Alteration of cognitive function and locomotor coordination by top-of-the-foot applied perturbations

Footwear is essential for human locomotion and can influence various aspects of human behaviour. While the impact of most footwear features on locomotion and human behaviours has been studied extensively during the last 50 years, the footwear upper is very little studied. In particular, the impact of the footwear upper on cognition, movement coordination, and task performance is virtually unknown. In this study, vibrations of different intensities applied to the foot upper during the execution of basic locomotory tasks were used to determine the impact of the footwear upper on cognition and movement coordination. Sixteen participants were recruited for this study and asked to perform several locomotory tasks while undergoing an auditory Stroop test. Vibrations of various intensities were applied to the footwear upper using a set of five vibrators placed on high-sensitivity areas of the foot. The effects of vibrations on comfort level using a Visual Analog Scale (VAS), and cognition, postural balance, and sway were quantified using an auditory Stroop test, and inertial sensors derived movement coordination. The findings revealed a clear linear relationship between the intensity of vibrations and the perceived level of comfort. However, during walking, no linear correlation was observed between the vibration intensity and reaction time. On the other hand, during standing, a significant correlation between the vibration intensity and reaction time was observed. Moreover, the results demonstrated that as the vibration intensity increased during the standing condition, the magnitude of body sway also increased non-linearly. Finally, the results suggest that attaining an optimal level of comfort can improve attention and cognitive processes. This study highlights the importance of footwear uppers on cognitive and biomechanical performance. Vibration intensity affects comfort and reaction time differently for standing and walking. Some of these findings could have implications for footwear design both from a comfort and performance perspective.