Human Movement Science 33 (2014) 25–32
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Human Movement Science journal homepage: www.elsevier.com/locate/humov
Time-motion analysis of acceleration demands of 4v4 small-sided soccer games played on different pitch sizes Craig Hodgson a, Richard Akenhead a,b, Kevin Thomas a,⇑ a b
Faculty of Health & Life Sciences, Northumbria University, Newcastle Upon Tyne, United Kingdom Newcastle United Football Club, Newcastle Upon Tyne, United Kingdom
a r t i c l e
i n f o
Article history:
PsycINFO classification: 3720 Keywords: GPS Time–motion analysis Football Fitness training Technical abilities
a b s t r a c t We aimed to quantify the time–motion characteristics and technical demands of small-sided soccer games (SSGs) played on small, medium and large pitches using a high frequency non-differential global positioning system (NdGPS) that allowed assessment of acceleration and deceleration patterns. Eight male soccer players competed in SSGs comprising 4 4 min quarters (3 min recovery) on small (30 20 m) medium (40 30 m) and large (50 40 m) pitch sizes. Time motion analysis using a NdGPS positioning system quantified distance covered sprinting (P6.7 m s 1), high speed running (P5.8 m s 1) and low (1–2 m s 2), medium (2–3 m s 2) and high (>3 m s 2) acceleration. The frequency of common technical actions (passing, turning, dribbling, shooting, tackling, heading and interceptions) was performed using a hand notation system. SSGs played on medium and large pitches had a greater physical demand than on small pitches, with significantly more distance covered in all movement categories. Total distance covered in acceleration categories ranged from 230 ± 111 (small pitch) to 356 ± 72 m (medium pitch). The small pitch imposed a greater technical demand on players (more passes, shots and tackles) compared to medium and large pitches. The study provides novel data demonstrating the acceleration patterns observed in SSGs are relatively greater than those observed during professional match play. Thus SSGs might offer a ‘‘density’’ type conditioning stimulus. Practitioners should be aware that changes in pitch size impact both the physical and technical demands of SSGs. Ó 2013 Elsevier B.V. All rights reserved.
⇑ Corresponding author. Address: Faculty of Health & Life Sciences, Northumbria University, Newcastle-Upon-Tyne, NE1 8ST, United Kingdom. Tel.: +44 191 227 4863; fax: +44 191 227 4713. E-mail address: [email protected] (K. Thomas). 0167-9457/$ - see front matter Ó 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.humov.2013.12.002
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1. Introduction Small-sided games (SSGs) are a popular and effective means of training soccer-specific fitness (Hill-Haas, Coutts, Rowsell, & Dawson, 2009; Impellizzeri et al., 2006), enabling coaches to combine the technical and tactical demands of match-play with a sport-specific conditioning stimulus. A number of variables can be manipulated by the coach that can impact the physical and technical demands of the game, including changing the number of players per team, the rules of the game, the use of goalkeepers, coach encouragement and the size of the pitch (Dellal et al., 2012; Hill-Haas, Coutts, Dawson, & Rowsell, 2010). An understanding of these subtleties can aid the coach in prescribing training based on specific technical and physical requirements. A limited number of studies have assessed the impact of pitch size on the physical and technical demands of SSGs (Casamichana & Castellano, 2010; Kelly & Drust, 2009; Rampinini et al., 2007). The majority of studies report an increase in mean heart rate, blood lactate and rating of perceived exertion as pitch size is increased and player number is held constant, attributing this to an increase in the effective playing area per player (Casamichana & Castellano, 2010; Owen, Twist, & Ford, 2004; Rampinini et al., 2007). The differences observed in these studies were relatively small, and indeed a well-controlled study by Kelly and Drust (2009) comparing heart rate responses and technical demands of 5v5 SSGs played on small, medium and large pitches, showed no difference in the heart rate response between pitch sizes. The same authors did report small differences in the frequency of technical actions, with more tackles and shots occurring on smaller pitches (Kelly & Drust, 2009). Whilst these studies have provided valuable insight into the demands of SSGs, the sensitivity of measures of heart rate, blood lactate and session rating of perceived exertion to accurately quantify the demands of intermittent exercise is questionable. The use of nondifferential global-positioning systems (NdGPS) to assess the time–motion demands of competitive match play is widespread in professional codes but few studies have attempted to quantify the movement demands of SSGs using such technology (Casamichana & Castellano, 2010; Dellal et al., 2012; Gabbett & Mulvey, 2008; Hill-Haas et al., 2010). In addition, these studies have been limited in their interpretation by the poor reliability of systems that sample at low frequencies, particularly for high-speed actions (Casamichana & Castellano, 2010; Coutts & Duffield, 2010). More recent advances in technology have increased the location sampling rate of NdGPS, allowing a greater level of precision and increased ability to account for discrete movements over short distances (Varley, Fairweather, & Aughey, 2012). These advances allow for a more precise study of the high-intensity activities that are thought to better characterise soccer-specific fitness (Mohr, Krustrup, & Bangsbo, 2003). Additionally, this higher frequency technology allows the acceleration demands of soccer to be quantified (Varley et al., 2012). Discriminating between constant-speed locomotion and the rate of change of velocity is important due to the greater energy cost and muscular demand of such movements, even when absolute speed is low (Osgnach, Poser, Bernardini, Rinaldo, & di Prampero, 2010). Thus it has been demonstrated that previous time–motion analysis research utilising traditional constant-speed thresholds have under-estimated the physical demands of soccer (Osgnach et al., 2010; Varley & Aughey, 2013). Moreover, recent research has demonstrated consistent, time-dependent decrements in acceleration capability occur during a 90 min game; monitoring these variables might therefore provide a better insight into the physical demands and resulting occurrence of fatigue during soccer (Akenhead, Hayes, Thompson, & French, 2013). To date the acceleration demands of SSGs have yet to be quantified; assessing the movement demands of SSGs with more precision would provide useful information for coaches employing these modes as a conditioning stimulus. Therefore, the aim of the present study was to assess the time–motion characteristics of SSGs played on small, medium and large pitches using a high-frequency (10 Hz) NdGPS. A secondary aim was to assess the effect of changing pitch size on the frequency of technical actions.
