As many as 88% of people worldwide have some kind of foot problem, yet opportunities to learn about foot health are still limited in Japan because podiatric care has not developed as far as it has in Europe and the United States. As a result, many people continue to struggle for years with stiff necks and low back pain that might otherwise improve if the feet were properly addressed.
To help improve foot function, strengthening the gluteal muscles is often recommended. In this article, we will look at the connection between the feet, low back pain, and neck stiffness, even though they may not seem closely related at first glance.
Overpronation: A common issue affecting three out of five people worldwide
One possible cause of low back pain is overpronation of the feet. Overpronation has been shown to be associated with bunions and low back pain.
Between 2002 and 2005, Menz et al. conducted a large-scale study involving 1,930 people (men and women aged 36–92) *1. They examined whether flat feet, high arches, pronation, supination, and left-right asymmetry were associated with low back pain.
The results showed the following:
- No association was found between flat feet or high arches and low back pain in either men or women.
- In women, an association was found between pronated feet and low back pain.
・Insoles (orthotics) are effective for preventing and treating low back pain
In other words...
Rheumatology (Oxford). 2013 Dec; 52(12): 2275–2282.
Women, in particular, are 1.48 times more likely to suffer from low back pain than women without any such abnormalities. Overpronation is a common condition affecting three out of five people worldwide. Based on the findings of this paper, let us look at what can be done about it.
What is ankle overpronation?
What exactly is overpronation? Pronation is a movement that also occurs in healthy feet, but when it becomes excessive, it is considered overpronation. To understand pronation more clearly, let us first look at two important mechanisms of the foot.
Feature 1: Flexible switching
When you walk, your feet bear a load equal to about twice your body weight. That is why they need a shock-absorbing function. To absorb impact, something soft, like a sponge, works well. But when it is time to push off and move forward, a firmer structure seems more useful than a soft one.
In fact, the body switches between a soft foot and a rigid foot. At landing, the foot instantly softens, and at the final push-off, the foot becomes firm so it can drive the body forward powerfully.
How do the feet switch between soft and rigid?
How does this switching between soft and rigid feet happen? Please look at the illustration below.
There is a movement called pronation, in which the foot rotates or tilts inward. When the foot pronates, the structure of the foot loosens and the arch lowers. You can think of the foot yielding slightly to absorb shock. This creates a soft, flexible foot.
Supination is the opposite. When the foot turns outward, the structure of the foot becomes tighter and the arch rises. It is like drawing a bow tight, storing tension and preparing to spring forward. This creates a firm, rigid foot.
How do pronation and supination occur?
Next, let us look at how pronation and supination occur. When you internally rotate your shin (turn it inward) while bearing weight, the foot also pronates. Conversely, when the shin externally rotates (turns outward), the foot supinates.
How does internal and external rotation of the shin occur?
How do internal and external rotation of the shin occur? The driving force comes from the twisting movement of the hips.
For example, when the right foot contacts the ground, the right leg internally rotates to create a flexible leg. Then the left leg swings forward. At that moment, the pelvis twists as the left leg swings forward. This twisting movement of the hips is transmitted in sequence to the thigh and shin, causing the shin to externally rotate. An externally rotated shin creates a rigid leg.
The diagram below shows how internal and external rotation switch from the pelvis down to the feet. Rotation is transmitted in sequence from the hips, skillfully switching between a flexible foot and a rigid foot.
If this switching function does not work properly, you end up walking with the arch collapsed, which can eventually lead to problems such as bunions.
Function 2: Move more efficiently! The foot’s rolling function
The foot also has a mechanism that helps the body move efficiently, almost like a round ball rolling forward endlessly. When the heel touches the ground, its rounded shape allows it to roll forward even without muscular effort. This is called heel rocker movement. (Rock: to sway) It can be compared to the rocking motion of a rocking chair. 
This forward rolling motion is then carried over into the next movement, the ankle rocker. In the heel area there is a bone called the talus, which includes a part called the trochlea of the talus. The talus is the only bone that has no muscle attached to it, and it helps transfer body weight forward smoothly.
The final stage is the forefoot rocker. This is when the MP joint bends and throws the body’s weight forward. Working together with the small sesamoid bones, it passes on the energy needed to propel the body forward efficiently.
However, this forefoot rocker movement only works when certain conditions are met, and if they are not, you end up walking while putting a brake on your own propulsion (abductory twist). This causes the forefoot to twist repeatedly against the ground, which can lead to excessive callus formation on the sole. I first noticed this myself when a hole developed in the big-toe area of my sneakers.
