Human Evolutionary Biology, Harvard University
Saturday All day, Clinch Concourse
Women tend to walk and run with greater hip adduction, internal rotation of the thigh and increased valgus angle during locomotion. These kinematic differences are generally assumed to be the result of sexually dimorphic aspects of body shape, but how these differences affect lower limb joint mechanics is unclear. Few inverse dynamics studies include women and sample sizes for both sexes are often small. This study compares moments, muscle force and effective mechanical advantage (EMA) of the lower limb joints during walking and running to determine if any systematic differences between men and women are present. Twenty-seven individuals (male =14, female = 13) provided informed consent to participate in this study (IRB approval from Washington University in St. Louis). Subjects walked and ran over a force-plate (AMTI model OR, 1000Hz) embedded half-way down a 7.8m long trackway while kinematics were simultaneously recorded (Vicon, 200Hz). Subject specific muscle moment arms and skeletal measurements were determined from full lower body MRIs (Avanto 1.5T scanner, isotropic 1.7mm resolution). An inverse dynamics solution was used to solve for joint moments and muscle forces. Results indicate that while the subjects were dimorphic in multiple aspects of body shape there were few significant differences in joint mechanics, muscle force or EMA. Women tended to have higher hip abductor moments and lower abductor EMA across gaits, while men had significantly higher ankle plantarflexor moments during walking. The results are discussed in relation to skeletal dimorphism and provide important baseline data on joint function in men and women.
This research was funded by: NSF #0850841, The Leakey Foundation, and The Wenner-Gren Foundation