Foot Function

Originally published in Pace Magazine Fall 2020

Runners tend to neglect their feet. I see this every day in the clinic when working with runners – most people get a bit freaked out by feet, think their feet are ugly, and don’t really understand how someone like myself can spend a day working with and touching feet. As long as they aren’t hurting, aren’t blistered, or their nails aren’t poking holes in their socks, most runners are perfectly content to shove their feet in their shoes and mosey on down the road each day.

As a physical therapist who cares for runners and especially those with foot and ankle problems, I get to see the other side of the story – runners with painful feet, bunions, heel pain, and blisters. One thing I try to make clear to every one of these runners is that feet should be given as much care as the rest of their body. It’s not unlike the old adage in the infantry – “take care of your feet, and your feet will take care of you.” But there is more – most runners don’t have a very strong pair of feet to start with. They rely on cushioned shoes and extra support to prop-up their feet, and rarely do their feet see the light of day. The purpose of this article is to help you understand how having a stronger foot will help to improve your ability to run, both longer and faster, and with less pain.

Anatomy and Function

The basics of the feet are this: 26 bones, 33 joints, lots and lots of ligaments (at least 107) that connect these joints together along with layers of muscles that allow us to do all that we do when standing, walking, running, balancing and hopping. We divide up the muscles in the foot into two basic types: the intrinsic muscles, and the extrinsic muscles. The intrinsic muscles, those inside the foot that act to stabilize the foot and compress the joints together, perform some of the fine movement of the toes. The extrinsic muscles, which originate in our lower legs around our shins and act as the big engines to lift our arches, curl the tips of our toes and turn and control the movement of our feet and ankles inward and outward. The bones in our feet are similar to those in our hands – some not unlike the stones in an arch-bridge, honeycombed with calcium and collagen to transmit load, others long (metatarsals and toes) to act as levers.

We have a large ligament bridge on the bottom of each foot, the plantar fascia. The plantar fascia stores energy during stance, through a mechanical arrangement called the windlass mechanism and guides our arches into a stiff, stable position as we roll over our toes during late stance and toe-off.

In technical terms, foot function can be simplified into a few basic concepts. The first concept is that they act as a rigid lever, a stiff arrangement of bones, ligaments, tendons, and muscles to help propel us during toe-off. They also act as a mobile adapter, adjusting the shape of the foot to the ground after footstrike, and this is where the concept of our feet storing energy comes into play. Our plantar fascia, along with the Achilles tendons, act as springs, storing potential energy during footstrike and midstance as they stretch and absorb the forces of our bodies landing, only to recoil that energy as we roll over our toes during push-off. Running is very much an elastic activity, not unlike skipping a golf ball over hard pavement – up to 50% of a runner’s force to propel their body comes from this elastic energy return.

Finally, the feet are sensitive! One of the things that most of us don’t even think about is the amount of sensory information that allows us to walk and run that comes from the nerve endings present in the skin, joints, and tendons in our feet. We all know that our hands are very sensitive. Likewise, we all have a heavy concentration of nerve receptors in each foot that send information about pressure, tension, temperature, and pain back to our nervous system to guide us during gait. Our brain uses this information along with the motor programs (the software in our nervous systems) to refine how we move over the ground.

An example of this is: compare how you walk or run with shoes on versus how you walk or run with shoes off. Most of us, within a few steps, switch how we footstrike (from our heels when in shoes to our midfoot or forefoot when barefoot). Compare this to people with sensory deficits, such as individuals with diseases like diabetes. They tend to develop sensation problems in their feet. Such individuals lose skill with walking, are at risk for falling, and require special footwear to protect the skin on their feet from injury.

Truths and Half-Truths:
Pronation and Arch height

I often hear the same questions and comments from runners when we talk about their problems. It’s understandable; some things, such as an arch that seems to pronate or flatten excessively when walking or running, do not appear to be healthy or normal. Truth be told, we have many variabilities when it comes to foot function. Pronation, an inward rolling of the arch, is a normal part of gait and a vital part of the stretching of the plantar fascia that provides the energy return at toe-off. Researchers on this topic do not have a definition of how much pronation is too much. And there isn’t strong evidence that a foot that pronates a large degree will lead to injury. Our bodies have a great deal of capacity to adapt to these stresses as long as we don’t advance our running volumes or the intensity of our training too aggressively. Likewise, having a “low arch” isn’t associated with an increased risk of running injury. Arch height is a dynamic function; your arch height when standing relaxed isn’t necessarily the same as it will be when you are walking, running, or when balancing on one leg. Finally, trying to prop-up or protect an arch by wearing a stiffer, motion control shoe is generally not the answer to foot pain. That doesn’t mean that there isn’t a place for a motion control shoe, it just means that most of us don’t benefit from them (and per Knapik’s research, may well be more prone to injury in a motion control shoe). Better to seek professional help to guide you when deciding whether to use such a shoe when you have foot pain.

