PHYSIOLOGICAL RESPONSES AND TIME-MOTION CHARACTERISTICS OF 4-A-SIDE SMALL-SIDED GAME IN YOUNG SOCCER PLAYERS: THE INFLUENCE OF DIFFERENT TEAM FORMATION METHODS YUSUF KÖKLÜ,1 GÜLFEM ERSÖZ,2 UTKU ALEMDAROĞLU,1 ALPER Asxc xı,3 AND ALI ÖZKAN4 1 School of Sport Sciences and Technology, Pamukkale University, Denizli, Turkey; 2School of Physical Education and Sports, Ankara University, Ankara, Turkey; 3School of Sport Sciences and Technology, Hacettepe University, Ankara, Turkey; and 4 Department of Sport Sciences, Basxkent University, Ankara, Turkey ABSTRACT Köklü, Y, Ersöz, G, Alemdaroğlu, U, Asxc xı, A, and Özkan, A. Physiological responses and time-motion characteristics of 4-A-side small-sided game in young soccer players: The influence of different team formation methods. J Strength Cond Res 26(11): 3118–3123, 2012—The purpose of this study was to examine the influence of different team formation methods on the physiological responses to and time-motion characteristics of 4-a-side small-sided games (SSG4) in young soccer players. Thirty-two young soccer players (age 16.2 6 0.7 years; height 172.9 6 6.1 cm; body mass 64.1 6 7.7 kg) voluntarily participated in this study. Anthropometric measurements, technical tests, and maximum oxygen uptake (V_ O2max) tests were carried out on the players. The SSG4 teams were then created using 4 different methods: according to the coaches’ subjective evaluation (CE), technical scores (TS), V_ O2max (AP), and V_ O2max multiplied by TSs (CG). The teams thus created played 4 bouts of SSG4 at 2-day intervals. During the SSG4, heart rate (HR) responses, distance covered, and time spent in HRmax zones were recorded. In addition, rating of perceived exertion (RPE) and blood lactate level (La2) were determined at the end of the last bout of each SSG4. Percent of HRmax (%HRmax), La2, and RPE responses during SSG4 were significantly higher for teams chosen according to AP and CG compared with that according to CE and TS (p , 0.05). In addition, teams chosen by AP and CG spent significantly more time in zone 4 (.90% HRmax ) and covered a greater distance in the high-intensity running zone (.18 kmh21) than did teams formed according to TS. Moreover, AP teams covered significantly greater total distance than TS teams did (p , 0.05). In Address correspondence to Yusuf Köklü, [email protected]. 26(11)/3118–3123 Journal of Strength and Conditioning Research Ó 2012 National Strength and Conditioning Association 3118 the conclusion, to spend more time in both the high-intensity HR zone and the high-intensity running zone, the teams in SSG4 should be formed according to the players’ V_ O2max values or the values calculated using both the V_ O2max and technique scores. KEY WORDS aerobic endurance, heart rate, blood lactate, rating of perceived exertion, time-motion analysis INTRODUCTION E ffective performance in soccer, a game that requires jumping, shooting, challenges, turns, dribbles, sprints, controlling the ball under pressure, running at different speeds, and sliding tackles is dependent on both aerobic and anaerobic metabolism (1,29). Because various movements are involved in this sport, a number of factors, such as technical ability and endurance capacity, are thought to affect the players’ performance on the pitch. Traditionally, most coaches have used running drills without the ball to develop soccer players’ physical endurance (23). However, small-sided games (SSGs) are thought to be more suitable than this traditional interval training for the development of the particular physical characteristics required for matches because they involve the actual movement types and patterns used in soccer (21). A number of studies have examined exercise intensity in SSGs (2,7,8,13,19,20,22,26–28). For example, Aroso et al. (2) found that increasing the number of players without changing the pitch size resulted in lower La2 levels over 3 bouts of 2-a-side, 3-a-side, and 4-a-side games, whereas the HR response in 3-a-side games was