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2. Methods 2.1. Participants With institutional ethics approval from the Northumbria University Faculty of Health & Life Sciences Institutional Ethics Review Board, eight University-level footballers (mean ± SD age = 20 ± _ 2max = 52.6 ± 7.5 mL kg 1 min 1) gave 1 year, stature = 1.81 ± 0.04 m, mass = 75 ± 7 kg, predicted VO written informed consent to participate in the study. All participants had a minimum of 5 years’ experience of regular soccer training (P2 times per week) and competition (P1 times per week). The study was conducted in-season during regular training sessions. Prior to each trial participants were instructed to refrain from caffeine (4 h), strenuous exercise and alcohol consumption (48 h) and to arrive in a fully rested hydrated state. Participants were also provided with a 24 h food diary and were asked to replicate their diet for the 24 h before each trial.
2.2. Experimental design Participants completed one practice and three experimental sessions on consecutive weeks separated by 7 days in a repeated measures design. Participants competed in 5v5 (including goalkeepers) small-sided games on small (30 20 m), medium (40 30 m) and large (50 40 m) pitch sizes, giving an active playing area per player of 60, 120 and 200 m2, respectively. These dimensions are commonly used in previous research (Hill-Haas, Dawson, Coutts, & Rowsell, 2009; Kelly & Drust, 2009; Owen et al., 2004). The sessions were performed as interval training consisting of 4 bouts of 4 min duration separated by 3 min of recovery between games. This training regime has previously been shown to result in positive adaptations in aerobic fitness when completed twice per week in a 4 week training programme in soccer players (Impellizzeri et al., 2006). Heart rate was recorded throughout each session, and all games were video recorded for subsequent analysis of technical actions (described below). During each session participants wore a NdGPS unit that recorded movement variables at a frequency of 10 Hz (MinimaxX, Catapult Innovations, Canberra, Australia), which allowed the assessment of distance covered accelerating and decelerating in addition to typical time–motion analysis variables. The validity and reliability of this system for the assessment of instantaneous velocity during acceleration and deceleration has been recently established (Akenhead, French, Thompson, & Hayes, 2013; Varley et al., 2012).
2.3. Procedures All sessions were completed outdoors on an artificial 3G rubber crumb pitch. During the practice session participants first completed a multi-stage fitness test (Leger & Lambert, 1982) to exhaustion _ 2to measure individual heart rate maximum (HRmax) and predicted maximum oxygen uptake ( VO max). The multi-stage fitness test required participants to run 20 m shuttles at increasing speed, as dictated by an audible beep, until task failure. Following this, participants competed in SSGs on the three pitch sizes to be used in the experimental trials to familiarise themselves with the demands of each. In sessions 2, 3 and 4 participants competed in 4 4 min (3 min recovery) SSGs on small (30 20 m), medium (40 30 m) and large (50 40 m) pitch sizes. The order of pitch sizes was randomised. Counterbalancing was not possible as the study was conducted in-season during the team’s regular training. Each game involved 5 players per team (including goalkeepers). The coach of the squad selected each team to ensure a balance of positions and abilities, and these teams remained consistent between conditions. The games were competitive and played in a tournament scenario in each condition with points awarded in each 4 min quarter for winning (+3 points), drawing (+1 point) and goal scoring (+1 point) to ensure a high motivation throughout. Footballs were placed around the perimeter of the pitch, with the team coach and a researcher quickly returning balls that went out of play where appropriate. To further ensure a high intensity, verbal support was given to all
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participants during the exercise bouts by the coach of the team and the researcher. All games were preceded by a standardised 15 min warm-up. During each session participants wore a NdGPS unit which sampled participant location at 10 Hz (MinimaxX, Catapult Innovations, Canberra, Australia). From location and time data, velocity and acceleration were calculated within the manufacturers’ software (Logan Plus v4.5, Catapult Innovations, Canberra, Australia). Acceleration was calculated as the change in instantaneous velocity (measured at 10 Hz) over time. To distinguish between acceleration movements where participants speed up vs. slow down, the term ‘‘deceleration’’ is used to describe a decreasing rate of change of velocity. A minimum effort duration criteria of 0.3 s was implemented to prevent brief thoracic movements from registering as locomotive efforts, but acceleration data were not smoothed in any way. Additionally, each player wore a tight fitting vest that housed the unit to reduce movement artefact. The NdGPS units were switched on and placed outdoors 15 min prior to commencement of the warm-up. Following collection, data from the NdGPS units were downloaded for analysis using the manufacturers’ software. Values (m) for total distance covered (TD), and distance covered at high speed (HSR P 5.8 m s 1) and during sprinting (SPD P 6.7 m s 1) were measured. Distance covered during low (>1–2 m s 2), moderate (2–3 m s 2), and high (>3 m s 2) acceleration and deceleration ranges was recorded, along with total (P1 m s 2) acceleration and deceleration distance covered. For clarity, an increase in speed from 4 to 6 m s 1 taking place in 1 s represents an acceleration of 2 m s 2, as would an increase in speed from 2 to 4 m s 1 in 1 s. However, the distance covered within the 1 s time period would be greater in the first case due to the greater mean speed (5 vs. 3 m s 1 for the purpose of this example, assuming a linear acceleration). This example demonstrates the rationale for reporting distance covered in acceleration rather than time spent accelerating, as distance is able to proportionately discriminate where time alone cannot. Heart rate was recorded via short range telemetry throughout each session (Polar RS400, Oy Kempele, Finland). The mean heart rates for each experimental trial were recorded and expressed as a percentage of individual maximum to provide an indication of the overall intensity of the SSGs. Video recordings of all SSGs were obtained using a video camera (Samsung PL201, China) positioned on a tripod (Vivitar, VIV-VPT-1250 Professional Series, Vivitar Corporation, China) 5 m from the side of the pitch, level with the half way line at an elevation of 1 m. A hand notation system was devised to record the technical actions performed during each session from the video. The analysis focused on basic skills that are commonly performed during game situations; pass, tackle, header, turn, interception, dribbling and shots (Fanchini et al., 2011). A ‘‘turn’’ was coded as a change of direction with the ball greater than 90°. Passes, tackles, dribbles and shots were coded regardless of their success. 