Monitoring the internal and external loads of young team handball players during competition

This study aimed to examine the internal- and external-training-load (ITL and ETL, respectively) during a match of young handball players. Field testing included heart-rate monitoring (memory belt, Suunto) as a marker of ITL and accelerometry (motion-biosensor, Actical Respironcis, Philips) as a marker of ETL. Time motion analysis data were obtained by recording the player's game activities and later analysed with the Matlab software package. T-test and Pearson-product-moment correlation coefficient were used to examine the differences and the relationship between variables collected in the study. The t-test analysis did not show significant differences between the total distance covered (2216.42-2135.42 m), steps conducted (1829.25-1829.83 steps), steps per minute (91.46-91.49 steps/min), energy expenditure (92.24-90.87 METS), time spent in higher intensity zones calculated by motion biosensor (13.08-12.75 minutes), training-load calculated by Edwards TRIMP method (91.54-88.56 scores) in the first and in the second half of the match. Physical activity variables show no significant correlations with the data assessed by heart rate monitors. Similar results in monitored training-load variables in the first and second halves are connected with the game intensity, which was consistent throughout the match. The lack of correlations between ITL and ETL variables indicates that accelerometry is not suitable for the assessment of metabolic training load in intermittent activities, such as handball. ITL measures used in this study are more suitable for controlling load during training and competition, while the ETL parameters used are more appropriate for better understanding players activity in periods in which the players do not train; other activities can influence players fatigue and training and competition performance

Levels and changes of physical activity in adolescents during the COVID-19 Pandemic: Contextualizing urban vs. Rural living environment

The COVID-19 pandemic and the social distancing implemented shortly after influence physical activity levels (PALs). The purpose of this investigation was to evaluate the changes in PAL and factors associated with PALs among Croatian adolescents while considering the impact of community (urban vs. rural living environment). The sample included 823 adolescents (mean age: 16.5 ± 2.1 years) who were tested on baseline (from October 2019 to March 2020; before COVID-19 pandemic in Croatia) and follow-up (in April 2020; during the COVID-19 pandemic and imposed rules of social distancing). Baseline testing included anthropometrics, physical fitness status, and evaluation of PALs, while follow-up included only PALs (evaluated by a standardized questionnaire through an internet application). The results showed a significant influence of the living environment on the decrease of PAL, with a larger decrease in urban adolescents. Logistic regression showed a higher likelihood for normal PALs at baseline in adolescents who had better fitness status, with no strong confounding effect of the urban/rural environment. The fitness status of urban adolescents predicted their PALs at follow-up. The differences between urban and rural adolescents with regard to the established changes in PALs and relationships between the predictors and PALs are explained by the characteristics of the living communities (lack of organized sports in rural areas), and the level of social distancing in the studied period and region/country

Psychological Distress in Elite Sambo and Recreational Athletes

Background: Previous studies suggest that engagement in any type of physical activity can be protective against mental health issues, whereas elite-level athletes can endure various mental health challenges. The aim of this study was to determine variations in the prevalence of psychological distress among elite sambo athletes and their recreational counterparts. Methods: A sample consisting of 245 athletes (127 males and 118 females) was chosen. Out of the total sample, 105 were elite-level athletes while 140 were recreational athletes. Participants were accessed via the Depression Anxiety Stress Scales-21 to determine their stress in various domains at a given time. Results: Data indicated that all tested differences between elite sambo athletes and recreational athletes were statistically significant; recreational athletes had a higher score on the depression scale, anxiety and stress, and a general distress score than sambo athletes. Although there are no gender differences in psychological distress in the total sample of athletes, elite sambo athletes achieve significantly lower scores in all tested variants than recreational ones. Women who engage in recreational activities have stood out as a vulnerable subsample in psychological stress. Conclusion: Future epidemiological and interventional studies should explore optimal strategies to identify mental health needs based on specific sport activity, especially in terms of gender. There is a need to place special emphasis on psychological distress in the context of combat sports

Determination of Microstructural Changes By Severely Plastically Deformed Copper-Aluminum Alloy: Optical Study

Our work deals with the problem of producing a complex metal-ceramic composite using the processes of internal oxidation (IO) and severe plastic deformation. For this purpose, Cu-Al alloy with 0.4wt.% of Al was used. IO of sample serves in the first step of the processing as a means for attaining a fine dispersion of nanosized oxide particles in the metal matrix. Production technology continues with repeated application of severe plastic deformation (SPD) of the resulting metal-matrix composite to produce the bulk nanoscaled structural material. SPD was carried out with equal channel angular pressing (ECAP), which allowed that the material could be subjected to an intense plastic strain through simple shear. Microstructural characteristics of one phase and multiphase material was studied on internally oxidized Cu with 0.4wt.% of Al sample composed of one phase copper-aluminum solid solution in the core and fine dispersed oxide particles in the same matrix in the mantle region. In this manner AFM, X-ray diffraction and Raman spectroscopy were used. Local structures in plastically deformed samples reflect presence of Cu, CuO, Cu2O, Cu4O3 or Al2O3 structural characteristics, depending on type of sample

