Regional Hypertrophy: The Effect of Exercises at Long and Short Muscle Lengths in Recreationally Trained Women.

The aim of the present study was to analyse the role of exercises' resistance profile in regional hypertrophy. Thirty-eight healthy women completed a 9-week resistance training program consisting of either 4 sets of 12 repetitions to volitional failure of inclined bicep curls (INC group) or preacher curls (PREA group), three times per week. Pre- and post-intervention muscle thickness was measured using B-mode ultrasound imaging with a linear-array transducer. Scan acquisition sites were determined by measuring 50%, 60% and 70% of the distance between the posterior crest of the acromion and the olecranon. Statistical significance was set at p < 0.05. No region of the INC group grew when comparing pre- to post-intervention. The 70% region of the PREA group grew significantly (muscle thickness increased from 2.7 ± 0.43 cm to 2.94 ± 0.44 cm). We found no growth differences between regions when analysing per group (p = 0.274), region (p = 0.571) or group*region (p = 0.367). Our results show that the distal region of the arm grows in response to the preacher curl that places the highest amount of strain in the range of motion in which the arm muscles are more elongated.

The soccer goalkeeper profile: bibliographic review.

OBJECTIVE: The main aim of this article was to review the existing scientific literature on the soccer goalkeeper. METHOD: This article has reviewed the scientific literature related to the soccer goalkeeper as long as they offered specific information about this position on the field, including a total of 56 scientific articles. RESULTS: The knowledge already recollected by authors to be able to apply it on training has been divided in the following chapters: anthropometric profile, conditional and performance profile (sprint, jump, agility, strength, aerobic capacity, mobility, and specific game technique), external load profile, and injury pathological profile. CONCLUSION: The most noteworthy conclusions obtained are: 1) the higher the level of the team, the higher and heavier the goalkeepers; 2) in early ages (9-13 years) the training of goalkeepers is not well posed, since compared to the players are worse both in physical capacities and technique; 3) the aerobic capacity at long distances does not influence the performance of the goalkeeper; 4) the sprint, the jump, the agility, and the mobility are factors that determine the performance of the goalkeeper; 5) the goalkeepers are less likely to be injured than the field players, but there are certain typical injuries in the position that must be protected by a proper way of strengthening and technique.

Analysis of Physical Demands in Four Tug of War World Indoor Championships (2010-2016).

Background: Tug-of-war (TOW) is one of the oldest sports in current existence and is an internationally played activity that includes professional and amateur sport athletes, played according to the rules laid out by the Tug of War International Federation (TWIF). In this type of competition, the two teams of eight members each pull against one another on a rope. The team that pulls the opposing team towards a centerline for a distance of 4 m in two pulls out of three is considered the winning team in an international competition. To the best of the authors' knowledge, no previous scientific articles have described data during a follow-up period of Championships in TOW. Therefore, the main aim of this study was to analyze the duration of the matches, differentiating between the first (T1) and second pull (T2) of each match. Methods: The pulls were compared in the qualification point phase and the final phase, as well as in each weight category. In addition, any differences between the statistics for each of the four World Championships studied were analyzed. Finally, the total volume of pulls in each weight category was studied, both in the open club competition and in the national team competition. Data were collected from four World Indoor Championships (2010−2016). A total of 1862 matches were registered (3724 pulls), differentiating the first (T1) and second (T2) pull. The data were expressed as means (M) ± standard deviations (SD). Results: (1) The second pull is shorter than the first: T1 < T2, p < 0.001, (Es = 0.452; small effect); (2) T1 and T2 times were longer in the final phase than the qualifying phase: T1 phase2 > T1 phase1, p < 0.05 (ES = 0.469; small effect) and T2 phase2 > T2 phase1, (p < 0.05), (ES = 0.486; small effect); (3) there are statistical differences (p < 0.005) in T1 and T2 at all weights, except for T1 at 500 kg and T2 at 640 kg; (4) the comparison among World Championships does not present significant changes in the duration of the pulls; (5) however, in females, significant differences (p < 0.05) between the 2010 World Championships and the remainder in T1 are observed; (6) the volumes that we should take into account when designing the preparation should be those obtained when 11 teams compete against each other, considering the maximum volume that we could find in the competition. Conclusion: This first aspect of the reality of TOW indoor competitions, specifically the duration of the matches, leads to a better understanding of the demands of the sport and the type of effort required. These ideas may help coaches in the design of training plans, maximizing their specificity and their effectiveness.

