Purpose: Vertical jump tests are used to assess lower-limb power of athletes in sport sciences. Flight time measurement with jump-mat systems is the most common procedure for this purpose. The aim of this study was to analyze the concurrent validity and reliability of two proprietary systems (Globus and Axon) and an open-source system (Chronojump).
Methods: A conditioning electric circuit governed by a controlled wave generator is designed to substitute athletes jumping on a physical mat. In order to look for possible differences associated to timekeeping by each microcontroller device, all three systems are fed by the circuit simultaneously.
Results: Concurrent validity was high for the three systems. Standarized typical error of estimate (TEE) was trivial, according to MBI interpretation as well as perfect Pearson correlation coefficient. Reliability was assessed based on the coefficient of variation of flight time measure, resulting in 0.17-0.63% (0.05-0.12 cm) for Globus, 0.01% (0.09 cm) for Chronojump and 5.65-9.38% (2.15-3.53 cm) for Axon. These results show that all jump-mat system produced nearly identical measures of flight time so they can be considered valid and reliable for practical purposes. In comparison, Chronojump showed the best performance whereas Axon showed enough variability and disagreement to pose a problem in testing elite athletes.
Conclusions: These experiments show that open-source jump mats are as valid and reliable as their proprietary counterparts at a lower cost. Therefore, practitioners can be confident in using Globus or Chronojump systems to test athletes' jump height because of their negligible errors and Axon system to monitor general population.