I was thinking about how to write this piece when Kelly Starret and Brian McKenzie posted a great video on how important foot function is. This is the video I’m talking about.
Now, here’s my take:
Believe it or not, your feet may well hold the key to unlock your hidden athletic potential. They are the contact point between you and the ground. When you run, jump, squat or clean; it is your feet that are the ‘switch’ that help access the power of the hips. Any dysfunction at the foot and ankle is going to cause a lack of power development from the hips and probably some degree of compensation from somewhere else in the body…from a part of the body that is not fundamentally designed to do the work of the hips. To understand how to ‘unlock’ the foot and allow it to function effectively, we first need to understand the anatomy.
The foot/ankle joint is widely viewed as a single joint, when it is actually a series of joints that are highly integrated. They are:
- The Talocrural Joint
- The Subtalar (talocalcanean) Joint
- The Talocalcaneonavicular Joint
- The Calcaneocuboid Joint
- The Transverse Tarsal Joint – Also known as the Mid Tarsal Joint or MTJ. This joint is the talocalcaneonavicular joint and the calcaneocuboid joint.
The focus of this piece will be on the Subtalar Joint (STJ), its construction, function, and how this all pertains to optimising hip function.
The Subtalar Joint – STJ
The STJ is the meeting of the talus and the calcaneus, where the inferior surface of the talus articulates with the superior surface of the calcaneus. Inversion and eversion are the main movements that occur at this joint. However, the joint also permits slight gliding and rotation that assist with inversion and eversion of the posterior part of the foot i.e. the calcaneus. Movements of STJ are closely associated with those at the talocalcaneonavicular and calcaneocuboid joints (parts of the transverse tarsal joint).
As we spend the majority of our time weight bearing, it is important to understand how the STJ affects the movement of the rest of our body. When we walk, run and squat; we are subject to gravity and ground reaction force. These forces then cause a reaction in the STJ. When we walk, the calcaneus everts, allowing the STJ to pronate. In turn this allows the mid tarsal joint (MTJ) to become mobile and the arch of the foot beings to lower. This sequence of events allows a couple of essential things to occur.
Firstly, it increases proprioception by allowing the foot to adapt to the surface it is working on and secondly and in my opinion, more importantly, it starts to eccentrically lengthen the muscles of the foot. This eccentric loading then changes to a concentric contraction causing the calcaneus to begin to invert. Calcaneal inversion causes the MTJ to lock up, which then makes the foot more stable. This stability conveniently comes at a point when the muscles are producing force.
That covers the distal happenings, but what about the proximal effects i.e. what happens at the tibia and femur? This is where things get interesting, and here’s why.
Calcaneal eversion, which is a frontal plane motion, translates to tibial internal rotation, which is in the tranverse plane. I’ve mentioned in a previous post, Thinking About The Squat, about how the transverse plane is the most powerful plane in the body. This lower leg transverse plane motion will cause a similar effect in the femur and pelvis. This chain reaction will drive torque into the hip joint. The hip joint reacts to calcaneal eversion with flexion (saggital), abduction (frontal) and internal rotation (transverse). These three movements all eccentrically load the glutes FOR FREE! This eccentric loading helps to decelerate the calcaneal eversion, causing allowing calcaneal inversion via econcentric muscle function (thanks to Jami Tikkanen for the edit!) and a reversal of the actions above ending in a powerful concentric contraction of the glutes causing hip extension; adduction and external rotation.
Any form of dysfunction of the STJ will not allow the chain reaction that has been explained above. For example, if you have very high arches and therefore an immobile STJ and MTJ you will not be able to cause the chain reaction of converting the frontal plain, calcaneal eversion to tibial rotation. The result of this is that the foot and hip muscles aren’t maximally loaded. If your hips do not like being internally rotated, this may well indicate that you are not getting effect calcaneal eversion and resultant STJ and MTJ function. This can cause excessive valgus at the knee and/or repeated ankle sprains. There is also an issue with fallen arches. With fallen arches the bones of the feet are already in the ‘loaded’ positions, being in the end range of their ROM means that the musculature can’t load and explode.
How can we restore function?
In two of my previous posts – Does Your Warm-up Help You Evolve and Restoring Joint Function, I discuss the need for tri planar movement and the different ways the movements can be driven into the joints. Check out the video below. Here Jami is demonstrating simple mobility drills to drive tri planar back into the mid and rear portions of the foot. As always, test and retest with something like an unloaded overhead squat. In the video Jami mentions The Gray Institute and AFS (Applied Funcitonal Science). I highly suggest you check out www.grayinstitute.com
These short and simple mobility drills will help restore normal function of the mid and rear foot, in turn helping to unleash the power contained in the hip.