Your body is essentially a load-bearing structure sitting on your feet as its foundation. Minor changes in the placement, orientation, and stability of the feet can affect how a load is transferred through the different body parts upstream. If you over pronate, for example, the load through your ankles, knees, and hips will be transferred much differently than if you over supinate. Both can lead to knee pain, hip pain, etc. When these instabilities occur, your body can sense it and will limit power output in an effort to keep you safe. If you try to lift a heavy weight while balancing on something unstable, you will notice that it is much more difficult than it would be on solid ground. This is an extreme example of the performance impact that an unstable base can have.
For all of these reasons, it is important to understand that your foot is meant to be strong on its own and that you need to work on gaining that stable base. An easy way to understand the structure of the foot is to think of it as a bridge. Everyone is familiar with a classic arched bridge design, but they may not understand the reasons that we design bridges with arches. An arch is special because downward loading can be distributed throughout the pieces of the structure purely in compression and transferred to the surroundings. The most vital part of an arch is the keystone. The keystone is the stone at the center that keeps the entire structure together.
The foot actually has three arches: the Medial Arch, the Lateral Arch, and the Transverse Arch. The Medial Arch is the classic arch everyone thinks of, and it runs along the inside of the foot. It is the largest and most pronounced arch in the foot. The Lateral Arch is much less pronounced, but it runs parallel to the medial arch along the outside of the foot. The Transverse Arch runs from left to right across the front of the foot. This one is probably the least visible, but it's there.
There are also three keystones for the three arches: the Talus for the Medial Arch, the Cuboid for the Lateral Arch, and the Middle Cuneiform for the Transverse Arch. If any of the keystones are out of alignment, the entire structure is weakened and compromised.
So how does all of this apply? Now we can understand that the arches of the foot can either be “locked” or “unlocked”. If you have zero arch engagement and the foot is relaxed, the structure will be unlocked and the arches will not have their strength because the pieces are not pushing each other in compression (imagine an arch bridge that you just flex apart into a flat line). If you actively create the three arches using the muscles in the feet and hips, the bones and ligaments come into alignment and create the desired bridge structure. This is why we preach to squat using three points of contact between the feet and the ground, like a bird’s talons. By cueing three points of contact, the three arches will naturally form. This is how you create the most stability during a lift, which in turn allows the nervous system to give you the most power output. It is also how you can understand some very important aspects of foot health.
This shows just how important a strong foot foundation really is, and how it all works. Rooting to the ground is how we optimize our stability, power transfer, and structural health during barbell movements. If you have issues with your feet during squatting, do your research to find out where the problem is. Maybe it is upstream at your hips, or maybe you have weak feet. If you want to move properly and maximize power output, the issue must be addressed.