Robinson A1 Pérez Sousa, Miguel Ángel AB Agility is a key component of physical fitness in adolescents. However, the measurement of this variable is usually complex, requiring high cost instruments and complex software. To test the validity and reliability of a novel iPhone app (Lap Tracker Auto-timer) to measure agility performance among adolescents. Twenty-four physically active adolescents (15.7 ± 2.3 years old) participated in two testing sessions (separated by 7 days). They performed three 4 x 10 m agility test trials measured by Photocell or the iPhone app. The correlation analysis revealed high validity (r = .92; 95% confidence interval [CI] = .88 – .95), with a standard error of the estimate of 0.56 s (p < 0.001). The coefficient of variation (CV; 0.09) and intraclass correlation coefficient (ICC; .93; 95% CI = .85 – .97) showed an acceptable reliability. This study demonstrated that the iPhone App Lap Tracker Auto-timer could be a valid, reliable and low-cost tool to evaluate agility performance in adolescents. However, more studies are required to guarantee the utility of this app. PB Asociación Española de Ciencias del Deporte SN 0214-0071 SN 2172-2862 (electrónico) YR 2020 FD 2020-12 LK https://hdl.handle.net/10272/25113 UL https://hdl.handle.net/10272/25113 LA eng NO Escobar-Alvarez, J. A., Carrasco, R., Olivares, P. R., Feu, S., Ramírez-Velez, R., & Pérez-Sousa, M. A. (2020). The validity and reliability of a novel mobile app to measure agility performance in the physically active youth population. In European Journal of Human Movement (Vol. 45, pp. 85–92). Universidad Miguel Hernández de Elche. https://doi.org/10.21134/eurjhm.2020.45.9 DS Repositorio Institucional de la Universidad de Huelva RD 1 jun 2026