Effects of small-sided games and high-intensity interval training on physical performance in young female handball players

This study was designed to compare the effectiveness of small-sided handball games in combination with handball training (SSG group) versus high-intensity interval training in combination with handball training (HIIT group) on physical performance of young female handball players during pre-competitive period. Twenty-four young female handball players, who have a 6.17 ± 1.54 years training experience and competition in the national league participated in this study. SSG group (n = 12; age 16.06 ± 0.80 years, body mass 61.27 ± 3.68 kg, body height 1.64 ± 4.7 m, body mass index 22.7 kg/m2) while HIIT group (n = 12; 16.20 ± 1.28 years, body mass 62.46 ± 7.86 kg, body height 1.68 ± 6.8 m, body mass index 22 kg/m2). Both groups applied training programs twice-a-week for 8 weeks. Before and after the training programs physical performances were assessed: Countermovement jump (CMJ), Squat jump (SJ), Sprint on 0–10 m; Sprint on 0–20 m; Sprint on 0–30 m, Throwing medicine ball and total distance covered during the Yo-YoIRT1. After 8 weeks SSG and HIIT groups significantly improved CMJ, SJ, 0–20 m sprint, 0–30 m sprint, throwing medicine ball and Yo-YoIRT1 (p ≤ 0.05). However, significantly greater improvement was achieved in Yo-YoIRT1 (m) in HIIT group (28.40%) than SSG group (17.63%). These results indicate that SSG group and HIIT group equally improve of physical performances (jump, sprint and upper explosive strength) among young female handball players in pre-competitive period.


INTRODUCTION
Handball is a strenuous contact team sport that involves highly demanding intermittent actions, such as sprinting, jumping, short accelerations and decelerations, blocking, pushing, and throwing, interrupted by a short period of low-intensity activities [1,2]. It is a high-intensity intermittent sport that requires successful female handball athletes to have well-developed agility, explosive power of the upper and lower extremities, speed, aerobic capacity, hand coordination and repetitive torso strength [3]. Many training methods have been used in female handball for the improvement of physical performance, such as plyometric training [4], training neuromuscular stabilization [5,6], training with a medicine ball [7], complex training [8] and training with elastic bands [9]. Moreover, this training programme improves two or three motor abilities, yet other abilities remain neglected. Therefore, well-designed small-sided games can, at the same time, develop the functional, motor and technical-tactical abilities of athletes, improve game play and allow coaches to use training time economically [10]. Training of different abilities and technical-tactical skills, during the annual planning, should be particularly taken into account because of the ultimate impact on the improvement of handball players' performance [11].

Effects of small-sided games and high-intensity interval training on physical performance in young female handball players
were completed in the same order, spaced 8 weeks apart. The subjects were instructed not to be involved in strenuous exercise for at least 24 hours before the testing. None of the subjects were injured 6 months before the initial testing or during the training programme.
Players were also asked to keep a regular diet (nutrition and hydration) during the testing, and were prohibited from consuming any known stimulant (e.g. caffeine) or depressant (e.g. alcohol) within 24 hours before testing.

Measurements
Body height was measured to the nearest 0.1 cm using a Martin anthropometer (GPM in Switzerland), while body mass was obtained to the nearest 0.1 kg using a calibrated balance beam (Avery Ltd, Model 3306 ABV).
Squat Jump (SJ) and Countermovement Jump (CMJ) were determined by a force platform (Kistler Instrument AG, Quattro Jump, 9290AD, Switzerland). This platform has a Bosco protocol, which objectively allows measurements of force and flight time and the calculation of jump height (cm) [21]. Each athlete performed 3 trials of each jump and the best result was recorded for further analysis. Throwing a medicine ball (1 kg) from a lying position was performed using the 21.5 cm diameter 1 kg rubber medicine ball (Tigar, Pirot, Serbia) as described by Metikoš et al. [22]. The results represent the distance from zero point to the point of first contact of the ball with the ground. Throwing distance was measured to the nearest 1 cm. Three trials were recorded, but the best result was taken for further statistical analyses.
Yo-Yo Intermittent Recovery Test Level 1 was performed as described by Krustrup et al. [23] The total distance (m) covered during Yo-YoIRT1 was considered as the testing score.

