Clean Run - March 2011 - 50

When the foot is pronating, the bones of the foot unlock for the purpose of creating shock absorption, keeping our balance, and allowing our foot to adapt to uneven terrain. When the foot is supinated, the bones of the foot lock and the foot becomes rigid to work as a lever arm to lift our body off the ground during propulsion. When the arch collapses, the foot pronates, and there is an increased stretch of the plantar fascia. Ideally, this occurs when the foot first hits the ground. At this time the weight-bearing leg is rotating internally. Then as you move forward, the opposite leg swings through the air and the weight-bearing leg starts to externally rotate, raising the arch to create supination (the arch gets higher). There is a decreased stretch on the plantar fascia during supination and the foot functions as a rigid lever arm to propel us forward. See Figure 3. Planter fasciitis develops when the foot is still pronated as we propel ourselves forward. Many people fail to regain their arch when they propel themselves forward. So the plantar fascia gets strained as it tries to compensate for the lack of foot rigidity that comes with a flattened arch. Simply put, do you want a strong foot that rolls forward easily like a wheel, or a weak foot that squashes flat and overstrains the plantar fascia and the other foot ligaments? Strong healthy feet do not develop plantar fasciitis. If you understood the last five paragraphs, congratulations. The key things to understand are that when the foot overpronates, the arch collapses and the plantar fascia pulls on the heel bone. When the foot supinates, the arch raises and the pull of the plantar fascia on the heel bone is decreased as seen in Figure 3. 3

How Does Agility Increase Your Vulnerability to Plantar Fasciitis?
So let’s look at our locomotion as handlers while we run our dog in agility. To the sports medicine specialist, our sport engages in quick acceleration and deceleration, and quick turns. Let’s look at quick acceleration and deceleration first. Acceleration involves weight-bearing mostly on our forefoot. If our arches are too flat, we accelerate inefficiently and with greater strain on the plantar fascia, especially at the attachment of the plantar fascia to the heel bone, which helps to create plantar fasciitis. We’re safer during the deceleration phase since it involves relatively more force on the midfoot and heel, rather then the forefoot. Now, look at quick turns. Front crosses, rear crosses, blind crosses, sharp turns, and so on all involve rotational movement. Usually we achieve these movements while we are on our forefoot and toes. While turning, one foot rapidly pronates and one foot supinates. With these quick turns, our body leans or banks, which also increases the pronation and supination of each foot. The rapid excessive pronation during quick turns will also create excessive pull on the plantar fascia, helping to create plantar fasciitis. See Figure 4.

Variables that Increase Your Vulnerability to Plantar Fasciitis
So you can see that a sport with quick acceleration/deceleration and quick turns can make you vulnerable to plantar fasciitis. However, if this by itself was the sole cause of plantar fasciitis, dog agility would be a sport where 100% of us would have the condition. So we must look at additional variables that can create excessive pronation and arch flattening. Some 4

Clean Run | March 11

http://www.trainingwithgrace.com http://www.trainingwithgrace.com http://www.cleanrun.com

Clean Run - March 2011

Table of Contents for the Digital Edition of Clean Run - March 2011