lower than that in both 2-a-side and 4-a-side games. In another study, Rampinini et al. (28) revealed that exercise intensity during SSGs can be influenced by both the field dimensions and coach encouragement by studying 3 bouts of 3-a-side, 4-a-side, 5-a-side, and 6-a-side games involving amateur soccer players. In contrast to Rampinini et al.’s results, Kelly and Drust (19) reported that changes in pitch size did not alter the HR TM Journal of Strength and Conditioning Research Copyright © National Strength and Conditioning Association Unauthorized reproduction of this article is prohibited. the TM Journal of Strength and Conditioning Research response over 4 bouts of SSGs involving the same number of players. In addition, Hill-Hass et al. (13) found that changes to playing rules in SSGs influenced physiological and timemotion responses in young elite soccer players, whereas Mallo and Navarro (26) reported that the inclusion of goalkeepers in SSGs reduced the tempo of the game because this led to less high-intensity running and increased lowintensity activities. In summary, previous studies have shown that factors such as field dimensions, the number of players, game rules, coach encouragement, and training regime can lead to changes in physiological responses, time spent in high-intensity exercise, and differences in distance covered during the SSGs (14,16,28). In addition to these parameters, the means of formation of opposing teams can influence exercise intensity during SSGs. Previous studies have used various methods for the formation of teams in SSGs. In most studies, SSG teams selected according to the coach’s subjective evaluation (7,13,18,20). More recently, some studies have taken issues of skill and fitness mismatches into account in the formation of SSG teams and have instead attempted to achieve a balance across opposing teams in terms of individual players’ composite skill and fitness ranking (4,14,16). However, the influence on SSG performance of different team formation methods is an issue that no previous studies have examined. Findings resulting from such a study are likely to be useful to soccer coaches who are interested in using SSGs to develop simultaneously the technical capacity and soccer-specific aerobic endurance of the players that they train. Therefore, the purpose of this study was to examine the influence of different team formation methods on the physiological responses to and time-motion characteristics of 4-a-side small-sided games (SSG4) in young soccer players. METHODS Experimental Approach to the Problem A number of studies have been conducted to investigate the various factors that can influence exercise intensity during SSGs. However, the influence of different team formation methods is a factor that has been largely overlooked, despite the fact that disregarding differences in players’ technique and fitness levels when selecting SSG teams may create imbalances between the players and the teams in terms of exercise intensity. With this gap in our current knowledge in mind, this study aimed to examine the influence of different team formation methods on SSG4 performance amongst young soccer players. This study was carried out over a 2-week preseason training period in September 2010–2011, during which the 32 young soccer players who participated were not involved in any other training or matches. On the first day, anthropometric measurements (height, body mass, skinfold thickness, circumference measurements) were carried out on the players. On the third day, a series of technical tests were carried out, including ball control using the body, | www.nsca.com ball control with the head, slalom dribbling with passing, slalom dribbling, passing accuracy, and shooting accuracy, to determine each player’s technical score (TS). On the fifth and sixth days of the study, each player’s V_ O2max was determined using an incremental test on a treadmill. After these tests, the SSG4 teams were created using 4 different