2.4. Statistical analysis No published data exist on the variability in distance covered in acceleration and deceleration categories in SSGs. Consequently, we used unpublished data from our laboratory on the reliability of these variables measured in SSGs similar to those employed in the current study (Typical error range = 8–10%). Assuming a typical error of 10%, a sample size of 8 would give 80% power to detect a 12% difference in total distance covered in acceleration and deceleration categories. Descriptive statistics are presented as means ± standard deviation. Differences between small, medium and large pitches were assessed for all outcome measures using one-way repeated measures ANOVA, with Bonferroni adjusted 95% confidence intervals calculated for pairwise comparisons. The statistical assumptions of this procedure; equal variance of difference scores, normal distribution of population samples, and non-dependence of measurement were verified using the threefold variance rule, visual inspection of box plots and visual inspection of scatterplots for each pairwise comparison, respectively (Newell, Aitchison, & Grant, 2010). Statistical significance was assumed at p < .05. Data analysis was conducted using SPSS 19.0 (IBM SPSS Statistics, 19.0, Chicago, IL.) and Microsoft Excel 2007. 3. Results Mean ± SD maximum heart rate measured in the multi-stage fitness test was 192 ± 8 beats min 1. During the SSGs, the heart rate responses were similar between pitch sizes (164 ± 14 beats min 1,
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168 ± 13 beats min 1 and 168 ± 17 beats min 1) corresponding to relative exercise intensities of 86 ± 3% HRmax, 87 ± 4% HRmax and 87 ± 4% HRmax for small, medium and large pitches, respectively. Table 1 displays the time–motion data for each pitch size. In summary, both medium and large pitches had a higher physical demand than small pitches, with no difference between medium and large pitches for all variables other than distance covered at high speed (Table 1). In comparison to SSGs played on a small pitch, total distance covered was higher on both medium (mean difference [95% CI’s] = 409 [219–600] m) and large pitches (mean difference [95% CI’s] = 402 [211–593] m), and total distance covered in acceleration and deceleration ranges were both higher on medium (mean difference [95% CIs] total acceleration = 126 [6–247] m, total deceleration = 116 [12–222] m) and large pitches (mean difference [95% CIs] total acceleration = 97 [4–190] m, total deceleration = 100 [20–181] m). The frequency of technical actions per player for each pitch size is displayed in Fig. 1. There were differences between pitch sizes for the number of passes played (p = .009) and shots attempted (p = .003). Specifically, players attempted more passes (mean difference [95% CI’s] = 3 [0–7]), and more shots (mean difference [95% CI’s] = 2 [0–5]) on the small pitch compared to the large pitch. There were no differences between medium and large pitches for attempted passes, but the number of shots attempted was higher on the medium pitch in comparison to large (mean difference [95% CI’s] = 2 [0–4]). The difference in the frequency of tackle attempts between pitch sizes approached statistical significance (p = .056) with a trend for more tackles on the small pitch compared to medium (mean difference [95% CI’s] = 2 [0–3]) but not compared to large (mean difference [95% CI’s] = 2 [ 1 to 4]). 4. Discussion We sought to characterise the physical and technical demands of SSGs in soccer played on different pitch sizes. This study is the first to quantify the acceleration demands of SSGs with a high-frequency data capture system, providing an explanation for the well-documented efficacy of this training mode in eliciting improvements in soccer-specific fitness (Helgerud, Engen, Wisloff, & Hoff, 2001; Hill-Haas et al., 2009; Impellizzeri et al., 2006; Owen, Wong del, Paul, & Dellal, 2012). Changing pitch size affects both the physical and technical demands of SSGs. Small pitch sizes are characterised by a reduced physical demand and an increased technical demand in comparison to large pitches. Medium pitch sizes seem to be optimal; providing both a high frequency of technical actions, and a high physical demand that is unchanged as pitch size increases. These data have important implications for coaches and practitioners utilising SSGs as a conditioning stimulus in soccer. The data provided by this study on the time–motion demands of SSGs support the use of this mode of training as a conditioning stimulus in soccer, particularly with reference to the acceleration demands. Osgnach et al. (2010) emphasised the importance of monitoring these variables as the
Table 1 Distance covered (m) for speed and acceleration variables in small-sided games played on small, medium and large pitches (Values are mean ± SD).
Total distance High speed distance Sprint speed distance Total acceleration High acceleration Moderate acceleration Low acceleration Total deceleration High deceleration Moderate deceleration Low deceleration a b
Small pitch
Medium pitch
Large pitch
1532 ± 145 0±0 0±0 230 ± 111 23 ± 18 57 ± 36 150 ± 58 198 ± 89 18 ± 15 46 ± 30 133 ± 44
1941 ± 148a 29 ± 28 11 ± 21 356 ± 72a 38 ± 10a 94 ± 24a 223 ± 40a 314 ± 67a 34 ± 12 83 ± 20a 198 ± 37a
1934 ± 133a 61 ± 47a,b 16 ± 27 327 ± 70a 32 ± 12 83 ± 24a 212 ± 37a 298 ± 68a 31 ± 12a 77 ± 26a 190 ± 31a
Significant difference in comparison to small pitch (p < .05). Significant difference in comparison to medium pitch (p < .05).
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Fig. 1. Frequency of technical actions per player during SSGs played on small, medium and large pitches. Values are mean ± SD. ⁄ Significant difference in comparison to small pitch (p < .05). Significant difference in comparison to medium pitch (p < .05).
