LET’S TALK MECHANICAL ADVANTAGE

So what exactly is mechanical advantage?

Mechanical advantage is the ratio of the moment arm through which an applied force acts to that through which a resistive force acts.

Now, if you are thinking what in the world does that mean, you are not alone. In simpler terms, it is essentially how much or how little force your muscles need to generate in order to lift a weight.

Therefore, although you might be lifting a 25lb dumbbell, depending on the lever system in your body, you might actually need to apply more (or less) muscular force than 25lbs to lift that weight.

LET’S LOOK AT SOME EXAMPLES…

If the ball in the picture above weighs 25lbs, because it is very close to the fulcrum, and the applied force (FA), which would be your muscles, is much further away, you actually would need less than 25lbs of force to lift that ball due to a significant mechanical advantage.

This is true for all lever systems in which the muscle is further away from the joint in our bodies. A great example of this is the calf raise. The calf muscles are always further away from the fulcrum (i.e., the ball of your foot) than your center of mass (i.e., the resistive force) which results in a mechanical advantage. Hence, why you can easily do a standing calf raise with a significantly greater amount of weight than just your own body weight.

However, what happens when we perform a seated calf raise? We have to use a substantially lighter weight. Why?

Because now the weight is much further away from the ball of our foot (i.e., the fulcrum) compared to our calves. This then creates a mechanical disadvantage making us have to supply a significantly greater force by our muscles to lift the same weight.

Now I am going to assume you have never thought about mechanical advantage when lifting in the past. And while I am not saying you should over complicate things and breakdown every movement, it is important to understand movement mechanics because while in everyday activities we want to make things as easy as possible, we actually want the opposite during resistance training. The purpose of resistance training is to stress the muscles, make then produce as much force as possible; meaning we want them to be at the biggest disadvantage as possible. And if we can stress the muscles more and more over time, growth will occur.

Let’s look at the standard bicep curl to bring this all together. When we keep our shoulder and elbow stable, we are creating the maximum amount of stress on the bicep as possible. By increasing mechanical disadvantage, we are requiring more than 25lbs of force to lift that 25lb dumbbell.

However, go to most gyms, and this is not what you see. At almost any moment, look at the DB section and you will likely find someone swinging up those 50lb dumbbells. And while this might look impressive (FYI it isn’t impressive) they are actually likely getting less productive work because as they swing their elbow out, it essentially is bringing the joint closer to the dumbbell in order to increase mechanical advantage and thus requiring less force of the biceps.

SO WHAT DOES THIS ALL MEAN FOR YOU?

When lifting, make sure you know what joint(s) and muscles are being targeted.

Understand the movement pattern desired for each movement – don’t just start lifting the weight any way you desire.

For all movements (especially isolation movements), keep excessive movement to a minimum. Feeling the exercise in more muscle groups does not mean it is better.

Try to make the muscle work as hard as possible to create: