Some anthropologic characteristics of elite female handball players at different playing positions

Differences in motor and psychologic variables according to playing positions were analyzed in a sample of 53 elite female handball players, members of junior and senior national team. Motor status included 8 variables for assessment of explosive strength of landing and throwing, agility, speed strength, movement frequency, and flexibility. Psychologic status was analyzed through 4 dimensions according to Eysenck: extroversion, psychotic behavior, neurotic behavior, and lie. The anthropologic features analyzed showed statistically significant differences. Considering motor abilities, differences were recorded in the variables for assessment of speed strength, agility and leg movement frequency, where wings predominated, whereas goalkeepers showed predominance in flexibility. In psychologic status, differences were present in the variable for assessment of extroversion, which was most pronounced in wings, whereas psychotic behavior was more expressed in those at pivot position. The differences were primarily consequential to the selection of players of a specific anthropologic profile for particular playing positions. The hypothesis of the impact of kinesiologic specificities of a particular playing position on the formation of the players' anthropologic profile should be scientifically tested. Study results may found application in training and contest practice, especially in forming anthropologic models for particular positions during the process of player selection.     

Competing with Lower Level Opponents Decreases Intra-Team Movement Synchronization and Time-Motion Demands during Pre-Season Soccer Matches

This study aimed to quantify the time-motion demands and intra-team movement synchronization during the pre-season matches of a professional soccer team according to the opposition level. Positional data from 20 players were captured during the first half of six pre-season matches of a Portuguese first league team. Time-motion demands were measured by the total distance covered and distance covered at different speed categories. Intra-team coordination was measured by calculating the relative phase of all pairs of outfield players. Afterwards, the percentage of time spent in the −30° to 30° bin (near-in-phase mode of coordination) was calculated for each dyad as a measure of space-time movement synchronization. Movement synchronization data were analyzed for the whole team, according to each dyad average speed and by groups of similar dyadic synchronization tendencies. Then, these data were compared according to the opponent team level (first league; second league; amateurs). Time-motion demands showed no differences in total distance covered per opposition levels, while matches opposing teams of superior level revealed more distance covered at very high intensity. Competing against superior level teams implied more time in synchronized behavior for the overall displacements and displacements at higher intensities. These findings suggest that playing against higher-level opponents (1^st league teams) increased time-motion demands at high intensities in tandem with intra-team movement synchronization tendencies.     

Leadership power perception of amateur and professional soccer coaches and players according to their belief in good luck or not

The purpose of this study was to analyze the leadership power perception of amateur and professional soccer coaches and players according to their belief in good luck or not. Data collected from 165 male soccer coaches and 870 male soccer players including professionals and amateurs. The coaches had a mean age of 40.24 years (SD = 8.40) and had been coaching for an average of 8.56 years (SD = 6.75). The players had a mean age of 18.40 years (SD = 4.00) and had been playing soccer for an average of 6.00 years (SD = 4.15) with license. Adapted Turkish version of Power in Soccer Questionnaire-Other (PSQ-O for soccer players), Power in Soccer Questionnaire-Self (PSQ-S for coaches) and an information form were used for the data collection. Cronbach Reliability Alphas of PSQ-O and PSQ-S range between 0.60 and 0.84. Players' and coaches' data were analyzed by Kruskal-Wallis and Mann Whitney Tests. Analysis of PSQ-O revealed significant differences related to Coersive Power-CP [chi2 (3) = 8.46, p < 0.037], Referent Power-RP [chi2 (3) = 14.84, p < 0.002] and Expert Power-EP [chi2 (3) = 7.63, p < 0.054], and no significant differences related to Legitimate Power-LP (p > 0.05). Results of PSQ-O and PSQ-S indicated complex relationships related to belief in good luck or not. Overall, there are differences between coaches' and players'perception of CP, LP and EP related to belief in good luck or not. The only similarity appears to be in perception of RP. However, there is lack of research to make more certain conclusions. Future researchers should also take into consideration gender, sport experience, age, taking responsibility, self-confidence, attributions, expectations, superstitions, emotions, perception of achievement etc.     