metabolic and neuromuscular demand of acceleration movements are high even when speed is low, and such movements are common in soccer. Data from 11v11 professional games collected with the same NdGPS system shows that, in a 90 min game, on average professionals cover 10,451 m total distance, with 1022 m spent accelerating, and 899 m decelerating (Akenhead et al., 2013). This equates to an average distance covered in acceleration and deceleration ranges of 9.7 and 8.6 m every minute respectively (half time period included), or 18% of the total distance covered. On the medium pitch in our study, the relative demand was higher than this, with our players covering 14.2 m accelerating and 12.6 m decelerating (recovery periods included) every minute on average, equating to 35% of the total distance covered. Considering the potential importance of these movements as an indicator of fatigue in soccer (Akenhead et al., 2013; Osgnach et al., 2010), the data suggest SSGs might provide a ‘density’ type stimulus; imposing relative demands on acceleration abilities in excess of those experienced during full match play. These data provide an explanation as to why this training method has proved to be equal to or superior than traditional interval training in the available research (Helgerud et al., 2001; Hill-Haas et al., 2009; Impellizzeri et al., 2006). The greater distances reported in acceleration vs. deceleration ranges reflects the predominant muscle actions involved in these movements. Acceleration requires the generation of propulsive forces predominantly through concentric muscle action, whereas deceleration requires braking forces produced predominantly by eccentric muscle actions. As human skeletal muscle is stronger eccentrically, players are able to exert greater braking then propulsive forces, thus slowing down quicker and covering less distance as a consequence during deceleration movements. The movement demands on medium and large pitches exceeded that of small pitches, with no difference between medium and large pitches. Players covered more total distance, and more distance during acceleration and deceleration ranges on medium and large pitch sizes. However, the exercise intensity as measured by heart rate was similar between pitch sizes (86% of HRmax for small pitches vs. 87% for medium and large pitches). These values are in line with previous similar studies by Rampinini et al. (2007) (87–91% HRmax) Casamichana and Castellano (2010) (93–95% of HRmax) and Kelly and Drust (2009) (89–91% HRmax). The finding of a similar heart rate despite large differences in the movement variables assessed could reflect the insensitivity of heart rate as a measure of exercise intensity in intermittent games. An alternative explanation might reside in the higher frequency of technical actions performed on the small pitch size (discussed below), and the smaller
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playing area requiring players to make quicker decisions more frequently, both of which could have imposed a higher metabolic load that was not reflected in the time–motion data. Thus, whilst changing pitch size might not significantly alter the heart rate response to SSGs (Kelly & Drust, 2009), the data from this study suggest that the movement demands that elicit this response are different between pitch sizes. The frequency of technical actions was similar across pitch sizes, with a tendency for a higher technical demand on small (more passes and shots, and a trend for more tackles) compared to medium and large pitch sizes. This finding regarding an added technical demand on smaller pitch sizes has been previously reported, particularly with regards shots and tackles (Casamichana & Castellano, 2010; Kelly & Drust, 2009; Tessitore, Meeusen, Piacentini, Demarie, & Capranica, 2006). The smaller pitch size reduces the active playing area and requires players to make faster decisions and execute skills with higher frequency. The potential for players to frequently accelerate and/or attain high running speeds is however compromised. The coach should consider the aim of the session when designing such games, with the knowledge that the technical and physical demands of the game can be manipulated by reducing or increasing the size of the active playing area. Whilst the use of a 10 Hz NdGP system is an improvement on previous research, there still remains a degree of error. For example, the acceleration values reported by Osgnach et al. (2010), using a higher frequency 25 Hz video camera system, were higher than those measured with a 10 Hz system in professional players by Akenhead et al. (2013) (Total acceleration = 1022 vs. 1767 m and total deceleration 899 vs. 1775 m). In addition, in this study we have been unable to distinguish between acceleration movements commencing from different speeds, which have different mechanical and physiological consequences. For example, an acceleration of 2 m s 2 resulting in a change of velocity from 0 to 2 m s 1 will pose a different physical demand to acceleration resulting in a change of velocity from 2 to 4 m s 1. Whilst we have not been able to accurately characterise the incidence of different starting speeds, by reporting the distance covered in acceleration ranges (as opposed to time) we have been able to proportionately discriminate between acceleration movements at high and low speeds. Thus whilst the current study provides an advance on previous research, there still remains scope to more accurately quantify the physical demands imposed on soccer players both in training and match play. The importance of acceleration movements in football is an area that warrants further research, both in training and match play situations (Osgnach et al., 2010; Varley & Aughey, 2013). If these movements characterise fatigue in football (Akenhead et al., 2013) then the ability of players to repeat acceleration efforts over the course of a 90 min game is an important ability to train; our data would indicate that SSGs might be an efficacious method to achieve this. Future studies should further attempt to characterise the demands of soccer training and match play with reference to these demands, and to assess the efficacy of sport-specific training interventions aimed at improving this fitness quality. In conclusion, the results of this study provide novel data on the movement demands of smallsided games in soccer, and further support for the assessment of the acceleration demands of training and match play. The distances covered during acceleration movements during SSGs are relatively higher than match play in professional players, supporting the use of SSGs as a training tool in soccer. Changing pitch size can impact both the physical and technical demands of SSGs. A medium pitch size is optimal in that it imposes a high physical demand on players whilst maintaining a high frequency of technical actions. Practitioners can use the data presented here to more accurately prescribe appropriate soccer-specific training stimuli. Acknowledgements No financial support was received for this project. No professional relationships with companies or manufacturers of the measurement tools used in this project exist. References Akenhead, R., French, D., Thompson, K. G., & Hayes, P. R. (2013). The acceleration dependent validity and reliability of 10 Hz GPS. Journal of Science and Medicine in Sport. http://dx.doi.org/10.1016/j.jsams.2013.1008.1005.
