Comparison between hand and electronic timing of 40-yd dash performance in college football players.

The purpose of this study was to determine the difference between hand and electronic timing of 40-yd dashes in college football players. National Collegiate Athletic Association Division II players (n = 59) were measured during a 40-yd sprint by electronic timing and simultaneously by 7 experienced hand timers using digital stopwatches. Electronic times were initiated by lifting the hand from a switch mat and stopped by the torso passing through an infrared beam. Hand timers initiated timing on first movement of the player from a 3-point stance. To establish performance and timing reliabilities, 32 players completed a second trial. Interrater reliability for hand timing was intraclass correlation coefficient (ICC) = 0.987 (p < 0.001). Five of the 7 timers did not differ significantly (p > 0.05) in their timing. The maximum difference among the hand timers on any given trial was 0.19 +/- 0.14 seconds, with a 95% confidence interval (CI) of -0.08 to 0.41 seconds. Hand timing (4.85 +/- 0.28 seconds) was significantly faster (p < 0.001) than electronic timing (5.16 +/- 0.28 seconds), producing an average difference of 0.31 +/- 0.07 seconds (6.0 +/- 1.3%) and a 95% CI on the average difference of -0.44 to -0.18 seconds. The correlation between electronic timing and hand timing was ICC = 0.985 (p < 0.001). Practically speaking, electronic timing produces the best measurement of 40-yd dash speed, and using the hand timing produces consistently but significantly faster times.