The mechanical characteristics of the human heel pad during foot strike in running: an in vivo cineradiographic study.
The compressive properties of the heel pad during the heel strike when running (barefoot and shod, two subjects, 4.5 m s-1) were studied by means of a high-speed two-dimensional cineradiographic registration (150 frames s-1) of an actual running step. Vertical ground reaction forces were measured with a force platform. In barefoot running the heel pad deforms to a maximal percentage deformation of 60.5 +/- 5.5%. In shod running the heel pad deforms only 35.5 +/- 2.5% and the nonlinear force-deformation relationship reflects an increasing stiffness when deformation rises. Although the amplitudes of the vertical ground reaction forces do not differ notably in both conditions, barefoot running implies a maximal deformation to the fatty heel tissue, reducing its functional role from shock reduction towards local protection of the heel bone. It is argued that embedding the foot in a well-fitting shoe increases the effective stiffness of the heel pad.
Department of Kinesiology and Sport Pedagogics, University of Ghent (RUG), Belgium.
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De Clercq
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Aerts
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Kunnen
D000273:Adipose Tissue / Q000033:anatomy & histology / Q000502:physiology; D000328:Adult; D002111:Calcaneus / Q000502:physiology; D002933:Cineradiography / Q000295:instrumentation / Q000379:methods; D004548:Elasticity; D005528:Foot / Q000033:anatomy & histology / Q000502:physiology*; D006365:Heel / Q000033:anatomy & histology / Q000502:physiology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D009068:Movement; D010865:Pilot Projects; D012420:Running / Q000502:physiology*; D012775:Shoes; D013314:Stress, Mechanical; D016474:Weight-Bearing / Q000502:physiology