The Foot Under Every Lift. The Smallest Muscles In Your Body Decide Where The Floor Pushes Back.
Every squat, sprint and tackle begins with the floor pushing back through the foot, yet most programs regard the foot as a fixed platform inside a shoe. Research over the last decade describes the arch as an active spring, controlled in part by small muscles that sit entirely within the foot. This article explains that system, what training it has been shown to change, what footwear does to it, and why an athlete returning from an ankle injury should train the foot as well as the ankle.
Opening. The ankle that is nearly ready
Marc is thirty one and plays rugby union at a competitive club grade. The ankle he rolled in the final game of the season came out of the moon boot on the ninth of September. Three weeks later it moves well, the swelling is gone, and the rehab his physiotherapist wrote is working through calf raises, balance and controlled hopping. His first preseason session is in mid October.
Last week, standing on one leg with his eyes closed, Marc noticed something he had not expected. The ankle felt solid. What wobbled was the foot underneath it. His toes clawed at the floor, his arch seemed to sag and recover, and the effort to stay balanced seemed to be happening in a part of his body he had never trained at all.
His physiotherapist was not surprised. The foot, the physiotherapist said, is not a platform. It is a set of muscles, and they had been asleep in a boot for ten days.
That conversation is the subject of this article.
Section one. The arch is a spring, not a bridge
For most of the last century, the foot arch was described as a passive structure. Bones shaped like a bridge, held by ligaments and the thick band of tissue under the sole called the plantar fascia. Muscles were thought to matter little once you were standing.
That picture has been revised. In 2015 Patrick McKeon, Jay Hertel, Dennis Bramble and Irene Davis proposed the foot core system in the British Journal of Sports Medicine. Their argument borrowed directly from the way we think about the trunk. Just as the deep trunk muscles stabilise the spine under the bigger movers, the small muscles that start and finish inside the foot, called the intrinsic foot muscles, stabilise the arch under the bigger muscles of the lower leg.
They described three parts working together. A passive subsystem of bones, ligaments and fascia. An active subsystem of the intrinsic and extrinsic muscles. And a neural subsystem, the sensory receptors in the sole and the joints that tell the brain where the foot is and how it is loaded.
The practical point was pointed. Clinicians had spent decades supporting the foot from the outside, with arch supports and stiff shoes, and very little time training the muscles designed to do that job from the inside.
Section two. What the small muscles actually do
The case for the arch as an active spring rests partly on careful laboratory work led by Australian researchers. Luke Kelly, Andrew Cresswell, Sebastien Racinais and colleagues published a study in the Journal of the Royal Society Interface in 2014 showing that the intrinsic foot muscles are recruited more as load on the foot rises, and that when stimulated, they can control how much the arch flattens.
A later study by Kelly and colleagues, published in the Journal of Applied Physiology in 2019, went further. It found that one of these muscles, flexor digitorum brevis, works close to isometrically while the foot is loaded, letting its tendon and the plantar fascia store elastic energy and return it.
Put together, the picture is a foot that adjusts its own stiffness. Under a light load it can be supple. As force rises, in a sprint, a landing or a heavy squat, the small muscles help stiffen the arch so that force passes cleanly from the leg into the ground and back again.
That is what Marc felt on one leg. A foot that cannot regulate its own stiffness hands the job to the toes, which claw, and to the ankle, which wobbles.
Section three. The foot after an ankle injury
An ankle sprain is usually discussed as a ligament injury, and it is. But the ankle and foot work as one system, and a period of immobilisation affects both.
Muscles that are not used lose strength and size, and the small muscles of the foot are no exception. The sensory side matters too. Much of the information the brain uses to balance comes from receptors in the sole and in the joints of the foot. A boot removes most of that input for days or weeks.
Researchers have begun testing whether foot training adds anything to standard ankle rehabilitation. Several small trials in people with chronic ankle instability have added the short foot exercise, described below, to rehab and reported improvements in balance measures. The trials are small and the quality is mixed, so the honest summary is promising rather than proven.
What is not in doubt is the principle. Marc's physiotherapist has already given him calf, balance and hopping work, and we described in The Other Side Is Training Too how training his healthy leg protected strength in the injured one while he was in the boot. Adding the foot is not a replacement for any of that. It fills a gap that a rehab focused only on the ankle can leave behind, and it should be added with the physiotherapist's agreement.
Section four. How foot strength is trained
The best known foot exercise is the short foot. Sitting or standing, you draw the ball of the foot toward the heel without curling the toes, so the arch lifts slightly and the foot shortens. It is subtle, often frustrating at first, and it trains the intrinsic muscles to act on the arch directly.
Beyond that, the foot can be loaded like any other muscle group. Toe curls against a towel or a light band. Doming and toe spreading. Calf raises done slowly with the big toe pressing deliberately into the floor at the top. Single leg balance, progressed from a hard floor to eyes closed to a softer surface. Each of these asks the small muscles to work under rising demand.
