**The Effects of Exercise Order on the Psychophysiological Responses, Physical and Technical Performances of Young Soccer Players: Combined Small-Sided Games and High-Intensity Interval Training**

**Ersan Arslan <sup>1</sup> , Bulent Kilit <sup>2</sup> , Filipe Manuel Clemente <sup>3</sup> , Yusuf Soylu <sup>1</sup> , Mustafa Sögüt <sup>4</sup> , Georgian Badicu <sup>5</sup> , Firat Akca <sup>6</sup> , Mine Gokkaya <sup>6</sup> and Eugenia Murawska-Ciałowicz 7,\***


**Simple Summary:** Small-sided games are very popular training methods, among other commonly used strategies, for enhancing the functional and sport-specific skills of young soccer players. In addition, high-intensity interval training has the potential to increase the aerobic capacity of youths. No study has compared the order effects of combined small-sided games and high-intensity interval training on the physical performances, psychophysiological responses, and technical skills of young soccer players. The results of this research show practical information that can help to design training programmes for youth soccer players.

**Abstract:** This study aimed to compare the order effects of combined small-sided games (SSGs) and high-intensity interval training (HIIT) on the psychophysiological responses and physical and technical performances of young soccer players. Twenty-four soccer players (aged 14.63 ± 0.71 years) were randomly divided into SSGs + HIIT (*n* = 12) and HIIT + SSGs (*n* = 12) for 6 weeks. The SSGs consisted of two 4–16 min rounds of 2, 3, and four-a-side games with 2 min of passive resting, whereas the HIIT consisted of 6–10 min of high-intensity runs at varying intensities (from 90 to 100%). Pre-test and post-test elements included a 5–30 m sprint test, countermovement jump test, zigzag agility test with the ball and without the ball, repeated sprint ability test, speed dribbling ability test, three-corner run test, and Yo-Yo Intermittent Recovery Test level 1. Both combined training interventions produced similar improvements in physical performance and technical responses (*p* ≥ 0.05, *d* values ranging from 0.40 to 1.10). However, the combined HIIT + SSGs training produced meaningfully lower perceived exertion (*p* = 0.00, *d* = 2.98) and greater physical enjoyment (*p* = 0.00, *d* = 4.28) compared with the SSGs + HIIT intervention. Furthermore, the SSGs + HIIT group showed a higher training load than those from the HIIT + SSGs group for all weeks (*p* ≤ 0.05, *d* values ranging from 1.36 to 2.05). The present study's results might be used by coaches and practitioners to design training programmes for youth soccer players.

**Keywords:** soccer; high-intensity; small-sided games; psychophysiological responses; combined training

**Citation:** Arslan, E.; Kilit, B.; Clemente, F.M.; Soylu, Y.; Sögüt, M.; Badicu, G.; Akca, F.; Gokkaya, M.; Murawska-Ciałowicz, E. The Effects of Exercise Order on the Psychophysiological Responses, Physical and Technical Performances of Young Soccer Players: Combined Small-Sided Games and High-Intensity Interval Training. *Biology* **2021**, *10*, 1180. https:// doi.org/10.3390/biology10111180

Academic Editor: Tetsuya Shiuchi

Received: 13 September 2021 Accepted: 11 November 2021 Published: 15 November 2021

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**Copyright:** © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

#### **1. Introduction**

High-level performances in soccer are combined with physical performance, psychophysiological responses, and technical abilities during small-sided games [1–3]. Therefore, several alternative training methods to traditional ones have been proposed to enhance the physical and technical capabilities of young soccer players. High-intensity interval training (HIIT), one of the increasingly popular training modalities, is defined as intense and intermittent exercises interspersed with recovery periods [4]. It requires a reduced amount of time and thus allows young athletes greater time to train their sport skills [5]. Earlier studies have documented the positive influences of HIIT on various physical fitness parameters [6] and soccer-specific performance characteristics in young soccer players [7].

Small-sided games (SSGs)—training strategies that are more enjoyable, effective, and time-efficient—are another commonly used method for training the functional and sport-specific skills of young soccer players [1,8]. SSGs, which are derived from street soccer and are played with fewer players, smaller pitch areas, and modified rules [9,10], simultaneously involve actual game dynamics, technical and tactical skills, and physical demands under changeable game conditions [8,11]. Consequently, some studies have shown the contribution of SSGs to aerobic fitness, repeated sprint ability, linear sprinting, agility, change of direction, and jumping performance in young players [1,12].

A recent systematic review demonstrated the effectiveness of combined HIIT and SSGs for soccer players [13]. As a result of this study, it was discovered that combining SSGs and running-based training methods induced higher external and internal load values and greater improvements in overall fitness capacity compared to the intervention using only SSGs. On the other hand, the researchers found a larger improvement in aerobic fitness for professional players who only participated in SSGs when compared to players who participated in combined training [14]. The inconsistency among these aforementioned studies shows that more research is needed to understand the efficiency of combined training.