Analysis of Tug of War Competition: A Narrative Complete Review.

Tug-of-war (TOW) is an internationally played activity including professional and amateur athletes, defined as early as 4000 years ago (as a rope-less version) in the artwork on Egyptian tomb engravings, and is played as per the rules laid out by TWIF, which has 73 member countries and administrative headquarters in the USA. Typically, two teams of "pullers" participate and apply enormous contra directional forces on the pulling rope. Originally, two types of competition are used: knockout and points. This narrative review describes the scientific state of the art of TOW. To the best of the authors' knowledge, no previous information has been published on this topic. Anthropometric parameters for competitors are near 83.6, lean body mass 69.4, and body fat 16. The VO2MAX is 55.8 mL/kg/min. In terms of relative strength, the dynamic leg power is 4659.8 N. Endurance TOW elicits minimal muscle damage. Injured strains and sprains comprised over half of all injuries: back (42%), shoulder-upper limb (23%) and knee (17%). Pulling movement in TOW contests can be divided into three phases, namely the "drop", "hold" and "drive" phases. The maximal pulling force was 1041.6 ± 123.9 N. The percentage of dynamic pulling force in the static maximal pulling force was 75.5 ± 14.4% and the dynamic ranged from 106.4 to 182.5%. There are two gripping styles: indoor and outdoor. The friction characteristics between surface and shoe in TOW is important in determining a suitable shoe for indoor TOW. A waist belt might be a useful piece of equipment for TOW sport. The EMG technique in TOW entails a high degree of dorsal muscle activity during the pulling. The factor of force vanishing was the coordination among athletes. The force vanishing percentage goes from 8.82 ± 5.59 for two contenders to 19.74 ± 2.22 for eight athletes, 6.4% in the sum of two pullers. However, in the drop phase, for female elite TOW team, only the 0.5% of the pulling force was wasted. Future studies are need in order to understand better this historical sport activity.

Influence of Different Small-Sided Game Formats on Physical and Physiological Demands and Physical Performance in Young Soccer Players.

ABSTRACT: Castillo, D, Rodríguez-Fernández, A, Nakamura, FY, Sanchez-Sanchez, J, Ramirez-Campillo, R, Yanci, J, Zubillaga, A, and Raya-González, J. Influence of different small-sided game formats on physical and physiological demands and physical performance in young soccer players. J Strength Cond Res 35(8): 2287-2293, 2021-The aim of this study was to quantify the acute impact of bout duration and individual interaction space on physical and physiological demands and on physical performance. Ten young male soccer players (age: 14.8 ± 0.6 years) from the same team playing in the National U-16 Division participated. Physical (total distance [TD]; distance covered at different speeds; and maximum velocity [Velmax]) and physiological (peak [HRpeak] and mean [HRmean] heart rate) parameters were collected for every bout during each small-sided game (SSG) format. Moreover, the effects of SSGs on horizontal jump (HJ) and 30-m sprint performances were evaluated. The SSG formats were composed of 6 players a side (including goalkeepers) and included 4 repetitions of 6 minutes in a space of 100 m2 (SSG1) or 200 m2 (SSG2) and 6 repetitions of 4 minutes in 100 m2 (SSG3) or 200 m2 (SSG4). The TD, the distance covered at different speeds, and Velmax were greater (p < 0.01, effect size [ES] = 1.25-5.95, large) in SSG2 and SSG4 than SSG1 and SSG3, respectively. Furthermore, the HRmean and HRpeak were lower (p < 0.05, ES = 1.53-2.23, large) during SSG3 than other SSGs. In addition, while a significant (p < 0.05, ES = 0.70-2.04, moderate to large) increase in SPR30 time in SSG1 and SSG3 was observed, HJ performance was not affected (p > 0.05, ES = 0.03-0.54, trivial to moderate) by any SSG format. These findings suggest increasing pitch size to induce greater physical demands and to use SSGs with smaller pitch size, and independently of the bout duration, to induce neuromuscular fatigue.

Analysis of Playing Area Dimensions in Spanish Professional Soccer: Extrapolation to the Design of Small-Sided Games With Tactical Applications.

