The Effect of Proprioceptive Insoles on Gait Kinematics in Healthy Participants

Introduction: Proprioceptive neuromuscular stimulating insoles (PNIs) enhance somatosensory information from the plantar region, thus modifying standing posture, balance, and ambulatory function. The present study investigated the short-term effects of customized PNIs on lower-limb kinematics during human locomotion. Materials and Methods: Fifteen able-bodied volunteers were recruited and first examined with clinical evaluation of postural and feet behavior. Subjects performed 3-dimensional gait analysis (GA) while walking at self-selected speed in three different conditions: baseline, subjects barefoot; placebo, subjects wearing neutral insoles; and proprioceptive, subjects wearing PNIs. Spatiotemporal and kinematics data of the main lower-limb joints were acquired through a system of six photogrammetric infrared cameras acquiring at a sampling frequency of 100 Hz. Then, acquired parameters were compared in the three different conditions. Results: We found a significant difference in the percentage of double-support phase (P = 0.022) and in ankle plantarflexion values during the toe-off phase of gait cycle (P = 0.022) between the three conditions. Post hoc analysis revealed that subjects wearing PNIs presented a significant reduction in percentage of double-support phase (P = 0.009) and reduced values of ankle plantarflexion during the toe-off phase of gait cycle (P = 0.02), compared with subjects in placebo condition. Conclusions: Results suggest that proprioceptive insoles may induce modifications of gait biomechanics in able-bodied subjects, thus modulating movement strategies during human locomotion. Clinical Relevance: These findings provide a basis for future investigation of the efficacy of these foot devices in a long-term period in able-bodied individuals and potentially in subjects with neurological impairment.