Relationship between physical fitness and playing ability in rugby league players

This study investigated the physiological, anthropometric, and skill characteristics of rugby league players and determined the relationship between physical fitness and playing ability in these athletes. Eighty-six rugby league players (mean +/- SD age, 22.5 +/- 4.9 years) underwent measurements of standard anthropometry (height, body mass, and sum of 4 skinfolds), muscular power (vertical jump), speed (10-, 20-, and 40-m sprint), agility (L run), and estimated maximal aerobic power (multistage fitness test). In addition, 2 expert coaches independently assessed the playing ability of players using standardized skill criteria. First-grade players had significantly greater (p < 0.05) basic passing and ball-carrying ability and superior skills under fatigue, tackling and defensive skills, and evasion skills (i.e., ability to beat a player and 2 verse 1 skills) than second-grade and third-grade players. While no significant (p > 0.05) differences were detected among playing levels for body mass; skinfold thickness; height; 10-, 20-, or 40-m speed; agility; vertical jump height; or estimated maximal aerobic power, all the physiological and anthropometric characteristics were significantly (p < 0.05) associated with at least 1 measure of playing ability. The results of this study demonstrate that selected skill characteristics but not physiological or anthropometric characteristics discriminate between successful and less successful rugby league players. However, all physiological and anthropometric characteristics were related to playing ability. These findings suggest that while physiological and anthropometric characteristics do not discriminate between successful and less successful rugby league players, a high level of physical fitness contributes to effective playing ability in these athletes. A game-specific training program that incorporates both physical conditioning and skills training may facilitate a greater transfer of physical fitness to competitive performances in rugby league.     

Aerobic capacities and anthropometric characteristics of elite female soccer players

Ingebrigtsen, J, Dillern, T, and Shalfawi, SAI. Aerobic capacities and anthropometric characteristics of elite female soccer players. J Strength Cond Res 25(12): 3352-3357, 2011-This study investigated aerobic capacities and anthropometric characteristics within a group of 29 elite female soccer players. The purpose was to identify and establish aerobic capacities and anthropometric characteristics for these players and to look for possible positional differences between keepers, defenders, midfielders, and attackers. We did this by measuring standard anthropometrical variables and maximal oxygen (VO(2)max) and anaerobic threshold (AT). One-way analysis of variance revealed no significant differences among anthropometric or physiological variables. However, a trend (p = 0.062) toward positional differences was found within running speed at AT. A subsequent Tukey post hoc test showed differences (p = 0.04) between keepers and defenders, with the latter running faster (～1.7 km·h) at AT. The present results suggest that few anthropometric and physiological differences exist between playing positions in elite female soccer players. Furthermore, the current results indicate that present elite players' physiological characteristics are similar to those previously shown, despite the rapid changes of the female soccer game. Based on well-established knowledge that different playing positions within a soccer team ought to have distinct capacities, we recommend regular testing programs to be able to construct and implement tailored training programs for players' physical capacities with respect to the demands of their playing positions.     

Changes in body composition, hormonal status, and physical fitness in 11-, 13-, and 15-year-old Finnish regional youth soccer players during a two-year follow-up

