Temporal and Spatial Characteristics of Pacing Strategy in Elite Women's 400 Meters Hurdles Athletes.

The main objective of the study was to assess the pacing strategy of running 400 m hurdles of the world-level female athletes over the past 40 years based on the functional asymmetry -temporal and spatial characteristics. The data were collected from 1983 to 2019 using the review of scientific literature. Over the 35 years of the study, 37 top-level competitions with 283 finalists-competitors were included. The analysis of the 400 m hurdle covered mainly spatial and temporal factors of the run, related to those technical skills, the level of motor skills, and somatic structure. In addition to the basic statistics, the ANOVA analysis of variance, regression analysis, Pearson correlation, the principal component analysis (PCA), and Kaiser's criterion was used for the multivariate analysis. The final result in the 400 mH run is determined not by the simple sum of the individual temporal and/or spatial characteristics of the run (the number of steps, the type of attacking leg, but their interaction in the area of functional asymmetry. The decisive factor in the 400 mH run strategy is the second curve, where the emphasis is on the optimal setting of the stride pattern in the context of minimizing the loss of running speed. Additionally, the application of multidimensional statistical methods is a valuable tool that allows to significantly deepen the interpretation of the obtained results, and thus optimize a strategy for a 400 mH run.

Pacing Strategy in Men's 400 m Hurdles Accounting for Temporal and Spatial Characteristics of Elite Athletes.

The final result in a 400 m hurdles race (400mH) is relative to the motor preparation, technique of clearing hurdles as well as the adopted strategy of the race, including temporal aspects (split times in particular parts of the race) and spatial elements (the number of strides taken between subsequent hurdles). The objective of the study was to identify an optimal strategy for the 400mH race, including the stride pattern and split times. Data employed for this study were derived from results of 273 races held during the men's finals of international events (Olympic Games, World and European Championships) held from 1968 to 2015. To determine the strategies in the race, three main hurdle sections were identified - 1-4H, 4-7H and 7-10H. In each part, the fast (best results), average and slow (worst results) performing groups of hurdlers were distinguished. The analysis of adopted strategies was carried out taking into account 26 variables (main, basic, temporal and spatial). Basic statistical data, correlations and analysis of variance (ANOVA) were used. Results highlight the use of a variety of strategies, of which selection depends, among others, on body composition and the level of motor abilities (speed, speed endurance and explosive strength), as well as hurdling technique. Especially, the endurance strategy appears to be the most effective one, as it is a characteristic of best performances of many hurdlers. The analysis demonstrates that at the highest sports level the strategy of 400 m hurdles should be analyzed individually.

Changes in blood antioxidant status in American football players and soccer players over a training macrocycle.

BACKGROUND: The effectiveness of sport training programs should be assessed regularly against biochemical indices. This study assesses changes in the antioxidant status indices in American football players (AF) and soccer players (SP) over a training macrocycle. METHODS: The study was carried out with Poland's American Football League players (AF, n = 11, age 24.0 ± 3.7 years) and first-league soccer players (SP, n = 11, age 26.5 ± 3.8 years). Resting venous blood samples were collected from the players at the beginning of the three periods (preparatory, competition, and transition) making up the training macrocycle to determine the activity levels of superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase (CAT), glutathione reductase (GR), creatine kinase (CK), and lactate dehydrogenase (LDH), as well as the concentrations of non-enzymatic antioxidants (uric acid-UA and glutathione-GSH) and the levels of malondialdehyde (MDA). RESULTS: The period effect on SOD (p < 0.001), CAT (p < 0.05), GPx (p < 0.05), GSH (p < 0.0001) and UA (p < 0.0001), and the group × period interaction effect on SOD, CAT and GPx (p < 0.05), GSH (p < 0.001), and UA (p < 0.01) proved to be significant. Also significant were the group effect on MDA (p < 0.001) and LDH (p < 0.0001) and the period effect on MDA (p < 0.01) and LDH (p < 0.001). The activity of SOD and CAT and the concentration of GSH were higher in both AF (12%, 2%, and 15%, respectively) and SP (33%, 10%, and 42%) at the start of the competition period than in the preparatory period, but the concentration of MDA and the activity of CK and LDH was lower (0.8%, 29%, 5% (AF) and 2%, 11%, 5% (SP). The highest activity of GPx and LDH and the greatest concentrations of UA and MDA occurred in the early transition period. CONCLUSION: The study revealed an association between American footballers' and soccer players' training loads in the preparatory period and moderate improvements in their blood antioxidant status at the beginning of the competition period.

