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Moment Arms

30
Sep

Moment Arms

We use levers every day. Rather than bore you with the definition you can find it here see also moment (physics). In layman’s terms it is a simple machine that aids in moving weight. We move weight everyday from the simplest thing like picking up a coffee cup to feed our cloudy sleep deprived bodies to complex like a 1 rep max deadlift of clean and jerk. Even the simplest tasks like standing, walking,  moving your head to look up, and other movements that we often take for granted, are perfectly designed levers

Our body is full of levers so when we have a workout routine like weightlifting it’s in our best interest to have a basic understanding on how we can get the most out of them. Consequently there are ways that we can also make our levers inefficient. On average we tend to move pretty well on our own…who wants to be average?

Starting Strength: Basic Barbell Training, 3rd Edition
by Mark Rippetoe


This is a great example of what happens when we create large moment arms the further the weight of an object gets from the fulcrum the heavier the strain is. In the squat we have two major levers the hip joint and the knee joint. 

For our purposes we are only going to be talking about a Barbell and our fulcrum which is our mid foot or center of gravity (COG). the further that a bar travels away from the COG the “heavier” the weight. The same force that we use to our advantage is also the same force that can cause a disadvantage. We are trying to create the most torque possible with our hip joint in the majority of our lifts.

 If we shift a bar forward in the bottom of the squat we have to shift the knee forward in order to maintain COG. If we shift forward we then reduce the lever arm of the major torque “engine” the posterior chain ( hip)  and end up utilizing smaller muscles to produce a high torque output (Knee). 

Ideally we would like to see an equal production of power so that both levers ( the hip and the knee) are working together to produce the equal application of torque but from my experience not everyone’s femurs and torsos are created equally. It doesn’t take a well trained eye to recognize that. So in order to squat adequately we need to find a suitable squat for everyone. With that being said if you are a competitive athlete you shouldn’t put all of your focus into one particular style of squat.

Are you interested in getting a deeper look into the reasons behind the movement ques and positions? Sign up for our 6 week weight lifting course. Space is limited!