V?nttinen, T, Blomqvist, M, Nyman, K, and H?kkinen, K. Changes in body composition, hormonal status, and physical fitness in 11-, 13-, and 15-year-old Finnish regional youth soccer players during a two-year follow-up. J Strength Cond Res 25(12): 3342-3351, 2011-The purpose of this study was to examine the changes in body composition, hormonal status, and physical fitness in 10.8 ± 0.3-year-old (n = 13), 12.7 ± 0.2-year-old (n = 14), and 14.7 ± 0.3-year-old (n = 12) Finnish regional youth soccer players during a 2-year monitoring period and to compare physical fitness characteristics of soccer players with those of age-matched controls (10.7 ± 0.3 years, n = 13; 14.7 ± 0.3 years, n = 10) not participating in soccer. Body composition was measured in terms of height, weight, muscle mass, percentage of body fat, and lean body weight of trunk, legs, and arms. Hormonal status was monitored by concentrations of serum testosterone and cortisol. Physical fitness was measured in terms of sprinting speed, agility, isometric maximal strength (leg extensors, abdominal, back, grip), explosive strength, and endurance. Age-related development was detected in all other measured variables except in the percentage of body fat. The results showed that the physical fitness of regional soccer players was better than that of the control groups in all age groups, especially in cardiovascular endurance (p < 0.01-0.001) and in agility (p < 0.01-0.001). In conclusion, playing in a regional level soccer team seems to provide training adaptation, which is beyond normal development and which in all likelihood leads to positive health effects over a prolonged period of time.     

Response of patients to upper gastrointestinal endoscopy: effect of inherent personality traits and premedication with diazepam.

The influence of personality traits on the reaction of patients to upper gastrointestinal endoscopy was studied prospectively in 86 patients. High N (neuroticism) scores on the Eysenck personality inventory were associated with poor tolerance to and future compliance with the procedure. Although premedication with diazepam did not affect the degree of discomfort and distress during the procedure, it guaranteed acceptance of repeat endoscopy by virtue of its strong amnesic effect. By contrast, not giving premedication to patients who were anxious and had high N scores jeopardized future compliance. These findings suggest that a version of the Eysenck personality inventory should be used to assess patients'' neurotic phenotype and their need for premedication before endoscopy. Alternatively, all patients might be given premedication.     

The relationship between preseason range of motion and muscle strain injury in elite soccer players

The purpose of the study was to determine the influence of preseason lower-extremity range of motion (ROM) on the risk of muscle strain injury during a competitive season for elite soccer players. Thirty-six elite male soccer players (age, 25.6 +/- 4.7 years) had maximum static ROM for 6 movements of the lower extremity measured prior to the 2003-2004 English Premier League season. Player age, body size, dominant limb, and playing position were documented also. All lower-extremity muscle strain injuries were recorded prospectively during the competitive season, as was the total amount of time spent in training and games for each player. Soccer players sustaining a muscle strain injury in the hip flexors or knee flexors had lower preseason ROM (p < 0.05) in these muscle groups compared with uninjured players. Similar trends were observed for the remaining muscle groups, but all failed to reach statistical significance (p > 0.05). Most significantly, soccer players with lower preseason ROM in the hip flexors and knee flexors had a statistically higher risk for a muscle strain injury to these muscle groups during a competitive season. Age, body size, limb dominance, and playing position were not significant intrinsic risk factors for the development of muscle strain injuries. Screening of flexibility for soccer players should be conducted during preseason, and flexibility training should be prescribed to players with reduced ROM to lower the risk of developing a muscle strain injury.     

Evaluating sprinting ability, density of acceleration, and speed dribbling ability of professional soccer players with respect to their positions

The aim of this study is to evaluate sprinting ability, density of acceleration, and speed dribbling ability of professional soccer players with respect to their positions.A total of 243 professional soccer players were examined. These soccer players are playing in different leagues of Turkey. The F-MARC test battery, which was designed by FIFA, was used for soccer players. We did not find any statistical differences for 30-m sprint test and four-line sprint test values with respect to positions of soccer players (p > 0.05). On the other hand, there was a statistical difference for speed dribbling test values in terms of positions of soccer players (p < 0.05). It was found that the test values of defense players, midfielders, and forwards were better than the test values of goalkeepers (p < 0.05). In conclusion, this study, which was done during the training season, shows that there is a similarity between the abilities of professional soccer players for 30-m sprint and four-line sprint tests. Therefore, it is believed that there must be fast players in all positions in terms of sprint ability. There is a similarity among defenders, midfielders, and forwards in terms of speed dribbling ability; in contrast, the speed dribbling ability of goal keepers is different from the players in those three positions. Although there are many more speed dribbling exercises within the training programs of defenders, midfielders, and forwards, the speed dribbling ability test is not used much for goal keepers. Correspondingly, speed dribbling ability is not a specific indicator for goal keepers, and this test should not be used for the choice of goalkeepers.     

