Content validity and reliability of reaction speed measures for football goalkeepers

Reaction speed assessment plays a crucial role in the success of football goalkeepers, as it involves athletes’ cognitive performance. However, existing measurement tools often rely on predetermined stimuli and manual time recording using a stopwatch, making the assessments highly predictable and less reliable. This study aimed to validate the content and reliability of a reaction speed measurement tool specifically designed for football goalkeepers. Seven subject matter experts and twenty elite goalkeepers under the age of twenty participated in the study. Based on the results, content validity and the item-level content validity index (i-cvi) were calculated, yielding an average value of 0.834. The reliability coefficient, measured using the intraclass correlation coefficient (icc), was 0.994 with p < 0.01 and a 95% confidence interval (95% ci). These findings indicate that the reaction speed measurement tool is both valid and reliable. Furthermore, it has practical applications in talent identification, training outcome monitoring, injury risk assessment, rehabilitation tracking, fatigue evaluation, neurological screening, and cognitive function assessment—especially for football goalkeepers.