Which tissues support the arches of the foot?

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Discussion

The results of this study suggest that the windlass mechanism in the seated posture is primarily influenced by the plantar fascia and the flexor digitorum brevis, whereas in the single-leg standing posture, it is mainly influenced by the flexor digitorum brevis. This finding may contribute to the ongoing discussion regarding the extent to which intrinsic foot muscle activity is necessary to maintain the shape of the MLA in the resting state12,14,

Reconsideration of the load-bearing functions of the plantar fascia and intrinsic foot muscles in the windlass mechanism

• Hiroshi Shinohara,
• Yasuyuki Umezaki,
• Airi Ikeda,
• Takara Ikeda &
• Nao Tateyama

Scientific Reports volume 15, Article number: 12923 (2025) Cite this article

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Abstract

This study aimed to explore the contributions of the plantar fascia and intrinsic foot muscles to medial longitudinal arch (MLA) support and the windlass mechanism under different toe extension angles in seated and single-leg standing postures. The study included 51 healthy adults (41 males, 10 females; mean age: 21.3 ± 1.2 years) with no history of lower extremity injuries or pain in the past 3 months. Ultrasound elastography was used to measure the stiffness of the plantar fascia and flexor digitorum brevis under toe extension angles of 0°, 15°, 30°, and 45°. Dorsal arch height and arch height index (AHI) were evaluated to assess MLA changes. The plantar fascia and flexor digitorum brevis contributed to the windlass mechanism in the seated posture, while in the standing posture, the flexor digitorum brevis played a more pronounced role, with stiffness approximately six times greater than in the seated posture. The AHI was significantly higher in the seated posture than in the standing posture, and greater toe extension angles enhanced the windlass mechanism. These findings highlight the importance of intrinsic foot muscle training, such as towel curls, to improve MLA support and the windlass mechanism. Future studies should investigate their role in dynamic activities like walking."

Towel curls are not an effective exercise for intrinsic foot muscle strengthening esp if you already have curled/deformed toes . I mean if you have claw toes, as many older people do, how do you claw them further ?

 

So standing on one foot and dorsiflexing the toes creates greater stiffness in the foot muscles than the plantar fascia. Ok , so maximum tension in the fascia is created as muscular activity ( i.e. gastrocnemious, soleus) causes the heel to lift from the ground.

The seated plantar fascia stretch is a primary treatment option for plantar fasciitis. But it seems this type of stretch, dorsiflexing the toes ,is creating stiffness/ tension in the intrinsic foot muscles, not the fascia. So what might this be telling us about medial heel pain . Might it be muscular in origin in many instances.