Physiological and anthropometric characteristics of young soccer players according to their playing position: relevance for the selection process

The aim of this study was to establish the anthropometric and physiological profiles of young nonelite soccer players according to their playing position, and to determine their relevance for the selection process. Two hundred forty-one male soccer players who were members of the Getxo Arenas Club (Bizkaia) participated in this study. Players, age 17.31 (+/- 2.64) years, range 14-21 years, were classified into the following groups: forwards (n = 56), midfielders (n = 79), defenders (n = 77), and goalkeepers (n = 29). Anthropometric variables of participants (height, weight, body mass index, 6 skinfolds, 4 diameters, and 3 perimeters) were measured. Also, their somatotype and body composition (weights and percentages of fat, bone, and muscle) were calculated. Participants performed the Astrand test to estimate their absolute and relative VO2max, an endurance test, sprint tests (30 meters flat and 30 meters with 10 cones) and 3 jump tests (squat jump, counter movement jump and drop jump). Forwards were the leanest, presenting the highest percentage of muscle. They were the best performers in all the physiological tests, including endurance, velocity, agility, and power. In contrast, goalkeepers were found to be the tallest and the heaviest players. They also had the largest fat skinfolds and the highest fat percentage, but their aerobic capacity was the lowest. In the selection process, agility and the jump tests were the most discriminating for forwards. In contrast, agility, height, and endurance were the key factors for midfielders. The defenders group was characterized by a lower quantity of fat. Thus, we may conclude that anthropometric and physiological differences exist among soccer players who play in different positions. These differences fit with their different workload in a game. Therefore, training programs should include specific sessions for each positional role.     

Anthropometric and physiological characteristics of young soccer players according to their playing positions: relevance for competition success

Lago-Pe?as, C, Casais, L, Dellal, A, Rey, E, and Domínguez, E. Anthropometric and physiological characteristics of young soccer players according to their playing positions: relevance for competition success. J Strength Cond Res 25(12): 3358-3367, 2011-The aim of this study was to establish the anthropometric and physiological profiles of young soccer players according to their playing position and to determine their relevance for competition success. Three hundred and twenty-one young male soccer players participated in the study. Players, age 15.63 (±1.82) years, range 12-19 years, were classified into the following groups: Goalkeepers (n = 35), Central Defenders (n = 53), External Defenders (n = 54), Central Midfielders (n = 61), External Midfielders (n = 46), and Forwards (n = 72). The anthropometric variables of participants (height, weight, body mass index, 6 skinfolds, 4 diameters, and 3 perimeters) were measured. Also, their somatotype and body composition (weights and percentages of fat, bone, and muscle) were calculated. Participants performed the 20-m progressive run test to estimate their relative VO(2)max, a sprint test (30 m flat), and 3 jump tests (squat jump, countermovement jump, and Abalakov test). External Midfielders were the leanest and shortest. In contrast, Central Defenders and Goalkeepers were found to be the tallest and heaviest players. They also had the largest fat skinfolds. In general, the results show that heavier and taller young soccer players performed better in vertical jumps and 30-m sprint, whereas leaner players performed better in the 20-m progressive run test. Players were classified into 2 groups according to the final ranking of their teams at the end of the season. Players from successful teams performed slightly better than players from unsuccessful teams in the physiological test, but these differences were not statistically significant. Moreover, players from successful teams were found to be leaner and more muscular than their unsuccessful counterparts.     

