Synovial Joints

Image courtesy of pages.uoregon.edu

Over the past week I've posted two posts (Post 1, Post 2) on the feet that mention synovial joints, so I wanted to take the time to dig a little deeper into what a synovial joint is.

First, there appears to be three different types or classes of joints in the human body--synovial joints, fibrous joints, and cartilaginous joints (p 25-26)*.  Synovial joints are of particular interest to me because that is the classification of joint of nearly all of the limbs and the one that is used for locomotion (p 26)*.

So these synovial joints have some pretty cool distinguishing features about them.  There is this joint capsule that brings the joint together and is made up of fibrous layer which has a synovial membrane lining it (p 25)*.  This synovial membrane does three things:  1) it secretes synovial fluid, which lubricates the joint; 2) it closes off the joint cavity, which contains a small space for the synovial fluid to go once it is secreted by the synovial membrane; and 3) it covers all of the internal surfaces of the joint except for where the two bones articulate with one another.  Those areas are covered with articular cartilage (p 25)*.

There are also these periosteum and perichondrium tissues that surround the bones (periosteum) and the cartilage (perichondrium) of the joint, serving to provide nutrients for these areas as well as serve as areas for new formation of bone and cartilage (p 25)*.  Additionally, synovial joints usually appear to have some type of ligamentous material reinforcing them, which are either completely separate tissues (called extrinsic accessory ligaments) or are where part of the joint capsule thickens (called intrinsic accessory ligaments) (p 26)*.

Of the many synovial joints in the human body, Clinically Oriented Anatomy groups them into six classifications based off of how they articulate and the type of movement allowed.  The first type is a plane joint such as the acromioclavicular joint.  The second type is called a hinge joint such as the elbow joint.  The third classification of synovial joints is called a saddle joint and the fourth is called a condyloid joint.  The carpometacarpal joint is an example of the former and the metacarpophalangeal joints are an example of the latter.  The fifth classification is more easily recognizable with it being a ball and socket joint such as the hip, while the sixth is a little more obscure being a pivot joint such as the median atlantoaxial joint (p 27-28)*.

Interestingly, Clinically Oriented Anatomy does not mention hyaline cartilage in reference to synovial joints at all, instead referring to articular cartilage but highlighting hyaline cartilage by name as a characteristic of primary cartilaginous joints, an example of which is given as the hip or coxyfemoral joint (p 26)*.  So, according to this source, joints can fall in multiple categories.

Finally, just a few words on the nerve and blood supply of synovial joints.  It appears that the joint capsule, specifically the synovial membrane, is both highly innervated and highly vascularized, containing articular nerves and articular veins (p 28)*.

Your body.  Your training.

Want to use this arti­cle in your blog, newslet­ter, or other plat­form? You may, but be sure to include all of the bio­graph­i­cal infor­ma­tion found in the yellow box below!

*Moore, Keith L; Dalley, Arthur F; Agur, Anne M. R. Clinically Oriented Anatomy Sixth Edition.  Wolters Kluwer; Lippincott Williams & Wilkins. 2010.

Why Take RTS?

Image courtesy of salvationarmy.org

I was reading through online forums earlier this week and I came across one in which the author had heard of RTS and had looked at information online about the courses but wasn't able to understand what made this series of courses different than, say, the biomechanics course he took as an undergrad.  This seems to be a fairly common response when people have asked me what I am going to Oklahoma City for and I have given them an abbreviated answer.  When I saw this forum post I got excited because I once again had the opportunity to answer this question but I didn't have to answer on the spot and I could take a little time to explore why, to me, the RTS courses are different than any other of a similar nature.

What follows is how I responded in that moment.  I could certainly go back and edit some of the verbiage or add additional viewpoints or thoughts, but for the sake of preserving an uninterrupted stream of consciousness, I haven't altered what I initially wrote, although there are certainly MANY more points that could be made.

"Okay, so what makes RTS different than other courses? A great analogy that is used in class is that of soup. So let's say you want soup. You can go to the store and pick out a can from the selection and there, you have soup. Or maybe you have a friend who likes to make soup so they help you make some because you don't feel comfortable going off on your own and making it. Then let's say after a while you do like to go off on your own and follow recipes out of cookbooks, and from that maybe you start experimenting with your own combinations of ingredients, kind of tossing things in that seem like they may go together. A while longer of that and now you have created some soups that are your own and that are pretty tasty. Tasty to you, at least. But what if a friend is allergic to some of your ingredients so you cannot share your soup with them? Or what if your soup is only palatable to you and a few others? Your ability to alter your soup and create a dish that isn't threatening to your friend's health and tastes good to them is rather limited due to how you learned and understand soup.

