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.


METHODS
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.


CONCLUSIONS
It is suggested that the body is able to detect small biomechanical changes in the external environment and alter gait patterns as a defensive mechanism. Understanding the relationship between neural feedback and gait patterns will help in the development of criteria for the proper application of inserts, and the prevention of lower extremity injuries.
Nurse
M A
MA
Human Performance Laboratory, Faculty of Kinesiology, The University of Calgary, 2500 University Drive N.W., Calgary, Canada. matthew@kin.ucalgary.ca
Nigg
B M
BM
D000328:Adult; D003430:Cross-Sectional Studies; D005260:Female; D005528:Foot / Q000502:physiology*; D005684:Gait / Q000502:physiology*; D006801:Humans; D008297:Male; D008465:Mechanoreceptors / Q000502:physiology; D011312:Pressure; D014110:Touch / Q000502:physiology*; D014732:Vibration