Physical fitness percentiles of Polish children aged 4-7 years.

The purpose of this study was to report sex- and age-specific physical fitness level in Polish children aged 4 to 7. 11.709 children participated in the study, including 5.684 girls and 6.025 boys aged 4 to 7 who attended kindergarten institutions throughout Poland. Physical fitness was assessed using four tests developed by Sekita including shuttle run 4 × 5 m with moving the block, standing long jump, throwing 1 kg medicine ball with two hands above the head and 20 m run. Percentile charts were developed separately for males and females using the LMS method. Boys showed higher physical fitness values than girls. In addition, an increase in the level of physical fitness was observed along with the age of the subjects. The developed reference values by age and sex in the field of physical fitness can be used for diagnostic purposes and assessing the level of physical fitness of preschool children. In addition, they can be helpful for healthcare professionals, parents and teachers to develop children's motor activation programs and monitor their physical fitness.

Postural Stability in Athletes during Special Hurdle Tests without a Definite Dominant Leg.

The purpose of this study was to analyze the body balance control of people walking and hurdling with or without a specific dominant leg in a monopodal position. This study involved 28 physical education students. The center of pressure (COP) was measured with a force plate under four conditions: single-leg standing (right and left) with eyes open and two upper limb positions (the arms were positioned in either a specific hurdle technique manner or alongside the body). A repeated measures analysis of variance (ANOVA) was conducted separately for five parameters of the COP in the medial-lateral (ML) and anterior-posterior (AP) directions under the four conditions. In the single-leg position, athletes without a dominant lower leg had better body balance than those with a dominant lower leg. The position of the upper limbs influenced the body position when hurdling. Accepting the correct position of the upper limbs helped to maintain balance (when overcoming hurdles). In hurdles, the position of the upper limbs should be improved to maintain postural stability and save this function for more demanding postural tasks.

Functional Laterality of the Lower Limbs Accompanying Special Exercises in the Context of Hurdling.

BACKGROUND: The purpose of this study was to investigate the lateralization of the lead leg during special exercises and the relationship with athletic performance throughout a hurdling session. METHODS: Thirty-eight physical education students participated in the study. A novel three-part "OSI" test (walking over hurdles arranged in a circle, spiral, and straight line) was performed, and various hurdle practices (jogging and running) were selected as research tools. The lead leg selected by the participants was taken into consideration, and the relationship between the chosen lead leg and athletic performance in the five tests was established. RESULTS: The lateralization of the lead leg changed depending on the shape of the running course. The results of further analysis showed (i) no correlation between the use of the right leg as the lead leg in three tests conducted at a marching pace, and (ii) a significant positive correlation between tests performed at the marching and running paces. CONCLUSION: Hurdlers flexibly change the dominant leading leg depending on the shape of the running course. The results of this research could prove helpful in the training of athletes for hurdling competitions, especially young runners in 400-m hurdles involving straight and corner tracks.

Planning Training Loads for the 400 M Hurdles in Three-Month Mesocycles using Artificial Neural Networks.

This paper presents a novel approach to planning training loads in hurdling using artificial neural networks. The neural models performed the task of generating loads for athletes' training for the 400 meters hurdles. All the models were calculated based on the training data of 21 Polish National Team hurdlers, aged 22.25 ± 1.96, competing between 1989 and 2012. The analysis included 144 training plans that represented different stages in the annual training cycle. The main contribution of this paper is to develop neural models for planning training loads for the entire career of a typical hurdler. In the models, 29 variables were used, where four characterized the runner and 25 described the training process. Two artificial neural networks were used: a multi-layer perceptron and a network with radial basis functions. To assess the quality of the models, the leave-one-out cross-validation method was used in which the Normalized Root Mean Squared Error was calculated. The analysis shows that the method generating the smallest error was the radial basis function network with nine neurons in the hidden layer. Most of the calculated training loads demonstrated a non-linear relationship across the entire competitive period. The resulting model can be used as a tool to assist a coach in planning training loads during a selected training period.

