Nathália Arnosti Vieira

Analysis of Soccer Players’ Positional Variability During the 2012 UEFA European Championship: A Case Study

Abstract The purpose of this study was to analyse players’ positional variability during the 2012 UEFA European Championship by applying principal component analysis (PCA) to data gathered from heat maps posted on the UEFA website. We analysed the teams that reached the finals and semi-finals of the competition. The players’ 2D coordinates from each match were obtained by applying an image-processing algorithm to the heat maps. With all the players’ 2D coordinates for each match, we applied PCA to identify the directions of greatest variability. Then, two orthogonal segments were centred on each player’s mean position for all matches. The segments’ directions were driven by the eigenvectors of the PCA, and the length of each segment was defined as one standard deviation around the mean. Finally, an ellipse was circumscribed around both segments. To represent player variability, segment lengths and elliptical areas were analysed. The results demonstrate that Portugal exhibited the lowest variability, followed by Germany, Spain and Italy. Additionally, a graphical representation of every player’s ellipse provided insight into the teams’ organisational features throughout the competition. The presented study provides important information regarding soccer teams’ tactical strategy in high-level championships that allows coaches to better control team organisation on the pitch.

Modelo competitivo da distância percorrida por futebolistas na Uefa Euro 2008

ABSTRACT: The aim of this study focuses on knowing the competitive model of distance covered by soccer players in the Uefa Euro 2008, in the positions of the game, times and the total distance covered during the matches. It was analyzed all matches from 16 teams, totaling 31 games of which involved 460 soccer players. Subsequently, produced descriptive and inferential information. The main results show that: i) European soccer players elite covered 10232 ± 852m; ii) a midfielders (10894 ± 648m) greater distance covered, followed by external defenders (10274 ± 694m), forwards (10108 ± 624m), central defenders (9498 ± 592m) and goalkeepers (4198 ± 610m); iii) the average of covered distance at first half (4907 ± 201m) for matches was higher than the second half (4890 ± 238m). KEY WORDS: Competitive model group; distance covered; soccer. modelo competitivo de la distancia recorrida por futbolistas en UefaEuro 2008 RESUMEN: El objetivo de este estudio se centra en conocer el modelo competitivo de la distancia recorrida por futbolistas en Uefa Euro 2008, por las posiciones de juego, tiempos y la distancia total recorrida durante los partidos. Se analizaron todos los juegos de 16 selecciones, totalizando 31 juegos que participaron 460 futbolistas. Posteriormente, fue-ran producidas informaciones descriptivas e inferencia. Los principales resultados indican que: i) futbolistas de la elite Europea recorreran 10232 ± 852m; ii) centro-campistas (10894 ± 648m) recorreran mayor distancia, seguido por laterales (10274 ± 694m), delanteros (10108 ± 624m), defensores (9498 ± 592m) y porteros (4198 ± 610m); iii) la media distancia recorrida en lo 1o tiempo (4907 ± 201m) de los juegos fue superior a 2o tiempo (4890 ± 238m). PALABRAS CLAVES: Modelos competitivos; distancia recorrida; futbol.

Adaptação de protocolos invasivos e não invasivos para avaliações aeróbias e anaeróbias específicas ao basquetebol feminino

OBJECTIVE: To adapted the critical velocity (CV), RAST test and lactate minimum (LM) to evaluation of female basketball players. METHODS: Twelve well-trained female basketball players (19 ± 1yrs) were submitted to four intensities running (10 - 14 km/h) at shuttle exercise until exhaustion, applied on alternate days. The linear model velocity vs. 1/tlim was adopted to determine the aerobic (CV) and anaerobic (CCA) parameters. The lactate minimum test consisted of two phases: 1) hiperlactatemia induction using the RAST test and 2) incremental test composed by five shuttle run (20-m) at 7, 8, 9, 10, and 12 km/h. Blood samples were collected at the end of each stage. RESULTS: The velocity (vLM) and blood lactate concentration at LMxa0 were obtained by two polynomial adjustments: lactate vs. intensity (LM1) and lactate vs. time (LM2). ANOVA one-way, Student t-test and Pearson correlation were used for statistical analysis. The CV was obtained at 10.3 ± 0.2 km/h and the CCA estimated at 73.0 ± 3.4 m. The RAST was capable to induce the hiperlactatemia and to determine the Pmax (3.6 ± 0.2 W/kg), Pmed (2.8 ± 0.1 W/kg), Pmin (2.3 ± 0.1 W/kg) and FI (30 ± 3%). The vLM1 and vLM2 were obtained, respectively, at 9.47 ±0.13 km/h and 9.8 ± 0.13 km/h, and CV was higher than vLM1. CONCLUSION: The results suggest that the non-invasive model can be used to determine the aerobic and anaerobic parameters. Furthermore, the LM test adapted to basketball using RAST and progressive phase was effective to evaluate female athletes considering the specificity of modality, with high success rates observed in polynomial adjustment lactate vs. time (LM2).

