Background: Examining coordination between segments is essential for prevention and treatment of injuries. However, traditional methods such as ratio, cross‐correlation technique, and angle‐time plot may not provide a complete understanding of intersegmental coordination. The present study aimed to quantify the coordination among the rearfoot, midfoot, and forefoot segments during walking.Methods: Twenty healthy young men walked barefoot on a treadmill. Reflective markers were fixed to their right shank and foot based on the Leardini foot model. Three‐dimensional joint angles were calculated at the distal segment, and were expressed relative to the adjacent proximal segment. The coupling angle representing intersegmental coordination was calculated by using the modified vector coding technique, and categorized into the following four coordination patterns: in‐phase with proximal dominancy, in‐phase with distal dominancy, tanti‐phase with proximal dominancy, and anti‐phase with distal dominancy.Results: The results showed that the midfoot was dominantly everted compared with the rearfoot and forefoot during the early stance (i.e., the rearfoot‐midfoot coordination and midfoot‐forefoot coordination were mainly in‐phase with distal and proximal dominancy, respectively).Conclusion: This result may suggest that the midfoot plays a more significant role than the rearfoot and forefoot during early stance. The results of the present study can help in understanding the interaction of the intersegmental foot kinematic time series during walking. The results could be used as data to distinguish the presence of injuries or abnormal inter‐segmental foot motions such as pes planus. Additionally, these data might be used in the future in a comparison with data on foot deformities.

Background: Women, as compared with men, have a higher proportion of injuries in the ankle/foot region. However, the reason for this sex‐related difference in foot injuries remains unclear. Recently, joint coordination and variability of coordination have been suggested to be a critical index for defining both the state of injury and the potential risk of injury. The purpose of this study was to investigate sex‐related differences in coordination and variability among the foot joints during running.Methods: Twelve healthy men and 12 healthy women ran on a treadmill. A modified vector coding technique was used to identify coordination and variability among foot joints involving the shank, rearfoot, midfoot, and forefoot segments, and categorized into the following four coordination patterns: in‐phase with proximal dominancy, in‐phase with distal dominancy, anti‐phase with proximal dominancy, and anti‐phase with distal dominancy.Results: There were no differences in all spatiotemporal parameters and in the foot strike angle between men and women. Coordination of variability of the foot joints during running was similar between men and women, but the anti‐phase with proximal dominancy in proportion of frontal rearfoot‐shank vs. midfoot‐rearfoot couple (men; 7.2%, women; 13.9%) and midfoot‐rearfoot vs. forefoot‐midfoot couple (men; 18.6%, women; 39.8%) in women was significantly increased compared to that in men. Other all coordination of the foot joints during running differed between men and women, and effect sizes of these parameters were all large.Conclusion: The results may be useful for understanding the underlying mechanism contributing to differences in injury risk in men and women, and may provide novel data on foot joint coordination and variability that could be used as reference data for both biomechanical and clinical running studies.