Effects of Intermittent or Continuous Training on Speed, Jump and Repeated-Sprint Ability in Semi-Professional Soccer Players

rpose of this study was to compare the effect of two different training interventions (Intermittent versus Continuous training) on semi-professional male soccer player's speed, jump and repeated-sprint ability. Thirty four play- ers were divided into an intermittent training group (INT, n=18, age=26.7±4.7, height=175.3±5.2cm, weight=72.9±4.8Kg) and a continuous training group (CONT, n=16, age=26.6±5.1, height=174.9±5.9cm, weight=73.2±7.2Kg). The study lasted for 12 weeks and consisted of 20 minutes per training session in physical conditioning following either CONT or INT training guidelines. The players were tested 3 times during 1st, 6th and 12th week of the season. Testing consisted of 15m and 30m sprint time, squat-jump and countermovement jump height and Bangsbo modified sprint test. Two-way re- peated measures ANCOVA (group: INT, CONT x TIME-POINT: Week1, Week6, Week12) showed that INT was faster than CONT in the 6 th and 12 th weeks for the squat jump, 15m, 30m and Bangsbo Modified Sprint Test and that INT re- covered better from intense efforts than CONT. Our results suggest that both training interventions were able to maintain initial values of speed and jump. However, the INT exhibit larger improvements in repeated-sprint ability. Therefore, the power endurance training (intermittent high intensity exercise) may be more beneficial to prepare soccer players accord- ing to the game cardiovascular and metabolic specific determinants. INTRODUCTION Success in soccer requires high-level technical, tactical and physical skills. Available research on soccer perform- ance has often focused on technique and tactics at the ex- pense of physical resources such as endurance, strength and speed [1]. When played at the elite level, soccer requires endurance, speed, agility and power. The rate of work

cardiovascular and metabolic specific determinants. INTRODUCTION Success in soccer requires high-level technical, tactical and physical skills. Available research on soccer perform- ance has often focused on technique and tactics at the ex- pense of physical resources such as endurance, strength and speed [1]. When played at the elite level, soccer requires endurance, speed, agility and power. The rate of work of a soccer player ranges between low-level activities like walk- ing, jogging and those of high-intensity like sprinting. Re- search in this area has consistently focused on creating new techniques for enhancing soccer player’s performance. These techniques have led investigators to create soccer-specific exercise testing protocols by extensively analysing match play at the elite level [2]. Studies have been conduced to monitor power endurance activity such as overall distance covered, average intensities, and percentage of time spent walking, jogging, running and sprinting during match play [2-4]. Studies results characterize soccer as a team sport based in explosive actions such as kicking, jumping and sprinting [5]. Furthermore, fitness improvements specific to this activity pattern have been defined as power endurance [6]. These studies of movement patterns have provided re- searches with the scientific basis for developing not only soccer-specific exercise testing procedures, but also applica- ble conditioning and training protocols [7, 8]. The condition- ing programs are based on the specific physiological de- mands of the elite game, and have been built to focus on the *Address correspondence to this author at the Department of Sports Sci- ences, University of Trás-os-Montes e Alto Douro, Vila Real, Portugal; E-mail: abrantes@utad.pt high-intensity, intermittent aspects of fitness [9, 10]. Com- monly used exercises include plyometrics, resistive training and various forms of intermittent training [10, 11]. The ef- fect of incorporating soccer-specific training into fitness pro- tocols and assessment procedures has been well documented at the elite level [4, 8-11]. However, this focus on elite level players creates difficulties when interpreting training proto- cols and testing procedures for coaches competing in lower competition levels. In fact, research on semi-professional players is less common and training protocols have to be modified to more closely simulate ‘‘nonelite’’

pro- tocols and assessment procedures has been well documented at the elite level [4, 8-11]. However, this focus on elite level players creates difficulties when interpreting training proto- cols and testing procedures for coaches competing in lower competition levels. In fact, research on semi-professional players is less common and training protocols have to be modified to more closely simulate ‘‘nonelite’’ match re- quirements. The literature reveals that soccer players running speed can be improved following several types of training interven- tions such as sprint training, towing, overspeed [12], and specific plyometrics exercises [13]. The jumping ability de- pends on interlimb coordination, muscle type fibre and occa- sionally, on maximum strength, depending on the level of the player [14]. Vertical jump is improved through various types of training interventions, such as jumping exercises [14-16], depth jump, resistance training [14, 15] and combi- nation of plyometric exercises and electroestimulation [17]. It has been demonstrated that explosive-type resistance training is more effective in improving vertical jump com- pared to high-resistance training [16]. However, it has also been reported that resistance training does not always result in enhancement of vertical jump, which is affected by other factors such as learning effect [18], training status [19] and volume training [20]. Other studies reported that combined training programs including resistance and explosive un- loaded tasks such as throwing, jumping or kicking in the same training session may improve muscular strength and the speed of execution on the task [5, 12, 14, 21-23]. Long

