Given that this question requires such an unapologetically straightforward answer - "Because it is our main point of contact with the ground, for most physical activity we do" - I must admit that I have not been as proactive as I'd like in getting my clients to strengthen their feet, against my better judgement.
I have two potential excuses, a personal one and pragmatic one:
For starters, I definitely took my foot strength and mobility for granted. Frankly, despite having developed very prominent bunions sometime before my teenage years, I rarely experienced pain in my feet, and as long as I can recall, my balance has been above average. Although my desire to pursue ballet as a child was steamrollered early on by a teacher pointing out I had knock knees and flat feet, I did Irish dancing for many years, which perhaps kept my feet relatively strong. In my first year of university I took up kung fu and kickboxing, which were practised barefoot and which I credit with keeping my feet strong and mobile. So perhaps I never really questioned foot strength, as it was always something I had at least enough of to do what I wanted to do.
On a more pragmatic level, and possibly the real reason I never tackled foot strength and mobility with clients; it's a hard sell. When people visit a personal trainer, which was the only title I used until mid-2020, they want what feels like a training session: sweating, burning muscles, increased breathing rate, fatigue. What doesn't get openly talked about is that we are essentially advertising our services with every session we deliver: we need to convince our clients to come back, week after week, and whilst on the face of it we are in charge of the session, we do have to meet at least some of the client's expectations. So if your client is expecting to get fit, they probably aren't expecting to spend 10-15 minutes working on foot strength and mobility.
However, having now spent some time learning more about the foot and how to strengthen it, I have learnt ways to incorporate foot exercises into more traditional whole-body exercises. The result of combining these elements is greater than the sum of its parts.
"My foot doesn't do that"
Most of us have learnt to move in shoes; anyone who has tried to do certain exercises barefoot can testify to how differently our foot operates in shoes.
Conventional shoes share the following features:
a narrow, tapered toe-box (even if you're not wearing pointy shoes, all shoes come to a point - which our feet don't)
a rigid sole
a heel drop (that is, a heel that is higher than the toes)
toe spring (a toe that curls up away from the ground)
None of these features occur naturally in our feet (as demonstrated by babies' feet, and the feet of people who live in cultures that don't wear shoes), so spending time in shoes alters how our feet work; you've probably heard the phrase "use it or lose it" so, yes, we have lost a lot of strength and dexterity in our feet.
Most of us have grown up with so little use of our feet that it's hard to imagine how much we could do with full foot function. So imagine you had to go around wearing boxing gloves all day, and weren't able to use your hands to manipulate objects: you could still pick most things up, maybe by curling your wrist around the object, and scooping it towards your body to pin it to your hip or torso with your wrist or arm. Over time, all the small jobs normally done by specialised muscles in the hand and forearm get picked up by the muscles in the chest and shoulder. But the chest and shoulder muscles are already overworked, so they eventually decide to go on strike: they lock up, creating painful spasms. When the shoulder is no longer able to function optimally, the upper back muscles take over to perform as much movement as they can. And so on.
Let's be honest: does this matter if we spend our lives in shoes? The answer will ultimately depend on your goals for your body, and your lifestyle may dictate the effort:benefit ratio of working on your foot mobility if you spend most of your day wearing shoes. However, while the effects of weakened feet will be less noticeable if you are always in shoes, eventually they will catch up.
For one, realistically, there will be times you aren't in shoes: even if you wear slippers at home, you might stay at someone's house where you remove your shoes but don't have slippers, or maybe you walk on the beach on holiday, and wind up with achey feet.
But even if you never spend enough time barefoot that your feet directly suffer from being deprived of their protective bubbles, the lack of activity (and therefore strength, mobility, and stability) in the foot reduces the level of activity that the lower leg can perform. In particular, it means the deeper stabilising muscles of the lower leg (namely the ones that control movements of the toes) become dormant, and the more superficial muscles (your calves, and tibialis anterior on the front of your shin) have to take over. These get overworked, and eventually lock up, passing the workload on to other muscles higher up the chain.
This means that, assuming you have not developed any injuries or niggles from a lack of foot mobility, you could well be missing out on the ability to activate some fibres of bigger muscle groups like your hamstrings and glutes; a classic example is of a person who is unable to bend their big toe enough to push off their back leg when walking or running, therefore missing out on gluteal muscle activation and strengthening, and overloading the quads, which often leads to knee pain.
"Do I need to take my shoes off?"
This is a bit of a conundrum for the strength & conditioning professional (less so for the diverse movement specialist): S&C is all about sports-specific training, and I have spent many years telling myself that if a client's goals are to run better, I should get them strong in their running footwear. But strength & conditioning principles are also heavily built on biomechanics, and efficiency of movement, so we need to get all aspects of the kinetic chain (that is, all the joints involved in an action) strong and efficient. Any movement that involves our foot being in contact with the ground, therefore, requires strong and functional joints from the big toe all the way to the hip and upwards.
In an ideal world, for an individual who needs to be functional in conventional shoes, we would warm up and activate the feet and ankles barefoot, before putting the shoes on for more sports-specific movements. This builds the connection between the brain and the muscles of the foot, so that even if the muscles are unable to perform at their fullest capacity once trapped inside the shoe, they remain active enough to stabilise and transmit force between the ground and the lower leg. It might also be enough activity that when that individual removes their shoes at home, those muscles can continue to fire, taking some of the load away from the bigger muscles of the lower leg and allowing them to rest and recover between sessions.
