Maintaining Back Leg Load - Back Leg Vertical Z Force

Featuring Justin Stone, one of the most in demand private instructors in the country. Justin teaches approximately 3,000 players from across the United States each year and teaches hitting, defense, pitching, and catching at Elite.

Back leg Z force measures the efficiency of your back leg load. Z force means vertical force and this is pressure directly into the ground. So think of myself taking a line from the ceiling down into the ground and we have a vertical line that is your vertical Z force. The effectiveness of our back leg load means this: I'm trying to get players to get 100 percent of their body weight into their back leg load before the forward advance. We want to hold that force as I work out into my positive move.

Now, generally, players will hold that forward advance and flat line it and this is what you're looking for on the blue metric in our Z force axis. Holding that force for a third of the way into the forward advance before you see it to start to trail off. Now, generally, when you're doing this analysis, you're going to see players create anywhere from 90 to 100 percent in their back leg load. And you think, well, 90 to 100 percent isn't that much different. But there's a drastic difference from a player that's ninety-two percent of body weight in their back leg load versus 100 percent in their back leg.

So just a couple percentile indifference does mean a lot. When we get to that 98 to 100 percent of back leg force in body weight, this is what I consider proficient. I want to hold that force in my forward advance so I know I'm controlling the body in a slow, controlled tempo. This is what's helping us in our adjustability as well as being able to take that force from the back leg and during rotation, transferring all of that energy into my front leg for greater angular speeds.

We also know that when players trail off early and they don't get the flat line on our blue graph and you'll see more of a rolling hill where it trails off immediately, these are players that are pushing away from their back side. And now we have a player that's falling into their front leg instead of holding a controlled advance where my body is gaining ground, but I'm still staying anchored to the ground. They're pushing away from their back shoot and now my body is out of control. This is something that has to be trained.

And you can train this in more of a dry setting. If the brain isn't comfortable of working out in dynamic balance, controlling one's body on one leg, then it's always going to have a sensation of falling into the front side. Just telling a player, ‘hey, stay in your backside’ isn't necessarily going to change this metric. What we have to do is get them comfortable in dynamic balance, which means comfortable on one leg for an extended period of time. We can do this in a dry setting of just working, ‘can I hold that flat line?’ - 98 or 100 percent of my body weight during my forward advance without a bat in my hand and without a ball in front of me.

Once a player is able to achieve that, they've achieved dynamic balance. And what this allows us to do is control the body in an efficient manner with good tempo, which is going to lead to better angular speeds and energy transfer in our kinetic sequencing.

Watch full video here: https://youtu.be/dpflleaUsHY

About the Author

Cameron Hobson is a mechanical engineer by training with a background as a professional sports athlete. He helps people improve human performance through the development of modern technology products.

Featuring: Justin Stone is one of the most in-demand private instructors in the country.  Justin teaches approximately 3,000 players from across the United States each year and teaches hitting, defense, pitching, and catching at Elite. Justin was a two sport Division 1 athlete in college at Eastern Illinois University as a starter in both baseball and football.