Validity and Reliability of a Phone App and Stopwatch for the Measurement of 505 Change of Direction Performance: A Test-Retest Study Design.

Zhili Chen,Kaifang Liao,Chris Bishop,Chao Bian,Yongming Li

doi:10.3389/fphys.2021.743800

Zhili Chen, Kaifang Liao + Show 3 more

Open Access

https://doi.org/10.3389/fphys.2021.743800

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Abstract

Purpose: The aim of this study was to explore the validity and reliability of a phone app [named: change of direction (COD) timer] and stopwatches for the measurement of COD performance.Methods: Sixty-two youth basketball players (age: 15.9±1.4yrs., height: 178.8±11.0cm, and body mass: 70.0±14.1kg) performed six trials of 505 COD test (with the left side being the plant leg first, then the right side). The completion time was measured simultaneously via timing gates (with error correction processing algorithms), the phone app, and stopwatches.Results: There was an almost perfect correlation and agreement between timing gates and COD timer (r=0.978; SEE=0.035s; and LoA=−0.08~0.06s), but a lower correlation and agreement between timing gates and stopwatch (r=0.954; SEE=0.050s; and LoA=−0.17~0.04s) with statistical significance in completion time (ES=1.29, 95%CI: 1.15–1.43, p<0.01). The coefficient of variation revealed similar level of dispersion between the three timing devices (timing gates: 6.58%; COD timer: 6.32%; and stopwatch: 6.71%). Inter-observer reliability (ICC=0.991) and test-retest reliability (ICC=0.998) were excellent in COD timer, while the inter-observer reliability was lower (ICC=0.890) in the stopwatches.Conclusion: In the 505 COD test, the COD timer was able to provide a valid and reliable measurement. On the contrary, stopwatch was not recommended because of large error. Thus, if timing gates are unavailable, practitioners can adopt the COD timer app to assess 505 COD speed times.

Highlights

Change of direction (COD)encompasses the skills and abilities needed to change movement direction, velocity, or modes (Nimphius et al, 2017), which plays a pivotal role in matchwinning situations of team sports (Taylor et al, 2017; Wen et al, 2018; Loturco et al, 2019; Stojanović et al, 2019)
Significant but trivial difference was observed between the COD timer and timing gates (Mean difference = 0.007 s; d = 0.19, 95% CI = 0.09–0.29; p < 0.001)
The mean bias and 95% limits of agreement (−0.01 s, 95% CI = −0.08 s-0.06 s) between the COD timer and timing gates revealed a trivial difference

Summary

Introduction

Change of direction (COD)encompasses the skills and abilities needed to change movement direction, velocity, or modes (Nimphius et al, 2017), which plays a pivotal role in matchwinning situations of team sports (Taylor et al, 2017; Wen et al, 2018; Loturco et al, 2019; Stojanović et al, 2019). The 505 COD test is one of the developed protocols to measure COD performance and involves a high-intensity cut which is often performed in competitions, is widely applicable to many team or racquet sports (Gabbett et al, 2008; Stewart et al, 2014; Nimphius et al, 2016). By measuring the completion time of left and right sides (as defined by the plant limb), the 505 COD test can be used to assess the imbalance between limbs (Wen et al, 2018). Previous studies have indicated that manual timing has large absolute errors during linear sprinting tasks (Brechue et al, 2008; Haugen et al, 2016), no study has explored the validity and reliability of stopwatch in COD tests

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