I understand that some individuals are not comfortable removing their shoes in a gym setting, for any number of reasons (self-consciousness, pain, and hygiene concerns come to mind). In that case, I will continue to offer cues to activate the feet, as I believe that can sometimes be enough to build awareness of the foot (a useful mindfulness practice, if nothing else) and even reverse some of the inertia in the foot. We've hopefully all had the experience of trying an exercise or skill that we just cannot do - no matter how hard we try, our limbs don't move, our muscles don't respond - and then one day, it just happens, without anything feeling any different to all the times we tried. That's because we had to develop the neural connection first: we had to build the phone line before we could hear the person on the other end. So it's always worth thinking about the foot and trying to activate it, no matter how immobile or encased it is!
"My podiatrist says I need orthotics"
My traditional stance has always been, "Who am I to question a podiatrist?".
I hope this will always be my first response, as I believe humility and respect for other professionals is the key to supporting my clients throughout their journey. But to answer my own question: I am someone who cares about your freedom of movement, who is passionate about reversing the effects of sedentary lifestyles and of ageing, who sees your body both as a series of joints and muscles and tendons as individual players and as section of an orchestra, but who also sees the symphony of all these parts coming together to create something fuller, richer, more flowing.
In other words, yes, your foot or knee or hip pain might be very quickly relieved by sticking orthotics in your shoes - but how is the cohesion of the whole orchestra affected by the muting of one section?
For many people, a problem that can be resolved by orthotics can also be resolved by strengthening and mobilising the feet: this takes time and energy, as well as potentially a financial cost in terms of manual therapy and coaching. Only the individual can decide whether the time and energy cost is something they can afford. Orthotics are notoriously expensive, may need replacing, and the issues that arose from the original foot issue may also take time, energy, and additional money to reverse (for example, a knee issue due to overpronation when running may be prevented from getting worse by orthotics, but may still require some manual therapy to release tight tissues and PT/S&C sessions to strengthen the under-active muscles).
Deciding whether to go down the orthotics route or not requires an honest and open discussions about the client's expectations and the benefits and drawbacks of each approach. There is no one-size-fits-all answer.
In an ideal world, professionals from a number of disciplines would readily work with one another on each case: the podiatrist could assess and diagnose the issue, the massage therapist works to release tight tissues, the coach works to activate and strengthen weaker areas or refine technique, the podiatrist re-assesses and the client can make a more informed judgement as to whether the corrective exercise approaches are working or whether it's too much effort and they'd rather just get an pair of insoles and be left alone.
If you know a podiatrist who would be willing to work with me (or is already working closely with a strength & conditioning coach or personal trainer) on these things, please give them a shout-out. In the meantime, the more realistic option is to wear an orthotic to relieve immediate discomfort, or in problematic shoes, whilst still working to mobilise and strengthen the feet. The problem with this is that it requires paying for and dedicating time to two potential solutions at once!
Fascia, nerves & more
I am far from an expert on the human foot. I have a foundational understanding of biomechanics, but given that the foot is the most complex structure in the body - more finely engineered than any human-made structure - even a postgraduate degree in biomechanics wouldn't make me an expert.
In both therapy and in training, fascia is rapidly emerging as a leading factor in pain and performance. Fascia is a network of connective tissue that quite literally connects every other tissue in our body; individual muscle cells, bundles of muscle cells, entire muscles, muscle groups, bones, organs, nerves; literally everything. Until relatively recently, it was thought this connective tissue was an inert entity, holding us together passively like a plastic shopping bag holds your groceries. It's turning out to be far more active than that, with an ability to contract and relax, as well as containing numerous nerves that can sense various stimuli like movement and pressure. Many previously unexplained-by-Western-medicine observations and practices may actually be attributed to the effects of (and effects on) fascia.
Although fascia is present everywhere throughout the body, there are areas where bands of it are thicker and more palpable, such as the iliotibial band (IT band or ITB) and the plantar fascia (which is often only known through the common affliction plantar fasciitis/fasciopathy). The plantar fascia is a thick band of fascia along the sole of your foot; so through the sole of your foot you can directly access this network that communicates sensation and pressure throughout the entire body. When we bounce, hop, jump, and skip - it may actually be the fascia and all the nerves within it responding to the contact with the ground, rather than any of our muscles. This has supremely important ramifications for injury prevention (the ability to sense the ground and respond, preventing falls and sprains) as well as sports performance at the highest levels.
There is also fascinating research around the role of the sensory neurons in the foot in activation of the brain at all its levels - there may be effects on focus and memory - but a discussion of that is far beyond the scope of this article or even my work.
So, wait... what? Why does this matter to me?
All I need to know in my day-to-day is: there are clear benefits to training the musculature and dexterity of the foot, at all levels of performance and athleticism.
Not only could we gain a competitive edge by training a structure so often overlooked, but we are very likely to be enhancing our ability to strengthen the bigger, more typically exciting muscles as a by-product. How cool to be able to get even stronger hamstrings and glutes just by paying a little more attention to our feet!
Stronger muscles in our feet, legs, and core help us balance and prevent injuries - but that's only a small part of the story. Much more likely, it is the fascia that makes this happen. Good news, that automatically gets ignored when we don't train our feet, so even a bit of foot work will go a long way towards activating and strengthening this system.
Oh, and also, there are likely benefits to our brain (and therefore, I would surmise, our moods) by stimulating our feet.
And even if somehow I haven't convinced you that our feet - literally the one part of our body holding us on stable (or unstable) ground - are worth more than an afterthought... What have you got to lose?