Training programme
Training programmes started 1 week after the baseline testing (January, 2018) and lasted 8 weeks in the pre-competitive period. After the training programmes ( The purpose of the present study is to determine which training group [small-sided games combined with handball training (SSG group) and high-intensity interval training combined with handball training (HIIT group)] is more effective in improving physical performance in female handball players during the pre-competitive period.
It was hypothesized that SSG and HIIT groups would induce similar improvements in physical performance of young female handball players. All players were healthy and were not taking any medication. During the study, participants were not allowed to participate in another training programme that could potentially bias the results. Parents of participants gave their written consent after receiving a detailed explanation about the experimental protocols. All participants were told about potential risks during the study. All procedures were conducted in accordance with the Declaration of Helsinki [20] and approved by the Ethics Committee of the Faculty of Sport and Physical Education, University of Novi Sad.

Procedures
The study was carried out in the period from January 2018 to March 2018. One week before the initial testing and intervention, participants had a familiarization session. During the familiarization session, the assessment protocols were introduced to all participants. The subjects underwent physical test assessments in an indoor stadium.
Before each testing, the subjects performed a standard 15-minute warm-up (which included jogging, dynamic stretching exercises, sprints and jumping drills). During the test, the air temperature ranged from 19°C to 22°C. Testing was conducted in one day starting at  Table 1). The small-sided handball games were organized in four teams (3 vs. 3) excluding goalkeepers, on a playing court with dimensions 20x20 m. The players adhered to the modified rules as described by Dello Iacono et al. [24].
The HIIT group applied high-intensity interval training in combination with handball training.
Handball training in the HIIT group was the same as in the SSG group.     In a systematic review and meta-analysis, the authors [31] state that when small-sided games are applied 2 to 3 times per week moderate to large improvements are achieved in speed, jumping, agility, repeated sprint performance and aerobic capacity in a team sport.

High-intensity interval
A study [29] on young female and male handball players showed that small-sided handball games can be an effective method for improvement of vertical jump (3.5%) while high-intensity interval training resulted in an improvement of 3.2%. A related study on male elite handball players (age 25.6 ± 5) showed improvement of vertical jump by 10.96% after 8 weeks of small-sided handball games, while high-intensity interval training improved it by only 7.58% [30]. The present study showed slightly smaller improvements compared to these findings; the SSG group improved vertical jump (CMJ (cm)) by 4.04% while in the HIIT group it improved by 2.63%. The main reason why the SSG group has more advantages compared to the HIIT group is that during small-sided handball games there are more activities that require a jump than during high-intensity interval training [30]. Dello Iacono et al. [30] found improvement in a 20-m sprint after small-sided handball games by 3.91% compared to high-intensity interval training with 1.79%. In the present study, after 8 weeks, the SSG group improved the 20-m sprint by 1.68%, and the HIIT group improved it by 1.94%. The discrepancy between the results was due to differences in participants engaged in studies, pauses between running and the duration of a training programme. It should be especially noted that participants in this study were young female players who were not at elite level, and they are still in biological maturation, which is very important for the further development of speed [32]. In the present study, results for throwing a medicine ball for SSG (6.43%) were higher than for HIIT (3.77%). These findings were a consequence of explosive actions of the upper body (throwing group (SSG vs. HIIT) on the physical performance variable. Cohen's effect size (ES) statistic was used to determine the practical significance of observations [27]. ES was classified as follows: < 0.2 was defined as trivial; 0.2-0.6 was defined as small; 0.6-1.2 was defined as moderate; 1.2-2.0 was defined as large; > 2.0 was defined as very large; and > 4.0 was defined as extremely large [28]. Statistical analyses were performed with SPSS software (Version 20.0; IBM SPSS, Inc., Chicago, IL, USA). Baseline and the effect of training methods on physical performance in young female handball players are summarized in Table 3. There was no effect of time, group, or interaction on Sprint 10 m (p > 0.05, Table 3). SSG and HIIT groups demonstrated improvements in Sprint 20 m (1.68% and 1.94%, p ≤ 0.05), but no group or interaction effects were observed (p > 0.05). When the impact of the SSG and HIIT programmes on the Sprint 30 m was analysed, there was a significant main effect for time after eight-week intervention (0.39% and 2.37%, p ≤ 0.05). There was no effect of group or interaction on Sprint 30 m (p ≥ 0.05).