ABSTRACT: Caro, O, Zubillaga, A, Fradua, L, and Fernandez-Navarro, J. Analysis of playing area dimensions in Spanish professional soccer: Extrapolation to the design of small-sided games with tactical applications. J Strength Cond Res 35(10): 2795-2801, 2021-The aims of this study were to examine (a) the width and length dimensions of the playing area in 4v4 situations during competition, (b) the influence of the pitch zone where the ball is on 4v4 dimensions, and (c) the influence of match status on the dimensions of 4v4 situations. Data were collected from 25 matches from the Spanish La Liga of the 2007-2008 season using the Amisco system. Length, width, and individual playing area (IPA) of the rectangle that included the nearest 4 players to the ball from each team were collected in a total of 8,727 4v4 game situations. The pitch zone and match status were also considered for these 4v4 situations. To determine factors that affect 4v4 game situations, 1-way analysis of variance was used. The influence of the pitch zone where 4v4 situations took place showed significant differences (p < 0.001) between the zones where different principles of the game apply. The areas of the 4v4 situations ranged from 14.70 ± 4.69 × 17.18 ± 6 to 17.09 ± 5.16 × 20.34 ± 5.93 m, and the IPA of the 4v4 playing rectangle ranged from 46.33 ± 20 to 35.48 ± 16.95 m2, being larger in the central zones of the pitch. The length of the 4v4 rectangle showed a significant reduction in the closer zones to the goal. Match status did not affect the dimensions of these 4v4 game situations significantly. The findings of this study suggest that the size of 4v4 situations proposed for training should be designed according to the pitch zone where playing actions take place.

Tactical Variables Related to Gaining the Ball in Advanced Zones of the Soccer Pitch: Analysis of Differences Among Elite Teams and the Effect of Contextual Variables.

Attacking tactical variables have been commonly studied in soccer to analyze teams' performance. However, few studies investigated defensive tactical variables during match-play and the influence of contextual variables on them. The aims of the present study were (1) to examine the defensive behaviors of soccer teams when gaining the ball in advanced zones of the pitch and (2) to evaluate the effect of contextual variables on these defensive behaviors. A sample of 1,095 defensive pieces of play initiated in the opposing half of the pitch obtained from 10 matches of the season 2010/11 of La Liga and involving 13 teams was collected using the semiautomated tracking system Amisco Pro. Five defensive tactical variables, the outcome of defensive pieces of play, and contextual variables (i.e., match status, venue, quality of opposition, and match period) were recorded for every defensive piece initiated in the opposing half of the pitch. Results showed that there were significant differences among teams in the outcome of defensive pieces of play originating from the opposing half (χ2 = 111.87, p < 0.01, φc = 0.22), and in the outcome of offensive pieces of play following ball gains (χ2 = 49.92, p < 0.001, φc = 0.22). Cluster analysis revealed four groups describing different defensive behaviors from high-pressure to a defense close to their own goal. Match status (χ2 = 25.87, p < 0.05, φc = 0.11) and quality of opposition (χ2 = 21.19, p < 0.05, φc = 0.10) were the contextual variables that showed a significant effect on defensive pieces of play initiated in the opposite half of the pitch. Teams winning gained more balls in the zone close to their own goal, and losing teams gained more balls in advanced zones of the pitch. Moreover, the greater the quality of the opponent the lesser the chance of gaining the ball in advanced zones of the pitch. Neither venue or match period influenced the defensive pieces of play analyzed. Soccer teams could employ a similar analysis to improve their performance and prepare for opposition teams in competition.

Attacking and defensive styles of play in soccer: analysis of Spanish and English elite teams.

The aim of this study was to define and categorise different styles of play in elite soccer and associated performance indicators by using factor analysis. Furthermore, the observed teams were categorised using all factor scores. Data were collected from 97 matches from the Spanish La Liga and the English Premier League from the seasons 2006-2007 and 2010-2011 using the Amisco® system. A total of 19 performance indicators, 14 describing aspects of attacking play and five describing aspects of defensive play, were included in the factor analysis. Six factors, representing 12 different styles of play (eight attacking and four defensive), had eigenvalues greater than 1 and explained 87.54% of the total variance. Direct and possession styles of play, defined by factor 1, were the most apparent styles. Factor analysis used the performance indicators to cluster each team's style of play. Findings showed that a team's style of play was defined by specific performance indicators and, consequently, teams can be classified to create a playing style profile. For practical implications, playing styles profiling can be used to compare different teams and prepare for opponents in competition. Moreover, teams could use specific training drills directed to improve their styles of play.