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Akenhead, R., Hayes, P. R., Thompson, K. G., & French, D. (2013). Diminutions of acceleration and deceleration output during professional football match play. Journal of Science and Medicine in Sport. http://dx.doi.org/10.1016/j.jsams.2012.1012.1005. Casamichana, D., & Castellano, J. (2010). Time–motion, heart rate, perceptual and motor behaviour demands in small-sides soccer games: Effects of pitch size. Journal of Sports Sciences, 28, 1615–1623. Coutts, A. J., & Duffield, R. (2010). Validity and reliability of GPS devices for measuring movement demands of team sports. Journal of Science and Medicine in Sport, 13, 133–135. Dellal, A., Owen, A., Wong, D. P., Krustrup, P., van Exsel, M., & Mallo, J. (2012). Technical and physical demands of small vs. large sided games in relation to playing position in elite soccer. Human Movement Science, 31, 957–969. Fanchini, M., Azzalin, A., Castagna, C., Schena, F., McCall, A., & Impellizzeri, F. M. (2011). Effect of bout duration on exercise intensity and technical performance of small-sided games in soccer. Journal of Strength and Conditioning Research, 25, 453–458. Gabbett, T. J., & Mulvey, M. J. (2008). Time–motion analysis of small-sided training games and competition in elite women soccer players. Journal of Strength and Conditioning Research, 22, 543–552. Helgerud, J., Engen, L. C., Wisloff, U., & Hoff, J. (2001). Aerobic endurance training improves soccer performance. Medicine and Science in Sports and Exercise, 33, 1925–1931. Hill-Haas, S. V., Coutts, A. J., Dawson, B. T., & Rowsell, G. J. (2010). Time–motion characteristics and physiological responses of small-sided games in elite youth players: The influence of player number and rule changes. Journal of Strength and Conditioning Research, 24, 2149–2156. Hill-Haas, S. V., Coutts, A. J., Rowsell, G. J., & Dawson, B. T. (2009). Generic versus small-sided game training in soccer. International Journal of Sports Medicine, 30, 636–642. Hill-Haas, S. V., Dawson, B. T., Coutts, A. J., & Rowsell, G. J. (2009b). Physiological responses and time–motion characteristics of various small-sided soccer games in youth players. Journal of Sports Sciences, 27, 1–8. Impellizzeri, F. M., Marcora, S. M., Castagna, C., Reilly, T., Sassi, A., Iaia, F. M., et al (2006). Physiological and performance effects of generic versus specific aerobic training in soccer players. International Journal of Sports Medicine, 27, 483–492. Kelly, D. M., & Drust, B. (2009). The effect of pitch dimensions on heart rate responses and technical demands of small-sided soccer games in elite players. Journal of Science and Medicine in Sport, 12, 475–479. _ 2max. European Journal of Applied Leger, L. A., & Lambert, J. (1982). A maximal multistage 20-m shuttle run test to predict VO Physiology, 49, 1–12. Mohr, M., Krustrup, P., & Bangsbo, J. (2003). Match performance of high-standard soccer players with special reference to development of fatigue. Journal of Sports Sciences, 21, 519–528. Newell, J., Aitchison, T., & Grant, S. (2010). Statistics for sports and exercise science: A practical approach. Harlow: Pearson Education. Osgnach, C., Poser, S., Bernardini, R., Rinaldo, R., & di Prampero, P. E. (2010). Energy cost and metabolic power in elite soccer: A new match analysis approach. Medicine and Science in Sports and Exercise, 42, 170–178. Owen, A., Twist, C., & Ford, P. (2004). Small-sided games: The physiological and technical effect of altering pitch size and player numbers. Insight, 7, 50–53. Owen, A., Wong del, P., Paul, D., & Dellal, A. (2012). Effects of a periodized small-sided game training intervention on physical performance in elite professional soccer. Journal of Strength and Conditioning Research, 26, 2748–2754. Rampinini, E., Impellizzeri, F. M., Castagna, C., Abt, G., Chamari, K., Sassi, A., et al (2007). Factors influencing physiological responses to small-sided soccer games. Journal of Sports Sciences, 25, 659–666. Tessitore, A., Meeusen, R., Piacentini, M. F., Demarie, S., & Capranica, L. (2006). Physiological and technical aspects of ‘‘6-a-side’’ soccer drills. Journal of Sports Medicine and Physical Fitness, 46, 36–43. Varley, M. C., & Aughey, R. J. (2013). Acceleration profiles in elite Australian soccer. International Journal of Sports Medicine, 34, 34–39. Varley, M. C., Fairweather, I. H., & Aughey, R. J. (2012). Validity and reliability of GPS for measuring instantaneous velocity during acceleration, deceleration, and constant motion. Journal of Sports Sciences, 30, 121–127.
Contents lists available at ScienceDirect
Human Movement Science journal homepage: www.elsevier.com/locate/humov
Time-motion analysis of acceleration demands of 4v4 small-sided soccer games played on different pitch sizes Craig Hodgson a, Richard Akenhead a,b, Kevin Thomas a,⇑ a b
Faculty of Health & Life Sciences, Northumbria University, Newcastle Upon Tyne, United Kingdom Newcastle United Football Club, Newcastle Upon Tyne, United Kingdom
a r t i c l e
i n f o
Article history:
PsycINFO classification: 3720 Keywords: GPS Time–motion analysis Football Fitness training Technical abilities
a b s t r a c t We aimed to quantify the time–motion characteristics and technical demands of small-sided soccer games (SSGs) played on small, medium and large pitches using a high frequency non-differential global positioning system (NdGPS) that allowed assessment of acceleration and deceleration patterns. Eight male soccer players competed in SSGs comprising 4 4 min quarters (3 min recovery) on small (30 20 m) medium (40 30 m) and large (50 40 m) pitch sizes. Time motion analysis using a NdGPS positioning system quantified distance covered sprinting (P6.7 m s 1), high speed running (P5.8 m s 1) and low (1–2 m s 2), medium (2–3 m s 2) and high (>3 m s 2) acceleration. The frequency of common technical actions (passing, turning, dribbling, shooting, tackling, heading and interceptions) was performed using a hand notation system. SSGs played on medium and large pitches had a greater physical demand than on small pitches, with significantly more distance covered in all movement categories. Total distance covered in acceleration categories ranged from 230 ± 111 (small pitch) to 356 ± 72 m (medium pitch). The small pitch imposed a greater technical demand on players (more passes, shots and tackles) compared to medium and large pitches. The study provides novel data demonstrating the acceleration patterns observed in SSGs are relatively greater than those observed during professional match play. Thus SSGs might offer a ‘‘density’’ type conditioning stimulus. Practitioners should be aware that changes in pitch size impact both the physical and technical demands of SSGs. Ó 2013 Elsevier B.V. All rights reserved.
⇑ Corresponding author. Address: Faculty of Health & Life Sciences, Northumbria University, Newcastle-Upon-Tyne, NE1 8ST, United Kingdom. Tel.: +44 191 227 4863; fax: +44 191 227 4713. E-mail address: [email protected] (K. Thomas). 0167-9457/$ - see front matter Ó 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.humov.2013.12.002
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1. Introduction Small-sided games (SSGs) are a popular and effective means of training soccer-specific fitness (Hill-Haas, Coutts, Rowsell, & Dawson, 2009; Impellizzeri et al., 2006), enabling coaches to combine the technical and tactical demands of match-play with a sport-specific conditioning stimulus. A number of variables can be manipulated by the coach that can impact the physical and technical demands of the game, including changing the number of players per team, the rules of the game, the use of goalkeepers, coach encouragement and the size of the pitch (Dellal et al., 2012; Hill-Haas, Coutts, Dawson, & Rowsell, 2010). An understanding of these subtleties can aid the coach in prescribing training based on specific technical and physical requirements. A limited number of studies have assessed the impact of pitch size on the physical and technical demands of SSGs (Casamichana & Castellano, 2010; Kelly & Drust, 2009; Rampinini et al., 2007). The majority of studies report an increase in mean heart rate, blood lactate and rating of perceived exertion as pitch size is increased and player number is held constant, attributing this to an increase in the effective playing area per player (Casamichana & Castellano, 2010; Owen, Twist, & Ford, 2004; Rampinini et al., 2007). The