ANALYSIS OF MATCH AND TRAINING PERFORMANCE IN SOCCER USING GLOBAL POSITIONING SYSTEM TECHNOLOGY

It generally accepted that soccer is one of the most popular sports in the world. Thanks to technology development, a progressively increasing in studies about external load monitoring in soccer match and training were published. Currently, several are the systems available to simultaneously analyze movement patterns of many players during a soccer match, including video-based time motion analysis equipment and global positioning system (GPS) devices. However, the use of one of the first two methods depends on various factors linked to the strengths and weaknesses of each methodologies. As far as concern GPS technology, it has been demonstrated that GPS devices are reliable instruments for monitoring the true metabolic demands during intermittent or high-intensity exercises such as soccer activities. However, there are several concerns about the use of GPS device to assess the very high-speed bouts, short sprints and/or movements with many changes of direction, even more when the sample rate of the GPS device is low. Different studies have shown that reliability of GPS devices gradually decreases in relation to increasing number of changes of directions and accelerations and to reducing running distance. Thus, first aim of this thesis was to investigate the validity and accuracy of GPS technology with a sampling rate ≧10Hz in order to evaluate if it could produce better information on brief activities speed during short shuttle runs. Supporting by GPS technology, categories of movement described in relation to speed, acceleration or power thresholds, difference between playing position, analysis of fatigue during the match and physical demand in different soccer population (i.e adult versus young) have been analyzed during the training or game by researchers to better understand the workload imposed. Results obtained, in adult male players during a soccer match, identified in the high-intensity distance covered an important indicators of match physical performance. Instead, in youth players most information is available for players between 12 and 17 yr of age but, for very young players (<11 yr of age), data describing the activity profile during match play are limited and thus a less clear picture of the movement demands of these developing players is evident. Contrarily, information on match analysis about women’s soccer is relatively few and more confused if compared to those of men. Indeed, so far, there is not universally agreement upon standard velocity thresholds utilized to quantify the distances covered in different locomotor activities, especially for high-speed running and sprinting. However, just recently some studies have presented common recommendation that are now being adopted. Finally, it has been demonstrated that GPS technology could help to better evaluate the workload imposed by specific soccer training. In the last years, the methodology in soccer is changing and it became more difficult to check and program training in order to prevent injury. Not enough time is spent on physical conditioning without ball. Commonly, several technical and tactical exercises are considered the main activities during the soccer. The “modern” problem could be monitoring the global training load imposed from these type of training modalities. In this contest, the new available technologies could help coaches and sport scientists to better assessed the soccer training workload. Unfortunately, few studies investigated the relationship between GPS data and muscle fatigue after soccer-specific training sessions, and to our knowledge no data are available about the muscle impairments after different soccer training modalities and their relationship with external workload calculated using GPS devises. Therefore, the aims of this thesis were to describe the use of GPS technology in soccer. Four studies are developed in which the purposes were: 1) to evaluate the accuracy and inter-unit variability of a GPS device with a sampling rate of 20Hz for measuring mean and speed of shuttle runs; 2) to characterize match running performance of very young soccer players and evaluate the relationship between these data and physical capacities and technical skills; 3) to examine high-intensity distance covered during matches by elite female soccer players using different velocity thresholds and 4) to compare the decay in muscle performance after soccer-specific aerobic and traditional interval running training session.