The use of small-sided games (SSGs) to develop physical fitness has been shown to be effective among soccer players (17,21). Furthermore, the flexible nature of SSGs means that the intensity can be altered by modifying a number of variables such as the number of players (18,29), the pitch size relative to the number of players (3,7,8,9,22,31), the use of coach encouragement (29), and the inclusion of floaters (16).
The bouts duration within SSGs is a key aspect when designing a training regimen because it determines the distribution and intensity of the drills used (14). However, very few studies have examined the effect of modifying this variable on players' physical and physiological performance. Fanchini et al. (14) compared different bout durations (2, 4, and 6 minutes) in SSGs and found that exercise intensity decreased as duration increased. For their part, Tessitore et al. (31) hypothesized that task duration would be associated with a given energy metabolism and found that players spent longer duration above the lactate threshold when bout durations lasted for 8 minutes rather than 3 minutes. Furthermore, another study (19) examined the effect of 2 regimes of SSGs in which the overall duration of training was the same: a continuous format (1 × 24 minutes) and an intermittent format (4 × 6 minutes, with 1.5-minute passive recovery time between each repetition). They found higher values for both heart rate (HR) responses and rating of perceived exertion in the continuous format, whereas physical response was greater in the intermittent format including longer distances covered at high speeds and a greater number of sprints. However, traditional SSG formats do not use durations as long as those proposed by Hill-Haas et al. (19). The SSG drill are usually proposed in drill durations that are shorter than those proposed by Hill-Haas (i.e., 24–33 minutes). It is difficult to imagine that players could provide their maximal physical and technical performance during the whole continuous 24-minute period without recovery period knowing that the fatigue in SSGs appears during the third or fourth bouts in an intermittent format of SGG (3- and 4-minute bout duration, respectively) (9,22). In this context, it appears that the interest and comparison between the continuous and intermittent format of SSG is still not well clarified. To illustrate this, the major part of studies examining the activity within a 5 vs. 5 SSG was applied during an intermittent format of 4 × 4 minutes (22), but none of the studies suggested a comparison with a longer intermittent or continuous format of this SSG (2 × 8 minutes or 1 × 16 minutes). The modification of the duration format of a SSG should have induced different physiological response, physical activity, and technical performance.
Therefore, this study aimed to examine the physical and physiological demands in 3 different duration formats of a 5 vs. 5 SSG for a total of 16 minutes: a continuous format (SSG1; 1 × 16 minutes), a long duration intermittent format (2 × 8 minutes, SSG2), and a traditional intermittent format (4 × 4 minutes, SSG4). During all this 3 different formats of 5 vs. 5, the total volume of training (16 minutes) was also divided in 4-minute periods to determine the extent to which fatigue affected the variables studied. It was hypothesized that a continuous format of SSG induces greater physical loads and fatigue on players as compared with a traditional intermittent SSG format.
Experimental Approach to the Problem
The 5 vs. 5 SSG was examined changing the distribution of the duration and therefore using 3 different formats: continuous, long intermittent, and traditional intermittent formats. A nonexperimental descriptive comparative design was used to examine the differences between intermittent (4 × 4 minutes and 2 × 8 minutes) and continuous (1 × 16 minutes) distribution of the time in the 5 vs. 5 SSGs and evaluating physical (distance covered in different speed and player load) and physiological (HR responses) demands to the players. Comparisons were performed examining male semiprofessional soccer players during the competitive season (2010–11). Players' drill physical demands were assessed using Global Positioning System (GPS) technology including a triaxial 100 Hz accelerometer to obtain the player load as it is previously recommended during SSG (6,26). The player load is calculated using the following formula:
where aca is the acceleration in the anteroposterior or horizontal axis, act is the acceleration in the transverse or mediolateral axis, acv is the acceleration in the vertical axis, i is the current time, and t is time.
The study was conducted over a 3-week period (in April) during the competitive season (2010–11). Weeks before the experimentation, players were familiarized with both the different format of SSGs and the material used in this study. Players performed the Yo-Yo Intermittent Recovery Test level 1 (Yo-Yo IRT1) to determine their HRmax during the week before the beginning of the study. This test was done on an outdoor artificial pitch with the players wearing football boots, and all the tests were performed on the same time of day to limit the circadian rhythms effect (12).
On an outdoor artificial grass pitch and at similar times of day (12), 3 training sessions were then held in 3 different weeks (in the same day and with same the schedule) to control the fatigue and the work performed the prior days. During each session, and after a standard 15-minute warm-up, 1 of the 3 SSGs formats was played. The order in which this was done is shown in Table 1.
