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Foot Muscle Weakness and Flat Feet

The arch of the foot is like a bridge. The two ends of this bridge are the heel and the front of the foot. The muscles in the foot are small, but they have a big job to do in supporting the arch.

medialarch

The muscles on the underside of the foot tie the two ends of the bridge together. They help keep the ends from separating when force is put through the foot.

Foot Muscles Forces

In addition to supporting the arch, the muscles inside the foot (also known as intrinsic muscles) compress the many joints of the foot. Compressing the joints allows the larger muscles of the lower leg to raise the arch.

Cause of Foot Muscle Weakness

There is no definite answer, but I suspect the biggest contributors to foot muscle weakness for me were:

  • footwear and
  • too much time spent walking on flat surfaces

Shoes that have rigid soles and narrow toe boxes constrain the movement of the toes. Inside of these types of shoes, the toes no longer have the ability to spread apart or grip.

It’s reasonable to think that too much time wearing shoes and not enough time spent barefoot could result in the muscles becoming weak or ineffective.

Arch Foot Muscles

How To Strengthen Weak Arches

Looking at the anatomy of the underside of the foot we see many muscles connecting the heel to the toes. These are the muscles responsible for keeping the ends of the bridge together.

Generally, a good first step to building foot muscle strength is to spend more time barefoot. When I began working on my arches, I would look for opportunities to go barefoot on different surfaces (e.g. grass, sand) wherever it was safe to do so.

I also gradually transitioned away from shoes with a lot of support into shoes that were more flexible with wider toe boxes.

The program I used to correct my flat feet included many arch strengthening exercises to improve the function of these intrinsic muscles. Two of my favorites are the short foot exercise and toe yoga.

References
  1. Headlee DL, Leonard JL, Hart JM, Ingersoll CD, Hertel J. Fatigue of the plantar intrinsic foot muscles increases navicular drop. Journal of Electromyography and Kinesiology. 2008 Jun 30;18(3):420-5.
  2. Mulligan EP, Cook PG. Effect of plantar intrinsic muscle training on medial longitudinal arch morphology and dynamic function. Manual therapy. 2013 Oct 31;18(5):425-30.
  3. Kelly LA, Cresswell AG, Racinais S, Whiteley R, Lichtwark G. Intrinsic foot muscles have the capacity to control deformation of the longitudinal arch. Journal of The Royal Society Interface. 2014 Apr 6;11(93):20131188.
  4. Shiroshita T, Fukubayashi T. Effect of the Toe Exercises on the Medial Longitudinal Arch of the Foot. Rigakuryoho Kagaku. 2012 Aug 1;27(4).
About James Speck

James is a physical therapist with a special interest in the foot and ankle. He created this site to share his own journey toward better arches. Read more

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