Comparison of the vertical compliance and rotational stiffness of natural, hybrid and artificial football surfaces

The playing surface in football plays a pivotal role in player performance, safety, and overall game quality. With evolving regulations and continuous technological advances in football surfaces (natural, hybrid, and artificial turf), understanding their performance characteristics is essential. This study evaluated the vertical compliance and rotational stiffness of football surfaces using two test devices adopted by the FIFA Quality Programme: the Advanced Artificial Athlete and the Rotational Traction Athlete. Measurements were taken from 126 football pitches and turf samples, assessed in-situ and in the laboratory, respectively, which encompassed various natural, hybrid, and artificial turf systems. Results indicated significant differences in vertical compliance, with artificial turfs exhibiting higher peak shock absorption, greater peak deformation, and increased energy return compared to natural and hybrid turfs, suggesting that artificial turfs are more compressible and more elastic. Rotational stiffness measurements revealed that while peak torque values were similar across most surface types, natural and hybrid turfs demonstrated significantly higher resistive torque at 10 degrees of rotation than artificial systems. The findings of this study informed revisions of the performance thresholds adopted within the FIFA Quality Programme, which specify the global quality requirements for football playing surfaces.