Influence of playing position on the site, nature, and cause of rugby league injuries

This study investigated the influence of playing position on the site, nature, and cause of injuries in rugby league. The incidence, site, nature, and cause of playing injuries was prospectively studied in 156 rugby league players over 2 seasons. An injury was defined as any pain or disability suffered by a player during a match that resulted in the player missing a subsequent match. The hooker (101 per 1,000 playing hours) and prop (92 per 1,000 playing hours) positions had the highest incidence of injury. Injuries sustained by the fullback (32 per 1,000 playing hours) and halfback (44 per 1,000 playing hours) positions were less common. Compared with other individual playing positions, props had a significantly higher incidence of overexertion injuries (22 per 1,000 playing hours), thigh and calf injuries (47 per 1,000 playing hours), and hematomas (19 per 1,000 playing hours), whereas the five-eighth position (31 per 1,000 playing hours) and the hookers and halves positional group (17 per 1,000 playing hours) had a significantly higher incidence of falling and stumbling injuries. These results demonstrate that the hooker and prop positions have higher injury rates than other rugby league positions. Furthermore, the site, type, and cause of injuries are different among individual playing positions and playing groups. These findings suggest that individual position training for injury prevention is warranted in rugby league.     

A valid field test protocol of linear speed and agility in rugby union

Field testing is a key component to measure player performance in all sports, which provides coaches and strength and conditioning staff information to evaluate player performance and measure desired training effects. Therefore, the purpose of this study was to investigate the reliability and construct validity of a rugby union field test protocol based on analysis of the components of the game. Participants were placed in an Academy (n = 17) or Club (n = 11) group determined by current playing level. Trials of 10- and 30-m linear speed (LS), change of direction speed, and reactive agility speed were measured to evaluate the field test protocol's utility in distinguishing players of different playing abilities. Reliability analysis of each field test demonstrated stable values allowing this field test protocol to be used to compare between groups. Furthermore, the Academy players performed significantly (p < 0.05) faster compared to Club players in all LS and agility components. These results suggest that this field test protocol is appropriate to identify rugby union players of varying playing abilities allowing coaches and strength and fitness staff to measure a player's capability to execute critical aspects of the game and may have application in performance evaluation and talent identification. The results from this study suggest that this test battery is an appropriate measure in identifying the varying playing abilities of rugby union players. This enables coaches and fitness staff to assess a player's capability in executing critical aspects of the game and also may have application in performance evaluation and talent identification.     

Correlates of tackling ability in high-performance rugby league players

This study investigated the tackling ability of high-performance rugby league players and determined the relationship between physiological and anthropometric qualities and tackling ability in these athletes. Twenty professional (National Rugby League) and 17 semiprofessional (Queensland Cup) rugby league players underwent a standardized 1-on-1 tackling drill in a 10-m grid. Video footage was taken from the rear, side, and front of the defending player. Tackling proficiency was assessed using standardized technical criteria. In addition, all players underwent measurements of standard anthropometry (height, body mass, and sum of 7 skinfolds), acceleration (10-m sprint), change of direction speed (505 test), and lower body muscular power (vertical jump). Professional players had significantly greater (p ≤ 0.05) tackling proficiency than semiprofessional players (87.5 ± 2.0 vs. 75.0 ± 2.3%). Professional players were significantly (p ≤ 0.05) older, more experienced, leaner, and had greater acceleration than semiprofessional players. The strongest individual correlates of tackling ability were age (r = 0.41, p ≤ 0.05), playing experience (r = 0.70, p ≤ 0.01), skinfold thickness (r = -0.59, p ≤ 0.01), acceleration (r = 0.41, p ≤ 0.05), and lower body muscular power (r = 0.38, p ≤ 0.05). When hierarchical multiple regression analysis was performed to determine which of the variables predicted tackling ability, playing experience and lower body muscular power were the only variables that contributed significantly (r2 = 0.60, p ≤ 0.01) to the predictive model. From a practical perspective, strength and conditioning coaches should emphasize the development of acceleration, lower body muscular power, and lean muscle mass to improve tackling ability in high-performance rugby league players.     

