了解动力链 Understanding The Kinetic Chain

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Understanding The Kinetic Chain  – By Dax MoyFebruary 5, 2011 By Dax Moy
In this current era of ‘functional’ training, core stability and balance-oriented training it’s easy to get carried away with learning what I call the ‘HOW’s’ of exercise.
HOW to balance on a swiss ball, HOW to integrate movement patterns and HOW to devise exercise programmes that have a high transfer into ‘real life’ situations.
After all, these are FUN elements that demonstrate a greater application of knowledge, skills and abilities to our clients. Or do they?
Interestingly, when asked, many of my students (all qualified personal trainers and therapists) had little real foundational knowledge of what makes their exercises ‘functional’ beyond “they have a carryover into real life”.
I call this a ‘lack of WHY?!’
This ‘lack of WHY’ is a ‘disease’ of almost epidemic proportions within our industry and one which, in my opinion, will keep us from ever reaching professional status if left unchecked.
Simply put, too many fitness instructors are prescribing exercise based upon the latest trends, personal preferences and outright exercise mythology.
This is like visiting your doctor and being prescribed medicine based upon ‘it works for me so let’s give it a go’. I’m sure that you wouldn’t be too impressed if this happened to you, but what about your clients?
What kind of ‘professional’ service are they receiving?
The aim of this series is to provide you with the WHY’s necessary to make your exercise prescription much more than a ‘hit and miss’ process and plant your feet firmly on the road to professionalism.
We start our journey with posture, the foundation from which our function, and ultimately all personal training is built.
What Is Posture?
According to the American academy of Orthopaedic Surgeons posture committee as far back as 1947, posture is:
‘That state of muscular and skeletal balance which protects the supporting structures of the body against injury or progressive deformity, irrespective of the attitude in which these structures are working or resting. Under such conditions the muscles will function most efficiently…’
The key to the above statement is Balance, for it is balance or it’s antagonist imbalance that appears to be one of the major influences in creating structural deformation resulting in pain.
Indeed there is much evidence to suggest that chronic imbalance can result in Postural Distortion Patterns that can perpetuate the cumulative injury cycle. This appears to make sense, especially if the kinetic chain concept is applied to the equation.
The kinetic chain is best described as a movement system consisting of myofascial (muscular),  Articular (joints) and neural (motor) components with each being dependent on the others for optimum performance, both statically and dynamically. This movement system requires precision of movement based on the alignment and mechanics of each joint as well as how these joints are recruited to create a movement pattern.
In simple terms, the movement produced at any joint in the kinetic chain directly affects the joints above and below it. Dysfunction in any one of these systems may have direct and detrimental effect on the function of its neighbours.
Clearly then, there is much to concern ourselves with when prescribing exercise and stretching programmes to our clients, as every programming decision we make will affect the systems of the kinetic chain. This is obvious of course, but have you ever stopped to think of it in this way before?
Now ‘understanding the WHY’ becomes much more important doesn’t it?
Why Do These Imbalances Occur?
Firstly, we are ALL imbalanced to some degree, even if our posture is considered optimal (we’ll talk about this later). This is because there is actually an inbuilt ideal imbalance between the muscles crossing any joint e.g. Knee extensors/flexors, plantar flexors/dorsiflexors. This is simply a reflection of the functional roles of these muscles and beyond the scope of this article.
The muscle imbalances that we must concern ourselves are those that create alignment distortions that affect structural function. These can be caused by but not limited to:
Postural Stress
Living, as we do, under the force of gravity has created a structure, which seems to have placed the ideal imbalance in favour of our extensors; after all, structure determines function.
Unfortunately, modern living creates a ‘synthetic’ environment where sitting dominates our function and as a result affects our structure.
For simplicity, it is useful to think in terms of postural stress as ‘training for posture’.
Imagine ‘training’ 16 hours/day 7 days/wk for a specific event. You’re probably going to get very good at it aren’t you? Well, most people get very good at ‘bad’ posture!
Many posture experts tend to use VladimirJanda’s ‘short and tight’ vs. ‘long and weak’ classification system (8) as a way of simplifying the processes that create and result from postural distortion and often classify muscles as ‘tonic’ and ‘phasic’.
This oversimplification tends to ignore individual differences in terms of ‘normal’ posture as well as making assumptions based purely on static posture.
When a muscle becomes facilitated (not necessarily ‘just’ short and tight) it increases in ‘tone’ and may decrease the neural drive to its antagonist. This is known as reciprocal inhibition and is a normal quality of the kinetic chain.
However,it becomes a problem when muscles that are supposed to be ‘turned off’ during a movement sequence remain ‘switched on’. This has the effect of creating a situation known as synergistic dominance, where synergists are forced to take on the role of a prime mover due to inhibition.
Pattern overload
Using our ‘training for posture’ analogy above, it becomes clear that any movement pattern repeated often enough has the potential to create strain upon the tissues creating that movement.
This may create stress patterns in the joint structure, leading to arthrokinetic inhibition where the joint itself causes inhibition of the surrounding tissues or lead to synergistic dominance as an avoidance pattern.
It is important that the stresses applied to our joints be changed regularly through changes in exercise, loads, planes and ranges as well as changes to postural alignment, if pattern overload is to be avoided.
Painful or prolonged noxious stimuli
Injury to a joint creating swelling and/or pain may activate the type 4 joint receptors (nociceptors) that are receptive to these stimuli. These receptors are capable of creating arthrokinetic inhibition in order to protect the joint from further damage.
Lack of core stability
This has been indicated as a possible cause postural distortion and pain. We all train for mobility but how many of us train for stability?
Just how much spinal flexion strength do we need in this vertically loaded body of ours?
Probably not that much! Simply stabilising the platform that our spines work off seems to improve the function most of the clients that I work with (myself included).
Other problems occur here when the tone/strength of Rectus Abdominis is greater than that of the Erector Spinae. Again, reciprocal inhibition and synergistic dominance have the opportunity to ‘take root’.
In Conclusion
Our postures are often the only clear indicators of the forces acting upon our bodies. More importantly, they illustrate our ability to cope with those forces.
A clear understanding of WHY muscular imbalance and postural distortion occur is fundamental to every exercise that you will ever prescribe.
With this knowledge of WHY, it becomes easier to see HOW, WHEN and WHERE to apply exercises and stretches to your clients in order to bring about functional and aesthetic improvement.
When, and only when, you can do this you will truly be applying personal to your training.



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