16 The Open Sports Sciences Journal, 2008, Volume 1 Aguiar et al. term changes in soccer players repeated sprint ability is not documented. Another question that remains unknown in the literature is the structure of training models and their long term impact on soccer players’ physical fitness. In fact, in order to meet the specificity principle of training, it seems that soccer training models should be based on competition physiologi- cal determinants and, soccer practices should prepare players to respond adequately to these requirements. Thus, the pur- pose of this investigation is to identify the effect of 12 weeks of intermittent aerobic versus continuous training interven- tions on speed and repeated-sprint ability in semi- professional soccer players. METHODS Subjects Thirty four Portuguese semi-professional soccer players were randomly assigned into two intervention groups: the intermittent (INT) training group and the continuous (CONT) training group (see Table 1). The groups were pair matched based on physical and performance data (i.e., they were not different from each other prior to commencing the specific training interventions). The players that didn’t com- plete all the testing or training for any reason were removed from the sample. Table 1. Characteristics of the Soccer Players (Mean±SD) INT (n=18) CONT (n=16) Age 26.67±4.69 26.63±5.06 Years of experience 15.22±4.41 13.88±5.07 Height (cm) 175.33±5.18 174.88±5.90 Weight (Kg) 72.94±4.76 73.19±7.22 BMI (W/H 2 ) 23.73±1.28 23.90±1.66 Testing Procedures Testing occurred in the first, sixth and twelfth week of the competitive season. In the pre-season, both groups per- formed 5 weekly training sessions (each one lasting 120 minutes) and played one game. In the competitive season, they performed 4 training sessions (each one lasting 90 min- utes) and played one game. During each training session, coaches spent 20 minutes to specific conditioning develop- ment according to each intervention guidelines. The groups were tested at the same hour of the day (19:00-21:00h), al- ways after the weekly rest day. Before the tests, all players performed a standardized 25 minutes warm up, that con- sisted of jogging, sprinting, stretching, and tests familiariza- tion. Intermittent Aerobic Training This training intervention was based on soccer external

develop- ment according to each intervention guidelines. The groups were tested at the same hour of the day (19:00-21:00h), al- ways after the weekly rest day. Before the tests, all players performed a standardized 25 minutes warm up, that con- sisted of jogging, sprinting, stretching, and tests familiariza- tion. Intermittent Aerobic Training This training intervention was based on soccer external structure. The workload for the whole training sessions was the following: warm-up during 15 min; intermittent aerobic training intervention during 20 min (see Table 2); small sided games during 40 min (3x3, 4x4, 5x5, 6x6). This inter- vention was adapted from Bal i nas et al. [24]. Continuous Training This training intervention was based on time motion analysis data. The drills were planed and performed continu- ously using game like situations. The workload for training sessions was the following: warm up during 15 min; con- tinuous training intervention during 20 min (see Table 2); small sided games during 40 min (3x3, 4x4, 5x5, 6x6). This intervention was adapted from Bal i nas et al. [24]. Speed Speed was evaluated by maximal 15m and 30m sprints, respecting the following protocol: players executed three maximal sprints with 15m and 30m, with 3 minutes rest in- terval between each sprint. The players started to run 1m before the photoelectric cells (Digest 1000, Digest Oy, Fin- land) and they only slowed 1m after they passed by the sec- ond pair of cells. The best of the 3 obtained times was re- corded for data analysis. Vertical Jump Vertical jumps were measured with both squat jump and countermovement jump protocols. The squat jump consisted of the subject performing a maximal vertical jump with their hands on the waist, starting from an angle of 90º at the knee. The countermovement jump consisted of subjects perform- ing a maximal vertical jump starting from a standing position with arm swing allowed. All jumps were performed on the Ergojump (Globus Inc., Italy) that recorded the flight time of all jumps. The flight time was used to calculate the change in the height of the body's centre of gravity [25].

