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Introducing the Functional Range Conditioning(F.R.C)™ method of flexibility training …..an introduction to stretching and its various myths

January 17, 2012

If you have been following this blog and/or taking the Functional Anatomy Seminars courses, you will no doubt understand our stance that assessment, treatment, rehabilitation, and conditioning of patients/clients should exist on a continuum with boarders which become more and more blurred as the knowledge of the practitioner increases.  Thus we have taken an approach to provide our community with all of the skills necessary to create that continuum starting with our courses on soft tissue palpation & assessmentFUNCTIONAL ANATOMIC PALPATION SYSTEMS (F.A.P.)™, leading into our seminars on soft tissue treatment & rehabilitationFUNCTIONAL RANGE RELEASE (F.R.).™  In our continued evolution, 2012 will mark the introduction (starting with this post) of the conditioning aspect of the Functional Anatomy Seminars.  Namely, FUNCTIONAL RANGE CONDITIONING (F.R.C).™  This system, focusing on the creation of ‘Flexible Strength’ will expand on the introduction in the Functional Range Release (F.R.) seminars of the concept of P.A.I.L’s, or PROGRESSIVE ANGULAR ISOMETRIC LOADING.  During F.R. seminars, the concept is introduced for the purposes of expanding the functional ROM during soft tissue application, as well as for progressive strengthening of newly acquired ranges.  Now with F.R.C.™ the concept is greatly expanded upon as it is taken out of the treatment room, and into the gym in order to build flexibility (more importantly flexible strength), and to improve agility as a consequence.

Certification courses (in the form of seminars, or online presentations….yet to be determined) will follow and will be open not only to manual therapy practitioners, but also to Strength & Conditioning specialists.  This will effectively allow the manual practitioner to transition their patient to a trainer who understands concepts such as progressive tissue loading, flexible strength, and others which will ensure the safety of the patients during their athletic/training endeavours.  If you are a manual practitioner reading this article, please share it with any physical conditioning colleagues that you might know.

An introduction of F.R.C.™ and the myths surrounding stretching…

by Dr. Andreo A. Spina, B. Kin, DC, FRCCSS(C), FR

Stretching and the pursuit of “flexibility” has long been a goal of many athletes, trainers, therapists, sports medicine practitioners, and society as a whole.  The intentions of attaining this goal have been numerous and include preventing injury, improving athletic performance, retarding the affects of aging, and developing long ‘athletic-looking’ bodies.  However as with all physical exercise activities, stretching and flexibility training has long fallen into the realm of ‘gym science,’ while the true science has failed to be recognized.  This has lead to the creation of flexibility training programs, which have been largely ineffective, misguided, and often times dangerous.

Even in the rare situations where flexibility is actually attained using such training regimens, more often than not what the individual has actually managed to acquire is what I commonly refer to as “useless range,” or “useless flexibility.”  In other words, they have managed to force their bodies to attain a range of motion in which they have absolutely no control.  The ability for say a martial artist to simply do the splits does not necessarily mean that they will be able to kick an opponent in the head … it simply means that he or she is able to do the splits!  That, in and of itself, has no real usefulness in sport, or in everyday life.  Similarly for the power lifting or weight training athlete, simply attaining enough flexibility to reach the bottom position of a proper squat does not automatically translate into the ability to generate strength from that position.  A person’s ability to attain certain range of motion has no usefulness unless he/or she is able to control that range.  In other words, the pursuit of flexibility in the absence of strengthening the newly acquired range does nothing more than produce “useless flexibility.”  Only those who are able to maintain control of their bodies, even when in extreme ranges, are able to benefit from their new found ‘elasticity.’

Thisarticle intends to first dispel some of the myths that surround the topic of stretching and flexibility training, then introduce a new adjunctive method of training used to create useful, functional flexibility termed Functional Range Conditioning (F.R.C.)™ 

Dispelling the stretching myths…

Before discussing the concepts and benefits of proper flexibility training programs, it is important to first learn the “myths” which have long been propagated throughout the fitness world on the topic.  Many of these fallacies have been entrenched into the minds of the so-called fitness or medical ‘experts,’ so dispelling such myths is not an easy task.  In order to do so, we must forget about what the “gym science” has told us, relinquish “common sense,” and trust the actual science.  Such science has been available for many years, however as it often does, science ruins perfectly wonderful theories, and thus is ignored by the masses.

Physiology of Stretching: What actually happens to our tissues when we stretch?

Historically stretching was believed to increase the range of motion of a joint through decreases in something termed “viscoelasticity,” as well as by increases in the “compliance” of muscle.  Viscoelasticity refers to the property of some materials that exhibit both “viscous” and “elastic” characteristics when undergoing deformation (a change in the shape or size of an object due to an applied force).  Human muscle is such a material that possesses the ability to exhibit both behaviors.  With a purely viscous substance, if a force is applied to it, the shape of the substance will change permanently.  Thus when the force is removed, it will not return to its original shape.  Further, the longer the force is applied to it, the greater the resultant change in shape (Molasses would be an example of a purely viscous substance).  A purely elastic material on the other hand will exhibit change in length for a given force, and will return to its original length when the force is removed.