methods, coaches’ subjective evaluation (CE), TS, AP, and TG: CE rankings were established according to the CE; TS rankings considered each player’s technical test scores; the AP method ranked players according to their V_ O2max scores obtained from the incremental treadmill test; TG rankings were created by multiplying each player’s V_ O2max score by his TS. Once an overall ranking had been obtained for all 32 players according to the CE, TS, AP, and TG methods, the players could be divided into 4 groups of 8 from ÔbestÕ to ÔworstÕ (1–8; 9–16; 17–24; 25–32), after which each group of 8 was divided into 2 teams of 4 using alternate rankings for the SSG bouts, as shown in Table 1. On the eighth, tenth, twelfth, and fourteenth days of the study, the players played 4 SSG4 bouts in teams formed using the AP, TS, CE, and TG methods, respectively. Subjects Thirty-two young soccer players (average age 16.2 6 0.7 years; height 172.9 6 6.1cm; body mass 64.1 6 7.7 kg; average training age 6.2 6 2.0 years; percentage of body fat 7.5 6 3.0%; HRmax 198.1 6 5.7 bmin21) voluntarily participated in this study. All the players were the members of the same youth team competing in an elite academy league and trained for 2 hours 5 dwk21. All the players and parents were notified of the research procedures, requirements, benefits, and risks before giving informed consent. Written informed consent was obtained from all the subjects and parents. The study was approved by the Ankara University Ethics Committee and was conducted in a manner consistent with the institutional ethical requirements for human experimentation in accordance with the Declaration of Helsinki. Procedures Incremental Treadmill Test. All the players completed an incremental treadmill test on a motorized treadmill (Cosmed, Gambettola, Italy) at an incline of 1% to determine maximal oxygen uptake (V_ O2max) and maximum heart rate (HRmax). The test began at 9 kmh21 and the speed was increased by 1 km h21 every minute with exhaustion being reached in 8–12 minutes (28). Achievement of V_ O2max was considered as the attainment of at least 2 of the following criteria: (a) a plateau in V_ O2max despite increasing speed, (b) a respiratory exchange ratio above 1.10, and (c) HR 6 10 bmin21 of age-predicted maximal HR (220 2 age) (3). During the test, expired gases were analyzed using a breath-by-breath automated gas-analysis system (Oxycon Mobile; Viasys Healthcare, Hoechberg, Germany). The flow, volume, and gas analyzer were calibrated before each test according to the manufacturer’s instructions. The HR was measured and the measurements stored using HR monitors (Polar Electro OY, VOLUME 26 | NUMBER 11 | NOVEMBER 2012 | 3119 Copyright © National Strength and Conditioning Association Unauthorized reproduction of this article is prohibited. Characteristics of 4-A-Side Small-Sided Game Small-Sided Games. A 36-m 3 24-m pitch size (length 3 TABLE 1. SSG4 team formation using CE, TS, AP, and CG rankings.* width) was used for the SSG4 (20,28). Each SSG4 consisted First teams (player ranks) Second teams (player ranks) of 4 bouts of 4 minutes’ duraFirst SSG4 match 1st, 3rd, 5th, 7th 2nd, 4th, 6th, 8th tion with 2 minutes’ passive Second SSG4 match 9th, 11th, 13th, 15th 10th, 12th, 14th, 16th recovery time between the Third SSG4 match 17th, 19th, 21st, 23rd 18th, 20th, 22nd, 24th bouts. No specific rules were Fourth SSG4 match 25th, 27th, 29th, 31st 26th, 28th, 30th, 32nd used in the games to influence *CE = coaches’ subjective evaluation; TS = technical scores; AP = V_ O2max; CG = V_ O2max their intensity, but spare balls multiplied by technical score; SSG4 = 4-a-side small-sided games. were kept all round the pitch to ensure that the game would restart immediately if the ball left the field of play. Moreover, Kempele, Finland) throughout the test. The stored data were the coaches continually offered verbal encouragement to the transferred to the computer and filtered by Polar Precision players during the games. The