The Blind Spot of Small-Sided Games: Missing High-Intensity Deceleration Demands in Elite Soccer Players

Small-sided games (SSGs) are widely used in soccer training to replicate the technical, tactical, and physical demands of competition. However, their ability to reproduce the multidimensional distribution of accelerative and decelerative actions observed during official matches remains unclear. This study compared multidimensional locomotor distributions between SSGs and official match play in eleven professional soccer players monitored across more than 20 official matches and multiple SSG sessions during a competitive season. Locomotor data were obtained using validated tracking systems and analyzed by integrating speed, acceleration/deceleration magnitude, and metabolic power. The resulting multidimensional distributions were compared using Jensen-Shannon (JS) divergence to quantify distributional similarity. For accelerations, differences between SSGs and official matches were minimal at low metabolic power but increased progressively, reaching the greatest divergence above 60 W·kg^-1 (JS = 0.196). Decelerations showed a similar trend; however, no deceleration events above 30 W·kg^-1 were observed during SSGs, whereas official matches included exposure across higher metabolic power bands. These findings indicate that the SSG formats examined only partially reproduced the multidimensional locomotor demands of competition. Although accelerative actions remained represented across several metabolic power domains, exposure to high-intensity decelerations was absent during the SSG formats examined. From a practical perspective, these findings suggest that complementary training strategies may be considered when greater exposure to high-intensity deceleration demands is desired; however, the effectiveness of such strategies was not directly evaluated in the present study.