The most interesting evidence comes from a trial that compared two routes to the same goal. Sarah Ridge and colleagues at Brigham Young University randomised fifty seven runners into three groups for eight weeks, publishing in Medicine and Science in Sports and Exercise in 2019. One group did a progressive set of foot exercises. One gradually increased the daily steps they walked in minimalist shoes. One changed nothing.
Both active groups increased foot muscle size and strength. The control group did not. Changing footwear gradually worked about as well as doing the exercises, at least over eight weeks in healthy runners.
Section five. What footwear does and does not do
That trial is often quoted as a case for throwing out supportive shoes. It is a narrower finding than that.
Cushioned, supportive footwear does part of the arch's work for it, and feet that are always supported get less practice at supporting themselves. Spending some time in flatter, more flexible shoes gives the intrinsic muscles more to do. That much is reasonable.
But the same research group had earlier seen bone stress injuries in runners who moved to minimalist shoes too fast, which is why the 2019 trial built up step counts slowly. A heavy rugby player who has just come out of a boot is precisely the person who should not change his footwear overnight. Match boots, training shoes and lifting shoes are chosen for traction, protection and the demands of the sport. None of that changes.
For lifting, the sensible middle ground is a flat, firm shoe for most work, with some warm up sets and accessory work done barefoot where the gym allows it. The foot can be trained without becoming an ideology.
Strength under the foot also shows up higher up the chain. A stable foot gives the knee a predictable base to travel over, which matters for the deep knee positions we defended in The Knee Over The Toe.
Section six. A defensible protocol for the returning athlete
This is the foot block Marc's physiotherapist approved, added to his existing rehab. It takes about ten minutes, five days a week, and builds over three weeks.
Weeks one and two. Short foot holds, seated, three sets of eight holds of five seconds each foot. Towel toe curls, two sets of fifteen. Toe spreading, two sets of ten. Single leg balance on a hard floor, three holds of thirty seconds each side, progressed to eyes closed once thirty seconds is easy.
Week three onward. Short foot holds standing, then on one leg. Slow calf raises with the big toe pressing into the floor, three sets of twelve on each leg, adding a dumbbell when twelve is easy. Single leg balance on a folded mat. Ten minutes barefoot in the warm up on lifting days, walking, light lunges and balance.
Keep footwear for training and matches unchanged. If you want to add time in flatter everyday shoes, add it gradually across weeks rather than days.
Stop and get it assessed for any new pain in the arch, the heel or the bones of the midfoot, any return of swelling, or any sense the ankle is giving way. Those belong with a physiotherapist, not a program.
For the rest of his return to preseason, Marc is following the speed and strength layers we described in The Hamstring At Full Speed and The Off Season. The foot block sits underneath them.
Section seven. The mastermind frame
We tend to train what we can see in a mirror. The foot is out of view, inside a shoe, beneath every lift we do, and for most lifters it has never received a single deliberate set.
Yet everything we load passes through it. The bar on the back, the push from the blocks, the contact in the ruck. A foot that cannot regulate its own spring hands that work to joints that were not designed to carry it.
Marc's injury gave him a reason to notice. Most of us never get one, which is part of why we came back to the same idea in The Game You Stopped Playing. The body we return to sport with is assembled from its smallest parts.
Train the ground contact. The rest of the chain has something to stand on. The floor pushes back through whatever you have built.
Frequently asked questions
Should I lift barefoot?
Some lifters do well with barefoot or very flat shoes for deadlifts and accessory work, and it gives the foot more to do. It depends on the gym's rules and your own history. Keep a firm shoe for heavier squats if it helps your position, and build barefoot time gradually.
Are arch supports bad for my feet?
Not necessarily. Orthotics have legitimate uses, and some people are prescribed them for good reason. The foot core idea simply suggests that supporting the arch from outside should not replace training the muscles that support it from inside. Any change to prescribed orthotics belongs with the clinician who prescribed them.
I have flat feet. Will foot training give me an arch?
Training can increase foot muscle size and strength, but there is limited evidence that it reshapes the arch in adults. Many people with low arches have no symptoms and need no intervention. If flat feet are painful or changing, see a physiotherapist or podiatrist.
How long until foot strength improves?
In the trial described above, changes in foot muscle size and strength were measured over eight weeks. Like any muscle, the foot responds to consistent, progressive work over weeks rather than days.
Can foot training replace my ankle rehab?
No. Ankle rehabilitation after a sprain includes strength, balance and graded return to sport work designed for the injured joint. Foot training is a reasonable addition, ideally agreed with your physiotherapist, not a substitute for the program they wrote.
Written for the Supplement Superstore Vault. We sell the supplements that support the work. We do not sell the work. Information here is educational and is not medical advice. Speak with a qualified health professional before changing any protocol, especially during pregnancy, breastfeeding, competitive training or while managing any clinical condition.
