Extended Abstract

1. Introduction and Objective

 Small-sided games (SSGs) are designed as advanced training modalities in football to precisely simulate official match demands. By manipulating constraints such as player numbers and pitch dimensions, SSGs reduce game complexity, allowing coaches to focus on tactical, technical, and physiological development. In modern football, SSGs have become a cornerstone of training programs due to their established ecological validity and efficiency. These games provide a dynamic, high-pressure environment that increases ball contact frequency and involves players in diverse, sport-specific scenarios. While High-Intensity Interval Training (HIIT) and SSGs are both recognized as effective methods for enhancing performance, research on their short-term effects during the competitive season with volume-matched protocols in elite youth players remains limited. Therefore, this study aimed to compare the effects of a six-week HIIT versus SSG intervention on key physical performance indices in elite youth football players to determine the more effective modality for optimizing these variables.

2. Materials and Methods

This semi-experimental study utilized a pretest-posttest control group design. The study population consisted of 34 elite male youth football players (aged 16–18 years) competing in the national first-division league. Participants were purposively sampled and randomly assigned into three groups: SSG (n=12), HIIT (n=12), and Control (n=10). Inclusion criteria required a minimum of two years of systematic training, absence of chronic disease or injury, and full attendance, while injury during the study or missing more than three sessions served as exclusion criteria. Physical fitness parameters were evaluated using a battery of validated tests: endurance performance was assessed via the Yo-Yo Intermittent Recovery Test (Level 1), while lower and upper-body explosive power were measured using the Sargent vertical jump and 5-kg medicine ball toss, respectively. Additionally, linear speed was determined using the 40-yard (36-meter) sprint test. The experimental groups underwent a 6-week intervention (3 sessions/week), consisting of a 15-minute standardized warm-up followed by four 4-minute intervals with 2-minute active recovery periods. The SSG group performed 6v6 games on a 30×40m pitch, while the HIIT group executed running intervals at 80% of maximum heart rate. The control group engaged only in routine technical-tactical team training. Internal training load was monitored using the Borg Rating of Perceived Exertion (RPE 6–20) and heart rate monitors to ensure physiological stimulus equivalence between protocols. Statistical analysis was performed using SPSS (v. 27). Data normality was confirmed via the Shapiro-Wilk test. Analysis of Covariance (ANCOVA) was employed to compare post-test scores while controlling for pre-test values, and paired t-tests evaluated within-group changes. Post-hoc comparisons were conducted using the Bonferroni test, with significance set at P < 0.05.

3. Results

The findings demonstrated that both training protocols significantly enhanced functional performance compared to the control group. ANCOVA revealed significant inter-group differences in agility (P < 0.001, F = 17.07), Yo-Yo test distance (P = 0.002, F = 7.51), and VO2max (P = 0.003, F = 7.01). Large effect sizes for agility η2 = 0.532) and endurance performance (η2 = 0.319–0.334) underscore the practical significance of these interventions. While both groups improved in agility and VO2max, the HIIT protocol exhibited broader effects, being the only modality to significantly increase Yo-Yo distance (P = 0.007) and 36m sprint speed (P = 0.016). Conversely, neither intervention significantly impacted upper or lower-body explosive power (P > 0.05).

4. Conclusion

Both SSG and HIIT are effective tools for enhancing performance in elite youth players, yet their selection should be goal-dependent. HIIT is superior for simultaneous improvements in linear speed and aerobic endurance, whereas SSG is prioritized for agility development within a sport-specific, multidirectional context. Coaches should note that since neither modality significantly enhanced explosive power, the integration of specific plyometric and resistance training is essential for comprehensive athletic development.

5. Acknowledgments and Funding

We extend our gratitude to all the athletes who participated in this study. This article is derived from a Master’s thesis at the Khavaran Institute of Higher Education.

6. Authors' Contributions

All authors contributed equally to the research, and have read and approved the final manuscript.

7. Conflict of Interest

The authors declare no conflicts of interest regarding the publication of this study.