The back extension is a simple move. You are bending and straightening your spine by consciously articulating every joint that makes up the spine. You are making an effort to engage the muscles around the back to get the job done. 

Think of it as a flipping a squat or hinge. Ordinarily your hips and knees are bending and straightening. Your back maintains a steady extended position (isometric). 

In a back extension, your legs are steady and maintaining tension without bending or straightening. Your spine gets its dose of bending and straightening. 

We are oversold on isometrics as the key to then health and strength of our back. When in reality like every other muscle group, the spine needs to bend and straighten and rotate too. 

So that’s what we do at our gym.

And you’ll notice in the video, we have two machines to perform the same movement. 

But what changing the angle does is change which portion of the exercise becomes harder. 

In the 45 degree back extension the majority of the effort is being done from the bottom through 60-70 percent up. The top isn’t challenging. 

In the 180 degree back extension. The starting and finishing positions are quite challenging. And the bottom half is relatively ‘easy’ compared to the 45 degree back extension.

The same rule applies for crunches, side bends and other exercises you can perform on this unit. 

And given the fickle nature of how tolerant people are to bending and straightening their backs (especially when they are hurt), having this option gives us more choices to build confidence and tolerance for harder positions and more complex movement.