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Friday, October 18, 2013

Spine Fusion & Hip Extension During Running

Spine Fusion & Hip Extension During Running

Throughout this blog, I speak of ways to improve efficiency of running.  Recently, I became acquainted with Jeff Gaudette of Runners Connect.  On his website he has a great tutorial about the importance of hip extension during running.  As with all aspects of running, there has to be purpose, intent, and proper execution behind it to maximize the benefit of this one aspect of running.  So, with this post, I've decided to cover a couple of different aspects of hip extension and running.  As usual, I want to provide information that is unavailable anywhere else with specifics to injury and running or sport in general. 

Proper hip extension is a key component with efficient running.  As with all aspects of running and its' mechanics, there needs to be intent and purpose behind a specific aspect of a specific phase of the running cycle.  With this post, I'd like to emphasize the importance of the incorporation of the abdominal muscles to check anterior pelvic tilting and it's effect on checking hyper extension of the hip during running.

As with anything used in excess or in a "too much" mode, bad things can happen.  Without the braking motion of the rectus abdominus muscle and psoas muscle during running and active hip extension, you increase your chance of overuse injuries in the form of lower back pain, psoas muscle tendonitis, and even greater trochanteric bursitis (hip bursitis).  Hip bursitis by itself can be extremely debilitating if treatment is not strictly adhered to.

For persons that have undergone lumbar spine fusion, the tension in the abdominal muscles is extremely important with regards to limiting anterior tilting of the pelvis and compression of the compromised spine segments.  Because of the attachment of the psoas muscle on the lumbar spine transverse process, the action of active hip extension is like using a chisel to break down the inter body fusion hardware.  For those that remember the mechanics of the spine, an anterior pelvic tilt is the same thing as bending backwards.  All of us that have had a lumbar spine fusion know that bending backwards is an action that you want to avoid at nearly all costs.

For Those Without Spine Pathology

Hip extension is an active motion that provides us with potential energy ready to be turned in to kinetic energy for the forward advancement of our thigh and leg.  The stored energy in the hip flexors via the hip extending is the potential or stored energy.  The resulting and forward motion of the thigh is the stored or potential energy turned in to kinetic energy.  It's basic physics.

Now, lets ad a support system to the hip extension.  To maximize the amount of energy being stored in the hip flexors there has to be a strong support system or base for the hip flexors to work from.  The act of hip extension is like cocking the trigger on a gun.  Another analogy is if you want to acquire height in a vertical jump, it would not be wise to jump off a soft cushy surface.  The force developed to propel you upward would be absorbed by the soft surface you are launching yourself from. You would want to jump up from a hard firm surface to provide as much propulsion upward as possible.  This law or rule of physics is based on Newton's Third Law of Motion:

Third law: When one body exerts a force on a second body, the second body simultaneously exerts a force equal in magnitude and opposite in direction to that of the first body.

Given this information, it would make sense to provide a strong base in which stored or potential energy can be maximized.  So, to provide a strong base of support, an antagonistic muscle body would have to be employed to maximize the energy return of good hip extension during running.

The Anatomy & Physiology of Good Hip Extension

Image I shows a side view or sagittal plane view of a torso.  The bony structure of the pelvis and lumbar spinous process' are visible too.  Also visible are the rectus abdominus muscle and transverse oblique muscle.  For our purpose, I'm going to be focusing on the rectus abdominus muscle.  In the case of hip extension and the actual elongation of the hip flexors, the rectus abdominus is the antagonist of the hip extension muscles.  When the hip is at full extension, it's the contracting or shortening of the rectus abdominus that provides the base structure or launch pad for maximum kinetic energy from passive hip extension to active hip flexion.  It gets a little confusing huh?  No worries, we'll fix any confusion.  If the abdominal muscles do not contract and engage, then the slowing and reversing of the hip extension motion is left up to maximum congruence of smashing together of bony surfaces and maximum elongation and tension on the supporting ligaments and tendons.  Over very high repetition, this can cause over use injuries in several areas of the torso, lower back, and hip. 

So, when the hip or thigh goes backwards (extends) there has to be a brake to stop it's backward motion.  This brake is the psoas muscle and the supporting contractile structure is the rectus abdominus muscle.  Let's look at Image 2.  

                                                                                Image 1 
Side View of Torso, Lumbar Spine, & Pelvis

Image 2
Overview of the Mechanics of the Torso, 
Lumbar Spine, & Pelvis During
Running and Hip Extension

The gluteus maximus, medius, minimus, and hamstring muscles are the major hip extension muscles.  If the action of these muscles are left unchecked, the pelvis tilts forward very hard.  Subsequently the small joints in the back become compressed in a very harsh and violent manner.  This is indicated by the black arrows.  The hard forward tilting of the pelvis is indicated by the blue arrows.  When the top of the pelvis tilts forward, this is referred to as a anterior pelvic tilt.  The green arrows indicate the elongation of the abdominal muscles when the pelvis tilts forward.  Basically, with an unchecked and strong hip extension moment we are literally bending ourselves backwards.  

Now, if we reverse the direction of the green arrows and contract the abdominal muscles to just the right amount, then this reduces the amount of extension in our spine and reduces the amount of passive anterior tilting of the pelvis.  This accomplishes three major events.

1. This increases the amount of stored energy in the hip flexors for a much quicker hip flexion moment and forward advancement of the thigh and leg.  This is done by the abdominal muscles providing a solid base of support to turn this stored energy into kinetic energy.
2. This significantly decreases the amount of joint compression in the spine and tensile forces on the passive stabilizers of our hip and lumbar spine.  These passive stabilizers are our ligaments and joint capsules.
3. This reduces the amount of unwanted anatomical events such as compression in the lumbar spine segments, unwanted "yanking" of the psoas muscle on the lesser trochanter of the femur, and unwanted yanking motion of the psoas muscle on the transverse process in the lumbar spine.
By checking active hip extension with the right amount of contraction in the abdominal and psoas muscles, the stored muscle energy used for efficient hip flexion will be significantly increased.

All of this translates into more efficient running and enjoyable running.

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Happy Bipeding!


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