Compliance refers to how easily a substance’s shape will be altered under a load.  A more compliant tissue will undergo length change under lesser force, whilst a stiffer tissue will require more force to create a comparable length change.

In theory, the fact that human muscle tissue acts as a vasoelastic material makes logical sense in the context of stretching.  When one stretches for a period of time the viscous component of the muscle will lead to increased ranges of motion, however the elastic component will return the muscle to a normal resting length making at least a portion of the stretch short lived.  If muscles were purely viscous, then the muscles length would remain in the stretched position permanently (i.e. ‘Gumby’).  If muscles were purely elastic, then there would be no such thing as permanent improvements in flexibility.

However, as was previously stated, science ruins perfectly wonderful theories!  What the science shows is that the immediate effect of stretching does appear to affect the viscoelastic behavior of muscles, but the duration of this effect has been shown to be short lived.1,2 Studies looking at long term stretching (over a 3-4 week period) reveal improvements in flexibility and range, however no change in viscoelasticity (in other words, their flexibility improves but with no lasting change to the muscles structure).3,4

If a person is able to increase flexibility over time in the absence of changes of the viscoelastic behavior of a muscle, then how does this improvement occur?  It would appear that the bodies’ reaction to prolonged stretching is to increase stretch tolerance.  In other words, with time, the body ‘allows’ more range to be achieved.  As with any other decision the body makes, this ‘allowance’ is the work of the central nervous system (CNS – the brain and spinal cord).  Stated simply, improvements in flexibility are the result of the nervous system allowing the tissues to stretch more, and not as a result of a change in the actual structure of the tissue.  Thus stretching could be considered a method of training the nervous system rather than muscles.

A simple experiment can further illustrate this point.  Stand next to a table that is approximately waist level.  Now abduct the leg closest to the table onto it such that your hip is at ninety degrees.  Are you able to do it?  Most healthy, moderately fit individuals should be able.  Now turn around so you’re opposite side is against the table and do the same thing.  If you were able to hold each of your legs out at 90o, then what is preventing you from being able to achieve a full split position (90+90=180o)?  In a full split, each hip is achieving the exact same range of motion, and the muscles ‘restricting’ that particular motion (the adductors) are ‘stretching’ the exact same amount as in our experiment …so why can’t they do it at the same time?  For those who need to brush up on their anatomy I will tell you that there is no muscle in the human body that crosses between hip joints.  Thus the only real ‘bridging’ tissue is your skin which is extremely flexible.  The reason for this phenomenon comes down to an unwillingness of the central nervous system to allow this position to occur due to both fear of injury, as well as fear of being unable to recover from the position once you are in it.  Thus, even though the position is well within the normal limits of the muscles length, because we are unable to control the weight of our body in the position, the nervous system does not allow it (Hence the need to develop strength in the outer ranges of motion as will be discussed in later posts).

Aside from the obvious benefits of improving flexibility and improving range of motion, research is also suggesting that stretching may also increase a muscle’s cross-sectional area (size) via a process termed “stretch induced hypertrophy.”5-7 In fact, a recent study demonstrated that stretching regularly over a period of weeks improves results on tests of maximal voluntary contraction, jumping height and possible running speed.8 These improvements may be attributed in part to muscular hypertrophy, however the author also offers an alternative hypothesis as well—a reduction in central neuromuscular inhibition.  In other words, stretching may somehow teach the CNS to more fully activate the muscles involved in the task.  Either way, this branch of research speaks to the various benefits of regular stretching.

Does pre-exercise stretching help prevent injuries?

For many years now, sports-medicine professionals and trainers alike have promoted stretching as a way to decrease the risk of injury.  To apply “common sense” to the matter, the more elasticity, or flexibility a tissue has the harder it is for that tissue to ‘snap.’  Paraphrasing an old Chinese saying “that which does not bend, breaks.”  Although this theory makes sense to common standards, the science demonstrates that this theory does not apply to tissue injury.

Although muscles are sometimes injured when stretched beyond their capability, the majority of injuries occur within the normal range of motion of a tissue during eccentric activity (muscle lengthening under tension).  The most important variable with respect to muscle injury is therefore not the length of the muscle, but the energy absorbed by the muscle.  In other words, during physical activity, the tissues of the body are subjected to forces or “tissue insults.”  When the amount of force, or insult, into the tissue exceeds the force absorbing capabilities of that tissue it causes injury.  Stretching has been shown to temporarily decrease the tissues “threshold” for force absorption and therefore stretching before training or competition has not only been shown to not prevent injury, it may actually increase your chances. 9-13

Does stretching outside periods of exercise prevent injuries?

When attempting to answer this question, one finds that the scientific literature is scarce.  In fact, there have been only three studies that isolated the effect of stretching outside periods of exercise on injury risk.  Both of these studies suggesta clinically relevant decrease in injury risk.14-16 Strengthening on the other hand has been long known to help with injury prevention.  Surprisingly, before the creation of Functional Range Conditioning™, which is introduced in part two of this article, there has been no system of training that effectively combines the two. 

