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The objective of this study was to evaluate the reliability and validity of two alternative systems used for jumping performance measurement. Methods: Two groups of subjects were tested. The first group consisted of 15 male adults (21.3 ± 1.7 years ) and the second group consisted of 16 female volleyball players (17.2 ± 0.9 years). We used three different systems of data collection in the study. Two of the used systems are based on optoelectric components. The Optojump Next system is referred to as the optoelectric system, and BTS Smart-E is refered to as the video system. Concurrent validity of these systems was verified with the use of “gold standard” which is force platform. All systems were used to estimate the height of vertical jumps. Results: Both optoelectric systems occurred to be highly reliable with the ICCs=0.98 for Optojump and 0.9 for BTS Smart. Their concurrent validity with the force platform data was also very high r=0.99 and r=0.97 respectively. Conclusions: Comparison of these two systems shows distinct differences between them where Optojump system is more suitable for quick and reliable sports testing, when BTS-Smart for research and clinical testing.
Content available remote Effect of increased load on vertical jump mechanical characteristics in acrobats
In this study, we attempt to answer the following question: To what degree the higher muscular activity determined by increased load in the extension phase (eccentric muscle action) of vertical jump affects its efficiency? Ten high performance acrobats participated in this investigation. The acrobats performed tests that consisted of five single “maximal” standing vertical jumps (counter movement jump – CMJ) and five single vertical jumps, in which the task was to touch a bar placed over the jumping acrobats (special counter movement jump – SCMJ). Subsequently, they performed five single drop jumps from an elevation of 0.40 m (DJ). Ground reaction forces were registered using the KISTLER 9182C force platform. MVJ software was used for signal processing [1] and enabling calculations of kinematic and kinetic parameters of the subject’s jumping movements (on-line system). The results obtained show that the height of jump (h), the mean power (Pmean) and the maximum power (Pmax) are statistically significant, and higher in DJ. The results prove fine adaptation of the nervous system in acrobats to muscle extension and workload, due to the 40 cm high drop jump. Presumably, this height is closest to that which acrobats experience during landing, after performing flic-flacs or round-off.
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