Comparison Between Hand and Electronic Timing of 40-yd Dash Performance in College Fo

Comparison Between Hand and Electronic Timing of 40-yd Dash Performance in College Football Players
Mayhew, Jerry L; Houser, Jeremy J; Briney, Ben B; Williams, Tyler B; Piper, Fontaine C; Brechue, William F
Published Ahead-of-Print
Mayhew, JL, Houser, JJ, Briney, BB, Williams, TB, Piper, FC, and Brechue, WF. Comparison between hand and electronic timing of 40-yd dash performance in college football players. J Strength Cond Res 24(2): 447-451, 2010-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 consist

0,31 s of difference, albeit statistically not significative…is a world of difference…

+/-.07 s could make it .38 s or .27 s, approximate sounds about right.

The difference was highly significant (p < 0.001).

We’ve known this all along, and it’s partially confirmed here. Now, since time starts with hand lifting, you can cheat the time and rock forward a little before lifting the hand (say 0.1), and a typically reaction time (0.15) gives a different of slightly under 0.6 seconds. So Bolt’s 4.35ish 40y in Berlin is more like 3.75 hand timed.

Sure, Was speaking in general, with some researchers using p 0.05.

??? P <0.001 is more significant than p 0.05.

Yes, but was pointing out that not all the researchers use the same coefficents in sport studies, and what seems not significant…in actual training could well become.
The research proved nothing new…except maybe for the NFL:)…and CJ!