Competitive model of distance covered by soccer players in Uefa Euro 2008

ABSTRACT: The aim of this study focuses on knowing the competitive model of distance covered by soccer players in the Uefa Euro 2008, in the positions of the game, times and the total distance covered during the matches. It was analyzed all matches from 16 teams, totaling 31 games of which involved 460 soccer players. Subsequently, produced descriptive and inferential information. The main results show that: i) European soccer players elite covered 10232 ± 852m; ii) a midfielders (10894 ± 648m) greater distance covered, followed by external defenders (10274 ± 694m), forwards (10108 ± 624m), central defenders (9498 ± 592m) and goalkeepers (4198 ± 610m); iii) the average of covered distance at first half (4907 ± 201m) for matches was higher than the second half (4890 ± 238m). KEY WORDS: Competitive model group; distance covered; soccer. modelo competitivo de la distancia recorrida por futbolistas en UefaEuro 2008 RESUMEN: El objetivo de este estudio se centra en conocer el modelo competitivo de la distancia recorrida por futbolistas en Uefa Euro 2008, por las posiciones de juego, tiempos y la distancia total recorrida durante los partidos. Se analizaron todos los juegos de 16 selecciones, totalizando 31 juegos que participaron 460 futbolistas. Posteriormente, fue-ran producidas informaciones descriptivas e inferencia. Los principales resultados indican que: i) futbolistas de la elite Europea recorreran 10232 ± 852m; ii) centro-campistas (10894 ± 648m) recorreran mayor distancia, seguido por laterales (10274 ± 694m), delanteros (10108 ± 624m), defensores (9498 ± 592m) y porteros (4198 ± 610m); iii) la media distancia recorrida en lo 1o tiempo (4907 ± 201m) de los juegos fue superior a 2o tiempo (4890 ± 238m). PALABRAS CLAVES: Modelos competitivos; distancia recorrida; futbol.

KNEE ISOKINETIC TORQUE IMBALANCE IN FEMALE FUTSAL PLAYERS

Rev Bras Med Esporte – Vol. 23, No 5 – Set/Out, 2017 ABSTRACT Introduction: The specificity of sports training can lead to muscle specialization with a possible change in the natural hamstring/quadriceps torque ratio (HQ ratio), constituting a risk factor for muscle injury at the joint angles in which muscle imbalance may impair dynamic stability. Objective: The aim was to evaluate the torque distribution of the hamstrings and quadriceps and the HQ ratio throughout the range of motion in order to identify possible muscle imbalances at the knee of female futsal athletes. Methods: Nineteen amateur female futsal athletes had their dominant limb HQ ratio evaluated in a series of five maximum repetitions of flexion/extension of the knee at 180°/second in the total joint range of motion (30° to 80°). The peak flexor and extensor torque and the HQ ratio (%) were compared each 5° of knee motion using one-way repeated measures ANOVA and Tukey’s post hoc test (p<0.05) to determine the joint angles that present muscular imbalance. Results: Quadriceps torque was higher than 50° to 60° of knee flexion, while hamstrings torque was higher than 55° to 65°. The HQ ratio presented lower values than 30° to 45° of knee flexion and four athletes presented values lower than 60%, which may represent a risk of injury. However, the HQ ratio calculated by the peak torque showed only one athlete with less than 60%. Conclusion: The HQ ratio analyzed throughout the knee range of motion allowed identifying muscle imbalance at specific joint angles in female futsal players.Introducao: A especificidade do treinamento esportivo pode levar a especializacao muscular, com possivel alteracao da razao do torque isquiotibiais/quadriceps (razao IQ) natural, constituindo um fator de risco de lesao muscular nos ângulos articulares em que o desequilibrio muscular pode prejudicar a estabilidade dinâmica. Objetivo: O objetivo foi avaliar a distribuicao do torque dos musculos isquiotibiais e quadriceps e da razao IQ ao longo de toda a amplitude de movimento, de modo a identificar possiveis desequilibrios musculares no joelho de atletas de futsal feminino. Metodos: Dezenove atletas amadoras de futsal feminino tiveram a razao IQ do membro dominante avaliada em uma serie de cinco repeticoes maximas de flexao/extensao do joelho a 180°/segundo na amplitude de movimento total (30° a 80°). O pico de torque flexor e extensor e a razao IQ (%) foram comparados a cada 5° de movimento do joelho pela one-way ANOVA de medidas repetidas e do teste post hoc de Tukey (p < 0,05) para determinar os ângulos articulares que apresentam desequilibrio muscular. Resultados: O torque do quadriceps foi maior que 50° a 60° de flexao do joelho, enquanto o torque dos isquiotibiais foi maior que 55° a 65°. A razao IQ apresentou menores valores que 30° a 45° de flexao do joelho e quatro atletas apresentaram valores abaixo de 60%, o que pode representar risco de lesao. No entanto, a razao IQ calculada pelo pico de torque mostrou apenas uma atleta com menos de 60%. Conclusao: A razao IQ analisada ao longo de toda a amplitude de movimento permitiu identificar desequilibrio muscular em ângulos articulares especificos em atletas de futsal feminino.

