The Ground-Body Interface
The foot provides initial contact with the ground while running. As such, it is very important in mitigating forces up the chain. The foot is a complex structure consisting of 28 bones, 33 joints, and 29 muscles. Every time your foot strikes the ground while running the foot joints and muscles react to be able to accommodate the ground reaction force. Timely and efficient engagement of the muscles of the foot leads to better ability to mitigate forces up the chain as well as turn ground reaction force into power that propels a runner forward.
As a runner, it is not important that you understand how every muscle and joint interact in the foot. However, it is important to understand three fundamental concepts of gait: the foot as a base of support, pronation, and supination.
The foot as a Base of Support
The plantar aspect (bottom) of the foot forms a triangle from the great toe to pinky toe to the heel. Within the triangle are bones and ligaments that provide inert structural support to the foot as well as muscles that provide dynamic contractile support.
To best mitigate forces through the foot your muscles need to work together to create a wide and strong base of support. By learning how to engage the intrinsic muscles of the foot a runner can increase the surface area of the triangle that makes up the base of the foot and better mitigate forces throughout the foot and rest of the body.
Below are several mobility and and strengthening exercises to help you get the most out of the base of your foot.
Interlaced Midfoot Mobility
Interlace your fingers between your toes. Stabilizing the foot with your other hand, move the forefoot back and forth with your hand that is interlaced with your toes.
Massage the Metatarsals
Keeping your foot relaxed, find the bones of foot that go on to form the digits. Massage the muscles in between the bones to release the intrinsic muscles of the foot.
Great Toe Abduction Taps
Keeping your lessor toes relaxed and quiet, lift your big toe up and then move it in towards the midline of your body.
Lift Spread and Reach
Lift all of your toes of the ground. Spread them as far out as you can. Then, reach your toes farther out and forward setting them on the ground.
Pronation is a component of gait where from heel strike to midstance the forces through the foot go from the outer edge to the inner edge, the heel turns out and the inside arch of the foot falls in.
Pronation gets a bad wrap amongst runners and the running injury as a motion that can cause injury. In reality, it is just a normal and necessary component in the gait cycle. Runners can develop an increased rate of pronation or stay in pronation too long during the gait cycle and this can contribute to injury.
Having a basic understanding of pronation and how to control pronation is important in both selecting shoes and strengthening your foot.
Make your foot more resilient over time by strengthening the muscles of your foot to be able to control pronation better. Below are several exercises for pronation.
Stand with your feet flat on the ground. Rotate through your hips, dropping the arch of your foot.
LAX Plantar Fascia
Standing on the lacrosse ball. Move from your heel to the base of your toes longitudinally along the plantar fascia. Can also go side to side along the plantar fascia.
Supination is the opposite of pronation, from midstance to toe-off the arch of the foot locks in an upright position in order to generate power for foot pushoff. The heel points in and the inside of the arch lifts and locks into a power generating position.
Most runners are notoriously bad at using their supinator muscles. Weakness in muscles that supinate the foot contribute to excessive and prolonged pronation and disorders like adult acquired flat foot deformity.
Below are several exercises that work to build the medial longitudinal arch of the foot and work to contribute to power generation with push-off.
Double Leg Arch Lift
Keeping your toes relaxed, lift your arch by pulling the balls of your feet towards your heel. The arch on the inside aspect of your foot should raise off the ground.
Big Toe Flexion + Abduction
Place a therapy band under your big toe and pull up with the other side so there is tension into the band. Lift your big toe up and then push it down and to the inside into the band.
Lessor Toe Flexion
Place a therapy band under your lessor toes and pull up with the other side so there is tension into the band. Lift your lessor toes up and then push it down and to the inside into the band.
Calf Raise with Ball Squeeze
Place a lacrosse ball between the heels of your feet. Keeping pressure into the lacrosse ball, lift your heels off the ground. Try to keep your heels pointed into the ball.