Emily Splichal: Small Nerve Stimulation – The Future of Proprioception Training
by Dr. Emily Splichal
When you hear the words “proprioception training” what comes to mind?
Perhaps you envision a patient rehabbing a sprained ankle or picture a client standing on a wobble board. If you were to do a Google image search for “proprioception training” you would get hundreds of pictures demonstrating balance exercises or single-limb exercises on unstable surfaces.
Despite the popularity of instability training and unstable surfaces, have you ever wondered how effective these techniques really are at improving joint proprioceptive awareness?
If we were to take a look some of the recent research you may be surprised to find out that unstable surfaces are not as effective at improving joint proprioception as their manufacturers would like us to believe.
A 2004 study by Verhagen et al. demonstrated that after six weeks of wobble board training there was no improvement in protective benefit to the ankle in both health and previously injured subjects.
Another study by Soderman et al. similarly demonstrated no benefit in elite soccer players when integrating instability training into their program. In fact, they actually saw an increase in knee injuries with instability training.
If the research doesn’t support instability training for improving joint proprioception, what techniques are supported by research?
To answer this question we must first ensure that we have an accurate understanding of proprioception and how it is measured in the body.
What is proprioception?
Often confused with kinesthetic awareness, proprioception is our internal messaging system which provides sensory information regarding local joint position to the central nervous system (CNS). In return the CNS provides motor responses back down to the joints (muscles) ensuring adequate dynamic joint stability.
There are many different types of proprioceptors found within the body all varying in nerve size, distribution and reaction time.
Large nerve proprioceptors are probably the most well known but are associated with a slower reaction time. Large nerve proprioceptors can be found in our muscle tendon junction, joint capsules, ligaments and hairy skin with the most common being the golgi tendon organs and the muscle spindles.
Conversely, the faster, small nerve proprioceptors can be found in plantar foot skin, palmar hand skin and within our fascia. These under-appreciated proprioceptors provide faster and more finite joint position information and if trained properly can lead to faster dynamic joint stability.
Targeting Small Nerve Proprioceptors
So ultimately if small nerve proprioceptors are faster at providing and processing joint position information we must shift our current proprioception training protocol from large nerve to small nerve.
So then how exactly are these small nerve proprioceptors targeted?
Anyone who follows the Barefoot Training Specialist® Certification knows that barefoot training is one of the most effective ways to stimulate the small nerves, however, is this the only way?
Despite the skin on the bottom of the foot being highly populated with small nerve proprioceptors, there is an area of the body that is even more densely populated with small nerves. Can you guess?
It is our fascia!
Our fascia is an interconnected web of connective tissue that is contiguous with muscles, tendons, ligaments, retinaculum, periosteum—all aspects of the human body are intertwined within this myofascial web. Let’s look a little closer at some of the most interesting facts in order to fully appreciate fascia.
The Fascinating Fascial System
Our fascial system is also known as the organ of form which means that it acts like an anti-gravity tissue, resisting forces (gravity) through integrated tension—often referred to as tensegrity.
Because our muscles and fascia are deeply intertwined many muscles actually attach to or originate off of our fascia. This means that as we contract our muscles, we create tension throughout our fascial system.
In addition, 10 times as many sensory nerves can be found in our fascia versus in our muscles. This means that when we contract our muscles what we actually “feel” is our fascia tensioning—not our muscles contracting.
Finally, when we look at joint specific tissue such as ligaments, retinaculum and joint capsule, all these connective tissue structures are continuous with each other and blend into the fascia. This means that many of the joint-specific connective tissue structures which are often viewed as large nerve actually contain small nerves—with the most common being the ligaments!
Small Nerve Proprioceptive Web
A 2007 cadaver study by Abu-Hijeleh et al. demonstrated that small nerve proprioceptors are found within fascia, ligaments and capsule. In addition Abu-Hijeleh et al. demonstrated a tight adherence between the different joint connective tissue suggesting that when tension is applied through our fascial web, all the joint connective tissue structures became tensioned. This interconnected tensioning is our bodies’ way of establishing dynamic joint stability.
If proper tensioning of our fascia translates to faster dynamic joint stability then we must ask ourselves, how do we properly create and establish fascia tension?
Understanding Fascial Tensioning
In early 2015, I began to integrate the concept of fascial tensioning into the Barefoot Training Specialist® Certification. Fascial tensioning or body tension is a technique that is often used in gymnastics as a means for maintaining optimal body control during rapid impact forces such as during a tumbling pass or on the vault.
I applied this same fascial tensioning concept when explaining how the body damps impact forces during walking and running. Based on research by Nigg et al., studies have demonstrated that during dynamic movements our muscles contract isometrically to damp vibrations and to allow the potential energy of impact forces to go into our fascia and tendons.
Through further research, Schleip et al. demonstrated that isometric contractions are the secret to peak fascial tensioning via our perimysium, or fascial web that surrounds our muscle fascicles. If we were to apply the concept of isometrics and fascial tensioning to when we perform the short foot and many of the barefoot balance exercise of the Barefoot Training Specialist® Program—fascial tension can be translated through our small nerve fascial web from the bottom of the foot into the tissue that surrounds the ankle joint creating joint stiffness or ankle stability.
The Future of Proprioception Training
So how do we begin to integrate the concept of fascial tensioning and small nerve stimulation into our client or patient programming?
Concepts of fascial tensioning can be applied for both the lower extremity as well as for upper extremity joint stability. Below are sequences and exercises that I use for establishing foot-to-core tension as well as hand-to-shoulder tension.
I encourage you to view these exercises as a form of movement prep and activation sequencing before large, integrated movements you may use throughout your clients programming.
To learn more about fascial tensioning and the Barefoot Training Specialist® Certification please visit ebfafitness.com
Stay barefoot strong!
Dr. Emily Splichal
For a more detailed discussion, Dr. Splichal delves further into this topic in a new 40-minute talk:
Abu-Hijeleh, M. et al. Deep fascia on the dorsum of the ankle and foot: Extensor retinaculum revisted. Clinical Anatomy. 20: 186-195 (2007).
Schleip, R. et al. Training principles for fascial connective tissues: Scientific foundation and suggest practical applications. J Bodywork Mov Ther. 17: 103-115 (2013).
Soderman, K. et al. Balance board training: prevention of traumatic injuries of the lower extremities in female soccer players? A prospective randomized intervention study. Knee Surg Sports Traumatol Arthrosc. 8(6):356-63. 2000.
Verhagen, E. et al. The effect of a proprioceptive balance board training program for the prevention of ankle sprains: a prospective controlled trial. Am J Sports Med. 32(6):1385-93. 2004
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