Your feet are incredibly important for running, for obvious reasons.
And for less obvious reasons, too!
The foot is a complex anatomical structure: though it may not seem like much, it’s chock full of passive and active tissues that allow it a wide range of motion and functionality.
In fact, there’s so much going on within the foot that we can’t fit it all in just one article… so, for brevity’s sake, we’re going to focus on the parts of the foot that matter most for your running biomechanics.
Read on to learn more about how these structures work and what you can do to make sure they’re at peak strength and functionality for your running.
Basic Anatomy of the Foot Muscles
Did you know that the foot is made up of 26 bones, 30 joints, and over 100 muscles, tendons and ligaments? (We weren’t kidding when we said “a lot goes into the foot”!)
Your foot comprises extrinsic and intrinsic muscles. The extrinsic muscles travel through the ankle and connect into the foot, whereas the intrinsic muscles are contained within the structure of your foot.
Reviewing both the ankle AND foot is a beast of a topic — the ankle joint adds many other biomechanical factors into the equation. When you account for the ankle, you’re also indirectly factoring in biomechanical issues of the hip and knee joints as well (courtesy of the kinetic chain).
So, to make things less complicated, we’re predominantly going to review the intrinsic muscles and dial into the details of how your foot core should function.
Within the core of your foot, there are two main groups of muscles: the hallucis brevis muscles (which control your big toe) and the digitorum brevis muscles (which control your other four toes).
Both sets of toes have corresponding flexor and extensor muscles. Your flexor hallucis brevis and digitorum brevis muscles allow you to bend your toes towards the ground, or curl them in. Your extensor hallucis brevis and digitorum brevis muscles do the opposite, allowing you to extend your toes out straight and lift them up and back towards your shins.
These muscles play a role in how effectively (or poorly) your foot moves from the point of initial contact through the stance phase and follow-through.
Another important muscle is the quadratus plantae, which runs from the back of your foot and ankle to about the middle of your foot. Its primary purpose is to further support flexion in those intrinsic foot muscles, especially within the base of the foot.
There are plenty of other tissues that work together to support the foot and arch, but these are the most relevant for the functionality of your foot while running.
So, let’s dive into that functionality!
Why Is the Foot So Important in Running?
Your feet are the first point of contact with the ground with every step you run — but you already knew that.
What you may not have known, however, is just how crucial that point of initial contact truly is.
How your foot hits the ground sets the stage for the rest of your running gait. In particular, it can dictate the effectiveness and efficiency of your biomechanics through the remainder of your stance phase.
Ideal mechanics include everything from where your foot lands on the ground, how hard it lands, and how your ankle is aligned upon landing, among other factors. (This is why so many runners are fixated on their foot strike and what types of shoes to buy.)
But it’s also imperative to address the mechanics after that initial landing. It all boils down to how the components of your foot work together to prepare the rest of your kinetic chain for proper shock absorption.
This is where your foot core matters most.
How Does the Foot Work While Running?
When you move from initial contact to stance phase, your stance foot has to take on a lot at once… It has to manage the impact forces of your landing while ALSO providing stability for your body as you begin bearing weight on one leg.
These responsibilities are managed concurrently by active and passive tissues.
With the intrinsic and extrinsic muscles, you have volitional control over them: you can consciously stretch, contract, and even strengthen them. Part of this is necessary for absorbing forces, and the other part is meant for providing single-leg stability as you start to move under load.
On the other hand, with non-contractile tissues like your plantar fascia or foot ligaments, you don’t have voluntary control. They instead play a passive role in taking much of the landing impact forces off of your muscles.
We often compare this functionality to that of a suspension bridge — the intrinsic foot muscles and non-contractile tissues help “suspend” your arch.
Then, as you move further into a weight bearing position, your arch flattens against the ground and bounces back up. This is referred to as medial longitudinal arch recoil, where your foot moves from complete contraction to complete stretch, then back to full contraction. (It’s similar to how the suspensions absorb shock in a bike or car.)
What’s important to remember, though, is that all of these foot structures have to play a role in full shock absorption. Each structure may have a different function, but they’re still working together for the same end goal.
This reliance among structures creates something known as the “concept of redundancy”: if one structure is unable to pull its weight, the other structures compensate to manage the forces. However, this overcompensation affects the mechanics of the foot and increases your risk of injury.
Common Foot Problems for Runners
Now that you know how much work your feet have to do with every step, it’s no surprise that many runners deal with foot problems that go beyond simple blisters and black toenails.
A majority of foot pain or injury is caused by improper shock absorption.
Take one of the most notorious running injuries: plantar fasciitis. This is a prime example of when one of your non-contractile tissues takes on more load that it was meant to handle. Plantar fasciitis usually occurs when your intrinsic foot muscles aren’t strong enough or aren’t activating properly, leaving the tissue to take on the brunt of the shock absorption.
Similar deficiencies can lead to problems within the bony anatomy of your foot, as well. Stress fractures are a common result of ineffective shock absorption, where impact forces are displaced directly onto the bone. Some runners also sustain Lisfranc injuries, which can present as either a fracture in the bones or torn ligaments in the midfoot.
Another important consideration is if you have flat feet — although it’s entirely possible to run well and safely with flat feet, you may be at a higher risk of pain or injury. (This is because your foot doesn’t have enough arch height to create that “suspension bridge” mechanism that aids your shock absorption.)
How to Improve Your Foot Core
Enough about the problems: let’s get to the solutions!