There are conditions under which locking and switching cannot occur.
We have now seen how the foot protects the body by switching to a soft foot while also rolling efficiently to transfer energy forward. When I first learned this, I was amazed by how well designed the foot is, and it inspired me to study it more deeply. However, despite how remarkable this function is, there are factors that can easily stop it from working.
One of those factors is overpronation. Pronation itself is a very natural movement and occurs even in healthy feet, but when it becomes excessive, the two functions described above stop working properly.
As a result...
・The foot can no longer switch between soft and rigid, so you end up walking with the foot always in its soft state
→ This can lead to problems such as bunions and flat feet.
・During forefoot rocker movement, the foot cannot roll properly, so you end up walking while braking yourself.
→ This can develop into abductory twist, calluses, bleeding under the nails, and similar problems.
Eventually, the damage in the foot can spread to more distant areas such as the hip joint, and may even contribute to pain in the low back, neck, head, and elsewhere.
What causes overpronation?
What causes overpronation? The pathomechanics are complex, and the causes are not yet fully understood. At present, it is thought to result from the interaction between the hip and knee joints together with dysfunction of the subtalar joint.
In the past, treatment has included top-down and bottom-up control methods such as the use of insoles (orthotics). Today, approaches that also include top-down methods targeting areas above the foot, such as the hip joint, are recommended. Ways to improve the condition include muscle training, insoles (orthotics), and correcting the way you walk.
Reason 1: Weak muscles
Reed et al. reviewed 283 papers on running injuries. Their findings showed a relationship between weak gluteal muscles and running injuries. *2 If these muscles do not function well, balance becomes unstable when standing on one leg. And if you look closely at walking, it is basically a continuous repetition of single-leg stance, so weakness in the gluteal muscles is a serious issue.
According to Kelli et al., 57% of participants actually showed improvement in overpronation after training their gluteal muscles. *3 Exercises such as deadlifts and back lunges are effective for strengthening the gluteal muscles.
Cause 2: Muscle imbalance and skeletal alignment issues
For example, if the talus begins to move poorly because of lifestyle habits or an injury, this can also affect the alignment of the knee and hip joints. As a result, you start using your feet incorrectly. Over time, faulty movement at the hips and knees is reflected in the feet, creating a vicious cycle.
Once that happens, no matter which side you try to correct, the other side may collapse. In some cases this can be adjusted manually, but from a structural standpoint it is difficult to maintain, because once you stand and walk, gravity tends to pull everything back into its previous pattern.
Insoles begin guiding the foot toward its natural movement from the moment you put them on, so they are effective for restoring disrupted muscle balance and skeletal alignment.
As Menz’s study also recommended insoles, they have become an effective option for podiatrists in Europe and the United States, where research in this area is advancing rapidly. *1 In addition, many companies now sell running shoes designed specifically to address overpronation.
Ideally, insoles should be fully custom-made for the individual. This is because changing the way the foot lands can sometimes cause so much pain that the insoles become impossible to wear. In such cases, a fully custom-made insole may be readjusted by applying heat.
Cause 3: Problems with walking style
In some cases, the walking styles taught in schools and the media can themselves lead to pronated feet. Some methods recommend landing with the knees fully straight, while others instruct you to grip the ground with your big toes, but these approaches can result in landing on a soft foot and pushing off while collapsing the foot. In addition, walking on a single straight line places strain on the body because of problems with weight transfer. We will discuss walking style in more detail on another occasion.
summary
The cause of low back pain may lie in the feet. Leaving foot problems unaddressed can eventually lead to trouble higher up the body, from the hip joints to the low back, shoulders, and even the head. Proper walking technique, appropriate strength training, and suitable insoles may increase the chances of resolving stubborn neck and low back pain that has not improved until now. Because the foot has such a complex structure, we recommend combining all three of these approaches for the most efficient improvement.
References
∗1 Menz HB et al.
Foot posture, foot function and low back pain: the Framingham Foot Study.
Rheumatology (Oxford). 2013 Dec;52(12):2275-82.
*2
Reed Ferber, PhD et al.
Suspected Mechanisms in the Cause of Overuse Running Injuries
Sports Health. 2009 May; 1(3): 242–246.
*3
Kelli R. Snyder et al.
Resistance training is accompanied by increases in hip strength and changes in lower extremity biomechanics during running
Clinical biomechanics (Bristol, Avon) 24(1):26-34 · November 2008
