External Perturbations and Internal Mechanisms of Locomotor Performance

点击翻译按钮获取中文摘要

The specific objectives that will be addressed by this research include: 1) to determine how footwear bending stiffness and cushioning influences internal musculoskeletal properties and lower extremity joint movements and 2) to determine how changes in internal musculoskeletal properties that result from footwear modifications influence locomotor performance. This research program will include a series of projects using human subjects to better understand the influence of external perturbations, namely changes in footwear properties, to internal musculoskeletal properties and ultimately performance. The footwear properties that will be investigated are cushioning and longitudinal bending stiffness. Recent research has shown that both footwear cushioning and forefoot bending stiffness can influence running performance, however, the underlying mechanisms affecting these performance improvements have not been explained. To properly identify the musculoskeletal changes that lead to these enhancements, internal measurements are required but to date have not been performed. For each property (cushioning and bending stiffness), three running studies will be undertaken. In one series of studies, subjects will run while wearing two different pairs of shoes with varying levels of cushioning. In another series of studies, subjects will run with two different pairs of shoes with varying forefoot bending stiffness. The running studies will be performed on a treadmill and will utilize: 1) motion capture to quantify running kinematics, an instrumented treadmill to quantify running kinetics and a metabolic cart to quantify running economy 2) a portable ultrasound system to quantify Achilles tendon strain and corresponding energy storage and return and 3) dual fluoroscopy to determine intrinsic movements of the foot and ankle bones. In addition to the running trials, athletes will undergo a series of strength measurements on a Biodex to provide each subject's specific torque-angle-angular velocity relationship. This information will be used to determine if muscle contractile properties can be optimized through manipulations in running footwear. Developing an understanding of what musculoskeletal changes actually occur when a shoe is softer or stiffer provides an opportunity to directly implement footwear designs to affect performance. Furthermore, by understanding how external perturbations affect internal mechanisms of locomotor performance, the results could have large ramifications on potential methods for assisting and supporting human locomotion (human performance in the most general sense).