No abstract

This study aimed to investigate the acute effects of simulated judo matches on fatigue and muscle damage markers. Twenty male judo athletes participated in this study. The athletes performed three 5-minute judo matches separated by 15 minutes of passive rest between each match. The following measurements were performed before and after each match: shoulder external/internal rotation isokinetic torque and countermovement jump (CMJ). Blood samples were taken before the first match and after the third match for serum creatine kinase (CK) and lactate dehydrogenase (LDH) analysis. T-tests for dependent samples and analysis of variance for repeated measures were used to compare the variables over the time; the level of significance was set at 0.05. An overall effect of the successive matches on shoulder internal (PTIN) and external (PTEX) rotation peak torque and CMJ performance was observed. PTIN and PTEX showed significant decreases in postmatch 2 and postmatch 3 when compared with the baseline (p < 0.01). Also, CMJ height declined in postmatch 2 and postmatch 3 (p < 0.01) when compared with the baseline. Serum CK and LDH activity increased significantly after the third match (p < 0.01). It was concluded that 3 successive judo matches induced a decline of peak torque and muscle power in the upper and lower limbs, respectively, and also provoked an increase of muscle damage markers. These findings may provide important knowledge for coaches and physical trainers to improve judo-specific strength training in both the upper and lower limbs.

This study evaluated force and velocity parameters of vertical jump performance in countermovement jump (CMJ) and squat jump (SJ) and compared results for sprint runners and volleyball players. Twenty-four male athletes (12 regional/national-level sprint runners and 12 national-level volleyball players) performed CMJ and SJ on a force platform. The following variables were analyzed: jump performance (jump height and power), peak velocity (PV), absolute and relative maximum force (MF), rate of force development (RFD,) and time to reach maximum force (TMF). In CMJ, jump height was correlated with PV (r=0.97) and normalized MF (r=0.47), whereas jump power was significantly correlated with all variables, except MF (r=0.12). In SJ, PV and normalized MF were significantly correlated with jump height (r=0.95 and r=0.51) and power (r=0.80 and r=0.87). In addition, TMF was inversely correlated with power (r=-0.49). Runners had higher performance variables (height and power), normalized MF and PV than volleyball players in both CMJ and SJ. Velocity and maximum force were the main determinants of height and power in the two types of vertical jumps. However, explosive force (RFD and TMF) was also important for power production in vertical jumps. Runners had a better vertical jump performance than volleyball players.

Purpose. This study aimed to relate strength parameters of the judogi pull test and countermovement jump (CMJ), and body fat with body mass and to compare strength parameters in the judogi pull test between the dominant and non-dominant hands. Methods. Eighteen male judokas took part in this study. The following parameters were analysed: maximal force (F max ), time to maximal force (TF max ), rate of force development (rFD) and rate of peak force decrement (rPFD) of the dominant and nondominant hands during the pull test. Jump height (H max ), power, F max , peak velocity (PV) and rFD in the CMJ were also measured. A t-test and Pearson's correlation were used. Results. F max (absolute and relative) and rFD were greater for the dominant hand, whereas rFPD was greater for the non-dominant hand during the pull test. There was a significant correlation only between absolute F max and body mass (r = 0.51) in the pull test. For the CMJ, relative power (r = -0.57), H max (r = -0.49) and PV (r = -0.53) were negatively correlated with body mass, while absolute F max (r = 0.84) and power (r = 0.69) were positively correlated with body mass. A significant correlation between body mass and body fat (r = 0.88) was found. Conclusions. There are differences in maximal and explosive force and the rate of peak force decrement between the dominant and non-dominant hand. Absolute values of power and maximal force increased according to body mass (and, therefore, a higher weight category); however jump per formance decreased with an increase in body mass (weight category).

This study analysed the modulation of jump performance, vertical stiffness as well as joint and intralimb coordination throughout a 30-s vertical jump test. Twenty male athletes performed the test on a force plate while undergoing kinematic analysis. Jump height, power output, ground contact time, vertical stiffness, maximum knee and hip flexion angles, and coordination by continuous relative phase (CRP) were analysed. Analysis of variance was used to compare variables within deciles, and t-tests were used to compare CRP data between the initial and final jumps. Results showed reduction in jump height, power output, and vertical stiffness, with an increase in contact time found during the test. Maximum knee and hip flexion angles declined, but hip angle decreased earlier (10-20% of the test) than knee angle (90-100%). No changes were observed in CRP for thigh-leg coupling when comparing initial and final jumps, but the trunk-thigh coupling was more in-phase near the end of the test. We conclude that fatigue causes reduction in jump performance, as well as changes in stiffness and joint angles. Furthermore, changes in intralimb coordination appear at the last 10% of the test, suggesting a neuromotor mechanism to counterbalance the loss of muscle strength.