Validity of Single-Beam Timing Lights at Different Heights

Abstract

Altmann, S, Spielmann, M, Engel, FA, Neumann, R, Ringhof, S, Oriwol, D, and Haertel, S. Validity of single-beam timing lights at different heights. J Strength Cond Res 31(7): 1994-1999, 2017-The purpose of this study was to quantify the effect of different timing light heights on sprint time and the validity of measurement. Two single-beam timing gate systems were used to measure 30-m sprint time (splits at 5 and 10 m) in 15 healthy and physically active male subjects. System 1 was set up at a height of 0.64 m and system 2 at 0.25 m (initial timing light) and 1.00 m (each following timing light), respectively. Participants performed 3 valid trials. The recordings of a high-speed video camera were used as a reference. Sprint times of system 1 and system 2 differed significantly between each other and from the reference system at all distances (p < 0.001). Intraclass correlation coefficients and Pearson's r values between both timing light systems and the reference system were low to moderate at 5 and 10 m and moderate to high at 30 m. Bland and Altman analysis revealed that the agreement intervals were considerably higher for the comparison between system 1 and the reference system than for system 2 and the reference system. A valid measurement of splits at 5 and 10 m via the systems used in this study is questionable, whereas 30-m times have an acceptable validity, especially when using system 2. This study confirms the influence of methodological approaches on sprint times. Coaches and researchers should consider that results gained by single-beam timing lights at different heights are not comparable.

Accuracy of single beam timing lights for determining velocities in a flying 20-m sprint: Does timing light height matter?

“…Compared to previous findings (Altmann, 2017;Cronin & Templeton, 2008), the similarity of both heights is a novelty and seems to be counterintuitive at first sight. The similarity of TL64 and TL100 is likely due to the fact that the running velocities in this study were not dependent from a timing light's accuracy at the start of the acceleration phase, which is associated with the largest measurement error and notable differences between different heights (Altmann, 2017).…”

“…The time intervals between the timing gates positioned at 10 m and 30 m were automatically generated via the timing light software. By determining the measurement accuracy of the timing lights through the video sequences, the times of the reference system (high-speed cameras) were calculated (Altmann, 2017). Subsequently the times captured by all systems were transformed into velocities (m/s).…”

“…For the purpose of this study, selected raw data of a previous published study (Altmann, 2017) were used. While the latter study focused on split (5 m and 10 m) and total times during 30-m sprints, the present research addressed the velocities reached in the last sprinting interval (10-30 m, representing a flying 20-m sprint), which have not been investigated to date.…”

“…A detailed description of the methods can be found in Altmann (2017). As only selected parameters of the mentioned study were used, merely the acquisition of the data analyzed for the present study is described in the following.…”

“…The validity of single beam timing lights to capture split and total times has been well investigated. Consistently, several researches question the accuracy at short distances (e. g., 5 m, 10 m, 20 m), whereas longer distances (e. g., 30 m, 40 m) can be measured with sufficient precision (Altmann, 2015;Altmann, 2017;Haugen, Tønnessen, Svendsen, & Seiler, 2014). However, little is known about single beam systems' validity in capturing interval sprinting times and corresponding velocities, and these studies used differing approaches (Roe et al, 2017) and objectives (Bond, Willaert, & Noonan, 2017;Haugen et al, 2014).…”