| Popis: |
Soccer is a demanding physical game which requires resistance on fatigue so as to improve the performance. The mechanisms which relate the fatigue and the performance (i.e. cognitive, physiological, physical, and technical factors) are described to the current study. Although, nowadays the small-sided games (SSG) are considered as the main method of increasing the physical condition there is a literature gap on the mechanisms that contribute to this relationship. Consequently, the aim of the current study was to examine how the 3Vs3 SSG affect the fatigue and how training either above or under the anaerobic threshold (AT) influence it differently. Six semi-professional male soccer players (age 17.4±0.5 years, height 1.70±0.14 m, body mass 65.0±4.8 kg), participated in the study. It was measured the anaerobic threshold, the maximal oxygen uptake (VO2max), and the maximal heart rate (HRmax) of each player on the treadmill. The researchers also examined the heart rate, the blood lactic acid, the visual reaction, the juggling and the maximal ball speed during shooting of each player. The statistical analysis that was used was descriptive statistics and pairwise comparisons. The results revealed the relationships between fatigue and technical skills (i.e. anaerobic threshold and maximal ball speed during shooting). Specifically, it was found that players who practiced above AT presented a stronger reduction of the maximal ball speed during shooting. INTRODUCTION The main target in soccer is the continuous improvement of the player’s and team’s performance, which is a consequence of the psychological, social, tactical, technical and physiological interactions (Bangsbo, 1994; Little & Williams, 2006). Soccer is mainly a physical game which requires techniques with (controls, passes, dribbles, shoots) and without the ball (jogging, sprints, tackles, jumps, challenges) and characterized as both an aerobic and anaerobic sport (Acikada, Hazir, Asci, Turnagol, & Ozkara, 1998; Stolen, Chamari, Castagna, & Wisloff, 2005). The significance of endurance in soccer is supported from literature which concludes that players cover around 10 to 12 kilometers during a match (Dellal, Chamari, Wong, Ahmaidi, Keller, Barros, Bisciotti, & Carling, 2010; Di Salvo, Baron, Tschan, Calderon Montero, Bachl, & Pigozzi, 2007). Three decades ago, Edwards (1983) defined fatigue as the failure to maintain the required or expected power output. Specifically, the fatigue is described as a decrease of maximal force and power which is connected to a sustained exercise and is reflected in a lower performance (Rahnama, Reilly, Lees, GrahamSmith, 2003). Many findings demonstrated a reduction in physical performance during the match as the players perform less sprints and running of high intensity on the second half of the match (Krustrup, Mohr, Steensberg, Bencke, Kjaer, & Bangsbo, 2006; Mohr, Krustrup, Bangsbo, 2003; Rampinini, Impellizzeri, Castagna, Abt, Chamari, Sassi, & Marcora, 2007). Specifically, soccer is a demanding sport in which more than 90% of the energy that a match requires is produced through the aerobic metabolism in means values close to the anaerobic (Bangsbo 1994; Helgerud, Engen, Wisloff, & Hoff, 2001; Stolen et al., 2005). The fatigue that the players present is also associated to the reduction of cognitive factors such as decision making, game intelligence and the team tactics which probably influence the technical characteristics (Bangsbo, 1994; Cian, Koulmann, Barraud, Raphael, Jimenez, & Melin, 2000; Hoff, Wisloff, Engen, Kemi, & Helgerud, 2002; Ostojic & Mazic, 2002; Williams & Reilly, 2000). The fatigue in high intensity intermittent exercise (i.e. soccer), is a consequence of the progressive loss of muscle glycogen, blood glucose, body fluids, disturbed muscle ion homeostasis and an increase of hyperthermia (Mohr, Krustrup, & Bangsbo, 2005). Factors such as the maximal oxygen uptake (VO2max) and anaerobic threshold (the exercise intensity at which blood lactic starts to accumulate in the blood stream), are also associated to the reduction of physical performance (Helgerud et al., 2001). It is obvious that performance is affected directly and indirectly by many factors. One factor that is connected to higher performance is reaction time to visual stimulus. Specifically, soccer players are required to analyze the information of the environment (ball movement, players’ pitch position) and take quick decisions on a basis of visual reaction ability (Ado, Kida, & Oda, 2001; Williams, Davids, Burwitz, & Williams, 1994). This ability is probably affected by the fatigue. There are also findings which support the relationship between fatigue and technical skills. Specifically, the researchers concluded that the speed and velocity of passing and shooting were decreased because of fatigue (Helgerud et al., 2001; Lyons, Al-Nakeeb, & Nevill, 2006; Russell et al., 2011; Stone & Oliver, 2009). However the findings about the influence of fatigue on dribbling are conflicted (Russell, Benton, & Kingsley, 2011; Stone & Oliver, 2009). Passing and shooting are very important factors which are associated to the score of a game and differentiate the high and low performance teams (Rampinini, Impellizzeri, Castagna, Coutts, & Wisloff, 2009; Sajadi & Rahnama, 2007). Fatigue also affects the technical abilities through changes on biomechanical characteristics of the skill (Kellis, Katis, & Vrabas, 2006). Although the obvious relationship between fatigue and technical skills, there is a lack of literature about the physiological factors which influence each technical skill. Nowadays, trainers use mainly small-sided games (SSG) so as to achieve an improvement by |
