A METHOD TO ANALYZE SOCCER OFFENSIVE SEQUENCES

There is a range of possibilities to analyze the soccer game in relation to physical-technical-tactical aspects. The importance of going toward the goal rapidly since the recovery of possession was defended by Grehaigne et al (1996). The main technique to analyze soccer attack speed in literature was presented by Yue et al (2008). The aim of this study was to propose a method to analyze offensive sequences in soccer based on goal progression velocity (GPV) and goal progression indicator (GPI)

3D KINEMATICAL ANALYSIS OF THE HAMMER THROW IN COMPETITIONS

This study analyzes 14 throws accomplished in Brazilian competitions and it compares with available international results in the literature. It calculates the angle, the velocity and the height of release of the hammer and the velocity curves in function of the time, starting from the 3D trajectory of the head of the hammer. The analyses relate the difference between Brazilian (averages of 55.38m male and 52.05m female) and international results (averages of 79.44m male and 70.60m female) and the release velocity (Brazilian averages of 24.59m/s male and 23.59m/s female, and international of 29.60m/s male and 28.89m/s female). The velocity curves in function of the time of the international releases show that the accelerations are higher and the deceleration lower during the turns, when compared with a Brazilian throw

COVERED DISTANCES OF HANDBALL PLAYERS OBTAINED BY AN AUTOMATIC TRACKING METHOD

The aim of this work is to obtain the distances covered by handball players and their velocities during a match using a new approach based on automatic tracking method described in Figueroa et. al. (2006a, 2006b) and the Adaboost detector (Okuma, 2004). A whole game of a Brazilian regional handball championship for players under age of 21 was recorded. Applying the mentioned automatic tracking, the accumulated covered distances and the velocities were calculated for all the players. The results of average covered distances (±SD) in the 1st and 2 nd halves were 2199(±230) and 2453(±214). The results of covered distances and the velocities allow individual and collective analyses of the players by the team staff. The proposed method revealed to be a powerful tool to improve physical analysis of the handball players

ANALYSIS OF THE SPRINTS FEATURES DURING FUTSAL MATCHES

The purpose of this study was to analyse the repeated-sprint sequences (RSS) and to characterise the sprints performed during futsal matches. Automatic tracking system was used to obtain the player’s trajectories (n=97) during five official matches. The sprints were analysed during the both halves and RSS were categorised according to the number of sprints and the time between them. The results showed a decrease in the number of sprints per minute in the second half. However, the duration of the sprints was greater in the second half. For the RSS analysis, the results showed that the most frequent RSS consisted of two sprints interspersed with a maximum of 15 s of recovery. The study characterised the features of sprinting of futsal players, which can help coaches to plan physical training and assessments according to the sport requirements

ANALYSIS OF THE SHOTS TO GOAL STRATEGIES OF FIRST DIVISION BRAZILIAN PROFESSIONAL SOCCER TEAMS

The purpose of this study was to analyze the shots to goal strategies during four soccer matches, through computational tracking. Software Dvideow was used to obtain data about players’ position and their technical actions and data treatment was performed in Matlab® environment. The results showed that the teams usually win the ball possession in their defensive soccer field and ball possessions that resulted in shot to goal can involve few or great number of passes depending on the game situation. Results do not corroborate with literature studies due to different methods of data treatment. Information about to these shots to goal strategies can help coaches to improve technical training, to find possible team mistakes and present it to players

CENTRE OF MASS INTRACYCLIC VELOCITY VARIATION IN THREE VARIANTS OF THE FRONT CRAWL WATER POLO TECHNIQUE

The purpose of this study was to analyse the intracyclic velocity variation (IVV) of the centre of mass (CM) in the x, y, z axes during the stroke cycle event in front crawl, water polo front crawl and water polo front crawl while leading the ball. Ten national level water polo players performed 3x15 m at maximum intensity in each variant of the front crawl technique, being videotaped by six cameras (two above and four underwater). One complete stroke cycle was analyzed for each 15 m test using the APASystem. The numerical treatment was conducted using MATLAB software. IVVx and IVVz showed less variation in the water polo front crawl, and IVVy showed less variation for the water polo front crawl leading the ball. These suggest that water polo players have a greater proficiency in water polo specific swimming techniques rather than in front crawl

Motion analysis of elite Polish soccer goalkeepers throughout a season

The study aims were to determine the distance covered by goalkeepers during matches in the context of game duration and result, to identify the area of their most frequent activity, and to assess goalkeepers' involvement in games finished with a win, draw, or loss. The investigation was based on two innovative tools: the goalkeeper's activity index (GAI) and an analysis of 5-min periods. A video tracking system was used to monitor 17 goalkeepers from Polish National League teams during 15 matches. The GAI was applied to assess their involvement in the game. Elite goalkeepers covered 72.7%, 25.8%, and 2.5% of the distance during the game by walking/jogging, running, and sprinting, respectively. The distances covered in lost, won, and drawn matches turned out similar (mean \ub1 SD: 4800 \ub1 906 m, 4696 \ub1 1033 m, and 4660 \ub1 754 m, respectively). There were no significant differences between the distances covered in the first and second halves. The area of most frequent activity was the middle sector of the penalty area between the goal and penalty area lines. ANOVA results showed that in drawn matches, goalkeepers' activity significantly differed in mean values of the GAI in comparison with that in won and lost games (p = 0.034, p = 0.039, respectively). It was noted that goalkeepers tended to intervene more often in games where their team was winning rather than in those with a losing result. Their direct involvement in defending the goal was the lowest in drawn games

