Physical Training Mar 2013
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Andreas ZAFIRIDIS2, Spyros KELLIS2

1. Department of Physical Education and Sport Science, Democritus University of Thrace, Greece
2. Department of Physical Education and Sport Science, Aristotle University of Thessaloniki, Greece


The aim of this study was to evaluate the effects of the short-term and extremely short-term interval training protocols on the aerobic performance in young soccer players. Thirty six (n=36) amateur players aged 16.2±1.1yrs participated in the present study. After the baseline laboratory evaluation (VΟ2max, vVΟ2max, RE, vAT), the subjects were subdivided in 3 groups: the short-term group [A(15s:15s)], the extremely short-term group [B(6s:30s)] and the control group (C). After the completion of the 10-week research protocols, the players’ aerobic performance was reevaluated. The repeated measures analysis of variance (ANOVA) was applied in order to evaluate the interactions of the 10-week interval training protocols on the players’ aerobic capacity. The results showed that the training groups presented a significant improvement in the VO2max (9.63% & 7.4%) and the vVO2max (5.8% & 5.35%) while the control group did not improve. In addition, the running economy (RE) did not improve significantly in the players of the interval training groups while the analysis of variance revealed that the intervention protocols did not affect the players’ velocity in the anaerobic threshold (vAT). Conclusively, the interval training protocols of 15s:15s and 6s:30s which were applied in a time period of 10 weeks contributed to the increase of both the VO2max and the vVO2max in young soccer players.

Key words: soccer, conditioning, aerobic, match.

Correspondence to:

Associate Professor Pilianidis Theophilos, PhD

Democritus University of Thrace

Department of Physical Education & Sport Science

University Campus

69100, Komotini, Greece

Phone & Fax: ++30531039683

Mobile: ++30932472967



Soccer is one of the most popular team sports in the world and millions of athletes desire to occupy themselves with it. The contemporary way of soccer playing requires from the athletes to maximize their performance which is consisted by factors such as the physical conditioning, the technical tasks, the team tactics and the psychological parameters (Ekblom, 1986; Balsom, 1994). Specifically in physical conditioning, the intensity, the volume and the rest periods are important components of the soccer annual training plan both in top-level as well as in amateur players (Wenger & Bell, 1986). Furthermore, it is significant for the soccer coaches to simulate the physical conditioning training to the high-intensity phases or the recovery periods of the match. In addition, it could be beneficial for the coaching procedures to work simultaneously on the player’s technique as well as on the team tactics during the conditioning training especially in top-level soccer players, (Reilly, 2005).

In the late 1990s the interval training programs presented the short-term high intensity protocols which were applied for the improvement of aerobic and anaerobic capacity of the soccer players. An improvement in the players’ VO2max was recorded for the first time in a 6-week program of high intensity bouts and short durations of rest intervals (Tabata et al., 1997). Similarly, in a 9-week interval training program with 4 repetitions of high intensity runs of 30s duration, an improvement was presented in both aerobic and anaerobic performance in top-level soccer players (Helgerud, Høydal & Wang 2007). Additionally, a 2 week training program of 15s maximal intensity runs and 45s rest intervals recorded an improvement in enzymatic activities of both aerobic and anaerobic metabolism in professional soccer players (Casajus, 2001).

In the 2000s a number of studies confirmed that the high intensity interval training affects positively the soccer players’ aerobic performance. During the competitive season, additionally to the normal team program, a high intensity 10-week interval training protocol increased the players’ aerobic capacity resulting in an important improvement of the overall team competitive performance (Dupont, Akakpo & Berthoin, 2004). Furthermore, the interval training was reported to improve the running fatigue resistance as well as the players’ speed-endurance in soccer because of its brief rest intervals (Hoff et al., 2002). In recent studies, a 7-week interval training program recorded an improvement of 6% to 7% in young soccer players’ VO2max (Impellizeri et al., 2006; Ferrari et al., 2008). Through the time, although a great number of studies have assessed the effects of the interval training in the soccer players’ competitive performance, very few studies have compared the interval training in young athletes’ performance during the competitive season. Therefore, the aim of the present study was to evaluate the effects of the two interval training protocols (short-term & extremely short-term duration) on the aerobic capacity of the young soccer players during the competitive season.

Materials and Methods


Thirty six (n=36) male soccer players from a Football Club were recruited for the study. Their mean age and training experience were 16.2±1.1yrs and 4±1.2yrs respectively, while the goalkeepers were excluded from the study. The selection of the participants for this study was based on the criteria of: i) the training experience (more than 2 years), ii) the absence of any drug treatment and iii) the frequency of training (4 sessions per-week). All participants completed a short questionnaire on their medical history and it was confirmed that they had no previous history of lower limb injury. Parents were informed about the research and they were asked to complete a written informed consent prior to their children’s participation. The study was performed according to the rules of the Ethics Committee of the Democritus University of Thrace.

