Bilateral deficit in the countermovement jump and its associations with Judo-specific performance

This study aimed to describe the bilateral deficit (BLD) during the countermovement jump (CMJ) in judo athletes and determine the relationship between the BLD and judo-specific performance. Fourteen male judo athletes participated. The athletes performed tree specific judo tests: Maximal Sprint Speed Judo Test, Maximal Aerobic Speed Judo Test, Special Judo Fitness Test (SJFT), and double-and single-leg CMJ. The follow CMJ variables were used: jump height JH, mean – MPO and peak – PPO power output, peak force – PF, peak velocity – PV and impulse – IMP. The Pearson’s or Spearman’s test were used (p<0.05). The results show that the BLD is found in all CMJ parameters (27% in JH; 20% in MPO; 22% in PPO, 61% in PF, 41% in PV and 31% in IMP). Negative correlations between first set of SJFTTT (total throws) and BLD in PF (r=-0.60; p=0.022) and between the second set of SJFTTT and BLD in MPO (r=-0.74;p=0.002), PV (r=-0.59;p=0.025) and IMP (r=-0.55; p=0.040) were found. Also, negative correlations between SJFTTT and the BLD in all CMJ parameters (r=-0.53 to -0.85;p<0.05) were found. The BLD in most CMJ variables is negatively correlated (large to very large) to the SJFTTT. So, high BLD values are related to poor SJFTTT performance

Effects of successive judo matches on interlimb asymmetry and bilateral deficit

Objective: To verify the effects of successive judo matches on interlimb asymmetry and bilateral deficit in judo athletes. Design: Repeated measures Setting: University Judo center Participants: Fourteen male judo athletes Outcome measures: Four simulated matches consisting of 4-min. Before the first match and after each match athletes were submitted to single leg tests – Countermovement Jump (SLCMJ) and Standing Long Jump (SLSLJ), and handgrip strength (HGS) in the dominant and non-dominant limbs. Interlimb asymmetry was calculated in both jumps and handgrip strength tests. Results: Most jump-derived variables did not change the magnitude of asymmetry throughout the matches (p>0.05), with the exception of jump height asymmetry in SLCMJ, that increased after the second match (p=0.001). The HGS decreased in both hands from the first match (p<0.001), without asymmetry. The highest bilateral strength deficit was observed in post-match 1 and post-match 2 (close to 10%). Conclusion: Four-successive judo matches did not change the magnitude of interlimb asymmetry, with exception of SLCMJ height, which increased after the second match. The handgrip strength decreased throughout the matches, but similarly in both hands. Finally, the direction of asymmetry showed consistency throughout the matches only for SLCMJ height

Quantum Response at Finite Fields and Breakdown of Chern Numbers

We show that the response to an electric field, in models of the Integral Quantum Hall effect, is analytic in the field and has isolated essential singularity at zero field. We also study the breakdown of Chern numbers associated with the response of Floquet states. We argue, and give evidence, that the breakdown of Chern numbers in Floquet states is a discontinuous transition at zero field. This follows from an observation, of independent interest, that Chern numbers for finite dimensional Floquet operators are generically zero. These results rule out the possibility that the breakdown of the Hall conductance is a phase transition at finite fields for a large class of models.Comment: 16 pages, 8 eps figures, LaTeX2e with IOP style. Many changes, including new materia

Predicting delay factors when chipping wood at forest roadside landings

Chipping of bulky biomass assortments at roadside landings is a common and costly step in the biomass-to-energy supply chain. This operation normally involves one chipping unit and one or several transport trucks working together for simultaneous chipping and chip transport to a terminal or end user. Reducing the delay factors in these operations is a relevant ambition for lowering supply costs. A method to estimate organizational delay based on: (1) the capacity ratio between the transport and the chipper, (2) the use of buffer storage, and (3) the number of transport units involved is suggested here. Other delays will also be present, and some of these may relate to the working conditions at the landing. A method to set a landing functionality index based on characteristics of the forest landing is also suggested. A total of 14 roadside chipping operations were assessed and the operators were interviewed to address the impact of machinery configuration and landing characteristics on machine utilization. At most sites, the chipper was the more productive part, and the chipper utilization was to a large extent limited by organizational delay. Still the utilization of the transport units varied between 37 and 97%, of which some 36% of the variation was explained by the landing functionality index. Knowledge from the work presented here should be a good starting point for improving biomass supply planning and supply chain configuration.acceptedVersio

Observation of Coherently Coupled Cation Spin Dynamics in an Insulating Ferrimagnetic Oxide

