Protective Sensation of the Plantar Aspect of the Foot

Abstract

The scientific literature suggests that barefoot activity may be beneficial. There is a current trend in recreational barefoot activity in children and adults, and barefoot running among athletes. Although the type of skin over most of the body (hairy skin) seems to be easily injured by painful abrading loads, little is known about protection provided by plantar sensory feedback against damage from excessive wear during barefoot locomotion. To evaluate this, we administered a volley of 35 painful abrading loads to glabrous and hairy skin sites over a 5-min period, and examined its effects for signs of cutaneous injury in a sample of 12 normally shod healthy male subjects. Compared with hairy skin of the thigh, plantar skin required approximately 600% greater abrading loads to reach pain threshold. Furthermore, painful stimulation produced visible redness and hypersensitivity in all subjects at the hairy skin site 24 hr after stimulation, whereas only 8.3% reported hypersensitivity and none showed erythema at the plantar area 1 day later. We found that plantar skin possesses a higher pain threshold to abrading stimuli than hairy skin. In fact, loading of the plantar area was limited to innocuous levels due to intolerable pain. We conclude that plantar skin is well protected through sensory feedback from abrasive injuries when barefoot. This information combined with previous reports suggests that risk of injury when normally shod individuals perform barefoot locomotion should be low.