Abstract
The relationship between step-bench structural rigidity and plantar-foot kinetics during exercise was examined in experienced athletes. Using FSCAN insole sensors (Tekscan, Boston, MA), we recorded peak vertical plantar-foot forces, impulses, and loading rates of subjects as they stepped and bounded onto structurally different step benches. Structural rigidity for each step bench was calculated from load/deformation curves that were generated from 3-point loading of the step benches. The structural rigidity of step bench A was 272% greater than that of step bench B and 325% greater than that of step bench C (p < 0.05). Results of the stepping activities, however, indicated that the plantar-foot forces and impulses associated with step bench A were only 1.7% and 3.0% greater, respectively, than step bench B, and 3.0% and 3.2% greater, respectively, than step bench C (p > 0.05). Results of the bounding activities indicated that the plantar-foot forces and impulses associated with step bench A were only 9.4% and 11.1% greater, respectively, than step bench B, and 3.7% and 11.1% greater, respectively, than step bench C (p > 0.05). Loading rates during the bounding activities, however, were significantly greater in step bench A. Our findings suggest that despite step-bench structural rigidity differences as great as 3 orders of magnitude, plantar-foot reaction forces during exercise remain similar. These similarities suggest an in vivo mechanism regulating lower extremity stiffness and plantar-foot loading.