Frequently Asked Questions: FAQs

What is proprioception?

Simply said, proprioception is the body’s “sense of itself.” It is how the brain/nervous system perceives the body’s position in space and the body’s movement through space. It is accomplished by a variety of receptor cells that are sensitive to a stimulus.  When the stimulus occurs, the proprioreceptor cell is stimulated, causing an impulse to travel through the sensory neuron to which it is attached.  This sensory neuron then carries that impulse into the CNS (central nervous system) to the cerebellum in the brain, where proprioception resides.  Proprioception occurs through all the body all the time. It is our body’s 3-D awareness map in the brain. It is how the nervous system can vary muscle contractions as an immediate response to incoming information from external forces. Proprioception is the “feel” in golf of the club and clubface throughout the golf swing.

 

Why is proprioception important?

When there is a proprioceptive  deficit, the map of the body in the brain becomes cloudy as to where that muscle and joint are in space, and as a response the nervous system goes into survival mode. It reduces the joint range of motion and reduces the amount of force that the muscles around the joint can produce. This protects the joint from more damage, and results in a compensation.  Certain muscles are facilitated, while other muscles become inhibited.  We become less efficient and our performance is hindered.  Our coordination is lessened and we become vulnerable to injury.  Our reflexes to stimuli are delayed, and if we continue training or playing in our sport, we drive that compensation in deeper. In the long term, our joints wear unevenly and this may lead to joint problems, including osteoarthritis.

 

What is neuro-proprioceptive  response testing?

This is a test designed to evaluate  proper neural input to a muscle. It is performed to see if a muscle can contract,  and if it can contract now,  rather than to determine the strength of a muscle. It provides an indication of whether  a muscle has proper neural input to adapt to forces applied in every day life. To perform the test, the body is positioned to emphasize a particular muscle, with the muscle attachments  approximated. This brings more of the neural component (intrafusal fibers) of the muscle into play during the test. Then a mild force of less than 30 lbs. is applied.  If the muscle is neurally connected , it will be stable (not move and spring back) when a force is applied. If it is inhibited, the person will not be able to control the test position, and the joint will be vulnerable to injury.

 

What is ground reaction force?

Ground reaction force occurs every time our foot hits the ground.  It is approximately 2-3 times our body weight pushing down, and 2-3 times our bodyweight pushing up from the ground (Newton’s 3rd Law of Motion). It is a non-propulsive force, it neither pushes us forward, or backward,  or in any direction.  Some say, with good reason, that it is the most important external force acting upon the human body in motion.

Let’s calculate  the force going up through our body in a single day. A SEDENTARY person takes an average of 3000 steps/day. So a 200pound man who hits the ground with 3x his bodyweight must deal with:      200 x 3 = 600lbs. in each step

600 x 3000 = 1,800,000 pounds of force EVERY DAY  

    

12,600,00 pounds per WEEK

55,200,000 pounds per YEAR

                          

Do you think a small joint issue could become a major problem?

Running increases the force to 6-9 x your bodyweight. Sprinting is 10-12 x your bodyweight.

 

Why is the foot so important?

With it’s 28 bones, 33 joints, and more than 100 muscles, the foot is truly a marvelous structure. The human foot sends a barrage of proprioceptive information to the brain. Baroreceptors on the bottom of the foot send variances in terrain to the brain and mechanoreceptors  around the joints and in the muscles inform the brain of proper movement.  If the communication is in any way impaired, the nervous system will respond by going into survival mode (reduce ROM and the force of muscle/s around the joint/s). This creates tremendous havoc up the chain of joints in the body.

From Normal and Abnormal Biomechanics of the Foot (Root, Orien, and Weed): “Any condition preventing the normal range of subtalar pronation will result in pathological amounts of stress being transmitted up the leg into the pelvis and the lumbar spine”.

The foot must be both stable and flexible during gait. In the early stages of the stance cycle, it must become a “mobile adapter” (pronation) to conform to the uneven ground surfaces it encounters and dissipate ground reaction force (shock absorption). Then it must immediately form a “rigid lever” (supination) in the toe-off phase, and propel the body forward through space by pushing off the ground.  Effectively transferring body weight from rear foot to forefoot after heel lift. The ability of the foot to change from being supple to rigid is created by the laxity/tautness of the plantar fascia of the foot.  Stability through these movements is the major function of the foot muscles.

 

What role does footwear play?

If the shoes you wear interfere with the movement of the joints in the feet, they create a disruption of proprioception.  This sends pathological forces up the body to be dealt with by joints up the chain. This causes the formation of compensations that reduce strength and performance and make you vulnerable to injury.  Think of your knee or elbow in a cast.  What do your muscles look like after you take the cast off in 6-8 weeks?  What do you think happens to the muscles in our feet after years or decades of being in shoes that don’t allow for proper movement?

 

What shoes do you recommend?

Any shoe that you can twist and flex easily, seems to not interfere with proprioception.  The barefoot or minimalist shoes fall in this category.  There is always exceptions, that I attribute to variations in foot architecture. (more in links section)

 

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