The foot's role in movement varies dramatically across stance, absorbing shock upon heel strike, storing strain energy during midstance, and generating power during push-off. However, how coordination patterns of multi-segment foot kinematics fluctuate with changes in walking speeds remains unknown. The purpose of this study was to quantify three-dimensional foot joint rigidity and multi-segment coordination and variability at two walking speeds. We hypothesized that faster walking speeds would elicit decreased rigidity and more tightly regulated coordination. Sixteen adults (6 males, 10 females; age: 26.9±5.2 years) completed two-minute barefoot walking trials on an instrumented treadmill at two speeds (1.0 m/s,1.4 m/s). We utilized a multi-segment foot model to define the ankle, arch, and toe joints to assess multi-segment foot rigidity (i.e. range of motion), and segmental coordination and variability between the rearfoot, midfoot, and forefoot across early, middle, and late stance phases. Supporting our hypothesis, faster walking reduced joint rigidity and resulted in more tightly regulated coordination, characterized by more synchronized (i.e., greater in-phase or lesser anti-phase) movement and decreased variability across most planes. As a notable departure, only the midfoot-forefoot showed greater anti-phase movement during late stance, indicating less tightly regulated coordination, which may allow for greater extension at faster walking to facilitate mechanical energy return. These findings provide a foundation for understanding changes in foot and ankle due to age and/or injury, surgical intervention, or disease.
Weaver et al. (Thu,) studied this question.