Functional Range Conditioning Review: Stretching

By Skyler Zarndt MS, ATC, CSCS

Yesterday we looked at Functional Range Conditioning and the idea of Progressive Adaptation.  In the FRC course, Dr. Spina discussed how the body undergoes certain adaptations and how we can better understand these adaptations.  Then we can apply these principles into our training and therefore increase the “usable” range of motion of our athletes and clients.

FRC goes into a lot of detail regarding stretching, flexibility, mobility, etc.  The old idea behind stretching was that it would increase range of motion, basically through increasing muscle compliance.  It was also believed that stretching would DECREASE viscoelasticity.  Viscoelasticity is the property of some materials that exhibit both “viscous” and “elastic” components when undergoing deformation or change.  This would allow the muscle to change shape temporarily (elastic) as well as permanently (viscous), by definition.  However, certain studies have shown that the effects of stretching are short lived.  There is a change in total range of motion, but there is no actual change in muscle structure!

So then the question becomes, “How then do we increase flexibility over time?”  One thing I’ve learned throughout my career (albeit short) is that the Central Nervous System (CNS) runs the show.  The brain and spinal cord are in charge.  So maybe we don’t necessarily need a change in structure of the muscles to increase range of motion, but we need to change the way the Central Nervous System is controlling everything.  For the people who don’t move very well or have certain restrictions, the CNS has put a “governor” on how much length it feels comfortable letting a muscle or joint move.  If the CNS feels that a certain range of motion is unsafe, it generally will prevent our body from getting to that range.  So therefore, we must find a way to reset the limit of our stretch reflex.

The stretch reflex is set by the CNS based on our previous experiences, and our muscles ability to function at a particular range.  The body always seeks homeostasis and is resistant to change.  The CNS is no different.  The body is use to living in certain ranges of motion.  If we are always in a certain position, a certain posture, our body will adapt to that because its the most efficient and the easiest thing to do.  Also, if the body finds itself in a range of motion that it deems unsafe, a range where it cannot control itself, then it will not allow you to function in that range.  Everyone has taken a joint past the point where it is “comfortable,” and the body reacts by trying to get you back into a “normal” range as soon as possible.  That’s the stretch reflex.

So with that being said, it could be assumed that since there is no change in structure, and the only thing “limiting” our range of motion is our central governor, then we have more range of motion than we realize.  We just have to figure out how to GET that range of motion.  Our body will allow us to move the way it is supposed to, we just have to convince our CNS to give it back to us.  We have the potential to move well!

So this is where FRC gets interesting.  Dr. Spina’s take on increasing range of motion really starts to come into play here.  I’ll give you a quick rundown.

We know that to improve mobility (movement through a range), we need to have increased flexibility (passive movement to an end range).  And according to FRC, the path to better mobility and reduced injury incidence has many components: stretching, strength, neurological, isometrics, and eccentrics.  Here are some quick bullet points highlighted by FRC.

  • Strength = increases force absorbing capacity.
  • Link between stretching and strength = “Stretch Induced Hypertrophy.”
  • Strength and Stretching prescribed simultaneously results in optimal improvement in flexibility.
  • Nervous System governs range of motion (Stretch Tolerance).
  • Stretching could be used as an analgesic.
  • All strength gains are first accomplished via neural adaptation.
  • Isometrics increase strength, protein production, and angular force production.
  • Principle of specificity relates to neurological function.
  • Eccentric training alone can improve flexibility.
  • Eccentric exercises can alter a muscles optimal functioning length
  • Eccentric exercise increases strength and protein production – can reduce injury rates.

So based on the principles of FRC, the path to gaining mobility requires more than simply stretching.  That’s very clear.  Tomorrow I will talk more about Controlled Articular Rotations, assessing where we can improve range of motion, and general joint health/maintenance.  These all tie into our path of moving and feeling better!


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