Discriminative ability of the Yo-Yo intermittent recovery test (level 1) in prospective young soccer players

We evaluated the sensitivity of the Yo-Yo intermittent recovery test-level 1 (Yo-Yo IR1) when discriminating among players in varying playing positions and different age categories in youth soccer. One-hundred and six prospective young soccer players, grouped on the basis of chronological age (under-13, under-14, under-15, under-16, under-17, under-18, and under-19) and playing position (center-backs, fullbacks, center midfielders, wide midfielders, and forwards), participated in the study. The players were administered a single Yo-Yo IR1 test at the beginning of the spring season. Analysis of variance revealed significant (F = 25.3; p < 0.001) group differences in Yo-Yo IR1 test performance scores among the observed age categories, and a systematic age-related increase in the Yo-Yo IR1 test performance was evident. Subsequent post hoc comparisons identified a number of significant differences among the selected age categories in Yo-Yo IR1 test performance. Analysis of covariance identified significant differences among playing positions (F = 3.1; p < 0.019) in the Yo-Yo IR1 test performance after controlling for age (F = 135.1; p < 0.001). Subsequent pairwise comparisons of the adjusted Yo-Yo IR1 test performance identified that center-backs had achieved significantly lower (all p < 0.01) performance scores than center midfielders, wide midfielders, and forwards, but not fullbacks. These results could be of practical value to coaches and scientists for further development of talent selection and profiling procedures in soccer, particularly because (a) the endurance performance represents a very important fitness component in selection and profiling of young soccer players and (b) the Yo-Yo IR1 test proved to be valid, reliable, and easily available measurement tool of a player's soccer-specific endurance capacity.     

Heart rate and blood lactate concentrations as predictors of physiological load on elite soccer players during various soccer training activities

The purpose of this investigation was to estimate the physiologic strain on players during various soccer training activities. Ten soccer players from the first division soccer league of Turkey were used as subjects. The heart rate responses were measured during 4 types of soccer training. First, the heart rates that corresponded to a blood lactate concentration of both 2 and 4 mM were measured, and then, during the 4 types of training, they were correlated with the proportion of time that the heart rate was below the 2-mM lactate line, between the 2- and 4-mM lactate lines, and above the 4-mM lactate line. Mean heart rates during friendly match, modified game, tactical training, and technical training activities were 157 +/- 19, 135 +/- 28, 126 +/- 21, and 118 +/- 21 b.min(-1), respectively. The differences between all of these soccer training activities were statistically significant (p < or = 0.01). The results demonstrate that (a) technical and tactical training consisted of very low exercise intensities (most of the heart rates were below the 4-mM lactate level) and (b) the percentages of time that the heart rate correlated to a point above the 4-mM lactate reference level during the friendly match and modified game were 49.6 +/- 27.1% and 23.9 +/- 24.5%, respectively. The practical implications of these findings are that, by using 2- to 4-mM reference lines, coaches can structure heart rate zones that can help determine the individualized exercise intensity for their players as well as estimate overall exercise intensity during soccer training.     

The social toll of Crohn's disease.

Eighty-five outpatients with Crohn''s disease who knew their diagnosis and that the disease was subject to relapse were interviewed. The personalities of the women as measured by the Eysenck personality questionnaire were similar to those of a control group, but the men were more neurotic and introverted. Most patients continued to live optimistic, useful lives; they felt well, continued to work, hoped that their disease would not deteriorate in the future, and often had an improved relationship with their spouse despite less frequent sexual intercourse. We found that the successful adaptation of patients to this chronic disease was more closely related to their personality than to the activity or extent of the disease.     

