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Supination and pronation may get a bad rap when they’re excessive, but they are actually necessary movements made possible by the your foot’s unique structure as a twisted plate. Read on to learn more! 

While excessive, habitual supination or pronation can lead to bigger problems down the line, the two movements are necessary for the proper functioning of our feet. Without supination or pronation, we wouldn’t be able to maintain stability, adapt to uneven ground, walk, run or otherwise move in any direction without a high risk of falling over.

Pronation and Supination Explained

In the simplest definition, supination is the inversion of your foot while pronation is the eversion, or rolling inward or outward, respectively.¹ But as you discovered with our previous post on basic foot anatomy, your foot’s movements and makeup are rarely simple. Our post on foot joints offers a more exacting definition of supination and pronation.²

Supination is actually a combination of three movements:

• Plantar flexion: Downward motion of the foot
• Inversion: Inward turning of the forefoot
• Adduction: Inward motion of the forefoot that accompanies inversion

Pronation is a combination of the opposite three movements:

• Plantar dorsiflexion: Upward motion of the foot
• Eversion: Outward turning of the forefoot
• Abduction: Outward motion of the forefoot that accompanies eversion

Your Foot as a Twisted Plate

So why are the feet able to move up and down, turn and roll inward and upward to create the movements of pronation and supination? One theory says it’s because your foot is not a rigid structure that stays completely parallel to the ground. It’s actually a rectangular twisted plate.^3,4,5

• The two front corners of the rectangle consist of the ball of your big toe and little toe.
• The two back corners of the rectangle are made up of the inside and outside of your heel.

The front of the rectangle generally maintains contact with the ground while you heel is able to twist and untwist the plate as needed. The twisting takes place at the transverse tarsal joint, which links the midfoot and hindfoot and is explained in greater detail in our foot joint post.

You can experience full pronation and supination by focusing on the movement of your calcaneus, which plays an important role. For full supination, stabilize your talus while swinging the calcaneus to a fully inverted position.

You’ll note inverting the heel causes the outside of your foot to drop much lower than the inside of your foot. The transverse tarsal joint becomes twisted, increasing your midfoot’s rigidity.

Perform the opposite movements and full pronation occurs. Swing your calcaneus to a fully everted position and your transverse tarsal joint untwists, increasing the flexibility of your midfoot.

You can try to picture this twisting of the rectangle by imagining a thin towel you hold flat. Now twist the back edge of the towel clockwise while twisting the front edge counterclockwise. The twist in your foot is similar to the gentle, subtle wringing of the towel.

The twisting and untwisting abilities of your feet are the reason you can maintain stability and adapt to uneven ground. The abilities are especially essential while walking, which involves alternating twisting and untwisting motions as you move forward.

Pay attention the next time you walk, and you may note the front of the rectangle typically remains aligned with the ground, while the rear of your foot twists and untwists to remain in sync with the movement of your leg. The result is a steady gait that adapts to the ground beneath it with each and every step.

 

REFERENCES

1. Hansen JT. Netter’s Clinical Anatomy. 3^rd Philadelphia, PA: Elsevier Saunders; 2014.
2. Lippert L. Clinical Kinesiology and Anatom 5th ed. Philadelphia, PA: F. A. Davis Company; 2011.
3. Sarrafian SK. Functional characteristics of the foot and plantar aponeurosis under tibiotalar loading. Foot Ankle.1987;8(1):4-18.
4. Dowd I. Kinesthetic Anatomy and Biomechanics of Motion: The Limbs. Presented as a lecture series; January 18 to April 19, 2014.
5. Aiello L, Dean C. An Introduction to Human Evolutionary Anatomy. Waltham, MA: Academic Press; 1990.
6. Neumann D. Kinesiology of the Musculoskeletal System. 2^nd St. Louis, MO: Mosby Elsevier; 2009.
7. MacConaill MA, Basmajian JV. Muscles and Movements: A Basis for Human Kinesiology. Revised ed. Malabar, FL: Krieger Pub Co; 1977.