El autoconcepto físico de jóvenes futbolistas de alto rendimiento / O autoconceito físico de jovens jogadores de futebol de alto rendimento / High-performance football young player's physical self-concept

Este estudio tiene por objeto precisar diferencias en el autoconcepto físico entre futbolistas jóvenes, noveles y veteranos, de alto rendimiento y estudiantes de su misma edad. Participan en el estudio 216 personas (114 futbolistas de alto rendimiento y 112 estudiantes que no tienen la condición de ser futbolistas de élite) de entre 14 y 23 años; los futbolistas, se dividen, a su vez, en 59 noveles (de 14 a 17 años) y 55 veteranos (de 18 a 23 años). Para la medición del autoconcepto se utilizó el Cuestionario de Autoconcepto Físico (CAF), de Goñi, Ruiz de Azúa y Rodríguez (2006). Los resultados ponen de manifiesto que el grupo de futbolistas de élite obtiene puntuaciones más altas, estadísticamente significativas, que el grupo de no-futbolistas en las autopercepciones de habilidad, condición, atractivo y fuerza así como en el autoconcepto físico general pero no en el autoconcepto general; no se verifican, sin embargo, diferencias entre futbolistas de élite noveles y veteranos (AU)

This study is intended to clarify differences in physical self-concept among high-performance football young players and students of the same age. Participating in the study 216 people (114 players, high-performance 112 students who have no status as elite players,) between 14 and 23 years; the players are divided, in turn, 59 junior and 55 senior, corresponding to the 14 age group to 17 and 18 to 23 years. For the measurement of self-concept questionnaire was used physical self (CAF), Goñi, Ruiz de Azua and Rodriguez (2006), composed of the following scales: physical ability, physical condition, physical attractiveness, physical strength and general physical self-concept as general self-concept. The results show that the group of elite players gets higher scores, statistically significant, than the group of non-elite players in five of the six dimensions of physical self-concept: skill, fitness, attractiveness, strength and self general physical self-concept but not in general, however, there are not differences between elite novel players and elite veteran players (AU)

Este estudo tem o objetivo de marcar as diferenças no autoconceito físico entre jovens jogadores, novatos e veteranos, de alto rendimento e estudantes de uma mesma idade. Participaram nesse estudo 216 pessoas (114 jogadores de futebol de alto rendimento e 112 estudantes que no eram jogadores de futebol de elite) entre 14 e 3 anos de idade; os jogadores de futebol se dividiam em 59 novatos (14 a 17 anos) e 55 veteranos (18 a 23 anos). Para medir o autoconceito foi utilizado o Questionário de Autoconceito Físico (CAF), Goñi, Ruiz de Azua y Rodriguez (2006). Os resultados manifestam que o grupo de jogadores de futebol de elite obtém pontuações mais altas estatisticamente significativas que o grupo de não jogadores de futebol nas autopercepções de habilidade, condição, atrativo e força, assim como no autoconceito físico geral, mas no autoconceito geral não foram encontradas diferenças entre jogadores de futebol de elite, novatos e veteranos (AU)

Analysis of entries into the penalty area as a performance indicator in soccer.

This study examines entries into the penalty area as a performance indicator that distinguishes between winning, drawing and losing soccer teams. It assesses whether entries into the penalty area are influenced by match status, a player's dismissal and the respective quality of the competing teams. Two observers analysed the relation between defensive and offensive strategies and their scoring consequences for all 64 matches played in the 2006 World Cup. Kappa values ranged between 0.93 and 0.98 for intra-reliability and between 0.88 and 0.98 for inter-reliability. It was found that winning teams received significantly fewer entries into their own penalty area (mean=41.42, s=11.86) than drawing (mean=50.07, s=14.75) and losing teams (mean=47.23, s=12.14). Teams that received more entries into their own penalty area than the opposing team were significantly more likely to concede a goal (P <0.001). Teams losing by one (mean=0.41, s=0.21), two (mean=0.42, s=0.26) or more than two goals (mean=0.34, s=0.13) received significantly fewer entries into the penalty area per minute than teams winning by one (mean=0.55, s=0.27) or two goals (mean=0.59, s=0.39). Teams with fewer players on the pitch received significantly more entries into the penalty area per minute than teams with more (mean=0.22, s=0.07) or the same number (mean=0.14, s=0.05) of players. Based on these results, it is suggested that teams should enter the opposing team's penalty area but should not allow their opponents to do the same. These results also highlight the significance of the dismissal of a player.

