Author(s): SLOMKA, K., HADYK, V., JURAS, G., Institution: INSTITUTE OF SPORT SCIENCES, ACADEMY OF PHYSICAL EDUCATION IN KATOWICE, Country: POLAND, Abstract-ID: 908

INTRODUCTION:
Success in sports competition is determined by a variety of criteria that are always complex. These components are in constant interaction, so every activity in a sports fight, for example, combines fitness training, coordination ability, and volitional factors. The study sought to explore the effect of acute isometric fatigue on force-velocity profiles in vertical jumps in young volleyball players.
METHODS:
The study involved 12 of volleyball players (aged 17.5 ± 0.52, body height 188.1 ± 5.8, body weight 79.6 ± 10.2) and 12 physical education course students (age 22.15 ± 1.86, body height 179 ± 5.59, body weight 74.08 ± 7.79). The participants task was to perform vertical jumps (CMJ) immediately after the fatigue protocol to the maximum height. For the correct determination and evaluation of the force-velocity profile for each of the conditions (before and after physical effort), it was necessary to perform 9 jumps, including 6 with additional load (9 kg and 27 kg) in each condition. A force platform were employed to gather force-velocity parameters and custom stabilization system for the fatigue protocol. Participants stood semi-squatting on the force platform and extended their lower limbs and bodies after installation modification. This assignment required isometric muscle contraction due to mobility restrictions. After analyzing the generated force during exercise, its drop by 50% for 7 seconds from maximum values defined the critical point and concluded the fatigue protocol, which was followed by the study method.
RESULTS:
The results obtained in the study indicate no differences in the force-velocity profiles in the studied groups during jumps. At the same time, empirical data showed higher values of F0 and V0 in the group of volleyball players obtained during maximum jumps. The possibility of using the force-velocity profile to assess the maximum power in maximum CMJ was also investigated using the real platform data and F-V profile model data.
CONCLUSION:
Higher parameters of muscle work are caused by the training regime of volleyball players. The force-velocity profile of the volleyball players did not differ from the force-velocity profile of the control group. The lack of the difference can be attributed to the difference in age. The jump height (HJ), average speed of the center of mass displacement (Vmean), and average generated power (Pmean) all decreased in response to the imposed physical effort; however, the amount of the average generated force remained unaffected (Fmean), meaning that the subject can introduce compensation mechanisms to mitigate fatigue and preserve performance. The general shape of the F-V was not affected by the fatigue. The actual maximum power of the subjects could not be determined using the method for calculating maximum power (Pmax) that utilized parameters (F0 and V0) extracted from the F-V profile of the study group. As a result, the F-V model data differs substantially from the Pmax calculated using the raw platform data.