Validity, Reliability, and Sensitivity of Mobile Applications to Assess Change of Direction Speed

Abstract

This study aimed to assess the validity, reliability, and sensitivity of mobile applications for assessing change-of-direction speed (CODS) performance. Thirty college athletes performed two Illinois CODS tests during one session. Assessments were carried out simultaneously using six devices (the CODTimer app, Seconds Count app, StopwatchCamera app, two analog stopwatches, and timing gates). Validity analyses included Pearson's product-moment correlation analysis, a linear regression model, and Bland-Altman plots. Reliability analyses included the intraclass correlation coefficient (ICC), the coefficient of variation (CV%), and the paired-sample t test. Sensitivity analyses included the typical error and smallest worthwhile change (SWC). The results showed that validity, reliability, and sensitivity values were higher for the CODTimer app (r = 0.99, R2 = 0.99, mean bias = −0.03 ± 0.10, CV% = 3.21, ICC = 0.89, SWC rating: good, p = 0.84) and the Seconds Count app (r = 0.99, R2 = 0.99, mean bias = −0.03 ± 0.08, CV% = 3.28, ICC = 0.88, SWC rating: good, p = 0.84) relative to the StopwatchCamera app (r = 0.98, R2 = 0.97, mean bias = −0.11 ± 0.22, CV% = 3.43, ICC = 0.86, SWC rating: marginal, p = 0.10), Analog Stopwatch 1 (r = 0.98, R2 = 0.96, mean bias = −0.09 ± 0.42, CV% = 2.95, ICC = 0.90, SWC rating: good, p = 0.91), and Analog Stopwatch 2 (r = 0.99, R2 = 0.97, mean bias = −0.12 ± 0.88, CV% = 3.51, ICC = 0.87, SWC rating: marginal, p = 0.96). In conclusion, compared to timing gates, the CODTimer app and Seconds Count app provided lower measurement bias and higher sensitivity for assessing CODS performance.

Evaluating Visual Dependence in Postural Stability Using Smartphone and Stroboscopic Glasses

“…Future research quantifying postural control may utilize the assessment protocol using stroboscopic glasses to identify existing or persistent dysfunction as one readiness measure used by healthcare practitioners in the return-to-sports decision. Increased visual dependence to maintain balance is common in musculoskeletal injuries, primarily in those with chronic ankle sprains [6,7] and those who have experienced a concussive event [8,9]. Creating conditions using smartphone apps and stroboscopic glasses during a protocol that involves static and dynamic tasks, in conjunction with Romberg Ratios from these conditions, may assist in the evaluation of the visual system's role in maintaining postural stability.…”

“…These conditions necessitate greater contributions from the vestibular and proprioceptive systems to maintain balance, especially on unstable surfaces like foam, which distorts proprioceptive feedback and increases the difficulty of maintaining postural control [5]. This is particularly evident in athletes who have suffered from musculoskeletal injuries, such as chronic ankle instability [6,7], or neurological impairments, like concussions [8,9], where an increased reliance on visual input for balance has been documented. In contrast, conditions such as visual perturbations-achieved through methods like stroboscopic training-alter normal visual processing and have been shown to potentially augment these capabilities by training athletes to rely less on consistent visual feedback and more on other sensory inputs [10].…”

Concurrent-Validity and Reliability of Photocells in Sport: A Systematic Review

“…As determinants of sports performance, sprinting, COD ability and jump height are part of periodically applied fitness assessment batteries ( Soler-López et al, 2022 ; Willberg et al, 2023 ). While instantaneous speed is regularly assessed using a radar gun or video-based analysis ( Bataller-Cervero et al, 2019 ; Romero-Franco et al, 2017 ; Uysal et al, 2023 ), sprinting time, COD time and jump height are usually measured using photocells.…”