The arch of the foot can be viewed as 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.
The muscles on the underside of the foot tie the two ends of the bridge together and keep them from separating when force is put through the foot.
On the top of the foot there are only two muscles. On the underside of the foot there are eighteen! In addition to supporting the arch, these muscles inside the foot (also know as intrinsic muscles) also compress the many joints of the foot. This allows the muscles of the lower leg to effectively raise the arch.
Cause of Foot Muscle Weakness
No one has the definite answer, but I suspect the biggest contributors to foot muscle weakness are:
- 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 inactive and losing strength.
How To Strengthen Weak Arches
Looking at the anatomy of the underside of the foot we can see the many muscles that run from the heel to the toes. These are the muscles responsible for keeping the ends of the bridge together. The anatomy of the foot is very similar to the hand. How strong would your grip be if you wore a tight box around your hand for most of the day?
Generally, a good first step to building up foot muscle strength is to spend more time barefoot. This could be as simple as taking a walk in the yard or going for a stroll along the beach. Even walking around the house barefoot can help establish a better connection between the feet and the ground.
Examples of specific foot muscle strengthening exercises, such as the short foot and toe yoga, can be found here.
- 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.
- 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.
- 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.
- Shiroshita T, Fukubayashi T. Effect of the Toe Exercises on the Medial Longitudinal Arch of the Foot. Rigakuryoho Kagaku. 2012 Aug 1;27(4).