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Tomasz Skowronek, Grzegorz Juras, and Kajetan J. Słomka

Purpose: To estimate the influence of global anaerobic fatigue on rhythm performance. Methods: Fifteen young males participated in the experiment. Anaerobic fatigue was induced with 2 consecutive running-based anaerobic sprint tests (RAST). The level of lactate was controlled before the first RAST and 3 minutes after each RAST. The rhythm performance was assessed by using Optojump Next (Microgate, Bolzano, Italy). The rhythm test was conducted 3 times, before fatigue and immediately after each RAST. Eight variables of the rhythm test were analyzed: the mean frequency of jumps for the assisted and unassisted phase (XfAP and XfUAP), SD of jump frequency for the assisted and unassisted phase (SDfAP and SDfUAP), and mean absolute error for the assisted and unassisted phases of the test (XERAP and XERUAP, respectively). Results: One-way repeated-measures analysis of variance showed a significant main effect of anaerobic effort on rhythm variables only in the unassisted phase of the test. Statistically significant differences were observed in XfUAP between the first and third rhythm measurements (F 2,28 = 4.98, P < .014, ηp2=26.23%), SD of jump frequency for the unassisted phase (SDfUAP; F 2,28 = 3.48, P = .05, ηp2=19.9%), and mean absolute error for the unassisted phase (XERUAP; F 2,28 = 3.36, P = .006, ηp2=19.43%). Conclusions: The results show that rhythm of movement may be negatively influenced after intensive anaerobic fatigue. The exact mechanism of this phenomenon is not precisely defined, but both central and peripheral fatigue are suspected to be involved.

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Kajetan J. Słomka, Slobodan Jaric, Grzegorz Sobota, Ryszard Litkowycz, Tomasz Skowronek, Marian Rzepko, and Grzegorz Juras

The aim of this study was to evaluate the effect of reduced effort on maximum countermovement jumps. Groups of unskilled and skilled jumpers performed countermovement jumps without an arm swing at 100% and 50% effort. The results revealed markedly reduced jump height and work performed at 50% effort, although the maximum force and power output remained virtually unchanged. The observed differences were consistent across individuals with different jumping skills. A possible cause of differences in changes across the tested variables was a reduced countermovement depth associated with the 50% effort jumps. It is known to cause an increase in maximum force and power outputs, but not in jump height. Therefore, the jump height and work performed may be more closely related to our sense of effort when jumping, rather than our maximum force and power output. From a practical perspective, the present findings reiterate the importance of maximizing effort for making valid assessments of muscle mechanical capacities, as tested by maximal vertical jumps and, possibly, other maximum performance tasks.