SSG4s were played without Performance SoftwareTM (PPP4, Finland). The highest HR a goalkeeper, and used small goals on a synthetic grass soccer measurement was recorded as HRmax. pitch. All the SSG4s were performed at the same time of the day to avoid any effect of circadian rhythms on the measured variables (9), with at least 2 days separating each session. Each SSG4 was performed after a 20-minute warm-up Technical Skill Tests. The technical skill test battery used by consisting of low-intensity running, striding and stretching. Malina et al. (24,25) was used to calculate the players’ technical skill scores. This test battery consists of 6 technical tests: ball control with the body, ball control with the head, slalom dribbling with passing (focusing on speed and accuracy), slalom dribbling (focusing on speed), passing accuracy, and shooting accuracy (24,25). After all the technical skill tests, Z scores were calculated for each test; the scores were reversed for the 2 timed items because lower times reflect better performance (25). The Z scores were summed to provide a composite soccer skill score for each player. The intraclass correlations for repeated measures (analysis of variance) indicated reasonable reliability: 0.72 for passing, 0.72 for ball control with the head, 0.73 for shooting, 0.88 for dribbling speed, 0.85 for ball control with the body, and 0.86 for dribbling with passing. Heart Rate Monitoring. The HR was recorded at 1-second intervals during the SSG4 bouts using short-range radio telemetry (Polar Team Sport System, Polar Electro). Exercise intensities during the SSG4 bouts were assessed using HR, expressed as a percentage of HRmax as measured in the treadmill test and classified into 4 previously defined intensity zones: zone 1 (,75% HRmax), zone 2 (75–84% HRmax), zone 3 (85–89% HRmax), and zone 4 (.90% HRmax) (14). Both the actual time and percentage of the total time spent in each zone for each player during all the SSG4s were recorded. The data were categorized into HR zones using Team AMS software (GPSports, Canberra, Australia). TABLE 2. Physiological responses associated with 4-a-side games according to different methods of team formation.*† CE %HRmax Time spent at ,75 % HRmax (s) Time spent at 75–84.9% HRmax (s) Time spent at 85–89.9% HRmax (s) Time spent at .90 %HRmax (s) La2 (mmolL21) RPE 88.3 65.1 130.2 239.5 525.1 6.41 5.0 6 1.7‡ 6 23.1‡ 6 32.4§ 6 55.6 6 79.9 6 0.6§ 6 0.8§ TS 88.1 6 62.0 6 131.8 6 263.2 6 502.9 6 6.2 6 5.5 6 3.5‡ 19.3‡ 31.9§ 50.4 65.4§ 0.7§ 1.0§ AP CG 90.1 6 1.8 43.7 6 27.1 95.6 6 35.3 235.9 6101.6 584.8 6133.8 7.0 6 0.7 6.1 6 1.0 89.2 6 2.8 52.2 6 29.1 105.4 6 46.6 222.0 6 88.3 580.2 6 136.6 6.8 6 0.6 6.1 6 1.0 *CE = coaches’ subjective evaluation; TS = technical scores; AP = V_ O2max; CG = V_ O2max multiplied by technical scores; %HRmax = percentage of maximum heart rate; La2 = blood lactate; RPE = rating of perceived exertion. †Values are given as mean 6 SD. ‡Significant difference from AP, p , 0.05. §Significant difference from AP and CG, p , 0.05. 3120 the TM Journal of Strength and Conditioning Research Copyright © National Strength and Conditioning Association Unauthorized reproduction of this article is prohibited. the TM Journal of Strength and Conditioning Research | www.nsca.com TABLE 3. Time-motion characteristics associated with 4-a-side games for different methods of team formation.*† CE Total Total Total Total Total distances distances distances distances distances 21 743.8 6 at 0–6.9 kmh (m) 888.6 6 at 7–12.9 kmh21 (m) at 13–17.9 kmh21 (m) 300.6 6 at .18 kmh21 (m) 66.4 6 (m) 1,999.5 6 TS AP CG 79.2‡§ 815.8 6 100.2 683.6 6 88.6§ 723.7 6 200.5‡ 872.4 6 199.0‡ 994.0 6 198.9 939.5 6 89.0§ 215.3 6 87.4 304.1 6 93.5§ 301.8 6 37.9 47.1 6 31.3 78.5 6 39.8§ 74.7 6 194.7 1,950.6 6 222.8‡ 2,060.3 6 199.6 2,039.7 6 122.2§ 160.9 103.7§ 32.7§ 151.7 *CE = coaches’ subjective evaluation; TS = technical scores; AP = V_ O2max; CG = V_ O2max multiplied by technical scores. †Values are given as