Testing and Exercising

Testing a runner’s feet, in simplest terms, comes down to assessing the things that a foot needs to be able to do when running. A runner’s foot needs to be able to do a few key things.

1. Be able to form a stiff arch.

2. Be able to flex and extend at the toes, ideally with good isolation of the first toe to help accomplish the goal above.

3. Be able to provide a firm foundation to balance on when in single-leg standing.

Goal 1: Stiff arch: We assess this by looking at a runner’s ability to lift their arch, even a small amount. Compare the pictures below.

The first picture is a relaxed, low arch position – the resting position for many of us. Next, we have a “short arch” posture – I’m using the muscles in my foot to lift my arch.

We use the muscles of our lower leg and foot, our extrinsic and intrinsic muscles, to lift our arch. This short arch position is considered a foundational skill when developing a strong foot. Test this yourself, starting while sitting with your feet relaxed on the ground. For some, it is not easy to get the concept of lifting the arch – you need to be able to do this without lifting the toes or ball of the foot off the ground. If you can do this while sitting, test yourself standing on both feet and finally while standing on one foot with hands on the wall or a table for balance. The test becomes the exercise; your goal is to be able to readily lift the arch while standing on one foot and holding that posture for up to 2 minutes.

Goal 2: Be able to flex and extend at the toes, ideally with good isolation of the first toe to help accomplish the goal above. What you discover when first trying to shorten your arch is that you will often twist, curl, and contort your toes to try to accomplish this. During gait, our toes need to be able to rest flat on the ground (not curled or clawed), and we need to be able to anchor our toes, especially the first toe, firmly against the ground to stabilize our foot. Compare the pictures below:

One thing our toes should be able to do is to spread – this aids one in being able to have a broader base of support to balance on. Again, this is something that many runners struggle to do. Feet that spend a lifetime in shoes with cramped toe boxes do not get much opportunity to spread and grip the ground, and so it is easy to lose the knack of doing this. Again, the test becomes a simple exercise that you can work on during the day (even with your shoes on).

The final part of the toe tests is checking the ability to isolate and press your first toe firmly into the ground and then alternate your small toes into the ground. This concept was popularized by Jay Dicharry, MS, PT, who coined the name of this test and exercise “toe yoga.” The idea is that we use our first toes via our flexor hallucis brevis (the muscle in our foot that attaches to the base of our first toe) to anchor the foot and help with forming a stiff arch. Test to see if you can do this and practice this – slowly at first, then work on doing this with rapid alternations, sitting, and standing.

Goal 3: Be able to provide a firm foundation to balance on when single-leg standing:

All these toe and arch tests/exercises would be useless unless they led to the practical concept of allowing us to stiffen up our foot to provide a firm foundation for us to push into the ground with. The baseline skill for this is single-leg balance. It is something that I test in each runner I treat. I want to see if a runner can stand on one leg, opposite hip flexed so that the thigh is parallel to the ground and that this position can be held for at least 30 seconds. Running is a series of singleleg hops – we spring from one foot to the next and balance for a very brief period (approximately a quarter of a second) during each stance. If a runner struggles with balancing on one foot, one source of this problem may be that their foot and leg muscles are not strong enough to provide a foundation and keep the foot still enough to act as a stable base. Balance is a very trainable skill, something that we can do every day, even while carrying out the routines of our day, such as working at a counter or brushing our teeth. I like to use a balance board as a training tool, with my favorite one being the Mobo Board (a balance tool developed by Jay Dicharry to help runners build strong feet, available at http://www.moboboard.com). It is designed to incorporate the concepts of using the first toe as an anchor while balancing, and it is a great tool to help you develop a strong foot.

So, there you have it – simple tools to develop strong, healthy feet. My final piece of advice is to be patient with the process and practice the tests a little each day – consistent bits of practice will give you a stronger foot to help you run faster!

Kent Kurfman, PT, DPT, OCS, MTC., a physical therapist for over 30 years and an avid runner for over 40 years. He oversees the Running Academy at ATI Physical Therapy, a multifaceted program of injury prevention and treatment. He continues to race regularly, including five finishes at the Boston Marathon.

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