Effects of synthetic turf and shockpads on impact attenuation related biomechanics during drop landing

Synthetic turf has been widely utilized in sports since 1964. Discrepancies, however, in injury incidence on synthetic turf and natural grass have been reported throughout studies. Adding a shock pad under synthetic turf carpet is claimed to aid in energy absorption and decrease impact loading. Although some studies have conducted materials tests and compared mechanical characteristics of synthetic turf with different shock pads, no studies have examined biomechanical characteristics of impact related human movements on an infilled synthetic turf system with different underlying shock pads. The purpose of this research was to investigate effects of an infilled synthetic turf with three shock pads of different energy absorption characteristics on impact attenuation related biomechanics of lower extremity during drop landing. Wearing running shoes, twelve active and healthy recreational male athletes performed five trials of drop landing from 60 cm with a controlled landing style (maximum knee flexion) on five surface conditions: a regular surface (force platform), an infilled synthetic turf, turf plus foam shock pad, turf plus a lower density shock pad, and turf plus a high density shock pad. A motion analysis system and force platform were utilized to collect kinematic and kinetic data. Furthermore, a mechanical test was conducted based on ASTM F355 standard. The turf plus shock pad systems resulted in lower 1st vertical peak ground reaction force (GRF) and its loading rates compared to synthetic turf without a shock pad. However, no differences in 2nd vertical GRF and joint kinematics and kinetics across surfaces were found. These results suggest that landing from 60 cm may cause a plateau effect in energy attenuation for the examined turf and turf plus shock pad systems. Future studies may be needed to explore the shock attenuation capacities of landing surfaces in landing activities from a lower height (< 60 cm).