mean 6 SD. ‡Significant difference from AP, p , 0.05. §Significant difference from TS, p , 0.05. Blood Sampling. Blood lactate samples were taken at 3 minutes after the end of the last bout. The twenty-five-microliter blood samples, taken from the ear lobe, were kept in YSI Preservative Kits (Code 2315, YSI Incorporated Life Sciences, Yellow Springs, OH, USA). Blood samples were taken from all the players; lactic acid analyses were carried out the same day using the YSI 1500 SPORT lactate analyzer (YSI Incorporated Life Sciences). The calibration of the analyzer was conducted according to the manufacturer’s instructions. characteristics. A Bonferroni post hoc test was applied to make a pairwise comparison between the different levels of withinplayer factors. The level of statistical significance was set at p # 0.05. Effect sizes (h2) were also calculated for physiological responses and time-motion characteristics. RESULTS Time-Motion Characteristics. Player movements during the SSG4s were measured using portable global positioning system (GPS) units (SPI ProX; GPSports) and were analyzed using Team AMS software (GPSports, Canberra, Australia). The SPI ProX equipment with a 15-Hz sampling rate was placed into a harness that positioned the device between each player’s shoulder blades; they were worn by all players during the SSG4 bouts. This technology has been previously determined as reliable and validated for monitoring players’ high-intensity and sprinting activities during soccer matches (5,17). For data analysis purposes, 4 speed zones were selected: speed zone 1 (standing and walking, 0–6.9 kmh21), speed zone 2 (low-intensity running, 7.0–12.9 kmh21), speed zone 3 (medium-intensity running, 13.0–17.9 kmh21), and speed zone 4 (high-intensity running, .18 kmh21) (4,16). Table 2 shows the physiological characteristics associated with SSG4 for the different team formation methods. Compared with teams selected according to CE and TS, SSG4 teams formed considering AP and CG measures showed a significantly higher percent of HRmax (F = 8.283; p , 0.05 and h2 = 0.211), La2 (F = 7.205; p , 0.05 and h2 = 0.473), and RPE (F = 15.150; p , 0.05 and h2 = 0.328) responses. In addition, AP and CG teams spent significantly more time than those formed considering TS measures at zone 4 (F = 7.177; p , 0.05 and h2 = 0.188 ), whereas TS and CE teams spent more time at zone 1 (F = 7.927; p , 0.05 and h2 = 0.204 ) than did AP teams and at zone 3 (F = 11.968; p , 0.05 and h2 = 0.279 ) than did AP and CG teams. Table 3 shows the time-motion characteristics associated with SSG4 for the different methods of team formation. The AP and CG teams covered significantly greater distances at speed zone 4 (F = 7.264; p , 0.05 and h2 = 0.190) than did TS teams. Moreover, SSG4 teams created according to AP covered significantly greater total distances (F = 4.155; p , 0.05 and h2 = 0.118) than did TS teams. Furthermore, TS teams covered greater distances at speed zone 1 (F = 14.265; p , 0.05 and h2 = 0.315) but less distance at speed zone 3 (F = 13.413; p , 0.05 and h2 = 0.302) than did teams selected using CE, AP, and CG methods. Statistical Analyses DISCUSSION The data are reported as means and SDs. Before using parametric tests, the assumption of normality was verified using the Shapiro-Wilk test. A 1-way repeated-measures analysis of variance was performed on each dependent variable, including percentage of HRmax, rating of perceived exertion (RPE), blood lactate concentration, and the time-motion The purpose of this study was to examine the influence of different team formation methods on physiological responses and time-motion characteristics during SSG4s in young soccer players. The main finding is that type of team formation method does have an influence on physiological responses and time-motion characteristics for these players in these games. Rating of Perceived Exertion. A perceived exertion rating scale, CR-10 (11), was completed by each player no more than 2 minutes