the knee. The countermovement jump consisted of subjects perform- ing a maximal vertical jump starting from a standing position with arm swing allowed. All jumps were performed on the Ergojump (Globus Inc., Italy) that recorded the flight time of all jumps. The flight time was used to calculate the change in the height of the body's centre of gravity [25]. Subjects per- formed three trials in each protocol and the best jump height was used in the analysis. Test reliability was high for both tests (respectively, SEM = 0.05% and SEM = 0.04%). Table 2. Characteristics of the Training Programs INT CONT Work-rest ratio (sec) 15:15, 5:25, 10:20, 15:30 15:15, 20:15 Duration of the series (min) 6 to 10 10 Number of series 2 or 3 3 Recovery between series (min) 6 to 10 3 to 5 Average intensity (% maximal heart rate) 80±15% 65±5%

Effects of Intermittent or Continuous Training on Speed, Jump The Open Sports Sciences Journal, 2008, Volume 1 17 Repeated-Sprint Ability The protocol consisted of seven maximal 34.2 m sprints [3, 4]. Each sprint was performed with a change in direction (indicated by a light-emitting diode) as showed on Fig. 1. Photoelectric cells (Digitest 1000, Digitest Oy, Finland) were used to measure the subjects' performance and to in- crease test reliability. Following each sprint there was a pe- riod of active recovery (25 s to cover a distance of 40 m), which consisted of jogging. Recovery was timed (stop- watch) in order to ensure that subjects returned to initial point of course between the 23rd and 24th second. Addition- ally, verbal feedback was given at 5, 10, 15, and 20 s of the recovery. Performance was measured as the mean sprint time in seconds and fatigue index. Fig. (1). Diagram of Bangsbo Modified Sprint Test protocol. Data Analysis A 3x2 repeated measures ANCOVA with Tukey’s HSD was used to assess within group differences between time points (1 st week, 6 th week, 12 th week) and between group differences (INT and CONT). When statistically significant differences were found, effect size (ES) was calculated ac- cording to Cohen [38]. All data undergoing ANCOVA were tested for assumptions of normality, homogeneity of vari- ance and covariance matrices and sphericity. Neither as- sumption was violated. Statistical significance was set at 5%. RESULTS The descriptive results (x±S.D.) and the statistically sig- nificance differences are found in Table 3. In general, results showed that INT was significantly faster than CONT (15m speed test and 30m speed test). The results from Bangsbo’s Modified Sprint Test showed that INT was faster and recov- ered better from the intense efforts than CONT. DISCUSSION The purpose of this investigation was to study the changes in semi-professional soccer player’s speed and re- peated-sprint ability, when performing intermittent or con- tinuous training programs. Such information would provide clear direction for coaches and players in the development of training programs. The results observed on sprint tests in the current study confirm the results

efforts than CONT. DISCUSSION The purpose of this investigation was to study the changes in semi-professional soccer player’s speed and re- peated-sprint ability, when performing intermittent or con- tinuous training programs. Such information would provide clear direction for coaches and players in the development of training programs. The results observed on sprint tests in the current study confirm the results found on other populations in previous studies [12, 16, 26-28]. The CONT group did not show any significant improvement while there were significant im- provements in the INT group in the sprint and jump tests. This suggests that the intermittent training intervention in- creased significantly the acceleration capacity and soccer Table 3. Descriptive Results (Mean±SD) and Statistical Significant Differences Test Time-Point Group 1 st Week 6 th Week 12 th Week CONT 2.30±0.08 2.31±0.09¥ 2.30±0.09¥ 15 m Speed* INT 2.19±0.08‡ 2.19±0.06 2.16±0.05 CONT 4.23±0.25 4.23±0.25¥ 4.20±0.26¥ 30 m Speed* INT 4.02±0.11‡ 4.03±0.15 3.97±0.13 CONT 39.9±1.3 38.6±1.5¥ 39.1±1.4¥ Squat-jump* INT 42.0±1.3‡ 42.6±1.4 44.1±1.3 CONT 38.3±1.3†‡ 40.2±1.4 40.1±1.1 Counter-movement jump INT 39.3±1.2†‡ 41.6±1.3 43.6±1.0 CONT 7.31±0.34†‡ 7.19±0.35¥ 6.93±0.39¥ Bangsbo Modified Sprint Test* INT 6.69±0.20†‡ 6.39±0.19 6.28±0.20 Bangsbo Modified Sprint Test * CONT 0.48±0.09†‡ 0.44±0.08¥ 0.37±0.04¥ (fatigue index) INT 0.34±0.08†‡ 0.25±0.07 0.18±0.04 ¥ denotes statistical significant differences in GROUP; † vs. TIME POINT 6th; ‡ vs. TIME POINT 12th; * in GROUP TIME POINT. There was statistical significant differences between the groups in the 15m Speed (F= 4.05 p 0.05 ES=0.13), 30m Speed (F= 5.15 p 0.01 ES=0.25) and Squat Jump (F= 4.50 p 0.05 ES=0.35). In Bangsbo Modified Sprint Test and fatigue index the differences between groups were also significant (F= 6.47 p 0.01 ES=0.36 and F= 8.97 p 0.01 ES=0.37, respec- tively). No significant differences were found in the Counter Movement Jump (F= 1.40 p=n.s.).