differences observed in these studies were relatively small, and indeed a well-controlled study by Kelly and Drust (2009) comparing heart rate responses and technical demands of 5v5 SSGs played on small, medium and large pitches, showed no difference in the heart rate response between pitch sizes. The same authors did report small differences in the frequency of technical actions, with more tackles and shots occurring on smaller pitches (Kelly & Drust, 2009). Whilst these studies have provided valuable insight into the demands of SSGs, the sensitivity of measures of heart rate, blood lactate and session rating of perceived exertion to accurately quantify the demands of intermittent exercise is questionable. The use of nondifferential global-positioning systems (NdGPS) to assess the time–motion demands of competitive match play is widespread in professional codes but few studies have attempted to quantify the movement demands of SSGs using such technology (Casamichana & Castellano, 2010; Dellal et al., 2012; Gabbett & Mulvey, 2008; Hill-Haas et al., 2010). In addition, these studies have been limited in their interpretation by the poor reliability of systems that sample at low frequencies, particularly for high-speed actions (Casamichana & Castellano, 2010; Coutts & Duffield, 2010). More recent advances in technology have increased the location sampling rate of NdGPS, allowing a greater level of precision and increased ability to account for discrete movements over short distances (Varley, Fairweather, & Aughey, 2012). These advances allow for a more precise study of the high-intensity activities that are thought to better characterise soccer-specific fitness (Mohr, Krustrup, & Bangsbo, 2003). Additionally, this higher frequency technology allows the acceleration demands of soccer to be quantified (Varley et al., 2012). Discriminating between constant-speed locomotion and the rate of change of velocity is important due to the greater energy cost and muscular demand of such movements, even when absolute speed is low (Osgnach, Poser, Bernardini, Rinaldo, & di Prampero, 2010). Thus it has been demonstrated that previous time–motion analysis research utilising traditional constant-speed thresholds have under-estimated the physical demands of soccer (Osgnach et al., 2010; Varley & Aughey, 2013). Moreover, recent research has demonstrated consistent, time-dependent decrements in acceleration capability occur during a 90 min game; monitoring these variables might therefore provide a better insight into the physical demands and resulting occurrence of fatigue during soccer (Akenhead, Hayes, Thompson, & French, 2013). To date the acceleration demands of SSGs have yet to be quantified; assessing the movement demands of SSGs with more precision would provide useful information for coaches employing these modes as a conditioning stimulus. Therefore, the aim of the present study was to assess the time–motion characteristics of SSGs played on small, medium and large pitches using a high-frequency (10 Hz) NdGPS. A secondary aim was to assess the effect of changing pitch size on the frequency of technical actions.
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2. Methods 2.1. Participants With institutional ethics approval from the Northumbria University Faculty of Health & Life Sciences Institutional Ethics Review Board, eight University-level footballers (mean ± SD age = 20 ± _ 2max = 52.6 ± 7.5 mL kg 1 min 1) gave 1 year, stature = 1.81 ± 0.04 m, mass = 75 ± 7 kg, predicted VO written informed consent to participate in the study. All participants had a minimum of 5 years’ experience of regular soccer training (P2 times per week) and competition (P1 times per week). The study was conducted in-season during regular training sessions. Prior to each trial participants were instructed to refrain from caffeine (4 h), strenuous exercise and alcohol consumption (48 h) and to arrive in a fully rested hydrated state. Participants were also provided with a 24 h food diary and were asked to replicate their diet for the 24 h before each trial.
2.2. Experimental design Participants completed one practice and three experimental sessions on consecutive weeks separated by 7 days in a repeated measures design. Participants competed in 5v5 (including goalkeepers) small-sided games on small (30 20 m), medium (40 30 m) and large (50 40 m) pitch sizes, giving an active playing area per player of 60, 120 and 200 m2, respectively. These dimensions are commonly used in previous research (Hill-Haas, Dawson, Coutts, & Rowsell, 2009; Kelly & Drust, 2009; Owen et al., 2004). The sessions were performed as interval training consisting of 4 bouts of 4 min duration separated by 3 min of recovery between games. This training regime has previously been shown to result in positive adaptations in aerobic fitness when completed twice per week in a 4 week training programme in soccer players (Impellizzeri et al., 2006). Heart rate was recorded throughout each session, and all games were video recorded for subsequent analysis of technical actions (described below). During each session participants wore a NdGPS unit that recorded movement variables at a frequency of 10 Hz (MinimaxX, Catapult Innovations, Canberra, Australia), which allowed the assessment of distance covered accelerating and decelerating in addition to typical time–motion analysis variables. The validity and reliability of this system for the assessment of instantaneous velocity during acceleration and deceleration has been recently established (Akenhead, French, Thompson, & Hayes, 2013; Varley et al., 2012).
2.3. Procedures All sessions were completed outdoors on an artificial 3G rubber crumb pitch. During the practice session participants first completed a multi-stage fitness test (Leger & Lambert, 1982) to exhaustion _ 2to measure individual heart rate maximum (HRmax) and predicted maximum oxygen uptake ( VO max). The multi-stage fitness test required participants to run 20 m shuttles at increasing speed, as dictated by an audible beep, until task failure. Following this, participants competed in SSGs on the three pitch sizes to be used in the experimental trials to familiarise themselves with the demands of each. In sessions 2, 3 and 4 participants competed in 4 4 min (3 min recovery) SSGs on small (30 20 m), medium (40 30 m) and large (50 40 m) pitch sizes. The order of pitch sizes was randomised. Counterbalancing was not possible as the study was conducted in-season during the team’s regular training. Each game involved 5 players per team (including goalkeepers). The coach of the squad selected each team to ensure a balance of positions and abilities, and these teams remained consistent between conditions. The games were competitive and played in a tournament scenario in each condition with points awarded in each 4 min quarter for winning (+3 points), drawing (+1 point) and goal scoring (+1 point) to ensure a high motivation throughout. Footballs were placed around the perimeter of the pitch, with the team coach and a researcher quickly returning balls that went out of play where appropriate. To further ensure a high intensity, verbal support was given to all
