| Background. The interrelationships between individual anthropometric variability, running mechanics, comfort, and injury are complicated and present a challenge to footwear designers as they try to provide safe, comfortable, efficient shoes within a limited product line. In previous research there has been relatively limited success in linking variations in lower limb anatomy or musculoskeletal function to movements or kinetics associated with injury. The present study was designed to include a more complete set of structural and functional measurements of the lower extremity than has previously been done. Specifically, this study investigated how lower extremity structure and function interact with two shoe types (Motion Control (MC) vs. Cushioning (CU)) to affect movement dynamics during running. This study aims to create a more specific categorization of the influence of footwear structure on kinetic and kinematic variables of running based on runner characteristics, including both anthropometric features and movement factors. Methods. 16 recreational runners (&ge10 miles per week) were recruited to participate in this study. 3-D kinematics and kinetics were collected as subjects ran at 3.58 m&bulls-1+ 5% along a 20m runway. Trials were performed in both MC and CU shoes. A number of anthropometric measures were collected during a separate session. The effect of shoe type on kinetic and kinematic variables were examined using a paired t-test. In addition, relationships were identified between lower limb anthropometric variables and shoe type differences using Pearson correlations. Results. CU and MC shoes demonstrated significant differences for ankle inversion moment, ground reaction force, and sagittal plane kinematic timing variables. Weight, Quadriceps angle, and ankle structure and range of motion (ROM) influenced differences between running mechanics in the two shoe types. No significant interactions between shoe type and arch group were found. Conclusions. Compared to the MC shoe, the CU shoe showed reductions in key force magnitudes and reduced the rate at which forces were applied. The stability features in the MC shoe were evident in ankle inversion moment maximum, positive impulse, and net impulse. An MC shoe may provide people that have larger Q-angles more support, while a CU shoe may be more beneficial for a heavier runner. Runners with an inverted subtalar joint neutral position (STJN) may be better suited for a CU shoe, while runners with an everted STJN might be better served with an MC shoe. In both of these cases the shoe attenuated forces that may be potentially harmful to the runner. Kinetic and kinematic differences among arch groups did exist, but were unaffected by shoe type. This study allowed us to reach a better understanding of the interplay among structural and functional parameters, shoe type, and lower extremity kinetic and kinematic responses. Future research should include a more diverse pool of subjects and focus on fatigue's role in cushioning. |
