The validity and reliability of a novel mobile app to measure agility performance in the physically active youth population


  • Juan A. Escobar Álvarez Faculty of Higher Education, South Essex College University Centre, Southend on the Sea, UK
  • Rocío Carrasco-Zahínos Facultad de Educación, Universidad de Extremadura, 06006 Badajoz, Spain
  • Pedro R. Olivares Facultad de Educación, Psicología y Ciencias del Deporte, Universidad de Huelva, Spain, Instituto de Actividad Física y Salud, Universidad Autónoma de Chile, Chile
  • Sebastián Feu Facultad de Educación, Universidad de Extremadura, 06006 Badajoz, Spain
  • Robinson Ramírez-Velez Navarrabiomed-Universidad Pública de Navarra (UPNA), Complejo Hospitalario de Navarra (CHN), Instituto de Investigación Sanitaria de Navarra (IdiSNA), Pamplona, Navarra, Spain; CIBER of Frailty and Healthy Aging (CIBERFES), Instituto de Salud Carlos III, Pamplona, Navarra, Spain
  • Miguel Ángel Pérez Sousa Universidad de Extremadura



app, agility, validity, reliability


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.


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