Compare this to a master chef who understands the intricacies of all the possible ingredients and how they interact with one another and the flavors and textures and scents they produce when certain portions of each are mixed together. This knowledge base would allow you to create a different soup for every single person that is both extremely tasty to that person as well as meets their nutritional needs.

Substitute exercise for soup, and when you really start to grasp the principles that are presented and explored in depth in RTS, that's when you start to become a master chef. Because of these principles, you can take any person and, if you know their medical history, you can appropriately assess their abilities and apply force and progress them in a manner that doesn't cause pain or degradation of their structure and actually allows them to enjoy the experience and feel good while they are exercising.

Image courtesy of shape.com

Creating experiences is a huge part of RTS, as well. From how you construct a specific exercise for them to how you cue them throughout the exercise, you can take a leg extension machine and put three different people on it with three different knee conditions and make them each feel twenty different sensations and provide them with infinitely more experiences with this one piece of equipment performing this one motion than if they were to do it on their own or be instructed by somebody who didn't understand all of the variables that are at their disposal.

Additionally, you develop the ability to objectively evaluate equipment and exercises for what they really are and what they are actually doing to the body instead of getting caught up in the hype or magic that seems to predominate much of today's exercise world.

So that's just kind of the tip of the iceberg with RTS. A huge thing to point out is that while the physics, mechanics, and anatomy may not be any different than what you were presented with in school, the viewpoints, thought processes, discussion, and exploration of these topics are almost certainly going to be different. To illustrate why this is so hugely important, consider the following quote,

"Quantum physics shows us that when you change the way you look at things, the things you look at change." - Dr. Wayne Dyer

Relate this back to the soup example. When you were creating your own soup, you had the exact same access to ingredients and cooking utensils as the master chef, but the difference was, to that master chef, those ingredients and how to go about preparing them with the utensils carried a COMPLETELY different meaning than to the average soup maker. The master chef could see all of possibilities that were before her while the average soup maker could really only provide others with what they had already tasted and made and approved of themselves.

This is where probably one of the biggest components of RTS comes in, and that is the application of the knowledge covered in the classroom to actual exercise. I cannot speak to the ability of undergraduate courses to prepare students to effectively apply what they have learned to any situation they come in contact with, but I feel that is certainly a strong suit of the RTS courses.

If you have taken or are taking the RTS courses, what makes them different to you?  If you haven't, why not?
Your body.  Your training.

Want to use this arti­cle in your blog, newslet­ter, or other plat­form?  You can, but be sure to include all of the bio­graph­i­cal infor­ma­tion found in the yel­low box below!

Flyes vs. Presses: A Joint Perspective

Let me ask you a question: What is the main difference between a dumbbell fly on a flat bench and a dumbbell press on a flat bench?

Now, there are a multitude of directions you could go with your answer, so for some semblance of direction we will say this question is to be looked at from the perspective of the joints involved in creating the respective motions.

Okay, that doesn't exactly narrow it down, either, because it could be correctly argued that every joint in the body is involved in both motions, but some joints have motion occurring at the joint while at other joints there isn't any motion occurring. SO, for sake of this post, I will once again narrow down the focus of my original question to say, "What is the main difference between a dumbbell fly on a flat bench and a dumbbell press on a flat bench from the prospective of the joints involved, with limiting the discussion to joints where there is motion at said joint?"

Longer than I had originally intended, but alas, hopefully my idea has been conveyed appropriately. So how would you answer this?

At first glance, almost everybody is going to cite the difference in elbow flexion and extension between the motions, and I would agree that is the main difference. Now, what would you say the second biggest difference is?