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participants during the exercise bouts by the coach of the team and the researcher. All games were preceded by a standardised 15 min warm-up. During each session participants wore a NdGPS unit which sampled participant location at 10 Hz (MinimaxX, Catapult Innovations, Canberra, Australia). From location and time data, velocity and acceleration were calculated within the manufacturers’ software (Logan Plus v4.5, Catapult Innovations, Canberra, Australia). Acceleration was calculated as the change in instantaneous velocity (measured at 10 Hz) over time. To distinguish between acceleration movements where participants speed up vs. slow down, the term ‘‘deceleration’’ is used to describe a decreasing rate of change of velocity. A minimum effort duration criteria of 0.3 s was implemented to prevent brief thoracic movements from registering as locomotive efforts, but acceleration data were not smoothed in any way. Additionally, each player wore a tight fitting vest that housed the unit to reduce movement artefact. The NdGPS units were switched on and placed outdoors 15 min prior to commencement of the warm-up. Following collection, data from the NdGPS units were downloaded for analysis using the manufacturers’ software. Values (m) for total distance covered (TD), and distance covered at high speed (HSR P 5.8 m s 1) and during sprinting (SPD P 6.7 m s 1) were measured. Distance covered during low (>1–2 m s 2), moderate (2–3 m s 2), and high (>3 m s 2) acceleration and deceleration ranges was recorded, along with total (P1 m s 2) acceleration and deceleration distance covered. For clarity, an increase in speed from 4 to 6 m s 1 taking place in 1 s represents an acceleration of 2 m s 2, as would an increase in speed from 2 to 4 m s 1 in 1 s. However, the distance covered within the 1 s time period would be greater in the first case due to the greater mean speed (5 vs. 3 m s 1 for the purpose of this example, assuming a linear acceleration). This example demonstrates the rationale for reporting distance covered in acceleration rather than time spent accelerating, as distance is able to proportionately discriminate where time alone cannot. Heart rate was recorded via short range telemetry throughout each session (Polar RS400, Oy Kempele, Finland). The mean heart rates for each experimental trial were recorded and expressed as a percentage of individual maximum to provide an indication of the overall intensity of the SSGs. Video recordings of all SSGs were obtained using a video camera (Samsung PL201, China) positioned on a tripod (Vivitar, VIV-VPT-1250 Professional Series, Vivitar Corporation, China) 5 m from the side of the pitch, level with the half way line at an elevation of 1 m. A hand notation system was devised to record the technical actions performed during each session from the video. The analysis focused on basic skills that are commonly performed during game situations; pass, tackle, header, turn, interception, dribbling and shots (Fanchini et al., 2011). A ‘‘turn’’ was coded as a change of direction with the ball greater than 90°. Passes, tackles, dribbles and shots were coded regardless of their success. 2.4. Statistical analysis No published data exist on the variability in distance covered in acceleration and deceleration categories in SSGs. Consequently, we used unpublished data from our laboratory on the reliability of these variables measured in SSGs similar to those employed in the current study (Typical error range = 8–10%). Assuming a typical error of 10%, a sample size of 8 would give 80% power to detect a 12% difference in total distance covered in acceleration and deceleration categories. Descriptive statistics are presented as means ± standard deviation. Differences between small, medium and large pitches were assessed for all outcome measures using one-way repeated measures ANOVA, with Bonferroni adjusted 95% confidence intervals calculated for pairwise comparisons. The statistical assumptions of this procedure; equal variance of difference scores, normal distribution of population samples, and non-dependence of measurement were verified using the threefold variance rule, visual inspection of box plots and visual inspection of scatterplots for each pairwise comparison, respectively (Newell, Aitchison, & Grant, 2010). Statistical significance was assumed at p < .05. Data analysis was conducted using SPSS 19.0 (IBM SPSS Statistics, 19.0, Chicago, IL.) and Microsoft Excel 2007. 3. Results Mean ± SD maximum heart rate measured in the multi-stage fitness test was 192 ± 8 beats min 1. During the SSGs, the heart rate responses were similar between pitch sizes (164 ± 14 beats min 1,
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168 ± 13 beats min 1 and 168 ± 17 beats min 1) corresponding to relative exercise intensities of 86 ± 3% HRmax, 87 ± 4% HRmax and 87 ± 4% HRmax for small, medium and large pitches, respectively. Table 1 displays the time–motion data for each pitch size. In summary, both medium and large pitches had a higher physical demand than small pitches, with no difference between medium and large pitches for all variables other than distance covered at high speed (Table 1). In comparison to SSGs played on a small pitch, total distance covered was higher on both medium (mean difference [95% CI’s] = 409 [219–600] m) and large pitches (mean difference [95% CI’s] = 402 [211–593] m), and total distance covered in acceleration and deceleration ranges were both higher on medium (mean difference [95% CIs] total acceleration = 126 [6–247] m, total deceleration = 116 [12–222] m) and large pitches (mean difference [95% CIs] total acceleration = 97 [4–190] m, total deceleration = 100 [20–181] m). The frequency of technical actions per player for each pitch size is displayed in Fig. 1. There were differences between pitch sizes for the number of passes played (p = .009) and shots attempted (p = .003). Specifically, players attempted more passes (mean difference [95% CI’s] = 3 [0–7]), and more shots (mean difference [95% CI’s] = 2 [0–5]) on the small pitch compared to the large pitch. There were no differences between medium and large pitches for attempted passes, but the number of shots attempted was higher on the medium pitch in comparison to large (mean difference [95% CI’s] = 2 [0–4]). The difference in the frequency of tackle attempts between pitch sizes approached statistical significance (p = .056) with a trend for more tackles on the small pitch compared to medium (mean difference [95% CI’s] = 2 [0–3]) but not compared to large (mean difference [95% CI’s] = 2 [ 1 to 4]). 4. Discussion We sought to characterise the physical and technical demands of SSGs in soccer played on different pitch sizes. This study is the first to quantify the acceleration demands of SSGs with a high-frequency data capture system, providing an explanation for the well-documented efficacy of this training mode in eliciting improvements in soccer-specific fitness (Helgerud, Engen, Wisloff, & Hoff, 2001; Hill-Haas et al., 2009; Impellizzeri et al., 2006; Owen, Wong del, Paul, & Dellal, 2012). Changing pitch size affects both the physical and technical demands of SSGs. Small pitch sizes are characterised by a reduced physical demand and an increased technical demand in comparison to large pitches. Medium pitch sizes seem to be optimal; providing both a high frequency of technical actions, and a high physical demand that is unchanged as pitch size increases. These data have important implications for coaches and practitioners utilising SSGs as a conditioning stimulus in soccer. The data provided by this study on the time–motion demands of SSGs support the use of this mode of training as a conditioning stimulus in soccer, particularly with reference to the acceleration demands. Osgnach et al. (2010) emphasised the importance of monitoring these variables as the
Table 1 Distance covered (m) for speed and acceleration variables in small-sided games played on small, medium and large pitches (Values are mean ± SD).
Total distance High speed distance Sprint speed distance Total acceleration High acceleration Moderate acceleration Low acceleration Total deceleration High deceleration Moderate deceleration Low deceleration a b
Small pitch
Medium pitch
Large pitch
1532 ± 145 0±0 0±0 230 ± 111 23 ± 18 57 ± 36 150 ± 58 198 ± 89 18 ± 15 46 ± 30 133 ± 44
1941 ± 148a 29 ± 28 11 ± 21 356 ± 72a 38 ± 10a 94 ± 24a 223 ± 40a 314 ± 67a 34 ± 12 83 ± 20a 198 ± 37a
1934 ± 133a 61 ± 47a,b 16 ± 27 327 ± 70a 32 ± 12 83 ± 24a 212 ± 37a 298 ± 68a 31 ± 12a 77 ± 26a 190 ± 31a
Significant difference in comparison to small pitch (p < .05). Significant difference in comparison to medium pitch (p < .05).