18 The Open Sports Sciences Journal, 2008, Volume 1 Aguiar et al. players' maximum speed, being more efficient in the prepa- ration of the players than the continuous training interven- tion. The improvements obtained by INT along the study could be the result of a combination of capacities (e.g. jump, sprint, tackle, direction changes, etc) worked with the appli- cation of the intermittent training intervention that according to the literature have an impact on strength and speed of tasks execution [4, 11, 14, 16, 21-23]. These improvements also can be attributed to neural adaptations and learning ef- fects induced by the training [5]. The results of the Bangsbo Modified Sprint Test con- firmed results obtained in the simple sprints tests. In these tests, INT was faster than CONT. This fact confirms the re- sults available in the literature [3, 29- 33], which identifies a high positive correlation between the speed and the time of the first two sprints. Aziz et al. [33] and Abrantes et al. [3] suggested that these results also have a high positive correla- tion with the repeated-sprint ability. Our results confirm also the existent controversy in the literature [33-37] about the relative importance of the aerobic and anaerobic energy sys- tems in performing repeated efforts. The INT group also maintain the capacity to recover between efforts. As sug- gested by Dowson et al. [30], our results show that the ca- pacity to accomplish repeated efforts of high intensity has a weak dependence of the aerobic capacity, The CONT sub- mitted to continuous training obtained weak improvements in the total average time and also on partial sprints. How- ever, the improvements obtained by CONT did not have re- percussions in recovery capacity between efforts as it was demonstrated by the increases of the times to accomplish the last sprints. It is in the recovery that some metabolic indica- tors of the aerobic preparation are clear in the repeated ef- forts [33, 34, 36], thus, the results obtained by INT, demon- strated that a training intervention based on the internal structure of the game, with great incidence in

demonstrated by the increases of the times to accomplish the last sprints. It is in the recovery that some metabolic indica- tors of the aerobic preparation are clear in the repeated ef- forts [33, 34, 36], thus, the results obtained by INT, demon- strated that a training intervention based on the internal structure of the game, with great incidence in the repeated- sprint ability, has more impact in this capacity than a training intervention only based on continuous training. CONCLUSION Our results suggest that both training interventions were able to maintain initial values of speed and explosive strength. The intermittent training intervention may be more beneficial to prepare semi-professional soccer players ac- cording to the game cardiovascular and metabolic specific determinants. REFERENCES [1] Helgerud J, Engen C, Wisloff U et al. Aerobic Endurance Training Improves Soccer Performance. Med Sci Sports Exerc 2001; 33(11):1925-1931. [2] Drust B, Reilly T, Cable N. Physiological responses to laboratory- based soccer-specific intermittent and continuous exercise. J Sports Sci 2000; 18(11): 885-892. [3] Abrantes C, Maçãs V, Sampaio J. Variation in Football players’ sprint test performance across different ages and levels of competi- tion. J Sports Sci Med 2004; 3(YISI 1): 44-49. [4] Bangsbo J. Physiology of soccer. Copenhagen, Storm 1994. [5] Kotzamanidis C, Chatzopoulos D, Michailidis C et al. The effect of a combined high-intensity strength and speed training program on the running and jumping ability of soccer players. J Strength Cond Res 2005; 19(2): 369-375. [6] Siegler J, Gaskill S, Ruby B. Changes evaluated in soccer-specific power endurance either with or without a 10-week, in season, in- termittent, high-intensity training protocol. J Strength Cond Res 2003; 17(2): 379-387. [7] Nicholas C, Nuttal, F, Williams C. The Loughborough intermittent shuttle. Test: A field test that simulates the activity pattern of soc- cer. J Sports Sci 2000; 18 (2): 97-104. [8] Ramsbottom R, Brewer J, Williams, C. A progressive shuttle run test to estimate maximal oxygen uptake. Br J Sports Med 1998; 22 (4): 141-144. [9] Hamilton A, Nevill M, Brooks S et al. Physiological responses to maximal intermittent exercise. Differences between endurance- trained runners and

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This study investigates training effects on soccer players' performance.