Showing posts with label joints. Show all posts
Showing posts with label joints. Show all posts

Thursday, August 30, 2012

What Is RTS?

Image courtesy of kcfitness.com
"There is no way to understand exercise, no way for this industry to move forward, until we fully comprehend that exercise is all about forces and joints!  Everything else exists and occurs to support the interaction between these two."--RTS

Saturday, June 2, 2012

Moment Arms

Image courtesy of chegg.com
**While all of this information can be found throughout various books and other texts, my experiences with the information have all come through different RTS lectures, study groups, workshops, courses, and discussions.  It is because of these experiences that I am able to write this post, in addition to many of my past and future posts.**

In Monday's post I wrote about the importance of seeing moment arms as they relate to joints and tissue when discussing joint motion during exercise, but I never actually defined what a moment arm is.  So, today I will give you a very brief overview and introduction to moment arms.
Image courtesy of http://en.wikipedia.org/
A moment arm is defined as the shortest distance from the axis of motion to the line of force that is perpendicular to the line of force and runs through the axis.  It is the measure of a force's ability to produce rotation of a lever around an axis, i.e. the greater or longer the moment arm the greater the force's ability to rotate a lever around an axis.

If we are going to divulge into moment arms then I should also explain what a line of force is.  A line of force is 1) a line, that is 2) created by a force (internal--mainly muscles, although other tissues can/may play a role; external--machines, free weights, tubes, bands, etc).  Remember, a line is infinitely long and goes in both directions, meaning the line of force created by gravity goes both up and down even though the vector will only go straight down.

One of the main reasons for knowing the length of a moment arm is to be able to calculate torque, which equals the force times the length of the moment arm an is a measure of rotational force.  This would be considered the resistance for that weight in that one position.  Once the weight starts to move you need to not only recalculate any changes in the length of the moment arm but also take into consideration any changes in the force, as well, which equals mass times acceleration.  That is beyond the scope of this post, though.

So, when looking at moment arms in relation to joints in the body you need to find the axis of the joint in the desired position, the line of force, and then draw a line that is perpendicular to the line of force and have it intersect the axis.  An example of the moment arm (rough estimate) to the coxofemoral joint (hip) at the starting position of a deadlift can be seen below:
Image courtesy of http://colinhaller.blogspot.com
Actually, you would need to lower the red line until it actually intersected with the axis of the coxofemoral joint, but hopefully the visual gives you a slight understanding of how moment arms can be found relative to the body.

Now, what if there is no moment arm to the joint, meaning the line of force goes directly through the axis of the joint?  A basic but crude/not completely accurate example of this would be at the top of a seated dumbbell shoulder press.
Image courtesy of broncofit.blogspot.com
In the picture on the right you can see that if you were to draw a straight line going up and down (ceiling to floor) through the middle of the handle of each respective dumbbell, that line would almost go right through each  respective axis of the glenohumeral (shoulder) joint.  This means that in this position there is almost no torque on that joint.  There are still joint forces, but there is almost no force that is creating rotation around the axis of that joint.
Compare that to this video:
 
Here we also have a shoulder press movement, but a completely different moment arm to the glenohumeral joint (GH).  Instead of there being a moment challenging humeral abduction et. al, there is now a moment challenging predominantly the external rotation capabilities of the GH, even though the motion is the same.  Can you see how the two moment arms are different?
Drop a comment below if I need to still clear some things up.

Your Body.  Your Training.

Get big or die tryin'.

Charlie Cates, MATs, CSCS
Self Made®, Owner and Founder

Charlie Cates is a Muscle Activation Techniques® specialist and a strength and conditioning specialist.  He is 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.
This article may be reproduced with biographical information intact.

Tuesday, April 24, 2012

Exercise Intensity and Your Joints

Image courtesy of http://recoveryourstride.blogspot.com
It is a well-known law of physics that force equals mass times acceleration (F=ma), but what does that have to do with your joints and your exercise?  A huge trend in the fitness industry right now is training at a very high intensity both relative to how fast you normally move throughout your day as well as how fast your body is physically able to move at that given point in time.  Whether it is doing plyos in P90X and Insanity, trying to "train like the pro's", or just simply lifting weights without regard to tempo, people's bodies may be trying to handle forces that they just are not ready for.

I say "may" because some people may in fact be very well-prepared to handle such forces and there may be specific times and reasons in which you would want to impose those forces on them, but in reality those people and times are probably few and far between.

In regard to forces and movement, there are internal forces that are generated by the muscles and external forces that are placed on the body from a multitude of sources including gravity and external forms of resistance (bands, weights, tubes, etc).  Without getting too deep into the physics, the result of these forces, in terms of the joint, is additional forces within the joint, known as joint forces.  These joint forces, if not appropriately applied and progressed, can have detrimental long-term effects on the structure of individual, possibly leading to conditions such as arthritis.

The key phrase from above is "appropriately applied and progressed".  If you have the physical capability to handle such forces, you have a lot more freedom regarding what you can do without as high of a risk of chronic pain and/or dysfunction.  The vast majority, however, do not, and therefore it has to be questioned whether programs which require such high forces to be generated and applied are actually doing your body any good in the long term.
Peter could definitely burn more calories by training at high intensities, but what is it doing to his structure?
Looking at the physics, it seems that in order to decrease the quantity of joint forces, there has to be a decrease in both in the internal and external forces, in particular the external forces as the internal forces seem to be a response to the external forces placed upon the body.  This can be done by either decreasing the mass that is moved or the amount of acceleration used to move the mass.  For the sake of this post, I would like to expand on the latter.

Next time you lift or train, I would like you to consider how fast you are moving.  This is particularly useful when moving forms of external resistance, such as lifting weights.  For the athletes out there who think they have to lift fast in order to move fast, I would say this:  First, if lifting is your only form of movement training, you are in trouble.  I am all for moving fast when it is appropriate, so consider other forms of movement training in which you are not overcoming an external load, i.e. only using your body weight.  Second, far and away the easiest means by which to completely screw up your season and/or career is to get injured.  While arthritis is not something that develops in a year, I am not sure of an acute injury that isn't caused by the body being unable to handle an excessive amount of force while in a specific position.  While you can certainly build up this threshold, this will only be effective if, once again, the forces are appropriately applied and progressed.

For the non-competitive athlete or for those who are not training for performance, I really question whether it makes sense to ever train at high speeds unless you have been properly prepared to do so.  The reality, though, is that most people sit all day and, when they do move, move relatively slow.  Even if you were at one time able to perform at a high level, if you haven't been doing that for even just a year or so, there has to be some time to build yourself back up before attempting to move like you once did.  Understand that being physically able to do it and being physically able to handle it are two different things.  A lot of people have the ability to push themselves really hard but very few are actually prepared for it.  I realize that training at a higher intensity is a more effective form of fat loss, but know that there is a tradeoff to doing so.

Be smart about your progression and apply it appropriately.  When it comes time for you to train hard and at a high intensity, by all means do it if it is in line with your goals because if you don't you will eventually lose the ability to, but make sure your body has first earned the right to do so.

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.

This article may be reproduced with biographical information intact.

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