Runners should predominantly focus on developing muscular activation, strength, control, and stability. (It should be noted that complete foot functionality also requires work at the ankle and calf as well, particularly mobility and stretching drills.)
Perhaps that sounds like a lot when you list it all out like that, but with the foot, since all the tissues and structures are so intertwined, many of the drills you practice will address more than one training facet at a time.
So let’s dive in!
#1. Short Foot
The short foot exercise is a common suggestion for runners — the goal is to raise the arch of your foot and shorten the distance between the ball of your foot and your heel.
But, you can’t use your big toe to boost your arch.
Perhaps it sounds simple in theory, but it’s more challenging than it sounds! Without using your big toe, lifting your arch takes more work than we realize; it requires you to recruit your posterior tibialis tendon instead, which is the tendon that (roughly) connects your calf muscle to the arch of your foot.
Engaging the posterior tib prompts the intrinsic muscles and tendons in your foot to lift the arch, which ultimately increases the stability in your foot. This will then alleviate tension that may be present in other areas of the foot too, like your plantar fascia.
The first few times you practice short foot, you may not even notice the lift. It’s a subtle mechanic, so if you aren’t sure if you’re doing it correctly, take a video of you performing the exercise! You should be able to notice a curving in the arch (even if it’s only a little bit!).
(If it’s difficult to execute at first, try this handy visualization cue: imagine a string is attached behind your first metatarsal, or the long bone that attaches to the ball of your foot. Then, imagine pulling that string towards your heel to bring your toe back and lift the arch.)
#2. Towel Scrunches
Also referred to as towel curls, this is a simple exercise that prompts you to grip or curl your toes.
The name is quite straightforward to the task: place a towel flat on the ground and use your toes to scrunch it!
Alright, there’s a little more to it than just that. As with any exercise, towel scrunches have to be more deliberate than simply curling your toes — you want to keep your heel planted firmly against the ground while you lift your toes, extend them up and back, stretch them as far forward as possible, and use the toes and arch to scrunch the towel. You can perform these either standing or sitting down.
Focus on deepening your arch when you curl your toes in, and make sure that you keep your heel still all throughout. This will challenge your intrinsic muscles to elongate, contract, and recruit strength with each “scrunch.”
#3. Toe Yoga
This exercise is great for strengthening those intrinsic tissues, but with a little more distinction between muscles.
Keeping your foot flat on the ground, lift your big toe up without moving your other four toes. Or, you can practice the inverse, where you lift your four smaller toes while keeping the big toe on the ground.
And that’s effectively all there is to it! (Definitely not as much contorting as actual yoga stretches.)
Toe yoga is a prime example of how foot core strengthening is a small yet essential habit. It doesn’t take much time, nor does it require a lot of physical exertion, but it’s necessary for the longevity of the tissues and structures in your foot.
#4. Picking Up Marbles with Your Toes
Perhaps this exercise might sound similar (or the same) as the previous ones… and you wouldn’t be wrong. In theory, there’s only so many ways that you can strengthen the muscles and tendons of your foot.
But, this one’s a little more unique than the others!
Using about 20 marbles or so, spread them out on the floor around your feet, keeping them within a comfortable range so your feet don’t have to stretch too far out. Then, use your toes to pick up one marble at a time, bringing it over to a nearby cup or bowl to put each marble in.
#5. Ankle and Foot Stability Drills
Foot core strength is one component to foot stability, but it’s essential to also address different tissues and movement in the ankle joint for full stability.
We know, we said we were focused only on the actual foot… but it’s not that cut and dry! Your ankle and foot are deeply interconnected, and improving one will often involve working tissues that travel through both structures.
For instance, the posterior tibialis is one of the extrinsic muscles that provides foot stability. Although the muscle is technically in your calf, the posterior tibial tendon connects the muscle to the bones in your foot core. This makes it a key player in providing medial arch support, in addition to assisting with plantarflexion and inversion. Strengthening this muscle helps ensure that it’s functioning at its best and provides ample support for the foot.
Beyond this, though, just about any drill that challenges your balance and stability will work the foot and ankle well!
You can practice exercises on squishy surfaces like a bosu ball, or while closing your eyes, or you could adapt double-leg exercises to single-leg (as long as you practice it for both feet, for the sake of symmetry!).
The key with any balancing or stability drills is to make sure you perform them with bare feet. Shoes can interfere with your arch’s natural ability to stabilize the foot, so you may not even be benefiting from these drills if you do them with footwear!
#6. Calf and Ankle Mobility
While we’re on the topic of things that impact foot stability but aren’t located in the foot core, we have one more important consideration…
Calf and ankle tightness.
Because these structures are directly and indirectly associated with foot stability, if either the muscles or joint are tight or restricted, they won’t be able to effectively support the arch.
So, truly improving your foot core should incorporate a mix of intrinsic foot strengthening in addition to regular calf stretches and ankle mobility!
Build a Strong Foundation, One Foot at a Time
Runners have a lot to include in their training plans, and it’s easy for smaller elements like foot strengthening and mobility to fall to the wayside — especially when most resources emphasize the need for strong glutes or proper leg alignment.
But remember: if you don’t also implement sufficient training for a strong foot core, your glute strength and alignment will only take you so far!
Proper foot core strength and stability plays a key role in maintaining ideal running form and biomechanics. If your foot core lacks the necessary training, it will impact the rest of your form up the entire kinetic chain.
So, carve out regular time for those foot workouts! It doesn’t take much work or physical exertion to do, and your body (and running) will thank you for it in the long run.