During the SSGs, coaches provided encouragements according to Rampinini et al. (29). In addition, several balls were distributed around the edge of the pitch to maximize the effective playing time (3), that is, ensuring that play could quickly continue whenever a ball went out of play. During rest periods of the intermittent SSGs format, “ad libitum” water was allowed and provided to players. All participants were advised to maintain their normal diet, with special emphasis being placed on a high intake of water and carbohydrates.
Ten male soccer players (age: 21.3 ± 3.4 years, height: 180 ± 7 cm, weight: 73.9 ± 6.6 kg, Yo-Yo IRT1: 2195.6 ± 310.8 m) from a team playing for the third Spanish Division took part in the study during the competitive season (2010–11). They had played federation soccer for a mean of 12.5 years. Their standard training involved 3–4 sessions per week (each lasting around 90 minutes), in addition to a competitive match.
All the players were notified of the research design and its requirements, as well as the potential benefits and risks, and they each gave their informed consent before the start. The Ethics Committee of the University of the Basque Country (CEISH) also gave its institutional approval of the study.
All variables except the training regimens were kept constant throughout the different situations of SSGs. All the SSGs composed for 5 players a side (without goalkeepers), and the task aimed to maintain ball possession. The size of the pitch was kept constant (55 × 38 m), and thus the relative pitch area per player was always the same (210 m2).
The first independent variable examined was training regimen, that is, the way in which the total 16 minutes of SSGs was distributed. Three formats of SSGs were used: SSG1 (1 repetition of 16 minutes) and 2 intermittent regimes (SSG2: intermittent format of 2 × 8 minutes; and SSG4: intermittent format of 4 × 4 minutes). There was a passive recovery time of 2 minutes between each period within SSG2 and of 1 minute between the periods within SSG4.
The second independent variable was the 4-minute period analysis. For each of the 3 SSGs formats tested, the 4-minute periods were also considered to compare the physical and physiological demands for each period and format. These periods were from 0 to 4 minutes (0–4), from 4 to 8 minutes (4–8), from 8 to 12 minutes (8–12), and from 12 to 16 minutes (12–16).
Heart Rate Responses
Heart rate responses were monitored during all the SSGs to provide the mean HR and the percentage of maximal HR reached in the overall SSGs. HR responses were recorded via telemetry device (Polar Team Sport System; Polar Electro Oy, Kempele, Finland) at 5-second intervals throughout each SSG and during the Yo-Yo IRT1 (1). The maximum HR was determined as the peak HR observed during the Yo-Yo IRT1 (23). The HR responses were analyzed with according to the standard HR zone (18) dividing in 4 intensity zones (<75% of HRmax, 75–84% of HRmax, 85–89% of HRmax, and >90% of HRmax).
Physical Profile: Distance Covered Within Small-Sided Games
The players' movements during SSGs were measured using a portable GPS device (MinimaxX, version 4.0; Catapult Innovations, Melbourne, Australia) operating at a frequency of 10 Hz. Each player wore a special harness, which enabled this device to be fitted to the upper part of his back. In accordance with the manufacturer's instructions, the GPS devices were activated 15 minutes before the start of each training session. After recording, the data were downloaded to a PC and analyzed using the software package Logan Plus version 4.4 (Catapult Innovations, 2010). A previous study has suggested that GPS devices underestimate the distance covered at high intensities compared with other methods of analysis (30). However, using a higher sampling frequency seems to increase the accuracy of the information provided by these devices (13). In this regard, the reliability, accuracy, and validity of the devices used in this study (4) can produce better results for 30-m runs (SE = 0.2 m; coefficient of variation [CV] = 0.7%; bias = 6.5%; and SEM = 5.1%) than those obtained in previous studies (13,28), which used a sampling frequency of 1 and 5 Hz.
To compare the different training regimes, the following variables were considered: (a) total distance covered and (b) distance covered in each of the established speed zones, that is, stationary/walking (0–6.9 km·h−1), jogging (7.0–12.9 km·h−1), running (13.0–17.9 km·h−1), high-intensity running (18.0–20.9 km·h−1), and sprinting (>21 km·h−1). These speed and movement zones are similar to those used in other studies (18,21,29).