Good
There was a significant main effect for time when examining the impact of the SSG and HIIT programmes on upper-body explosive strength (throwing a medicine ball) (6.43% and 3.77%, p ≤ 0.05).
There were no effects of group or interaction on upper-body explosive strength following the 8-week training programme.
The SSG group improved aerobic endurance by 17.63% while a 28.40% improvement was observed in the HIIT group.
Biology of Sport, Vol. 38 No3, 2021 365 Small-sided games and high-intensity interval training in handball the ball, pushing players) during small-sided games, which probably caused a better improvement in throwing a ball in the SSG group compared to the HIIT group [33]. A new finding from the present research was that the HIIT group made significantly greater improvement in Yo-YoIRT1 (m) than the SSG group. Since both groups participated in the same traditional handball training, during the study period, such differences in endurance running are likely due to the specific training adaptations that resulted from high-intensity interval training. Some authors [17] noted significant gains in Yo-YoIRT1 (m) after 7 weeks of high-intensity interval training in handball compared to small-sided handball games. In soccer, after 8 weeks of high-intensity interval training, greater results are achieved in Yo-YoIRT1 (m) than in small-sided games [34]. Buchheit, Lepretre, Behaegel et al. [35] explain that small-sided games may not represent such an appropriate exercise stimulus for individual players as high-intensity interval training. The authors consider that high-intensity interval training is effective because the intensity can be individualized and controlled, such as running speed associated with VO 2 max [29] or the speed achieved at the end of Yo-YoIRT1 [30]. Our hypothesis stated at the beginning of the paper can be accepted because both methods of training improved physical performance in young female handball players, while the HIIT group achieved better results only in the endurance test. Despite many benefits observed in this study, there are a few limitations. Firstly, our study lacked a control group. However, the absence of a control group is common in studies comparing training interventions. Secondly, in this study a field test was used to assess total running distance and not a laboratory test, which would have given us more valid values of VO 2 max.

CONCLUSIONS
This study demonstrated that an 8-week intervention period, including a combination of small sided games and handball training or a combination of high-intensity interval training and handball training, could improve the physical performance of young female handball players during the preparation period for a season. Both types of training (SSG and HIIT) were found to be effective for the improvement of countermovement jump, squat jump, sprint 0-20 m, sprint 0-30 m, throwing a medicine ball, and total distance running in Yo-YoIRT1 of young female handball players. Specifically, a combination of high-intensity interval training and handball training was more effective in Yo-Yo IRT1 (m) compared to a combination of smallsided games and handball training. Therefore, the results of this study reveal that small-sided games are as effective as high-intensity interval training in terms of improving the pre-season physical performance of young female handball players. Moreover, alongside a significant improvement in physical performance that is similar to HIIT training, SSG produce greater enjoyment compared to HIIT [36], which is very important for younger players. These outcomes provide information to handball coaches that situational conditioning training (small-sided handball training) can improve some kinds of physical performance essential to handball similar to traditional conditioning training (high-intensity interval training) in the pre-competitive period in young female handball players. Future studies should measure handball-specific tests, such as specific agility, reactive agility in handball, and technical and tactical skills.