Several studies recently compared the effects of combined game-based and HIIT programmes in team sports [13,15]. While some coaches routinely use the combined SSGs and HIIT approach (starting with SSGs and then performing HIIT or the opposite) to optimise sport-specific technical and tactical learning without any physiological or psychological fatigue effect on performance, others may prefer the combined HIIT and SSGs approach to have players undertake game performance, including technical and tactical tasks, under fatigue conditions [16,17]. The mechanisms related to running-based and game-based training are naturally different, although both tax aerobic and anaerobic metabolisms. Running-based HIIT seems to elicit a greater proportion of anaerobic metabolism. Blood lactate concentrations vary between 4 and 9 mmol/L in short/long HIIT [6], while SSGs vary between 0.5 and 4 mmol/L [18]. Moreover, neuromuscular effects are also different. Short HIIT or nonmaximal efforts produce peripheral fatigue (e.g., alterations to muscle excitability and excitation–contraction coupling), while SSGs can produce more variability based on the type of stimulus occurring in a match [19]. Therefore, it can be expected that starting with one type of HIIT over another might constrain the physiological responses, which would interfere with the next method. In a pioneering study, researchers examined the influences of combined training with different exercise orders on semi-professional soccer players [20]. Their results indicated that changing exercise orders yielded a similar enhancement in intermittent fitness performance. However, to the best of the authors' knowledge, there are no additional data on the impacts of combination order on multiple performance parameters in soccer players. Therefore, the aim of the present study was to compare the order effects of combined SSGs and HIIT on the psychophysiological responses and physical and technical performances of young soccer players.

#### **2. Materials and Methods**

### *2.1. Study Design*

A two-group, matched, experimental design was used in the present study. The study was completed over a total of 9 weeks, consisting of 1.5 weeks of pre-testing, 6 weeks of combined training interventions (SSGs + HIIT or HIIT + SSGs), and 1.5 weeks of posttesting. The players completed a 30–15 intermittent fitness test (30–15 IFT), speed dribbling ability (SDA) test, 5–30 m sprint test, countermovement jump (CMJ) test, repeated sprint ability (RSA) test, zigzag agility test with the ball (ZAWB) and without the ball (ZAWOB), three-corner run test (TCRT), and Yo-Yo Intermittent Recovery Test level 1 (YYIRT-1) before and after the 6-week combined intervention period. Both training interventions were performed twice a week and each daily training session was separated by a minimum of 2 days to avoid fatigue-induced adverse effects. During the present study, the players performed the same type of daily training, and combined training interventions were added to their training sessions. After 15 min of standardised warmup, which consisted of jogging and dynamic stretching at each training session, players performed combined training, including SSGs + HIIT or HIIT + SSGs. All tests and training sessions with the same order were performed on a natural grass soccer pitch.

#### *2.2. Subjects*

Twenty-four young male soccer players participated in the present study. The players were separated into two combined groups: the SSGs + HIIT group (*n* = 12, age: 14.67 ± 0.65 years) and the HIIT + SSG group (*n* = 12, age: 14.58 ± 0.79 years). All players were also members of the U-16 regional amateur league teams. They were accustomed to a training workload of ≥3 training units per week, consisting of core strength, plyometric and technical drills, and had been involved in soccer training and competitive soccer matches for at least 2 years. Before the study, all players and their parents were fully informed about the procedures to be used and completed voluntary written consent forms. The study was performed in accordance with the Declaration of Helsinki and the Research Ethics Committee of the local university.

#### *2.3. Procedures*

Testing Procedure. On the first day, to calculate body fat percentage, the skinfold thickness technique was used with a Holtain Tanner–Whitehouse skinfold calliper (Holtain, UK) before breakfast. Skinfold thickness was measured twice at each site and the mean of two measurements was used to calculate body fat percentage. Body fat percentage was calculated using the equation that has been validated for males aged 15 to 24 years in young Turkish athletes [21]. After anthropometric measurements, determination of individual players' high-intensity intermittent running performance with changes in direction was assessed using the 30–15 IFT. The test, which consists of 30 s of running and 15 s of passive recovery, is a reliable progressive field test according to the procedures performed by Buchheit [22]. On the third day, the SDA test was used for the evaluation of soccer-specific technical skills and according to procedures described by Rosch et al. [23]. Briefly, the test, which is available in the F-MARC test battery designed by FIFA, allows for the assessment of coordinated speed dribbling under time pressure. After the technical test, each player performed three straight 30 m sprint test (5 m, 10 m, and 20 m splits) performances with 2 min of passive resting.

On the fifth day, each player was tested on their vertical jump height using the CMJ test according to the procedures performed by Arslan et al. [1]. A portable force plate (Newtest, Finland) was used to assess the CMJ test performances. Following the CMJ test, each player performed 6 repetitions of a 30 m maximal sprint with a 180◦ change of direction (15 m + 15 m). Twenty seconds of recovery were allowed between shuttle sprints [24]. The ZAWB and ZAWOB tests were performed to evaluate the agility performances of the players on the seventh day. The test, which included soccer-specific movement patterns [25], consisted of four 5 m sections with each change of trajectory

angled at 100◦ as reported by Mirkov et al. [26]. The TCRT was performed to assess the speed endurance and anaerobic endurance of the players on a natural grass pitch [23]. The running times in these tests were measured using a timing gate photocell system. We found high test–retest reliability (ICC = >0.86) for tests such as sprinting, jumping, agility, and technical skill. On the ninth day, to evaluate maximum oxygen consumption (VO2max), the YYIRT-1, which is an acoustically progressive field test [27], was performed according to procedures explained by Bangsbo et al. [28]. After the test, the estimated VO2max was calculated using the following formula:
