Abstract
Purpose: The purpose of this study was to develop an algorithm for the detection and timing of foot contact/off timing for each lateral repetition and assess the validity/reliability of the calculated timings.Methods: Participants performed a modified Edgren Side Step Test in which they moved laterally along a 4-m path as quickly as possible while wearing an accelerometer on each ankle. Time of completion of each attempt was recorded using a stopwatch and digital video was obtained. Accelerometer-based (ACC) events were determined for the start of the test (START), foot contact at the end-line (FC) and the lifting of the foot when transitioning to the other direction (FO). Based on these ACC events the Overall, Split (ST) and Lag (LT) times were determined and compared to either the stopwatch or video-based timings (p < 0.05). The ACC event criterion was then applied by independent reviewers to assess inter/intra-rater reliability of identifying the events.Results: There was no significant difference in ACC (12.37 ± 2.19 s) based Overall Time compared to the Stopwatch (12.42 ± 2.25 s, p = 0.34). Bland-Altman plots for ST and LT revealed very good agreement between the ACC time to the Video (ST: Bias = 0.11 s, LOA −0.57 to 0.79; LT: Bias = −0.11 s, LOA −0.43 to 0.22). Intra and inter-rater reliability was moderate to excellent for all reviewer identified events.Conclusions: This study demonstrates methodology to identify ACC based timings during an agility test. The inclusion of an accelerometer supplements standard timing options with the added benefit of assessing sided split and lag times.
Highlights
Studies have been conducted demonstrating the accuracy and reliability of collecting overall performance time in various functional agility tests (Lundquist, 2007; Hetzler et al, 2008; Mayhew et al, 2010)
The Overall, Split (ST) and Lag (LT) times for the 11 attempts of the test used to develop the event criterion were compared across methodologies
The results of the repeated measures ANOVA on the Overall times showed that there was a significant difference across methodologies (p < 0.01)
Summary
Studies have been conducted demonstrating the accuracy and reliability of collecting overall performance time (including split times) in various functional agility tests (Lundquist, 2007; Hetzler et al, 2008; Mayhew et al, 2010). Zaferiou et al (2017) demonstrated the utility of placing sensors on both feet during an agility drill to objectively quantify foot contacts with the ground and further identify strategies associated with higher performance Signal analysis of these high performers revealed that they performed the test using strategies involving sharper turns and larger changes in body speed (Zaferiou et al, 2017). The utility of this methodological approach to quantify mechanical movement patterns during a fitness test has been demonstrated in children (Barnes et al, 2017). High performing children demonstrated unique movement patterns which included linearly increasing speed (Barnes et al, 2017)
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