Comparison of Leg Stiffness and Maximum Ground Reaction Force on Area-Elastic Surfaces with Different Stiffness with Focus on Surface Familiarity

The purpose of this study was to compare vertical stiffness and maximum ground reaction force on elastic surfaces with different stiffness with focus on surface familiarity. Vertical stiffness and maximum ground reaction force during hopping and landing from height on five surfaces with 200–500 kN stiffness were measured for 30 young men. The results of the analysis of variance showed that there were significant differences in leg stiffness on different surfaces, and also before and after familiarity with surfaces. According to the results of this study, unlike other objects, human adapts himself when encountering new surface and in this way, depending on the task, can keep normal center of mass pattern and reduce the forces.