Many technologically useful magnetic oxides are ferrimagnetic insulators, which consist of chemically distinct cations. Here, we examine the spin dynamics of different magnetic cations in ferrimagnetic NiZnAl-ferrite (Ni$_{0.65}$Zn$_{0.35}$Al$_{0.8}$Fe$_{1.2}$O$_4$) under continuous microwave excitation. Specifically, we employ time-resolved x-ray ferromagnetic resonance to separately probe Fe$^{2+/3+}$ and Ni$^{2+}$ cations on different sublattice sites. Our results show that the precessing cation moments retain a rigid, collinear configuration to within $\approx$2$^\circ$. Moreover, the effective spin relaxation is identical to within $<$10% for all magnetic cations in the ferrite. We thus validate the oft-assumed ``ferromagnetic-like'' dynamics in resonantly driven ferrimagnetic oxides, where the magnetic moments from different cations precess as a coherent, collective magnetization

Accuracy and reproducibility of a novel device for monitoring resistance training performed at self-selected movement velocity

oai:repository.mdx.ac.uk:y796vResistance training does not necessarily require repetition failure, whereas Velocity-Based training and “training not to failure” are available alternatives to know the optimal point to interrupt the sets. Nevertheless, Velocity-Based training require exclusively maximal intended velocities and training not to failure currently relies on subjectivity to estimate repetitions in reserve. This study evaluated the accuracy and precision of a linear encoder in estimating the maximum number of repetitions during sets performed until failure at self-selected movement velocity. Fifty-seven males were evaluated in three resistance exercises: close-grip lat pulldown, knee extension, and bench press. Accuracy was evaluated by comparing the mean and median of actual and estimated repetitions using t-tests and Wilcoxon signed-rank tests, respectively. Additionally, the fatigue effect in consecutive sets was analyzed using two-way ANOVA for repeated measures. Levels of agreement were assessed through Bland-Altman analysis, and reproducibility was determined by calculating the Intraclass Correlation Coefficient (ICC). The results showed no significant difference between actual and estimated repetitions (t178 = 0.307; p > 0.05; ES = 0.02; Z = -0.45; p > 0.05; ES = -0.02), even in the presence of fatigue between consecutive sets. The reproducibility for estimating maximal repetitions was good (ICC3,2 = 0.88 [95% CI = 0.83-0.91], F177,177 = 8.07, p < 0.001), with an acceptable degree of agreement. Errors of less than or equal to two repetitions occurred in over 90% of the series for the close-grip lat pulldown and bench press, with knee extension exhibiting a slightly lower frequency. Hence, practitioners and trainers should consider using this linear encoder for the evaluated exercises, especially when failure is not desired under self-selected velocity conditions

Concurrent validity and technological error-based reliability of a novel device for velocity-based training

The aim of this study was to verify the concurrent validity and the biological error-free reliability of a novel low-cost commercial encoder (Ergonauta I). Validity protocol involved comparisons with a custom system and other encoder commercially available (Vitruve). Reliability protocols involved inter devices and inter unit comparisons. No participants were recruited, and reliability assessments were performed in a Smith Machine by bar free fall tests. Our results showed a significant bias for mean velocity (MV) estimated by both encoders only in one of the four conditions investigated (bias=0.05 m/s). Regarding sensitivity, the smallest detectable change suggests only values higher than 0.03 m/s must to be considered as real changes in performance, when monitoring MV and mean propulsive velocity (MPV) through Ergonauta I and Vitruve. Between-days intra-device reliability showed Ergonauta I remains highly reliable after one week for most assessments, whereas slightly less sensitive for peak velocity and peak power output

Strength and Conditioning (S&C) Practices of Judo Athletes and S&C Coaches: A Survey-Based Investigation

Weldon, A, Cloak, R, Kirk, C, Ruddock, A, Langan-Evans, C, Detanico, D, Loturco, I, and Kons, R. Strength and conditioning (S&C) practices of judo athletes and S&C coaches: A survey-based investigation. J Strength Cond Res 38(4): e160–e173, 2024—The benefits of strength and conditioning (S&C) for improving judo performance and reducing injuries have been widely studied. However, the S&C practices used and perspectives held by those delivering S&C have yet to be elucidated. Therefore, this study investigated the S&C practices and perspectives of judokas and S&C coaches working within judo. Forty-two judokas and 9 S&C coaches completed an online survey comprising 6 sections: (a) written informed consent; (b) background information; (c) education, qualifications, and prescription; (d) views on S&C; (e) exercise selection; and (f) issues and improvements. Frequency analysis was used to report responses to fixed-response questions and thematic analysis for open-ended questions. Results indicated that S&C coaches were primarily responsible for delivering S&C programs (60%), and S&C information was predominantly sourced from S&C coaches (43%). Strength and conditioning was deemed very important for randori (78–88%), overall judo performance (67–79%), and judo fitness (62–78%). Similarly, S&C was considered very important for the development of speed and power (76–89%), strength (71–89%), and injury reduction (69–78%). Novel findings were also observed, such as integrating judo-specific training within S&C practice, which may be partly explained by more S&C coaches holding judo belts (67%) than S&C qualifications (11%). This study supports practitioners delivering S&C in judo by offering a base of information to critique or align with their existing S&C practices and perspectives. Furthermore, our results may help identify potential gaps between methods used, proposed guidelines, and actual practice, facilitating the development of research and education resources tailored to the current climat