Normalizing expressions of strength in elite rugby league players

Physical strength has often been expressed per kilogram of body mass. Research suggests that strength increases in proportion to a body mass raised to a power between 0.6 and 0.7 rather than the ratio held exponent of 1. The current study was designed to identify differences in the strength of elite-level rugby league players and to identify whether ratio (per kg(-1)) expressions would penalize heavier subjects. Fifty-four elite rugby league players were recruited to the study during the preseason. Subjects were classified according to their highest playing level. Players performed 3 maximal lifts, using a dynamometer, to determine leg strength. Body mass and muscle mass estimations were also recorded. Results showed that absolute expressions of strength revealed differences by playing level (p < 0.05). These differences were removed when a ratio scaling technique was applied (p > 0.05). Mass and muscle mass exponents of 0.62 and 0.63 were derived and applied to the strength data. Differences in strength by playing level were reestablished following this adjustment (p < 0.05). These findings emphasize that ratio (per kg(-1)) expressions, despite being commonly used, can penalize heavier athletes and mask differences in performance. Coaches and sports scientists should reconsider using the ratio expression due to its potential for error when describing physical strength.     

Comparative study of field and laboratory tests for the evaluation of aerobic capacity in soccer players

The purpose of this study was to evaluate the maximal oxygen uptake (Vo(2)max) values in soccer players as assessed by field and laboratory tests. Thirty-five elite young soccer players were studied (mean age 18.1 +/- 1.0 years, training duration 8.3 +/- 1.5 years) in the middle of the playing season. All subjects performed 2 maximal field tests: the Yo-Yo endurance test (T(1)) for the estimation of Vo(2)max according to normogram values, and the Yo-Yo intermittent endurance test (T(2)) using portable telemetric ergospirometry; as well as 2 maximal exercise tests on the treadmill with continuous (T(3)) and intermittent (T(4)) protocols. The estimated Vo(2)max values of the T(1) test (56.33 ml.kg(-1).min(-1)) were 10.5%, 11.4%, and 13.3% (p < or = 0.05) lower than those of the T(2) (62.96 ml.kg(-1).min(-1)), T(3) (63.59 ml.kg(-1).min(-1)) and T(4) (64.98 ml.kg(-1).min(-1)) tests, respectively. Significant differences were also found between the intermittent exercise protocols T(1) and T(3) (p < or = 0.001) and the continuous exercise protocols T(2) and T(4) (p < or = 0.001). There was a high degree of cross correlation between the Vo(2)max values of the 3 ergospirometric tests (T(2) versus T(3), r = 0.47, p < or = 0.005; T(2) versus T(4), r = 0.59, p < or = 0.001; T(3) versus T(4) r = 0.79, p < or = 0.001). It is necessary to use ergospirometry to accurately estimate aerobic capacity in soccer players. Nevertheless, the Yo-Yo field tests should be used by coaches because they are easy and helpful tools in the training program setting and for player follow-up during the playing season.     

The influence of a congested calendar on physical performance in elite soccer

The aim of this study was to investigate recovery via analysis of activity profiles in a professional soccer team over an intense period of matches. A total of 172 outfield players from 27 Spanish League matches played by a professional team during the 2005-2006 season were analyzed using a multiple-camera match analysis system. The dependent variables were the distance covered by players at different intensities. Data were analyzed using an independent-sample t-test and a linear regression analysis with 5 independent variables: the number of matches played per week (1 or 2), match status (i.e., whether the team was winning, losing or drawing), match location (i.e., playing at home or away), quality of the opponents (strong or weak), and the individual playing position of the players. The main finding of this study suggests that the activity profiles of professional soccer players were not influenced by short recovery between matches. Although those players who played 2 matches a week covered less distance at maximal (>23 km·h(-1)), submaximal (19.1-23 km·h(-1)), and medium (14.1-19 km·h(-1)) intensities than those players who played 1 match a week, no significant differences were found. Moreover, results from this study seem to confirm that the elite soccer players' distance covered at various speeds is dependent on match contextual factors. The top-class players performed less high-intensity activity (>19.1 km·h(-1)) when winning than when they were losing (p < 0.05), but more distance was covered by walking and jogging when winning (p < 0.05). The home teams covered a greater distance than away teams at low intensity (<14.1 km·h(-1)) (p < 0.01). Finally, the better the quality of the opponent, the higher the distance covered by walking and jogging.