Regulation of Protein Tyrosine Kinase 6 Stability and Activation

Protein Tyrosine Kinase 6 (PTK6) is an intracellular tyrosine kinase whose functions depend on its localization. When localized at the plasma membrane in prostate cancers, PTK6 promotes oncogenic signaling and is associated with worse patient outcomes. PTK6 acts growth inhibitory when it is localized in the nucleus. PTK6 lacks membrane targeting domains and nuclear localization sequences, and mechanisms of regulation of intracellular localization are not well understood. The SH2 domain of PTK6 was identified as crucial for the interaction with plasma membrane lipids which was shown to be mediated by two arginine residues, R131 and R136. Mutation of these residues did not lead to reduction in lipid binding. We show that PTK6 preferentially binds monophosphorylated phosphoinositides. Mutation of R131 and R136 led to increase in PTK6 stability. In contrast, mutation of amino acid residues R85 and H126 which are involved in binding of phosphotyrosines, led to accumulation of PTK6 in cellular granules and reduced stability. We demonstrate that wild type PTK6 and phosphotyrosine binding mutant interact with Cul1 and SKP1, which are components of Cullin Ring Ligase 1 E3 ubiquitin ligase complex. The more stable previously described as lipid binding mutant, does not interact with this complex. Mutation of PTK6 amino residue R131 has been reported in some cancers, which may contribute to increased PTK6 stability, activity, and cancer signaling. We show that activity of PTK6 is inhibited by Vemurafenib, in vitro and in vivo. Vemurafenib reduces proliferation and increases cell death in xenograft tumors, which suggests that PTK6 could be targeted in cancers. I found that calcium-binding protein, calmodulin can bind PTK6 and increase its autophosphorylation, which could be one of the pathways PTK6 is activated in differentiation of keratinocytes upon increase in calcium ion levels

Rapid Weight Loss Coupled with Sport-Specific Training Impairs Heart Rate Recovery in Greco-Roman Wrestlers

Wrestling is a sport that can be classified with the use of alternating aerobic–anaerobic metabolism with moderate but high-impact energy expenditure. Heart rate recovery (HRR) is the difference between heart rate during exercise and a certain amount of time after the start of recovery. The goal of this study was to determine the difference in HRR between two phases: high-intensity sport-specific training (HISST) combined with rapid weight loss (RWL)—phase 1 (P1) and HISST only—phase 2 (P2). Ten national-level wrestlers were included in this study. All participants underwent HISST along with RWL procedures for P1. Seven days later, during P2, an identical training session was performed with no RWL included. We found a statistically significant difference in the values obtained after the first and second minutes of recovery in the second set for both cases (p = 0.034 and p = 0.037, respectively), with higher HR values recorded in P1. It can be concluded that there is undoubtedly a difference in HRR during training and RWL compared to HISST alone. Additionally, HISST along with RWL could compromise the aerobic component of recovery

Prevalence of rapid weight loss in Olympic style wrestlers

Background: The methodology applied for rapid weight loss (RWL) among elite wrestlers is quite unexplored. Therefore, the aim of this study was to analyze the prevalence of sources of influence and methods used for RWL and to determine the differences between wrestling styles. Methods: A total of 229 wrestlers who competed at the World Championship held in Belgrade, Serbia, participated in this research. All respondents completed a questionnaire designed to evaluate RWL patterns in combat athletes. Participants were classified according to wrestling style: Greco-Roman, freestyle, and women wrestling. Results: Sixty-nine percent of wrestlers had previously lost weight to compete. Most respondents start losing weight approximately seven days before a competition. Athletes reported that they com- monly reduced 3.84 ± 2.82 kg to reach the target weight. The wrestling coach represents the most influential person in terms of RWL strategies, while nutritionists and physicians have the least impact on the weight-cutting process. Regarding the methods applied, differences between all the three styles were found in the following variables: training in a heated room, restricting fluid ingestion, training in plastic suits, gradual dieting, increased exer- cise, diet pills, and sauna. The most frequently used techniques were increased exercise, gradual dieting, training in a heated room, and sauna for all competitors. Diet pills, diuretics, laxatives, and vomiting were the least implemented methods. Conclusions: The obtained results suggest that most wrestlers practice RWL despite the harmful health effects. The education of wrestling coaches is necessary in order to control and decrease the negative impact of RWL

Characterization and luminescence kinetics of Eu3+ doped YVO4 nanopowders

In this paper we describe the synthesis and characterization of the YVO4:Eu3+ nanopowder. The material was prepared using simple solution combustion synthesis. X-ray powder diffraction (XRD), scanning electron microscope (SEM), Raman and photoluminescence (PL) techniques were used to confirm and characterize the prepared material. The time resolved analysis of emission spectra was achieved by using the streak camera system. Beside luminescence lifetime of slow decayed transitions we also measured their rise time and lifetime of fast decayed transitions. We also determitied the excitation spectra of this nano material. Results of our analysis prove that YVO4:Eu3(+) nanopowder is appropriate material for various optoelectronic devices. (C) 2016 Elsevier Ltd. All rights reserved

Photoluminescence spectroscopy of CdSe nanoparticles embedded in transparent glass

In this paper we present photoluminescence measurements of CdSe nanoparticles embedded in transparent glass. Sample is prepared using an original technique, which combines both heat treatment and ultraviolet laser irradiation. Photoluminescence spectra displayed one main emission band at 2.14 eV. We identify this bands energy as basic interband transition in CdSe nanoparticle. We calculated energy of basic (1s(h)-1s(e)) transition in spherical CdSe quantum dot (QD), within infinite potential barrier, in effective-mass approximation. On the basis of this model, average radius of synthesized CdSe QDs is about 3 nm, which is in consistence with AFM measurements and UV-VIS absorption measurements