Flywheel Training: Iso-Inertial Training. What the heck is it?

Flywheel Training: Iso-Inertial training. What the heck is it?

You may have seen our videos utilizing the Versa-Pulley; You may have seen the K-box as well. A rope goes inside a machine and then the athlete pulls back on the rope. It all seems simple, but it is not so simple. 
How does it work? I think the easiest way to understand it is to think of a yoyo. The harder you throw the yo-yo down the quicker it comes back up. A yo-yo is just a smaller version of a flywheel that is inside the Versa-pulley. Imagine a really big yo-yo.
So let’s discuss the physiology of how this works and why I like it so much for training power.
There are primarily two muscle actions in a movement when trying to generate power. The first is an eccentric (stretching of the muscle or a pre-load) and then a subsequent concentric action (shortening of the muscle) after you pre-load to produce a powerful following movement. 
The best example of this is a diver on a springboard. They approach the end of the board, then jump up and land on the end of the board to pre-load it with elastic energy so the subsequent jump off of the board launches them high into the air. This is the same idea with your body when you want to get maximum power. Think of the pre-load when you are dropping down to jump for a basketball like the diving board as it stores the elastic energy. You load up the muscle by stretching it during the pre-load and then the subsequent power produced in the opposite direction is like the springboard rebounding and launching the diver into the air. 
So how does a yo-yo have anything to do with all of this? The principle of a yo-yo is the same as how the flywheel spins, creating resistance to the user. 
Iso-inertial flywheel training is like a springboard in any range of motion. Imagine the diving board in a sideways position. The rope attached to a flywheel is like you using a diving board sideways or in any other movement angle. 
I will be discussing the advantages to this type of training more in future posts, but what I like most is the ability to measure the output of power and also determine at what velocity the athlete produces the greatest amount of power in any direction. With the Versa-Pulley I can create a pre-load in any range of motion which gives me lots of ways of training for different sports. DM me if you want to find out more.

Truth in Fitness,
Jacques DeVore, CSCS