Objective Reaction time is commonly impaired following concussion, but recent work indicates current clinical reaction time measures lack sport-related applicability. We aimed to determine the intra-rater, inter-rater, and test-retest reliability, standard error of measurement (SEM), and minimal detectable change (MDC) of a sport-emulating measure called the Standardized Assessment of Reaction Time (StART).

Design Prospective, repeated measures.

Setting Clinical laboratory.

Participants Healthy, physically active participants (n=20; age: 20.3±1.8 years; 60% female; 75% no concussion history).

Interventions (or Assessment of Risk Factors) StART at two testing sessions with seven days between.

Outcome Measures StART was assessed using a penlight and smartphone video recording at 240-frames-per-second. StART examined reaction time across three movement conditions (standing, single-leg balance, cutting) under two cognitive states (single-task, dual-task[subtracting by 6’s or 7’s]) for 5 trials each condition. Reaction time was the time (ms) between penlight illumination and first movement, and outcomes included single- and dual-task standing, single-leg balance, cutting, single-task aggregate, dual-task aggregate, and StART composite. We used intraclass correlation coefficient (ICC) models for reliability and standard formulae for SEM and MDC.

Main Results Inter-rater and intra-rater reliability for all outcomes was good to strong (inter-rater ICC_2,k range:0.83–0.99; intra-rater ICC_3,k range:0.91–0.99). Test-retest reliability ranged from moderate to strong across outcomes (ICC_3,k range: 0.69–0.89). The SEM values ranged from 8–31ms, and MDC values ranged from 21–85ms across all outcomes.

Conclusions StART demonstrated overall strong reliability with relatively small measurement error, making it a suitable assessment for examining functional, sport-like reaction time in clinical practice. StART diagnostic properties should be determined before clinical use.