Effects of Task Constraint Manipulation on Physical, Physiological and Technical-Tactical Demands of Small-Sided Games in Soccer: A Systematic Review.

Background: Small-sided games (SSGs) are widely used in soccer training to develop physical, physiological, and technical-tactical capacities under game-representative conditions. Although task constraints have been investigated individually, evidence integrating their effects across major categories remains limited. This systematic review synthesized the effects of six task-constraint domains on SSG demands in association football. Methods: Following PRISMA 2020 guidelines, systematic searches were conducted in PubMed, SPORTDiscus, Web of Science, and Scopus. Forty studies published between 2015 and 2025 met the eligibility criteria and were categorized into six task-constraint domains: pitch size or area per player (n = 13), player number (n = 8), goalkeeper inclusion (n = 6), goal type (n = 5), numerical imbalance and floater players (n = 8), and transition games (n = 6). The review protocol was prospectively registered in PROSPERO. Results: Larger pitch areas consistently increased high-speed running but were insufficient to reproduce match-level sprint demands. Goalkeeper exclusion increased physiological intensity, particularly in smaller formats, whereas mini-goals reduced external locomotor load while maintaining comparable internal responses. Numerical disadvantage increased sprinting and high-intensity running demands for outnumbered players, while floaters experienced substantially lower physical loads than regular players. Transition games elicited the greatest locomotor demands, exceeding match values for high-speed running and sprinting across several playing positions. Conclusions: No single SSG format adequately addresses all match-relevant physical demands. Accordingly, practitioners should systematically manipulate and combine task constraints in accordance with specific training objectives. These findings provide evidence-informed guidance for optimizing SSG design to elicit targeted physical, physiological, and technical-tactical adaptations.