Testing Procedures

The laboratory measurements were applied to the participants two days before and two days after the training intervention, at the same time of the day (15:00–20:00) and under similar ambient conditions (22o–23oC) and relative humidity (35–40%). A motorized treadmill (H-p Cosmos) was used for the estimation of the players’ VΟ2max while the expired gas was analyzed with a breath-by-breath automated gas-analysis system (Quark PFT Ergo, Cosmed). Before each test flow, the volume and the gases were calibrated according to the manufacturer’s recommendations. During the incremental running test the VO2, VCO2, VE and RER were estimated every 15s. After the baseline assessment completion, the players were divided in three equal groups: Α [interval training 15s:15s (120% vVO2max)], Β [interval training 6s:30s (145% vVO2max)] and C [control group]. The criteria for the groups’ subdivision were the initial ergo spirometer values so that the participants of the 3 groups would be equal in VO2max and vVO2max. After the 10 weeks of the interval training intervention the laboratory measurements were repeated in order to evaluate the adaptations of the training in the participants’ aerobic capacity. In the amount of the participants in this study, the obtained vVO2max from the baseline laboratory measurement ranged between 15 and 17km.h-1. The shuttle running distances which were covered by the interval training groups (Α:15s:15s & Β 6s:30s) in relation to their vVO2max are presented in figure 1.


15s running in 120% vVO2max

vVO2max: 16km/h

15s running in 120% vVO2max 



15s running in 120% vVO2max 



6s running in 145% vVO2max 



6s running in 145% vVO2max 



6s running in 145% vVO2max 


Research Protocol

During the 10 week research, the players of all groups participated in the soccer team normal training program which consisted of technical and tactical skills, high intensity games as well as the official game of the team every Sunday. The players of the interval training groups (A & B) performed their programs every Monday and Thursday complementary to the normal training of their team, while on Wednesdays the players of all groups trained with equal training intensities. The interval training consisted of 3 set x 6-8 runs with a passive recovery of 3min between the running bouts, while the players of the control group were trained only with the normal weekly training program of the team. After the first 3 weeks of the interval intervention the number of bouts gradually increased from 6 to 8 repetitions per set from the 4th to the 10th week. All training sessions were conducted outdoors on a grass pitch and all players wore soccer shoes. The A and B groups’ interval training programs are presented in Table 1.

Table 1. The 10-week-training programs which were applied in the players in Groups A and B.

Training parameters

Group A

Group B

Number of soccer training/week



Number of interval training programs/week



Duration of interval bouts



Resting periods



Running intensity

120% vVO2max

145% vVO2max

Rest type



Bouts per training session



Set recovery



Duration of interval training



Duration of resting interval



Duration of interval training programs



Statistical analysis

Descriptive statistics with exploration and cross-tabulation were firstly applied for all the continuous variables (mean±SD). The scatterplots were used in order to determine whether a linear model is reasonable for the variables of players’ performance in relations to the research protocols. The data normality was confirmed by using the Kolmogorov-Smirnov test, while the equality of variances in all testing variables was assessed by using the Levene’s Test. The statistical design for the measured variables of this study was based on the Analysis of Variance (ANOVA). The interaction among the evaluated parameters in each group was assessed by analysing the dependent factor “measurement” (pre-post) with the independent factor “Group” [(A:15s:15s)-(B:6s:30s)-(Control Group)]. The Bonferroni correction (post hoc comparisons) was applied in order to identify the inter groups statistically significant differences in the evaluated variables of this study. The acceptable level of significance was set at 0.05. All statistical analyses were carried out by employing the PASW-SPSS software, version 18.0 for Windows (SPSS, Inc., Chicago, IL).


The statistical analysis showed that the VO2max and the vVO2max were significantly affected only in the players of the interval training groups, while no differences were recorded in the VO2max and the vVO2max between the intervention groups. In addition, the interaction of the variables “measurement x training intervention” was significant only in the VO2max of the participants of the interval training groups (A) 15s:15s and (B) 6s:30s (F1.33=47.66, p<0.05), while the pre and post vVO2max did not differ significantly in the interval training groups (F1.33=1.22, p=0.31). The post hoc Bonferroni comparisons showed that in the interval training groups the players improved significantly in both post VO2max [(A:9.63%) & (B:7.4%)] and vVO2max [(A:5.8%) & (B:5.35%)]. Finally, the Control Group did not present any significant differences from the baseline to the final laboratory measurement as far as the VO2max and the vVO2max is concerned.