Here's the reason I bring this up: When looking at movements, don't just take into consideration the muscles that are allegedly working during said movement; look at the stress placed on the joints, as well. When you perform a flye on a flat bench, there is a tremendous about of stress placed on the gleno-humeral (GH) joint of the shoulder. The reason for the increased stress on this joint is because the moment arm of the applied force is significantly longer when the humerus is at 90 degrees of abduction and the elbow is in a position of 0 degrees of flexion (as is the case during a flye on a flat bench) than when the humerus is horizontally abducted and the elbow is flexed at approximately 90 degrees (as is the case during a dumbbell press on a flat bench).**

**Side note: An appropriate precursor to this post probably would have been along the lines of defining a moment arm and defining what abduction is in relation to the humerus. If you are confused, Google it, or drop a comment below and I'll make sure to post on these subjects in the future.

So, how much greater is the stress on the GH in this position? Well, this is going to vary completely on the individual. BUT, for the sake of this post, let's say the three divisions of pec major attach 1" away from the axis (the GH, in this case). We'll say the person's humerus is 10" long (the distance between GH and elbow) and the distance between the elbow and where the weight (length of radius and ulna plus some--RU+) is in their hand is 10". That means that at a position of 90 degrees of humeral abduction and 0 degrees of elbow flexion (flye) the length of that lever is 20", whereas at a position of 90 degrees of humeral abduction and 90 degrees elbow flexion (press) the length of that level is 10". There is also a component of external rotation, among other things, in both of these scenarios.

Let me stop here and say that this is an INCREDIBLY simplified model, with many, many assumptions, not the least of which is that the person in question can both achieve enough elbow extension to allow for a full ten inches of distance between the weight in their hand and the elbow joint as well as actually be in this much elbow extension at the bottom of their flye rep. Also, I would like to say that for this example we will not be taking into consideration the stress upon the joint at all of the infinite number of positions throughout the flye and press motions, nor will we be considering what is actually happening during the motions. I will simply (or not) be explaining the scenario from the two positions described--90 degrees of humeral abduction with 1) 0 degrees of elbow flexion and 2) 90 degrees of elbow flexion.

Okay, back to the numbers. First, let's look at the press.

At a position of 90 degrees of humeral abduction and 90 degrees of elbow flexion, there is a moment of resistance that is 10" long. The moment of effort is, as stated before, 1". Assuming the person is holding a 5-pound dumbbell, the fibers that horizontally adduct the humerus will have to generate 50 inch-pounds of force to horizontally adduct the humerus from that position. The 45-pound difference between the weight that is being held and the force that has to be generated to move it is what is placed on the GH.

Now, looking at the flye.

At a position of 90 degrees of humeral abduction and 0 degrees of elbow flexion, there is a moment of resistance that is 20" long. We still have the same 1" moment of effort and are using the same 5-pound dumbbell, BUT there will have to be 100 inch-pounds of force generated to horizontally adduct the humerus from this position. This will result in an excess of 95 pounds of force being placed upon the GH, over twice as much as with the press.

One could argue that you use less weight with a flye than with a press, so that might make the stress on the GH equal. True, but once we talk about actually moving the weight there are too many other variables to take into consideration because now we are talking about a moving resistance instead of a static resistance so inertia and other variables will come into play.

What is my point of writing this? It is not to say flyes are bad, or even that presses are superior or something along those lines. Quite frankly, the hierarchy of good and bad regarding different exercises is 100% based on the limitations of the individual performing them and his or her goals, so I could not logically talk about this in a blog post. My reason for writing this is to get you to think in a different light about the movements you are performing and the toll that they may or may not be taking on your body.

An Educated Approach To Training

If we all can begin to take a more educated approach to our training, one in which we actually understand what we are doing, we can begin to truly manipulate these variables to our advantage to create positive adaptations in a safe and effective manner instead of randomly flinging our bodies and weights in different directions and assuming the intended outcome will be the actual outcome.

Also, I am by no means an expert on the terminology I used in this post today, and this way of viewing movement is very new to my thought process. If you are and notice I have messed something up in my verbiage or explanation, please let me know via the comment section or e-mail at charlie@selfmadefitness.com. Many thanks!

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Get big or die tryin'.

Charlie Cates, CSCS

Self Made®, Owner and Founder

Charlie Cates is a strength and conditioning specialist and the owner and founder of Self Made® (http://selfmadefitness.com/) in Chicago, IL. He has worked with competitive and everyday athletes of all ages and ability levels, from 9-year-old kids to NFL MVP’s. He can be reached via e-mail at charlie@selfmadefitness.com.

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