[Purpose] To assess the influence of plantar sensory input and task guidance produced by a protrusion on lower limb joint dynamics during gait by changes in muscle activity and two-dimensional motion analysis. The protrusion seals on the soles of the feet, named "Perceptual Stimulus Protrusion" were used in this study. [Participants and Methods] In this study, 40 and 42 healthy adults were recruited for muscle activity and two-dimensional analysis, respectively. In addition to walking without perceptual stimulus protrusion ("Control" condition), the testing conditions included attachment of the protrusion to the heel ("Heel Condition") and the hallucal ("Hallucal Condition"). As task guidance, participants were orally instructed how to walk for each conditions. The muscle activities of the rectus femoris, vastus medialis, tibialis anterior, and medial head of the gastrocnemius were measured. The two-dimensional analysis was compared with the angle of ankle dorsiflexion and plantarflexion, the toe height during the swing phase between the test conditions, respectively. [Results] In the Heel Condition, the tibialis anterior and vastus medialis activity in the stance and swing phases, toe height, and angle of ankle dorsiflexion and plantarflexion increased. In the Hallucal Condition, tibialis anterior activity during the stance and swing phases, gastrocnemius activity during the stance phase, toe height, and angle of ankle plantarflexion increased. [Conclusion] Plantar sensory input and task guidance using perceptual stimulus protrusion influences active motion control. Therefore, the application of this procedure can be expected to support motion guidance, such as gait and load practice.
Keywords: Enhanced lower limb dynamics; Muscle activity; Plantar perception of protrusion.