after the end of the last bout. Before the SSG4s, all the players were informed about, and familiarized with, the CR-10 scale, which has been validated as an indicator of training intensity in intermittent bouts of small-sided games (6,14). VOLUME 26 | NUMBER 11 | NOVEMBER 2012 | 3121 Copyright © National Strength and Conditioning Association Unauthorized reproduction of this article is prohibited. Characteristics of 4-A-Side Small-Sided Game Small-sided games are thought to be suitable for developing the particular physical characteristics that players need to be able to perform under conditions of pressure and fatigue (12). This is because these types of game include high-intensity activities (short sprints, tackling, and sliding) involving various movement types and patterns similar to those used in soccer matches (21). These games are played on different pitch sizes, with a different number of players and periods of time. Factors such as enlarging or decreasing the playing area, increasing or reducing the number of players, changing the rules (e.g., 1 touch play, controlled passing), and the coach encouragement are thought to affect physiological responses during SSGs (28). For example, Köklü et al. (20) demonstrated that a decreased number of players results in increased La2, HR, and % HRmax responses over 6 bouts of SSGs. Moreover, Aroso et al. (2) reported that an increase in the number of players with a constant pitch size results in significantly different HR, %HRmax, and La2 responses among the SSGs. Similarly, Williams and Owen (30) found that an increased number of players with a constant pitch size results in a decrease in physiological responses during SSGs. Fanchini et al. (10) demonstrated that exercise intensity in 3-a-side SSG is influenced by bout duration, with a reduction in the HR for SSGs of 6-minute duration. Rampinini et al. (28) reported that %HRmax, La2, and RPE responses during small-sided games can be influenced by varying the exercise type, the field dimensions, and presence of coach encouragement. Moreover, Hill-Haas et al. (13) found that changes to SSG rules or game formats may influence the %HRmax and RPE responses independently. In this study, physiological responses are determined according to %HRmax (22,28), time spent on different HRmax zones (4,16), La2 (2), and RPE (6) during the SSG4s. The findings of this study are that the highest physiological responses to SSG4s are produced in teams created according to AP scores, followed by CG, CE, and TS scores, respectively. This study also demonstrates that the players in teams created using AP and CG formation methods have significantly higher %HRmax, La2, and RPE responses compared with CE and TS in SSG4 bouts. In addition, teams created according to AP and CG spent more time than those selected by TS at zone 4 Moreover, players in teams created according to TS and CE spent more time at zones 2 and 3 than did those in teams created by AP and CG methods. These findings indicate that type of team formation method can influence the physiological responses in SSG4. In addition to the physiological measures of exercise intensity during SSGs, recent technological advances now allow for data relating to the movement of soccer players to be collected (15). Previous studies have shown that factors such as pitch area and rule modifications can influence such time-motion characteristics during SSGs. For example, Hill-Haas et al. (14) examined acute time-motion characteristics of youth players in 3 different small-sided soccer game formats (2-a-side, 4-a-side, and 6-a-side) when the pitch area per player was kept constant. Their results indicated that both mean and maximal sprint 3122 the durations and distances increased with larger SSG formats. Similarly, Casamichana and Castellano (4) showed that when the individual playing area increased, the effective playing time, total distance covered, distance covered per minute, maximum speed, work-to-rest ratio, and sprint