The data are presented as mean ± SD. The homogeneity of variances was examined by means of Levene's test. The presence of significant differences was determined by means of a 1-tailed repeated-measures analysis of variance, applied to each of the dependent variables in relation to the training regimes (continuous format, intermittent format of 2 repetitions, and intermittent format of 4 repetitions) and the 4-minute periods (0–4, 5–8, 9–12, and 13–16 minutes). Whenever a significant difference was found, a post hoc Bonferroni's test were used, whereas a Dunnett's T3 post hoc test was applied when the variances were not homogeneous. The effect size (ES) was calculated to assess the meaningfulness of differences (5). The ESs of above 0.8, between 0.8 and 0.5, between 0.5 and 0.2, and less than 0.2 were considered as large, moderate, small, and trivial, respectively. All the statistical analyses were performed using SPSS16.0 for Windows (SPSS Inc., Chicago, IL), with significance being set at p <0.05.
The 5 vs. 5 SSG-induced HR responses comprised between 87.5 ± 3.1 (SSG1, SSG4) and 87.1 ± 3.1 (SSG2) % of HRmax, a total distance covered ranged from 1,855.6 ± 149.9 m (SSG1) to closed 2,000 m for intermittent formats (1,912.7 ± 163.1 in SSG2 and 1,963.1 ± 197.7 in SSG4), and a player load from 219.5 ± 63.7 (SSG4) and 257.7 ± 39.8 (SSG2), being 246.4 ± 26.2 to SSG1, expressed in Arbitrary Units. No significant differences were found for any of the variables.
Figure 1 illustrates the total distances covered in the different speed zone according the different period of 4 minutes composing the different SSGs. In absolute values (in meters), the distribution of the distances covered followed the same pattern in each of the 3 training regimes. Moreover, there were no significant differences between the 3 regimes in terms of the distances covered in the different speed zones studied.
Values of %HRmean obtained by the players in each of the 4-minute periods and for each of the training regimes were showed in Table 2. There were no significant differences between the periods within any of the training regimes, nor for each individual period across the 3 regimes. Figure 2 illustrates the distance (meters) covered in each 4-minute period for each of the training regimes studied with no significant differences found between periods within the same regimen, nor for each period across the 3 regimes were observed.
Figure 3 displays the distance (meters) covered in each 4-minute period among the 3 SSGs in relation to the different speed zones that were studied. The results for intermittent format of 4 repetitions show that a greater distance was covered at a speed of 7–12.9 km·h−1 in the first period (0–4 minutes) than in the last period (12–16 minutes; p < 0.05; ES = 1.84). This same speed zone (7–12.9 km·h−1) was also associated with a significant difference in the third period (8–12 minutes), in this case between continuous format and intermittent format of 2 repetitions (p < 0.05; ES = 1.54).
The physiological characteristics associated with the SSG played with different periods from each work regimen are presented in Figure 4. There was only one significant difference between period 12–16 minutes > 4–8 minutes in SSG4 for the percentage of time played at more than 90% of HRmax (p < 0.05; ES = 2.63).
The aim of this study was to examine the physical and physiological responses of soccer players in training regimes lasting the same total duration of 16 minutes, in which only the distribution of these 16 minutes was altered during a 5 vs. 5 SSG. It seems that in intermittent format of 2 × 8-minute, the distance covered at a speed of 7–12.9 km·h−1 was greater in the 0- to 4-minute period than in the 12- to 16-minute period. Furthermore, the distance covered at a speed of 7–12.9 km·h−1 during the 8- to 12-minute period was greater in intermittent format as compared with the continuous format.
Previous studies showed that 4 × 4-minute training induce intensity close to 90% of HRmax and that improve the physical fitness of players (14,15,20). However, it is not known at which point the intensity of a player's response begins to decrease or how to distribute the training time to maintain high intensity for as long as possible. Concerning the results for HR responses, it should be noted that all 3 training regimens in this study resulted in very high HR values (>87% of HRmax), but no significant difference was found between the regimens. These values are similar to those reported in other studies (3,8,18,24,25,27) and represent an adequate intensity for improving the V[Combining Dot Above]O2max of players.
Contrary to the results of this study, Hill-Haas et al. (19) showed that the 5 vs. 5 played in intermittent format induced lower HR responses than during a continuous format. It could be due to the differences in study design such as Hill-Haas et al. (19) employed a smaller ratio of pitch size (158 vs. 209 m2) and a longer total duration (33 vs. 16 minutes) in comparison with this study. Moreover, the presence of recovery period between SSG intervals may decrease the HR values in the subsequent intervals, which may contribute to the difference of HR responses with the continuous format. This information suggests that the HR responses could reach higher values during the continuous format probably because of the longer exercise duration. In this study, results also showed that the duration is not long enough to induce different HR responses between intermittent and continuous SSG formats because it has been found in previous studies (3,7,8,10,11,16,19,24,25). It demonstrates that the manipulation of rules, especially the length of work period and pitch size, could alter the physiological responses within SSG, whatever of the format.
