The Physics Series Volume 2: What’s my Angle?

Often when I’m dealing with clients (or even other trainers) and start talking about things like moment arms and force angles or resistance profiles I get a blank stare.  I understand that because I’m a geek and like to learn about things like this, just like I would give someone a blank stare if they started telling me about their ’68 Ford and how they replaced the carburetor.  Different strokes for different folks.

So when I’m working with clients and start adjusting things often I get asked why I’m doing it.  Something as simple as changing an angle during a movement can provide a totally different exercise experience not only for the person involved, but more importantly for the muscles and what you are trying to do to them.  A change as insignificant as 10 degrees in the knee during a knee extension depending on the position of the person’s hips can change the amount that a muscle is getting stimulated in ways that you might not think.  I’m not going to get into details, but if you want to take a look at THIS study go ahead as an example of what I’m talking about.  If you’re really keen I can direct you to about a few dozen more covering similar topics.  Another example when dealing with shoulders is that at a certain angle of shoulder abduction (like a lateral raise) the deltoid isn’t working as the primary mover, and then all of a sudden it is.

For our purposes we can call an angle as the measure of a rotation (or an amount of rotation) around a fixed surface – that being your knee, elbow, or finger joint.  In the strength work we take this to mean what angle one joint is achieving most often.  For example, “going to parallel” generally means that the angle of the thigh relative to the floor is parallel, but some people also take this as achieving 90 degrees in the knee joint.

So here’s the major question that most people are asking right now – why the heck does this matter in my exercise program?

I have clients ask me all of the time how they can change up their workouts, and this is one of the simplest ways to change a fundamental movement pattern and make it do something just a little bit different to the joints in question.  In RTS we call this “rotating the tires”.  For example, doing a flat bench press, or a 45 degree incline press stimulate the shoulder joint (and a few others) in different ways.  A pull down from straight above is different than a pull from in front of you.  All of the muscles that cross the joints are still moving and being stressed – just in different ways.

Angle also can contribute a lot into how much force is required to move an object.  Example – bicep curl.  When a curl is at 90 degrees the force in question on the bicep muscle is potentially twice as much as it is when the elbow is at 30 degrees (towards the end of the movement).  This also has to do with how far the weight is away from the joint in question like I discussed in my previous article about distance.  Suddenly a ten pound weight is now a twenty pound weight and can start to cause a problem for the person moving it or put more force into their joint than it can handle, causing tendon and ligament damage.

With something as complex as a back loaded squat, there are many angles in question.  The ankle, knee and hip joint all have to move together along with achieving a certain angle in the back, the feet and legs in order to provide not only safety but the ability to provide force along a chain that makes sure the muscles are being used to their maximum capacity.  The ability to maintain an even hip and knee angle is essential for deep squatting, and then if the whole chain is limited by the ankle joint it will throw everything off and you won’t be able to go as deep, therefore not providing as much stimulation or even tracking into injury.  There is a reason that people who have heavy loads on their back often do quarter range squats – because they simply can’t create the force to move the weight if they are at a certain angle.  Here’s an illustration:

Better squat angle.

Better squat angle.

Here's a restricted squat angle.

Here’s a restricted squat angle.

Simple things like achieving a larger range of motion during a movement can actually alter your exercise in a very significant way.  One of the reasons that I’m all over my clients during workouts is because there is simple intention behind every exercise, and if it is performed differently, or with sloppy form then we can’t accomplish the goal for that particular exercise in the way it has been designed.  This simple squat illustration can also show us where a person might be restricted due to something else and allow us to alter the current workout to help, not hinder progress.  Imagine in each diagram what the different forces might be on the ankle, knee, hip and spinal joints.

A person’s physical structure can also have a lot to do with this.  A person with longer levers like a basketball player would have a totally different movement path than someone a foot shorter and much wider like a powerlifter.  If my femur is longer then the whole movement changes again and I may not be able to achieve the perfect angle.  There is nothing wrong with that, but it does need to be considered when designing an exercise program.  Would an exercise like a squat be as “good” for someone who can’t achieve the depth they need to get to in order to stimulate what you are trying to stimulate?  Or would something else maybe be safer and more effective?

So here’s an idea – during your next workout, change a couple of angles of movement (while reducing load in order to be safe) and see if it doesn’t stimulate your body in an entirely different way.  I can almost guarantee that your body will thank you for the rotation of the tires you are giving it, and your experience will be much more fulfilling.  Feel free to report back to me and let me know how it went.

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