In-shoe multi-segment foot kinematics measurement during the stance phase of running using a stretch strain sensor.

Multi-segment foot kinematics during shod running are difficult to investigate in clinical settings. Stretch strain sensors can measure foot kinematics; however, whether they can evaluate foot kinematics during shod running or at the midfoot kinematics remains unclear. The aim of this study was to investigate the stretch strain sensor could reveal differences between shod and barefoot conditions and midfoot kinematics during running. Eighteen healthy adults were included in the study. A stretch strain sensor and three-dimensional motion capture system were used to measure foot kinematics during barefoot and shod running with a rearfoot strike pattern. The correlation between the amplitudes of the two signals during barefoot running was investigated, and the similarity between the two signals was evaluated using the cross-correlation coefficient. Statistical parametric mapping was used to compare shod and barefoot conditions. Shod running had significantly lower sensor strain from 30 % to 100 % stance compared to barefoot running ( < 0.05). The sensor amplitude was significantly correlated with the shank-rearfoot frontal ( = 0.668,  = 0.002), the rearfoot-midfoot transverse ( = 0.546,  = 0.02), and the midfoot-forefoot sagittal planes ( = 0.563,  = 0.01). A high cross-correlation was observed between the sensor signal and the shank-rearfoot sagittal, frontal, and transverse planes and the midfoot-forefoot sagittal plane. This sensor can be used to investigate foot kinematics during shod running. The sensor signal mainly reflects the shank-rearfoot frontal and midfoot-forefoot sagittal planes, as well as the maximum kinematic range of the rearfoot-midfoot transverse plane.