In terms of the different 4-minute periods, it should be noted that although no significant difference has been found in the %HRmean, it was lower in both the third (8–12 minutes) and fourth periods (12–16 minutes) of the continuous regimen as compared with the intermittent regimens. The present results are consistent with those of Fanchini et al. (14), who also failed to observe a reduction in HR across repetitions in 3-a-side games; in fact, they observed lower values for the first repetition than for the second and third ones. In the intermittent format, the lowest mean HR was obtained in the 0- to 4-minute period. This finding may be because of the time needed to “enter into the match” (14) and that the HR responses need a longer time to reflect the aerobic metabolism contribution (2). With respect to the percentage of time spent in each intensity zone, it is found that players spent 60–70% of the exercise time at the intensity more than 84% of HRmax. Furthermore, there was only one significant difference for more the zone higher than 90% of the HRmax between the third and fourth bouts in the SSG4.
Concerning the distance covered, players covered a greater total distance in the 2 intermittent SSGs formats as compared with the continuous SSG format. In this regard, although Hill-Haas et al. (19) reported a greater total distance covered during the intermittent format SSG in comparison with the continuous SSG format, no significant differences were revealed between these 2 formats regardless of the speed zones.
The distance covered was greater during the first period of time (0–4 minutes) for all the regimens. In intermittent format of 2 repetitions (SSG2), players covered a similar distance after the rest period as they had in the first 2 repetitions of training. However, in this same format, the distance covered in the first 4-minute period of each period of training (i.e., 0–4 and 8–12 minutes) was greater than that covered during the second period of each 8-minute period (i.e., 4–8 and 12–16 minutes). Moreover, the results for intermittent format of 4 repetitions (SSG4) also suggested that players failed to recover entirely because a greater distance was covered during the first period (0–4 minutes) when using this format. A possible explanation for these findings is that the 1-minute passive rest (used in the SSG4) is insufficient to enable players to recover and achieve similar distance covered to those obtained in the absence of fatigue (i.e., during the first 4-minute period of training).
With respect to the distances covered in different speed zones in relation to the 4-minute periods, the results showed that in intermittent format of SSG4, a greater distance was covered at a speed of 7–12.9 km·h−1 in the first period (0–4 minutes) than in the last period (12–16 minutes). This same speed zone (7–12.9 km·h−1) was also associated with a significant difference in the third period of time (8–12 minutes), in this case between continuous format and intermittent format of 2 repetitions (SSG2).
Montgomery et al. (26) reported high correlations between player's load and HR. In the contrary, in this study, the results did not follow this pattern in the distance covered because player's load was greater in continuous format than in intermittent format (SSG4). This suggests that player load also captures jump and sprinting in addition to the distance covered. The player load seems to reflect the real physical activity of the players during an SSG. This findings justify that the continuous format of SSG induce a greater fatigue on the players because of the lack of recovery periods and the longer duration of the SSG (16 minutes). Thus, the value of player's load seems to be in adequation with the other parameter and findings presented in this study.
This study showed that both continuous and intermittent training SSG of 16 minutes enable players to achieve high intensity, which is required to improve their fitness. However, the total distance covered was greater during the intermittent SSG formats. Particularly, we found significant higher total distance coverage in intermittent SSG at a moderate running speed (7–12.9 km·h−1) during the 8- to 12-minute period, as compared with the continuous SSG. Furthermore, player's HR response appears to remain more stable across the periods of training when using an intermittent format. The results of this study help coaches to optimize the content of their training schedules by increasing and stabilizing the intensity in varying the SSGs' durations and format. The manipulation of the regimes format could allow to induce different physiological and physical demands. Coaches have now valuable information providing different possibilities to apply the SSG in different formats (intermittent vs. continuous) and, therefore, they should use one of them according to the aim and the objectives of the training and the period of the season.
This study is part of the project entitled Avances tecnológicos y metodológicos en la automatización de estudios observacionales en deporte, funded by Spain's Dirección General de Investigación, Ministerio de Ciencia e Innovación (PSI2008-01179) over the period 2008–2011. In addition, we thank the Basque Country University (UPV/EHU) and the Department of Physical Education and Sport provided funding. We also thank Dr. Del P. Wong for the valuable help in the correction of the document. No conflicts of interest exist for this research.
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Keywords:© 2013 National Strength and Conditioning Association
heart rate response; GPS device; football association; motion analysis; fitness training