Reliability of Three Timing Systems Used to Time Short On Ice Skating Sprints in Ice Hockey Players.Bond, Colin W. MS; Willaert, Emily M. MS; Rudningen, Kyle E. MD, DPT; Noonan, Benjamin C. MD, MSJournal of Strength & Conditioning Research: Post Acceptance: August 26, 2017 doi: 10.1519/JSC.0000000000002218 Original Research: PDF Only Abstract Speed and acceleration are highly valued in ice hockey and frequently assessed using timing systems. Coaches must use reliable timing systems to assess these attributes, but many systems have not been thoroughly evaluated and the required number of sprint repetitions to obtain the coach's desired degree of reliability for a system may be impractical. This study aimed to compare the reliability of a single photocell (PC), a single laser with a microprocessor (LA), and a digital video camera (VC); and in doing so, evaluate the influence of completing additional sprint repetitions on each systems' reliability. We hypothesized that PC and LA would yield different times, have inferior reliability, and require a larger number of sprint repetitions to obtain the same degree of reliability compared to VC. Seventeen male ice hockey players completed five repetitions of a 9.15-m on ice skating sprint timed simultaneously by PC, LA, and VC. The times obtained from VC were narrowly distributed around the mean compared to PC and LA, and resulted in a mean sprint time approximately 0.05- and 0.07-s faster than PC and LA, respectively (PC: 1.74-s (95% CI [1.72-1.76]); LA: 1.76-s [1.74-1.78]; VC: 1.69-s [1.67-1.70]). When two sprint repetitions were completed, PC and LA typical error (TE) and smallest worthwhile difference (SWD) were 2.8- and 4.3-fold greater than VC, respectively. As more repetitions were completed TE and SWD for PC and LA improved but remained approximately 2-fold greater than VC even when five repetitions were completed. With a smaller TE and SWD, VC was able to detect smaller "real" changes in a player's sprint performance over time compared to PC and LA. Copyright (C) 2017 by the National Strength & Conditioning Association.