1Department of Anthropology, University of Cincinnati, 2School of Energy, Environmental, Biological and Medical Engineering, University of Cincinnati
Saturday 4:30-4:45, Ballroom C
Although modern bipeds walk and run with ease, the biomechanics of bipedalism are anatomically and functionally complex. We examined timing and magnitude in forward advance of the lead swing foot with respect to heel elevation (plantarflexion) of the lagging support foot to further understand how human bipeds achieve economical stride lengths. We investigated foot anatomy with high-resolution MRI and walking kinematics with 3D motion capture in 40 healthy adults. Given the support foot rises via plantarflexion as the swing foot dorsiflexes into touchdown, we expected 1) adults with a relatively short rearfoot to contact the ground with a swing foot positioned farther from the lag foot than adults with a relatively long rearfoot and 2) adults with greater mid-rearfoot length to increase stride length for a given foot angle.
This late terminal phase of walking gait represented 7.4 ± 0.5% of the stride cycle, yet accounted for 18.8 ± 2.0% of stride length. Small angular excursions characterized the lead limb contributing little to stride length: 0.2° dorsiflexion, 2.0° knee extension, 1.0° hip flexion. However, excursions of the lag limb were significantly larger and correlated more strongly with lead foot translation: 13.5° plantarflexion (r, 0.52), 2.0° knee extension, 7.4° hip flexion (r, 0.78). When sex differences were taken into account, mid-rearfoot length had a significant effect on lead foot translation (p = 0.04). Thus, foot proportions and lag limb rotations that occur late in the gait cycle contribute markedly to stride length with implications for human evolution and locomotor energetics.
This study was funded by the University of Cincinnati and The Charles Phelps Taft Research Center at the University of Cincinnati.