By Luke Khoury

As practitioners interested in providing care for active populations, we find ourselves regularly assisting runners overcome injuries which just may have not been necessary to start with.

In review of current literature, the most common injuries among runners were chronic or overuse in nature, with patellofemoral pain syndrome, Achilles tendinopathy, and shin splints (medial tibial stress syndrome), plantar fasciitis and chronic exertional compartment syndrome being the most common. As a result of the high injury rate there are ongoing debates regarding the benefits of barefoot training to restore "natural" mechanics and hopefully reducing injury incidence.

Time and time again we read of the rehabilitative treatment protocols to repair these pathologies, so my question to is… what if we are targeting the resulting issue rather than the primary one?

This review aims to change your pattern of thought to care.

If we review the anatomy of the foot and ankle there are some amazing facts:
26 (28 including Sesamoids) bones with 33 joints
107 ligaments and 19 muscles
over 100 muscles, tendons & ligaments (site of the strongest tendon in the body)
over 200,000 nerve endings (densest concentration in entire body)
over 250,000 sweat glands (expel 1 pint of sweat per day)
a network of blood vessels

So what can we take out of this. Personally, understanding the feet have the densest concentration of nerve endings in the body astounds me.

Think of a runner, at any given time throughout their gate there is only ever one foot in contact with the ground. For this split second the foot makes contact, it rapidly receives and processes the external environment to maintain postural balance through the cutaneous receptors on the plantar aspect of the foot, articular receptors and tendon and muscle receptors all providing feedback via our CNS to our sensory homunculus.

Lets break this down in a step by step manner...

These first order sensory neurons (as discussed above) transmits information such as pressure, touch, temperature, pain and body position from sensory receptors in the periphery to the CNS.

This information is then passed on to the second-order neurons which communicate with various reflex networks and sensory pathways in the spinal cord and travel directly to the thalamus. At this stage, some second order neurons carrying proprioceptive feedback ascending via the spinocerebellar pathway end their journey at the cerebellum (concerning position of muscles, tendons and joints).

Third-order neurons relay information from the thalamus to cerebral cortex to be processed in the sensory homunculus, the brain then processes this information and informs its neighbour, the motor cortex , what muscle activation is required to meet the desired result. The Alpha motor neurons descend back down the spinal cord to let the extrafusal muscle fibers (motor units) to let let them know it's time to work to maintain mechanical integrity or we are in trouble… and the loop continues.

Obviously the process is much more complex, however an appreciation of the speed and accuracy of this process from a clinical perspective can shift our way of thinking to assist runners prevent unnecessary injury. So what if step 1 of the sensorimotor loop is impeded. How are our sensory receptors expected to receive all the appropriate information from the external environment to make a correct decision to maintain ideal mechanics.

A brief example which sticks in my mind is the difficulty one would have trying to use a knife and fork to eat dinner or picking up a wine glass to drink whilst wearing oven mitts. Our perception of our environment is altered, our pressure receptors in our skin are hindered potentially resulting in applying excessive force to grip. Our pain and temperature receptors almost become obsolete. We lose dexterity and fine motor control required to complete complex tasks. Now think what happens when we place a thick barrier between our foot and the ground.

"without perception..there is no correction"

For this reason clinical balance tests have become an invaluable element in our physical examination. They provide quick and easy assessments of postural stability and sensorimotor deficits which have been associated with risk of ankle sprains, instability and lower limb dysfunction.

In summary we are not suggesting to go barefoot and pound the pavement. Rather, lets start taking care of the our feet... these amazing structures which allow us to do what no other animal on earth can do with such grace and efficiency.... remain upright and live on 2 feet.

For further review and information may I recommend the following readings:

ACTIVE STANCE: Barefoot balance training for runners By Emily Splichal, DPM, MS, CPT. Lower Extremity Review March 2012.

Balance assessments for ankle instability by Scott E. Ross, PhD, ATC, Shelley W.