frequency all also increased. Hill-Haas et al. (13) also found that SSG rule modifications or changes in game format may influence timemotion characteristics. The results of this study demonstrate that teams created according to TS covered more distance at speed zone 1 compared with those created using CE, AP, and CG methods, whereas those created according to AP and CG covered greater distances at speed zones 3 and 4 than did TS teams. Thus, young players created according to AP and CG methods covered significantly greater distances at highintensity running speeds. It is therefore possible to conclude that type of team formation method can influence the timemotion characteristics in SSG4. This suggests that future studies in this area should take team formation factors into account in a more systematic way. PRACTICAL APPLICATIONS This study indicates that different formation methods in SSG4 can influence %HRmax, time spent in different HRmax zones, La2, RPE responses, and time-motion characteristics. Previous studies have reported that factors such as pitch size (28), the number of players (30), rule modifications (13), absence or presence of a goalkeeper (26), and coach encouragement (28) influence exercise intensity in SSGs. In addition to these factors, the findings of this study indicate that coaches and sports scientists should also take into consideration ways that teams are selected in SSG training. The findings suggest that when the aim of SSGs training is to improve the maximum oxygen uptake, SSG teams should be selected either according to the players’ relative V_ O2max values or by considering the rankings calculated from both the players’ V_ O2max and technique scores because these methods appear to lead to greater physiological responses and superior time-motion characteristics compared with other team formation methods, such as those that only consider the players’ technique test scores or that rely on the coach’s subjective evaluation alone. Therefore, coaches who want their teams to spend more time in the high-intensity zone should form teams according to players’ V_ O2max or both V_ O2max and technique scores. REFERENCES 1. Ac xıkada, C, Hazır, T, Asxxcı, A, Turnagöl, H, and Özkara, A. Physical and physiological profiles of a second league division soccer team during preparation period. Hacettepe J Sports Sci Technol 1: 3–14, 1998. 2. Aroso, J, Rebelo, N, and Gomes-Pereira, J. Physiological impact of selected game-related exercises. J Sports Sci 22: 522, 2004. 3. Bravo, D, Impellizzeri, FM, Rampinini, E, Castagna, C, Bishop, D, and Wisloff, U. Sprint vs. interval training in football. Int J Sports Med 29: 668–674, 2008. 4. Casamichana, D and Castellano, J. Time-motion, heart rate, perceptual and motor behaviour demands in small-sides soccer games: Effects of pitch size. J Sports Sci 28: 1615–1623, 2010. TM Journal of Strength and Conditioning Research Copyright © National Strength and Conditioning Association Unauthorized reproduction of this article is prohibited. the TM Journal of Strength and Conditioning Research | www.nsca.com 5. Coutts, AJ and Duffield, R. Validity and reliability of GPS units for measuring movement demands of team sports. J Sci Med Sport 13: 133–135, 2010. 17. Jennings, D, Cormarck, S, Coutts, AJ, Boyd, LJ, and Aughey, RJ. Validity of GPS units for measuring distance in team sport movements. Int J Sports Physiol Perform 5: 565–569, 2010. 6. Coutts, AJ, Rampinini, E, Marcora, SM, Castagna, C, and Impellizzeri, FM. Heart rate and blood lactate correlates of perceived exertion during small-sided soccer games. J Sci Med Sport 12: 79–84, 2009. 18. Jones, S and Drust, B. Physiological and technical demands of 4 v. 4 and 8 v 8 games in elite youth soccer players. Kinesiology 39: 150–156, 2007. 7. Da Silva, CD, Impellizzeri, FM, Natali, AJ, de Lima, JRP, Bara-Filho, MG, Silami-Garcxia, E, and Marins, JCB. Exercise intensity and technical demands of small-sided games in young Brazilian soccer players: Effect of number of players, maturation, and reliability. J Strength Cond Res 25: 2746–2751, 2011. 