Core Strength Training and Foot Function
Patients often come to see a podiatrist with a variety of complaints that include plantar fasciitis, tendinitis, a neuroma, joint pain, etc,.
They are often surprised when I direct them to the Iron Strength Training link on the office website. The question is why consider core strength training as a way to treat these common foot complaints?
Before I elaborate on that, I want to mention some predictable patterns in the way our bodies change with age. Though we all have different areas and degrees of weakness and imbalance, common ones include the head dropping forward, protracted or forward shoulders, tight hip flexors and weakening of the gluteal muscles.
How do these weakness or imbalances affect the feet? Take the gluteal muscles. Among other functions, they're responsible for turning the leg, via their connection to the thigh, inward or outward. They also can prevent unwanted motion of the leg. If weak or inhibited in their function, the result may be an in-toeing of one or both sides. This occurs because the weak glute can't keep up the external, or outward pull on the leg, therefore allowing excess motion in the opposite, or inward direction. Sometimes an intoe gait is a result of this type of weakness.
With an intoe gait, the foot will tend to 'auto-correct' by pointing straight ahead in the direction that you're walking or running. It does this at a joint in the foot, the subtalar joint. This rolling inward, or pronation, may be excessive. Excessive movement in the subtalar joint may cause faulty energy transmission, impaired efficiency, friction, shearing forces and excess mechanical stress.
The glutes also support the pelvis during walking and running. As your leg swings forward on the non-weight bearing side, the glutes prevent the pelvis from dropping down. This can be demonstrated while standing on one leg.
A 'dropped' pelvis on one side may result in excessive pronation on the opposite side. This happens because as your body weight falls to one side outside your center of gravity, it draws the opposite foot into rolling in that direction to maintain balance.
The tight hip flexors I mentioned above? As the hips stiffen, flexion, extension and rotation become limited. As is often the case when motion is limited at one joint, compensatory excess movement can occur elsewhere. Besides the low back and knees, the subtalar joints may also compensate resulting in excessive pronation.
So there is a definite link between weak core function and increased pronation. The friction and shearing forces which result from pronation are a significant contributing to many foot problems.
A related issue is that, during locomotion, normal function of the knee is dependent upon normal subtalar joint motion. This helps illustrate what is called the closed kinetic chain. In a nutshell, the term is used to explain that a problem with any link can cause compensatory movement elsewhere along the chain.
So just as a mechanical problem in the foot can affect other, higher links in the chain, core training can have a positive effect on foot function. You might see this as a type of feedback loop.
These are just a few of the ways in which core training, including better hip flexibility and strengthening of the strong muscles located near the center of the body (including the glutes, abdominals, hamstrings, quadriceps and hip flexors) affect foot function.