Abstract
Objective. Lower-limb strength and power is commonly assessed indirectly by measuring jump performance. A novel portable system (gFlight) that can be used in applied settings provides measures of jump performance. The aim of this study was to validate jump performance measures provided by the gFlight to those provided by a force plate. Approach. Thirty-six participants performed three countermovement jump (CMJ) and drop jump (DJ) trials. Jump height (JH), contact time, and reactive strength index (RSI) were simultaneously recorded by a force plate and gFlight sensors to assess concurrent validity. Main results. The gFlight provided significantly higher measures of JH during the CMJ (mean: +8.79 ± 4.16 cm, 95% CI: +7.68 to 9.90 cm, P < 0.001) and DJ (mean: +4.68 ± 3.57 cm, 95% CI: +3.73 to 5.63 cm, P < 0.001) compared to the force plate. The gFlight sensors displayed significantly higher measures of RSI (mean: +0.48 ± 0.39 m·s−1, 95% CI: +0.37 to 0.58 m·s−1, P < 0.001) and lower measures of contact time (mean: −0.036 ± 0.028 s, 95% CI: −0.044 to −0.029 s, P < 0.001) during the DJ compared to the force plate. The bias displayed by the gFlight for JH, contact time and RSI measures are reduced using corrective equations. Significance. The gFlight sensors are a cost-effective, portable measurement system with high concurrent and ecological validity for the objective measurement of jump performance in applied settings. Corrective equations should be used to reduce measurement biases so comparisons can be made to force plate measurements of jump performance.
Highlights
Introduction cri ptLower-limb power is commonly assessed indirectly by measuring jump height (JH) performance during vertical jumping tasks such as the countermovement jump (CMJ) and drop jump (DJ) [1,2,3]
The aim of this study is to provide a novel evaluation of the concurrent validity of the gFlight compared to the ‘gold standard’ force plate to measure JH, CT, and reactive strength index (RSI) during a countermovement jump and drop jump
The gFlight displayed a significant systematic bias with higher measures of JH provided in comparison to the force plate during the CMJ (Mean: +8.79 ± 4.16 cm, 95% CI: +7.68 to 9.90 cm, d: 1.25, P
Summary
Introduction cri ptLower-limb power is commonly assessed indirectly by measuring jump height (JH) performance during vertical jumping tasks such as the countermovement jump (CMJ) and drop jump (DJ) [1,2,3]. In order to make traditional lab-based performance tests more accessible, advances in technology have provided applied practitioners and athletes with access to field-based measures of JH that can be used in their own environments These include contact mats (Just Jump system), velocity systems (GymAware), linear position transducers (MyoTest, Vertec), optical photoelectric cells (OptoJump), and mobile phone applications (MyJump), [6,9,11,12]. These field-based alternatives, all use different software and calculations to provide JH measurements meaning results can vary depending on the system used. With portable and wearable technologies increasing in popularity, more research is pte being published to evaluate the reliability and validity of these measurement systems [13,14]
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