The Foot Core System: Understanding the Function of Your Fabulous Feet

When you stop to think about all the work your feet do from day to day, you cannot help but wonder at their amazing strength. If you play sports or do high intensity fitness activities, you should have an even greater appreciation for your foot’s ability to withstand high force loads and produce its own forces.

With so much knowledge of human anatomy in the realm of sports medicine, it may seem surprising to learn that the foot is one of the least understood structures in the human body, and feet are only recently getting the attention they deserve from the human movement scientific community.

The Foot’s Complex Design

The foot is a complex structure whose functions are governed by numerous muscles, ligaments, tendons, nerves and joints that work together to provide balance and stability and produce movement. As such, the human foot has the potential to become weaker or stronger, and sustain and recover from chronic and acute injuries, depending on how it is used.

With that understanding in mind, you might think that rehabilitation of the foot would be approached in the same manner as any other area of the body, using therapeutic exercises, stretches and other treatment measures aimed at restoring or improving strength, range of motion and overall function. Yet interventions for foot-related problems tend to focus on providing external support for the foot through shoes and orthotics, rather than attempting to rehab the foot muscles to function with maximum efficiency.

Your Golden Arches

Central to overall foot function is the arch, or instep. Its ingenious design enables you to walk, run, jump and maintain balance through the recruitment of local stabilizer muscles and global movement muscles. In essence, the arch can be regarded as the “core” of the foot, just as the lumbropelvic region forms the core of the trunk.

Until recently, it was thought that the arch was held in place by passive structures such as bones, joints and ligaments. However, a growing body of research has brought to light the important role played by the intrinsic foot muscles that govern arch function.

The foot’s local stabilizers are the plantar intrinsic muscles that originate and insert on the foot, and the global movers are muscles that originate extrinsically in the lower leg, crossing the ankle joint and inserting on the foot. Both play a role in the foot’s ability to function as designed.

Intrinsic Foot Muscle Function

As we begin to understand more fully the important role played by the intrinsic foot muscles, it becomes increasingly clear that therapy geared toward stretching and strengthening those muscles should be an important part of any rehabilitation treatment protocol.

Functional qualities of the intrinsic foot muscles include:

Providing support for the foot arches: When weakened, intrinsic foot muscles lead to negative alterations in foot posture, while strengthening enhances foot posture.

Adapting to specific activities: Dynamic movements such as walking or running recruit the intrinsic foot muscles to a greater extent than standing.

Adapting to specific loads: Intrinsic foot muscles become more active when greater load demands are placed on them, such as single limb vs double limb stance.

Gait synergy: During the propulsion phase of the gait cycle, intrinsic foot muscles work together as a unit to provide dynamic arch support.

Modulation during standing and propulsion: Whether your feet are used as a platform for standing or a lever for dynamic propulsion, the intrinsic foot muscles provide support for the foot and arch.

When you consider the important roles played by the intrinsic foot muscles, it seems incomprehensible that they should be ignored during treatment for foot-related problems.