Estimation of hurdle clearance parameters using a monocular human motion tracking method.

This paper presents a method of monocular human motion tracking for estimation of hurdle clearance kinematic parameters. The analysis involved 10 image sequences of five hurdlers at various training levels. Recording of the sequences was carried out under simulated starting conditions of a 110 m hurdle race. The parameters were estimated using the particle swarm optimization algorithm and they are based on analysis of the images recorded with a 100 Hz camera. The proposed method does not involve using any special clothes, markers, inertial sensors, etc. As the quality criteria, the mean absolute error and mean relative error were used. The level of computed errors justifies the use of this method to estimate hurdle clearance parameters.

Spatio-temporal characteristics of hurdle runs and ergometric tests during athletic preparation / Características espaço-temporais de corridas com obstáculo e testes ergométricos durante a preparação no atletismo

The main goal of this study was to assess the appropriateness of both ergometric and modified hurdles tests for an annual cycle of hurdlers who were working on mastering the 400 m distance. Nine Polish hurdlers (personal best: 54.46±2.16 s, age: 20.67±1.87 years) were chosen as the research participants. In each of two mastering periods in the research, an ergometric test and a specific test were implemented during a hurdle run. In February, an interval ergometric test (5×6 s) and an interval hurdle test (IHT) were performed. Additionally, in May, a classic Wingate test and a 200 m hurdle run were introduced. With regard to the ergometric tests, we assessed the following measurements: maximum power (Pmax) and mean power (P×) reached in five repetitions as well as total work (Wtotal) performed in five attempts. The Mann-Whitney test was used to distinguish between the athletic test results obtained in the preparation period outlined above and those obtained in the first period. Lactate (LA) concentrations were assessed with the Chi-square test. Moreover, Spearman's rank correlation coefficients were used in the analysis. The achieved study results indicate the lack of significant differentiation of the ergometric test parameters (p≥ 0.05). The spatial structure of both specific tests (5×2 H v. 200 m H) was similar given that the first and the second parts of both hurdle races and the number of steps taken were similar. The basic parameters of the ergometric tests did not exhibit any relationship with the recommended record time achieved for the 400 m hurdle run.

O objetivo deste estudo foi avaliar a idoneidade de seleção dos testes ergométricos e testes modificados de corridas com barreiras ao longo do ciclo anual de treinamento dos atletas na distância de 400m. Participaram do estudo nove atletas poloneses (melhor resultado: 54,46±2,16s, idade: 20,67±1.87 anos). Em duas temporadas de treinamento foram realizados dois testes: ergométrico e especial (=na corrida com barreiras). Em fevereiro foi efetuado o teste ergonómico em intervalos (95x6s) e o teste com barreiras Rest com intervalos (IHT). Em maio foi efetuado o teste clássico de 30 s Wingate e uma corrida de 200m com barreiras (200mH). Nas corridas com barreiras foram considerados os parâmetros de tempo, potência máxima (Pmax), potência média (Px) e trabalho total (Wtotal). Para avaliar as diferenças entre os resultados dos testes numa temporada foi aplicado o teste de Mann-Whithney. As diferenças de concentração do lactato (LA) foram avaliadas com o teste Chi-square. Na análise foram considerados também os coeficientes de correlação de postos de Spearman. Os resultados dos estudos demostram a ausência de diferenças pertinentes nos parâmetros dos testes ergométricos (p ≥ 0,05). A estrutura espacial de ambos os testes especiais (5x2H vs. 200mH) foi semelhante: na primeira e segunda parte de ambas as corridas foi efetuado o número parecido dos passos. Os parâmetros essenciais dos testes ergométricos (Pmax, Px, Wtotal) não demostraram relações importantes com o resultado recorde na corrida de 400m com barreiras. A análise demostrou a possibilidade de utilização seletiva dos testes ergométricos na avaliação do grau de preparação dos atletas para a distância de 400m com barreiras.