QUANTITATIVE ANALYSIS OF FUTSAL PLAYERS’ ORGANIZATION ON THE COURT

The purpose of this study was to quantify and analyze professional Futsal teams’ organization on the court in shots to goal and tackles situations. Two-dimensional coordinates of 22 players’ positions were obtained during a match between Brazil and Paraguay using a computational tracking system. Team organization in 58 specific situations of shots to goal and 120 tackles were analysed. The variables quantified were teams’ coverage area and distance between teams’ centroids. Results showed that defending team coverage area was greater (

The validity and reliability of a novel indoor player tracking system for use within wheelchair court sports

The aim of the current study was to investigate the validity and reliability of a radio- frequency based system for accurately tracking athlete movement within the wheelchair court sports. Four wheelchair specific tests were devised to assess the system during i) static measurements ii) incremental fixed speeds iii) peak speeds, and iv) multi-directional movements. During each test, three sampling frequencies (4, 8 & 16 Hz) were compared to a criterion method for distance, mean and peak speeds. Absolute static error remained between 0.19-0.32 m across the session. Distance values (test ii) showed greatest relative error in 4 Hz tags (1.3%), with significantly lower errors seen in higher frequency tags (< 1.0%). Relative peak speed errors of < 2.0% (test iii) were revealed across all sampling frequencies in relation to the criterion (4.00 ± 0.09 m·sˉ¹). Results showed 8 and 16 Hz sampling frequencies displayed the closest to criterion values, whilst intra-tag reliability never exceeded 2.0% coefficient of variation (% CV) during peak speed detection. Minimal relative distance errors (< 0.2%) were also seen across sampling frequencies (test iv). To conclude, the indoor tracking system is deemed an acceptable tool for tracking wheelchair court match-play using a tag frequency of 8 or 16 Hz

Penjerap komposit “lignoselulosa-karbon teraktif (buah semarak api)” dan kaolin dalam rawatan air sisa getah asli mentah

Pembangunan industri getah asli mentah menyumbang kepada krisis alam sekitar akibat daripada penjanaan air sisa yang berlebihan. Air sisa getah asli mentah ini mengandungi BOD, COD, ammoniakal nitrogen dan pepejal terampai yang tinggi. Dengan itu, teknologi baharu penjerap komposit dalam rawatan air sisa berpotensi menyingkirkan bahan pencemar. Penjerap komposit yang dihasikkan ini dari buah semarak api (lignoselulosa dan karbon teraktif) dan kaolin. Ujikaji kelompok dan turus lapisan tetap digunakan dan nisbah optimum komposit ditentukan menggunakan kaedah reka bentuk campuran D-optimal. Pencirian penjerap komposit dibuat terhadap luas permukaan BET, Mikroskop Imbasan Elektron Analisis Elemen-Sinar-X Sebaran Tenaga (SEM-EDX), Potensi Zeta dan Spektroskopi Inframerah Transformasi Fourier (FTIR). Dua model isoterma penjerapan Langmuir dan Freundlich digunakan untuk menyelidik isoterma penjerapan. Model kinetik Pseudo-tertib pertama, Pseudo-tertib kedua, Elovich dan Intra-partikel untuk meneliti sifat kinetik. Penjanaan semula bahan penjerap komposit sehingga lima pusingan penjerapan atau nyahjerapan juga disiasat. Keputusan mendapati nisbah komposisi optimum komposit ialah 0.4 g lignoselulosa, 0.8 g karbon teraktif dan 0.8 g kaolin. Keadaan optimum penjerapan COD, NH3-N dan warna bagi penjerap komposit pada dos 4 g bahan penjerap, pH 8, halaju goncangan 150 PPM dan 120 minit masa sentuhan dengan penyingkiran maksimum masing-masing ialah 81.7%, 80.2% dan 93.3%. Luas permukaan (BET) bahan penjerap komposit ialah 63.60 m2/g dan nilai negatif potensi zeta menunjukkan potensi dalam proses penjerapan. Analisis pencirian FTIR dan SEM-EDX mendedahkan penukaran ion sebagai mekanisma utama sebelum dan selepas penjerapan. Model isoterma penjerapan menunjukkan bahawa data isoterma penjerapan komposit ini sesuai dengan isoterma Langmuir dan kinetic penjerapan menunjukkan pematuhan yang baik untuk model Pseudo-tertib kedua. Turus lapisan tetap dianalisa dan keputusan menunjukkan bahawa pada kadar aliran rendah 2 mL/min mematuhi model Thomas dan Yoon-Nelson berbanding dengan model Adam-Bohart. Analisis penjerapan atau nyahjerapan telah mencapai tiga kitaran kebolehgunaan penjerap komposit. Kesimpulannya, kajian ini telah membuktikan bahwa penjerap komposit berpotensi dalam menyingkirkan COD, NH3-N dan warna daripada air sisa getah asli