The running economy (RE) which is defined as the oxygen consumption ( at the 70% of the vVO2max, was not significantly improved in the players of the interval training groups. From the results it is shown that there were no interactions in the players’ RE after the 10-week training intervention. In spite of the fact that the oxygen consumption of the players who participated in the interval training groups decreased [(A:2.8%) & (B:1.7%)], the mean RE of the players marginally increased with no statistical significance (F1.33=0.97, p=0.76). Furthermore, no differences were found in the oxygen consumption and in the RE of the players in the Control Group. In addition, the analysis of variance revealed that the training protocols did not significantly affect the players’ vAT. However, the participants of the group A (15s:15s) presented an increase of 7.8% in the vAT while the players in the group B (6s:30s) improved their vAT as high as 6.1%. Finally, in the participants of the Control Group a marginal increase (2.5%) in the vAT was recorded. The pre and post research protocol measurements of the players’ aerobic capacity are illustrated in table 2.

Table 2. VO2max, vVO2max and RE measuring parameters in all group studied players, (mean±SD).

Interval Group (A)

Interval Group (B)

Control Group (C)


















VO2max (















vVO2max (km.h-1)















RE (















vAT (km.h-1)









The results of the present study are in agreement with a similar design research which showed that the players of the intervention groups improved their VO2max. This confirms that the high intensity of the interval training increases linearly the VO2max as a result of the greater mitochondrial respiratory capacity (Brooks, Fahey & White, 1996). In addition, the soccer players of the training group A (15s:15s) presented a greater improvement in both the VO2max and the comparison to those of the training group B (6s:30s). The above findings are in conjunction with studies which agree on the fact that the interval training with intensities of the 120% of the vVO2max is more effective for the increase of the VO2max compared to the interval training with exercise intensities of 145% of the vVO2max which are mostly focused on the anaerobic capacity improvement of the soccer players (Franch, Madsen & Djurhuus, 1998; Billat, 2001). Furthermore, another explanation for the greater improvement of the VO2max of the A group players (15s:15s) compared to the players of group B (6s:30s) is that the players of the group A had the benefit of the aerobic adaptations from this interval program even in the recovery periods of this type of training (Dupont, Akakpo & Berthoin, 2004).

In addition, the results of this study showed that both interval training programs improved the participants’ vVO2max as measured during the final aerobic performance laboratory measurement. Specifically, the increases of the soccer players’ vVO2max were 5.8% for the 15s:15s group (A) and 5.35% for the 6s:30s group (B). The above findings regarding the rate of the vVO2max improvement are better than other studies which presented that the level of increase of the vVO2max ranged from 3% to 3.8% (Billat, Flechet, Petit, Muriaux & Koralsztein, 1999; Smith, McNaughton & Marshall, 1999). Moreover, the 10- week duration of the interval training intervention confirmed that the program of the 15s:15s group improved the adolescent soccer players’ vVO2max (Lacour et al., 1991). Finally, the results of this study confirm that the rate of the athletes’ improvement in the vVO2max is greater when the VO2max in young sport participants ranges between 45 and (Dupont, Blondel, Lensel & Berthoin, 2002; Ferrari-Bravo et al., 2008).

Moreover, the current bibliography for the interpretation of the running economy is still in conflict mainly with the duration of the training programs. The marginal improvement of the running economy of the participants in the intervention groups is in agreement with the studies which denoted that the 6-week training could positively affect the running economy in moderate trained athletes (Bailey & Pate, 1991; Sperlich, 2011). In contrary, the majority of the relevant studies are in agreement with this study which presented that the running economy of the athletes improves in a time period of 13 to 104-weeks (Anderson et al., 1996; Bishop, Girard, Mendez-Villanueva, 2011).

In addition, the increases of the post intervention measurement in the vAT in both interval training groups players (A:7.8% & B:6.1%) are interpreted by the literature, which reports that the intensities of the interval training above the anaerobic threshold and close to the vVO2max improve the athletes’ anaerobic threshold (Burke, Thayer & Belcamino 1994; Impellizzeri et al., 2008). However, the lack of significance in the above increase in the vAT in the two training groups makes the researchers unable to justify why the interval training programs (15s:15s & 6s:30s) are beneficial for the anaerobic threshold improvement of the soccer players.

In summary, the findings of the current study showed that the short bouts and the extremely short bouts of the interval training seem to improve the VO2max and increase the vVO2max in young soccer players. More specifically, the 15s:15s in relation to the 6s:30s interval training during the competitive season has a potential to the physiological adaptations which are related to an increase on the aerobic metabolism in young soccer players. Future research is required for the evaluation of the metabolic, hormonal or psychological factors which could provide valuable information to the coach regarding the team training plan in order to enhance the competitive performance in developmental age and professional soccer players.


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