Designing small-sided games for training tactical aspects in soccer: extrapolating pitch sizes from full-size professional matches.

The aims of this study were to examine the (1) individual playing area, (2) length and width of the rectangle encompassing the individual playing area and (3) distance between the goalkeepers and their nearest team-mates during professional soccer matches and compare these to previously reported pitch sizes for small-sided games (SSGs). Data were collected from four Spanish La Liga matches of the 2002-03 season, and notated post-event using the Amisco system. The pitch sizes obtained from real matches were smaller and different from those used previously for SSGs. In addition, the current pitch sizes show significant (P < 0.001) effect of ball location in all variables examined. For example, overall individual playing area (F [5, 2562] = 19.99, P < 0.001, η2= 0.04) varied significantly across six different zones of the pitch. Based on these empirical results, pitch sizes with individual playing areas ranging from 65 m2 to 110 m2 and length to width ratio of 1:1 and 1:1.3 are generally recommended for training tactical aspects according to different phases of play. It is possible to design SSGs with a more valid representation of the tactical conditions experienced in full-size matches and their use may improve the training effect of tactical aspects of match performance in soccer.

Perfil condicional en jugadores de élite internacionales de baloncesto. Diferencias entre croatas y japoneses / Fitness profile in elite international senior male basketball players. Differences between Croatian and Japan team

Introducción: Existen numerosos estudios descriptivos sobre el perfil fisiológico, antropométrico y neuromuscular de jugadores de baloncesto. Estos trabajos analizan deportistas de diferentes países con tradición en nuestro deporte, jugadores de Serbia o Francia, pero también de territorios Donde no es una practica deportiva habitual, como por ejemplo la India. Sin embargo, no existe información científica que compare sujetos de diferentes países con diferentes niveles de rendimiento. Objetivo: El objeto de estudio fue comparar las diferencias entre 2 selecciones de baloncesto, un mes antes de iniciar el Campeonato de Europa y el Campeonato del Mundo, en relación a las capacidades fisiológicas, antropométricas y neuromusculares. Sujetos: 27 jugadores senior de baloncesto [equipo nacional Croata (Cro), n=14 y equipo nacional Japonés (Jap), n=13] participaron voluntariamente en este estudio. Métodos: Todas las medias fueron realizadas con el mismo aparataje. Se analizaron variables antropométricas [(Peso (W); Altura (H); porcentaje graso, Formula: Jackson, et al. (1980)],capacidades fisiológicas y neuromusculares [Test de contra movimiento(CMJ); Abalakov (AB) y Squat jump (SJ), Test de máxima velocidad (MST)], VO2 máx y Flexibilidad (FX).Resultados: Se observaron diferencias significativas entre equipos en H [Cro: 2.01 ± 0.8 cm vs. Jap: 1.91 ±0.8 cm; (p<0.05)] y en W (Cro: 102.94 ± 13.5 kg vs Jap: 88.00 ± 13.24kg; (p<0.05)]. Igualmente se describieron diferencias en las capacidades neuromusculares [CMJ (Cro: 36.30 ± 3.9 cm vs.Jap: 33.60 ± 4.3 cm; (p<0.01)], [AB (Cro: 61.73 ± 5.7 cm vs.Jap: 57.31 ± 4.4 cm; (p<0.05)], [SJ (Cro: 47 ± 2.3 cm vs. Jap:44.6 ± 3.8 cm; (NS)] y MST (Cro: 17.04 ± 1.4 m/sg vs. Jap:18.19 ± 1.4 m/sg; (p<0.01)]. Los croatas presentaron valoresmás altos en CMJ, AB y MST. [(FX) (Cro: 17.1 ± 3.23 cmvs. Jap: 18.3 ± 4.4 cm; (NS)]. No se describieron diferencias significantes en VO2 máx, SJ y FX. Conclusión: Los croatas son más altos y pesados que los japoneses, además de explosivos y rápidos, con valores superiores en variables neuromusculares. No se presentó diferencia alguna entre grupos ni en la capacidad aeróbica ni en el test de flexibilidad (AU)

