Functional and anatomical characteristics of the heel fat pad based on different sports events

This study investigated the thickness and stiffness of the heel fat pad among male university athletes involved in sports with different performance characteristics: with shoes, barefoot, and in water. Participants included 34 male athletes-12 judo players (barefoot competition), 10 American football players (shoe competition), and 12 swimmers (water-based)-as well as 12 male non-athlete controls. Using ultrasonography, we measured the thickness of the shallow and deep layers of the heel fat pad under 0%, 50%, and 100% loading conditions, along with their respective rates of change. Stiffness (elasticity) of both layers was also assessed. At 0% load, both the shallow and deep layers were thickest in swimmers and thinner in judo and American football athletes. In the shallow layer, swimmers showed the greatest rate of change in thickness with loading. In the deep layer, significant changes were found in the judo and swimmer groups compared to the American football group, and in swimmers compared to controls. Elasticity in the shallow layer was lower in American football players than in the judo and swimmer groups. In the deep layer, judo athletes had the lowest elasticity, whereas swimmers had the highest. These findings indicate that the heel fat pad's morphology and mechanical properties differ across sports disciplines, likely reflecting adaptations to sport-specific loading patterns.