8. Dellal, A, Hill-Haas, S, Lago-Penas, C, and Chamari, K. Small-sided games in soccer: Amateur vs. professional players’ physiological responses, physical, and technical activities. J Strength Cond Res 25: 2371–2381, 2011. 9. Drust, B, Waterhouse, J, Atkinson, G, Edwards, B, and Reilly, T. Circadian rhythms in sports performance-an update. Chronobiol Int 22: 21–44, 2005. 10. Fanchini, M, Azzalin, A, Castagna, C, Schena, F, Mccall, A, and Impellizzeri, FM. Effect of bout duration on exercise intensity and technical performance of small-sided games in soccer. J Strength Cond Res 25: 453–458, 2011. 11. Foster, C. Monitoring training in athletes with reference to overtraining syndrome. Med Sci Sports Exerc 30: 1164–1168, 1998. 12. Gabbet, TJ and Mulvey, MJ. Time-motion analysis of small-sided training games and competition in elite women soccer players. J Strength Cond Res 22: 543–552, 2008. 13. Hill-Haas, SV, Coutts, AJ, Dawson, BT, and Rowsell, GJ. Timemotion characteristics and physiological responses of small-sided games in elite youth players: The influence of player number and rule changes. J Strength Cond Res 24: 2149–2156, 2010. 14. Hill-Haas, SV, Dawson, BT, Coutts, AJ, and Rowsell, GJ. Physiological responses and time-motion characteristics of various small-sided soccer games in youth players. J Sports Sci 27: 1–8, 2009. 15. Hill-Haas, SV, Dawson, BT, Impellizzeri, FM, and Coutts, AJ. Physiology of small-sided games training in football: A systematic review. Sports Med 41: 199–220, 2011. 16. Hill-Haas, SV, Rowsell, GJ, Dawson, BT, and Coutts, AJ. Acute physiological responses and time-motion characteristics of two small-sided training regimes in youth soccer players. J Strength Cond Res 23: 111–115, 2009. 19. Kelly, DM and Drust, B. The effect of pitch dimensions on heart rate responses and technical demands of small-sided soccer games in elite players. J Sci Med Sport 12: 475–479, 2009. 20. Köklü, Y, Asci, A, Kocak, FU, Alemdaroglu, U, and Dundar, U. Comparison of the physiological responses to different small-sided games in elite young soccer players. J Strength Cond Res 25: 1522–1528, 2011. 21. Little, T. Optimizing the use of soccer drills for physiological development. Strength Cond 31: 67–74, 2009. 22. Little, T and Williams, AG. Suitability of soccer training drills for endurance training. J Strength Cond Res 20: 316–319, 2006. 23. Little, T and Williams, AG. Measures of exercise intensity during soccer training drills with professional soccer players. J Strength Cond Res 21: 367–371, 2007. 24. Malina, RM, Cumming, SP, Kontos, AP, Eisenmann, JC, Ribeiro, B, and Aroso, J. Maturity-associated variation in sport-specific skills of youth soccer players aged 13–15 years. J Sports Sci 23: 515–522, 2005. 25. Malina, RM, Ribeiro, B, Aroso, J, and Cumming, SP. Characteristics of youth soccer players aged 13–15 years classified by skill level. Br J Sports Med 41: 290–295, 2007. 26. Mallo, J and Navarro, E. Physical load imposed on soccer players during small-sided training games. J Sports Med Phys Fitness 48: 166–172, 2008. 27. Owen, AL, Wong, DP, McKenna, M, and Dellal, A. Heart rate responses and technical comparison between small- vs. large sided games in elite professional soccer. J Strength Cond Res 25: 2104–2110, 2011. 28. Rampinini, E, Impellizzeri, FM, Castagna, C, Abt, G, Chamari, K, Sassi, A, and Marcora, SM. Factors influencing physiological responses to small-sided soccer games. J Sports Sci 25: 659–666, 2007. 29. Stølen, T, Chamari, K, Castagna, C, and Wisløff, U. Physiology of soccer. Sports Med 35: 501–536, 2005. 30. Williams, K and Owen, A. The impact of player numbers on the physiological responses to small-sided games. J Sports Sci Med 10: 99–102, 2007. VOLUME 26 | NUMBER 11 | NOVEMBER 2012 | 3123 Copyright © National Strength and Conditioning Association Unauthorized reproduction of this article is prohibited.
© Copyright 2026 Paperzz