Introduction: There are many descriptive studies about the physiological, anthropometrical and neuromuscular profile of top level basketball players. These articles describe players from different countries with tradition in basketball, Serbian, French players and also from countries where basketball is not a traditional sport, such as Indian players. However, there is no scientific data comparing players from different countries with different level of performance. Objective: The aim of this study was to compare the differences between two teams of top level basketball one month before starting either the European or the World Championship, in relation to discriminate physiological, anthropometrical and neuromuscular capacities. Subjects: 27 senior male basketball players [Croatia national team (Cro), n=14 and Japan national team (Jap), n=13] were volunteered for the study. Methods: All measurements were performed with the same equipment. Anthropometric characteristics [(Weight (W); Height(H); Body fat: Jackson, et al. (1980)]], Neuromuscular capacities[Countermovement Jump test (CMJ); Abalakov Jump (AB)and Squat Jump (SJ), Max Speed test (MST), Maximal Aerobic Capacity (VO2 máx)] and Flexibility (FX) were measured. Results: We have found significant differences between teams in H [Cro: 2.01 ± 0.8 cm vs. Jap: 1.91 ± 0.8 cm; (p<0.05)], and in W (Cro: 102.94 ± 13.5 kg vs. Jap: 88.00 ± 13.2 kg; (p<0.05)]. Equally, the statistical analysis described significant differences between groups in the neuromuscular capacities [(CMJ) (Cro: 36.30 ±3.9 cm vs. Jap: 33.60 ± 4.3 cm; (p<0.01)], [(AB) (Cro: 61.73 ±5.7 cm vs. Jap: 57.31 ± 4.4 cm; (p<0.05)], [(SJ) (Cro: 47 ± 2.3cm vs. Jap: 44.6 ± 3.8 cm; (NS)] and MST (Cro: 17.04 ± 1.4m/sg vs. Jap: 18.19 ± 1.4 m/sg; (p<0.1)]. Cro presented higher values in neuromuscular capacities (CMJ, AB and MST). [(FX)(Cro: 17.1 ± 3.2 cm vs. Jap: 18.3 ± 4.4 cm; (NS)]. No significant differences between teams were found in VO2 máx, SJ and FX. Conclusion: The Croatian players are higher and heavier than the Japanese, as well as explosive and fast with highest values in neuromuscular variables. There was no difference between groups, either in aerobic capacity or the flexibility test (AU)

Application of four different football match analysis systems: a comparative study.

Using a video-based time-motion analysis system, a semi-automatic multiple-camera system, and two commercially available GPS systems (GPS-1; 5 Hz and GPS-2; 1 Hz), we compared activity pattern and fatigue development in the same football match. Twenty football players competing in the Spanish second and third divisions participated in the study. Total distance covered during the match for the four systems was as follows: 10.83 + or - 0.77 km (semi-automatic multiple-camera system, n = 20), 9.51 + or - 0.74 km (video-based time-motion analysis system, n = 17), 10.72 + or - 0.70 km (GPS-1, n = 18), and 9.52 + or - 0.89 km (GPS-2, n = 13). Distance covered by high-intensity running for the four systems was as follows: 2.65 + or - 0.53 km (semi-automatic multiple-camera system), 1.61 + or - 0.37 km (video-based time-motion analysing system), 2.03 + or - 0.60 km (GPS-1), and 1.66 + or - 0.44 km (GPS-2). Distance covered by sprinting for the four systems was as follows: 0.38 + or - 0.18 km (semi-automatic multiple-camera system), 0.42 + or - 0.17 km (video-based time-motion analysing system), 0.37 + or - 0.19 km (GPS-1), and 0.23 + or - 0.16 km (GPS-2). All four systems demonstrated greater (P < 0.05) total distance covered and high-intensity running in the first 15-min period and less (P < 0.05) total distance covered and high-intensity running during the last 15-min period than all other 15-min intervals, with a reduction (P < 0.05) in high-intensity running from the first to the last 15-min period of 46 + or - 19%, 37 + or - 26%, 50 + or - 26%, and 45 + or - 27% for the semi-automatic multiple-camera system, video-based time-motion analysis system, GPS-1, and GPS-2, respectively. Our results show that the four systems were able to detect similar performance decrements during a football game and can be used to study game-induced fatigue. Rather large between-system differences were present in the determination of the absolute distances covered, meaning that any comparisons of results between different match analysis systems should be done with caution.