Quantifying a relationship between tactile and vibration sensitivity of the human foot with plantar pressure distributions during gait

Objective. To quantify the relationship between the tactile and vibration sensitivity thresholds of the sole of the human foot with plantar pressure distribution while walking and running. Design. Cross-sectional study performed in a laboratory setting. Background. Results of previous studies of human locomotion have identified potentially dangerous variations in locomotion patterns. A common approach to manage these variations is with the use of orthotics. Individual responses to differences in the construction and shape of orthotics cannot be fully explained with a mechanical model. It has been suggested that sensory feedback from the receptors in the feet may play an important role in regulating gait patterns. Methods. Fifteen subjects were recruited for this study. Pressure (tactile) and vibration thresholds were determined from each subject. Plantar pressure distributions were obtained while walking at 1.5 m s(-1) and running at 3.5 m s(-1). Sensitivity measurements were correlated to pressure measurements under the foot. Results. Significant negative correlation exists between the vibration threshold of the hallux at 125 Hz and peak pressures under the hallux while walking (P = 0.02) and running (P = 0.01). A significant negative relationship was shown between the foot mean vibration threshold at 125 Hz with peak force during running (P= 0.038). A similar trend was seen at the heel, lateral arch and first metatarsal head. Conclusions. The results from this study support recent hypotheses that suggest that the body can detect and respond to external stimuli. The relationship between plantar sensitivity and peak pressures at the hallux, and the relationship between sensitivity to higher frequency vibrations and peak force during running suggests that neurological feedback should be incorporated in to any model that attempts to explain gait patterns.