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Fig. 1. Frequency of technical actions per player during SSGs played on small, medium and large pitches. Values are mean ± SD. ⁄ Significant difference in comparison to small pitch (p < .05). Significant difference in comparison to medium pitch (p < .05).
metabolic and neuromuscular demand of acceleration movements are high even when speed is low, and such movements are common in soccer. Data from 11v11 professional games collected with the same NdGPS system shows that, in a 90 min game, on average professionals cover 10,451 m total distance, with 1022 m spent accelerating, and 899 m decelerating (Akenhead et al., 2013). This equates to an average distance covered in acceleration and deceleration ranges of 9.7 and 8.6 m every minute respectively (half time period included), or 18% of the total distance covered. On the medium pitch in our study, the relative demand was higher than this, with our players covering 14.2 m accelerating and 12.6 m decelerating (recovery periods included) every minute on average, equating to 35% of the total distance covered. Considering the potential importance of these movements as an indicator of fatigue in soccer (Akenhead et al., 2013; Osgnach et al., 2010), the data suggest SSGs might provide a ‘density’ type stimulus; imposing relative demands on acceleration abilities in excess of those experienced during full match play. These data provide an explanation as to why this training method has proved to be equal to or superior than traditional interval training in the available research (Helgerud et al., 2001; Hill-Haas et al., 2009; Impellizzeri et al., 2006). The greater distances reported in acceleration vs. deceleration ranges reflects the predominant muscle actions involved in these movements. Acceleration requires the generation of propulsive forces predominantly through concentric muscle action, whereas deceleration requires braking forces produced predominantly by eccentric muscle actions. As human skeletal muscle is stronger eccentrically, players are able to exert greater braking then propulsive forces, thus slowing down quicker and covering less distance as a consequence during deceleration movements. The movement demands on medium and large pitches exceeded that of small pitches, with no difference between medium and large pitches. Players covered more total distance, and more distance during acceleration and deceleration ranges on medium and large pitch sizes. However, the exercise intensity as measured by heart rate was similar between pitch sizes (86% of HRmax for small pitches vs. 87% for medium and large pitches). These values are in line with previous similar studies by Rampinini et al. (2007) (87–91% HRmax) Casamichana and Castellano (2010) (93–95% of HRmax) and Kelly and Drust (2009) (89–91% HRmax). The finding of a similar heart rate despite large differences in the movement variables assessed could reflect the insensitivity of heart rate as a measure of exercise intensity in intermittent games. An alternative explanation might reside in the higher frequency of technical actions performed on the small pitch size (discussed below), and the smaller
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playing area requiring players to make quicker decisions more frequently, both of which could have imposed a higher metabolic load that was not reflected in the time–motion data. Thus, whilst changing pitch size might not significantly alter the heart rate response to SSGs (Kelly & Drust, 2009), the data from this study suggest that the movement demands that elicit this response are different between pitch sizes. The frequency of technical actions was similar across pitch sizes, with a tendency for a higher technical demand on small (more passes and shots, and a trend for more tackles) compared to medium and large pitch sizes. This finding regarding an added technical demand on smaller pitch sizes has been previously reported, particularly with regards shots and tackles (Casamichana & Castellano, 2010; Kelly & Drust, 2009; Tessitore, Meeusen, Piacentini, Demarie, & Capranica, 2006). The smaller pitch size reduces the active playing area and requires players to make faster decisions and execute skills with higher frequency. The potential for players to frequently accelerate and/or attain high running speeds is however compromised. The coach should consider the aim of the session when designing such games, with the knowledge that the technical and physical demands of the game can be manipulated by reducing or increasing the size of the active playing area. Whilst the use of a 10 Hz NdGP system is an improvement on previous research, there still remains a degree of error. For example, the acceleration values reported by Osgnach et al. (2010), using a higher frequency 25 Hz video camera system, were higher than those measured with a 10 Hz system in professional players by Akenhead et al. (2013) (Total acceleration = 1022 vs. 1767 m and total deceleration 899 vs. 1775 m). In addition, in this study we have been unable to distinguish between acceleration movements commencing from different speeds, which have different mechanical and physiological consequences. For example, an acceleration of 2 m s 2 resulting in a change of velocity from 0 to 2 m s 1 will pose a different physical demand to acceleration resulting in a change of velocity from 2 to 4 m s 1. Whilst we have not been able to accurately characterise the incidence of different starting speeds, by reporting the distance covered in acceleration ranges (as opposed to time) we have been able to proportionately discriminate between acceleration movements at high and low speeds. Thus whilst the current study provides an advance on previous research, there still remains scope to more accurately quantify the physical demands imposed on soccer players both in training and match play. The importance of acceleration movements in football is an area that warrants further research, both in training and match play situations (Osgnach et al., 2010; Varley & Aughey, 2013). If these movements characterise fatigue in football (Akenhead et al., 2013) then the ability of players to repeat acceleration efforts over the course of a 90 min game is an important ability to train; our data would indicate that SSGs might be an efficacious method to achieve this. Future studies should further attempt to characterise the demands of soccer training and match play with reference to these demands, and to assess the efficacy of sport-specific training interventions aimed at improving this fitness quality. In conclusion, the results of this study provide novel data on the movement demands of smallsided games in soccer, and further support for the assessment of the acceleration demands of training and match play. The distances covered during acceleration movements during SSGs are relatively higher than match play in professional players, supporting the use of SSGs as a training tool in soccer. Changing pitch size can impact both the physical and technical demands of SSGs. A medium pitch size is optimal in that it imposes a high physical demand on players whilst maintaining a high frequency of technical actions. Practitioners can use the data presented here to more accurately prescribe appropriate soccer-specific training stimuli. Acknowledgements No financial support was received for this project. No professional relationships with companies or manufacturers of the measurement tools used in this project exist. References Akenhead, R., French, D., Thompson, K. G., & Hayes, P. R. (2013). The acceleration dependent validity and reliability of 10 Hz GPS. Journal of Science and Medicine in Sport. http://dx.doi.org/10.1016/j.jsams.2013.1008.1005.
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