Determinação do limiar anaeróbio por dois ajustes matemáticos em teste específico para canoagem Slalom

O estudo objetivou propor um teste especifico para identificar o limiar anaerobio (Lan) em atletas de canoagem slalom. O Lan foi determinado por teste progressivo ate a exaustao nas velocidades de 5,6,7,8,9 e 9,5km/h, realizado em lagoa onde comumente eram realizados os treinos. O Lan foi obtido por dois metodos matematicos: inspecao visual e bissegmenta- cao da curva lactacidemica (LanBI), e utilizacao das concentracoes fixas de lactato 4mM e 2,5mM (LanOBLA). O LanBI e LanOBLA foram analisados por Anova One-Way e correlacao de Pearson (p<0,05). O LanBI foi obtido em 6,98 ± 0,16 km/h, a 2,53±0,25mM, e o Lan OBLA 4,0 ocorreu em 7,80±0,21km/h, superestimando em 11,5% o LanBI.. Desse modo, e possivel determinar o Lan por teste especifico para canoistas e, se adotado o OBLA, a concentracao 2,5mM parece ser mais adequada a modalidade.

Determinación del umbral anaeróbico por dos métodos matemáticos en test específico en canotaje Slalom

O estudo objetivou propor um teste especifico para identificar o limiar anaerobio (Lan) em atletas de canoagem slalom. O Lan foi determinado por teste progressivo ate a exaustao nas velocidades de 5,6,7,8,9 e 9,5km/h, realizado em lagoa onde comumente eram realizados os treinos. O Lan foi obtido por dois metodos matematicos: inspecao visual e bissegmenta- cao da curva lactacidemica (LanBI), e utilizacao das concentracoes fixas de lactato 4mM e 2,5mM (LanOBLA). O LanBI e LanOBLA foram analisados por Anova One-Way e correlacao de Pearson (p<0,05). O LanBI foi obtido em 6,98 ± 0,16 km/h, a 2,53±0,25mM, e o Lan OBLA 4,0 ocorreu em 7,80±0,21km/h, superestimando em 11,5% o LanBI.. Desse modo, e possivel determinar o Lan por teste especifico para canoistas e, se adotado o OBLA, a concentracao 2,5mM parece ser mais adequada a modalidade.

Determination of anaerobic threshold by two mathematical methods in specific test on Slalom kayak

O estudo objetivou propor um teste especifico para identificar o limiar anaerobio (Lan) em atletas de canoagem slalom. O Lan foi determinado por teste progressivo ate a exaustao nas velocidades de 5,6,7,8,9 e 9,5km/h, realizado em lagoa onde comumente eram realizados os treinos. O Lan foi obtido por dois metodos matematicos: inspecao visual e bissegmenta- cao da curva lactacidemica (LanBI), e utilizacao das concentracoes fixas de lactato 4mM e 2,5mM (LanOBLA). O LanBI e LanOBLA foram analisados por Anova One-Way e correlacao de Pearson (p<0,05). O LanBI foi obtido em 6,98 ± 0,16 km/h, a 2,53±0,25mM, e o Lan OBLA 4,0 ocorreu em 7,80±0,21km/h, superestimando em 11,5% o LanBI.. Desse modo, e possivel determinar o Lan por teste especifico para canoistas e, se adotado o OBLA, a concentracao 2,5mM parece ser mais adequada a modalidade.

Modelo competitivo de la distancia recorrida por futbolistas en Uefa Euro 2008

ABSTRACT: The aim of this study focuses on knowing the competitive model of distance covered by soccer players in the Uefa Euro 2008, in the positions of the game, times and the total distance covered during the matches. It was analyzed all matches from 16 teams, totaling 31 games of which involved 460 soccer players. Subsequently, produced descriptive and inferential information. The main results show that: i) European soccer players elite covered 10232 ± 852m; ii) a midfielders (10894 ± 648m) greater distance covered, followed by external defenders (10274 ± 694m), forwards (10108 ± 624m), central defenders (9498 ± 592m) and goalkeepers (4198 ± 610m); iii) the average of covered distance at first half (4907 ± 201m) for matches was higher than the second half (4890 ± 238m). KEY WORDS: Competitive model group; distance covered; soccer. modelo competitivo de la distancia recorrida por futbolistas en UefaEuro 2008 RESUMEN: El objetivo de este estudio se centra en conocer el modelo competitivo de la distancia recorrida por futbolistas en Uefa Euro 2008, por las posiciones de juego, tiempos y la distancia total recorrida durante los partidos. Se analizaron todos los juegos de 16 selecciones, totalizando 31 juegos que participaron 460 futbolistas. Posteriormente, fue-ran producidas informaciones descriptivas e inferencia. Los principales resultados indican que: i) futbolistas de la elite Europea recorreran 10232 ± 852m; ii) centro-campistas (10894 ± 648m) recorreran mayor distancia, seguido por laterales (10274 ± 694m), delanteros (10108 ± 624m), defensores (9498 ± 592m) y porteros (4198 ± 610m); iii) la media distancia recorrida en lo 1o tiempo (4907 ± 201m) de los juegos fue superior a 2o tiempo (4890 ± 238m). PALABRAS CLAVES: Modelos competitivos; distancia recorrida; futbol.