足部ねじれ剛性の違いによる走行時の足部内運動協調性の比較

抄録

Disruption of coordination patterns, one of the characteristics of overuse injuries, is considered to be influenced by joint stiffness. However, it is unclear how foot stiffness affects the foot coordination pattern during running. The purpose of this study was to compare the coordination pattern of the inter-foot segment during running between groups with low and high foot torsional stiffness. Sixteen men who ran with midfoot and forefoot strike participated in this study. We simultaneously measured midfoot passive resistance torque and midfoot frontal plane motion from maximal pronation to maximal supination to calculate foot torsional stiffness. Participants ran barefoot at 3.3 ± 10% m/s on the 10 m runway and we collected three-dimensional kinematics of shank, rearfoot, midfoot, and forefoot. The coupling angle was calculated using the modified vector coding technique and categorized into four coordination patterns. Participants were divided into two groups according to foot torsional stiffness. The proportion of coordination patterns in early, mid, and late stance was compared between low and high foot torsional stiffness groups using the Mann–Whitney U test (p< 0.05). There was no difference in demographic data except foot torsional stiffness between the two groups. Sagittal midfoot vs sagittal forefoot, frontal midfoot vs sagittal forefoot, and frontal rearfoot vs frontal midfoot coordination were significantly different between the two groups. These results suggest that foot torsional stiffness influences the coordination pattern of the inter-foot segment during running. In particular, low torsional stiffness foot seems to be associated with less propulsive efficiency in mid-to late stance.