The Exercise Insight That Changed Everything

Understanding this concept completely changed my understanding of exercise.

Very few insights on their own (in any domain) alter the lens through which you view an entire topic.

And I’m not talking about some fancy, “magic pill” concept you learn about one day, apply for the next couple of days, and forget about the following week.

I’m talking about a first-principles concept that applies to every exercise you can do in the gym - be it a deadlift, a curl, a leg press, or anything else.

What is it?

The concept of an arc.

What’s an arc?

And what does it have to do with training?

An arc is a semi-circle.

It looks like this:

Many of you probably already know this.

And many of you are probably thinking… “Ben, how can something so simple be so important”?.

Exercise is defined as human motion with added resistance (and not the other way around).

Although force and resistance are important to understand, we cannot fully grasp exercise without first recognizing how humans move.

Humans move through joints.

Joints are the connections between bones, and many joints are structured so that motion between bones occurs through an arc.

Take the example of a traditional dumbbell biceps curl.

Below is a photo of two versions of me (stacked on top of one another) doing a curl - one representing a more elbow-bent position and another representing a more elbow-straight position.

Superimposed on top of these photos is my hand's path to get from point A to B: an arc!

This presents powerful implications insofar as the execution of a curl is concerned.

Why?

At the “bottom” of the motion, the direction that my hand is going to travel is directly forward, away from me.

But, at the “top” of the motion, the direction that my hand is traveling is 90º from the initial direction, up toward the ceiling:

At the “bottom”, one should think about the hand moving “forward”, and at the top, one should think about the hand moving “upward” and eventually “backward” towards the biceps.

As a rule of thumb, it’s helpful to remember that the direction of motion of a segment that’s moving around a single pivot point is always 90º from that segment.

In this case, the relevant lever is the forearm, and so the direction of motion is drawn 90º from it (represented by the red arrows).

Because of this, a single cue may not be sufficient to properly execute the entire motion.

For a beginner lifter, it is potentially beneficial to reduce the range of motion to account for the range that they can confidently control without the rest of their body moving.

For someone capable of understanding the above concepts, it would be wise to first cue the hand “away” from the body and then “up and back” toward the body.

Without an awareness of this concept, many people begin with the idea of moving the hand “forward”, but don’t recognize that the direction of motion of the forearm segment changes 90º (or more) by the time you reach full elbow bending (individuals that have more elbow range into flexion will need to shove the hand directly backward toward the body in the end-range of the squeeze).

This often leads to poor execution, because the elbow is incapable of continuing to move the hand “forward” past a certain point.

Only the shoulder can continue to move the hand forward, which is part of the reason why you often see people’s shoulders moving all over the place as they curl.

This applies to all motions in the gym, even motions wherein the moving joints themselves don’t create an arc.

Look at the facet joints of the spine, which slide on top of one another, rather than creating rotation (like the elbow would):

Even though these joints “slide” and don’t create a clear arc as the elbow does to the forearm, the gross motion of these joints creates an arc in the trunk.

Check out this side-crunch variation, where my spine as a whole moves in an arc:

Note how, just like in a traditional curl, the direction of motion changes 90º from the bottom to the top of the motion (represented by the green arrows).

And this change in direction requires you to alter the direction that you intend to move.

If you do not cue yourself according to an arc, it’s much more likely that you’re going to execute a motion poorly, performing it with muscles that you do not intend to target and motion you do not intend to create.

Understanding this concept of the arc will change the game for you - I know it has for me and many of the clients, coaches, and trainers I’ve helped along the way.

When you can see the arcs of motion in one exercise, you’ll see them everywhere.

Cuing exercise becomes far less complicated when you understand this, and properly executing motion becomes far more seamless as a consequence.

If you liked this and want to learn more about arcs, check out my online course, which has an entire section on basic physics - with more than an hour of content JUST dedicated to understanding arcs of motion.

I hope this helps.

-Ben

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