Can you have too much flexibility?

Yes!  Despite the recent upsurge in the practice of Yoga amongst athletes, extreme flexibility should not be the goal of every athlete.  Research suggests that you only need a small flexibility reserve above the demands of your particular sport.  Further flexibility may actually hinder athletic technique by ‘dispersing’ the acting forces on the body.  For example, a very flexible spine may cause a loss of force along the kinetic chain when jumping, or performing a shot put.  Increasing muscle length may also alter the length where it is able to generate the most force (usually midrange), which is not necessarily a good thing for sports that require a lot of power in a small range of motion.  Although every athlete and layperson can benefit from regular stretching, there are situations where excessive flexibility can hinder performance.

Conclusion

The most important concepts to take from this introduction article of the concepts behind Functional Range Conditioning™ are as follows:

  • Improvements in flexibility are mostly the result of a change in the function of the central nervous system and not as a result of a change in the actual structure of muscle tissue.
  • Research demonstrates that the benefits of flexibility training also includes “stretch induced hypertrophy” which refers to an increase in muscle size leading to increased strength.
  • Research studies have not found that pre-exercise stretching prevents injury.  In fact, it would theoretically increase the chance of injury by temporarily reducing the muscles ability to absorb force.
  • Research suggests that stretching between bouts of exercise likely reduces the chances of injury during exercise.
  • More important than simple flexibility is end range control/strength.  Improvements in flexibility in the absence of end range strength produces “useless flexibility” said ranges will be unattainable during functional movements.  Future posts will further examine the concept of “useless flexibility” as well as introduce Functional Range Conditioning™, a method of training that combines stretching with strengthening in order to quickly improve flexibility while also creating “flexible strength.”

References:

  1. Magnusson SP, Simonsen EB, Aagaard P, Kjaer M.  Biomechanical responses to repeated stretches in human hamstring muscle in vivo.  Am J Sports Med 1996;24:622-628.
  2. Magnusson SP, Aagaard P, Larsson B, Kjaer M.  Passive energy absorption by human muscle-tendon unit is unaffected by increase in intramuscular temperature.  J Appl Physiol 2000;88:1215-1220.
  3. Magnusson SP, Simonsen EB, Aagaard P, Soukka A, Kjaer M.  A mechanism for altered flexibility in human skeletal muscle.  J Physiol (Lond) 1996;497:291-298.
  4. Halbertsma JPK, Goeken LNH.  Stretching exercises: effect on passive extensibility and stiffness in short hamstrings of healthy subjects.  Arch Phys Med Rehabil 1994;75:976-981.
  5. Goldspink DF, Cox VM, Smith SK, Eaves LA, Osbaldeston NJ, Lee DM, et al.  Muscle growth in response to mechanical stimuli.  Am J Physio 1995;268:E288-E297.
  6. Always SE.  Force and contractile characteristics after stretch overload in quail anterior latissimus dorsi muscle.  J Appl Physiol 1994;77:135-141.
  7. Yang S, Alnaqeeb M, Simpson H, Goldspink G.  Changes in muscle fibre type, muscle mass and IGF-I gene expression in rabbit skeletal muscle subjected to stretch.  J Anat 1997;190:613-622.
  8. Shrier I.  Does stretching improve performance?  A systematic and critical review of the literature.  Clin J Sport Med 2004;14:267-273.
  9. Thacker SB, Gilchrist J, Stroup DF, Kimsey CD.  The impact of stretching on sports injury risk: a systematic review of the literature.  Med Sci Sports Exerc 2004;36:371-378.
  10. Weldon SM, Hill RH.  The efficacy of stretching for prevention of exercise-related injury: a systematic review of the literature.  Man Ther 2003;8:141-150.
  11. Herbert RD, Gabriel M.  Effects of stretching before and after exercising on muscle soreness and risk of injury: systematic review.  Br Med J 2002;325:468.
  12. Amako M, Oda T, Masuoka K, Yokoi H, Campisi P.  Effect of static stretching on prevention of injuries for military recruits.  Mil Med 2003;168:442-446.
  13. Malliaropoulos N, Papalexandris S, Papalada A, Papacostas E.  The role of stretching in rehabilitation of hamstring injuries: 80 athletes follow-up.  Med Sci Sports Exerc 2004;36:756-759.
  14. Garrett WE Jr.  Muscle strain injuries: clinical and basic aspects.  Med Sci Sports Exerc 1990;22:436-443.
  15. Safran MR, Seaber AV, Garrett WE.  Warm-up and muscular injury prevention: an update.  Sports Med 1989;8:239-249.
  16. Shellock FG, Prentice WE.  Warming-up and stretching for improved physical performance and prevention of sports-related injuries.  Sports Med 1985;2:267-278.
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One Comment leave one →
  1. January 24, 2012 7:25 pm

    Great article – thank you!

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