Engaging the Lower Half to Create Power… Ground Reaction Forces – Part 2

By Nunzio Signore (BA, CSCS, CPT, NASM, FMS)

In Part 1 of this series (click here), we talked about the importance of loading the lower half to help avoid a “quad dominant” delivery, some of the mechanical disconnects associated with quad dominance and certain things we can do to help get that ever elusive hip hinge.  Today, we’re going to look at early hip rotation and its effect on maintaining force into the ground longer. This is a big disconnect we often see which ironically begins with the inadequate glute load we talked about in Part 1.

As the pitcher moves towards the target, the hips should hinge back and the knee should bend SLIGHTLY. Loading should continue until the optimal amount of tension is achieved. This is followed by rotation of the back hip and foot. Zach Greinke does a great job of demonstrating this below.

(Zach Greinke)

Every pitcher’s size and strength are different and as a result, so will his timing to reach that optimal amount of tension. Hitting your spots, lighting up the gun and throwing pain free will tell each individual athlete about their optimal time to rotate.

From a force/power standpoint, keeping the back foot remaining flush to the rubber longer ensures proper loading and maintaining force into the ground (Ground Reaction Forces, “GRF”) longer throughout the acceleration phase. The longer we can wait to create the final push, the harder we will hit at foot strike giving us a quicker arm action. Much like a car hitting a wall and the crash test dummy (in our case the arm) goes flying.

(Crash Test Dummies)

From a stability standpoint, once the back foot rotates to the toe, the hip turns, placing the front foot down (foot strike) as the back quad begins to do its thing (which is to help stabilize the hips from the back). This helps create a great, centered position of the front leg in the hip socket at foot strike which in turn sets the foundation for a better positioned body overall. This also better sets up a clear path to transfer energy up the chain and into a better positioned arm.

The graph below is from a 1988 study in The Journal of Applied Biomechanics (click here) that showed throwers with lower velocities reached an average peak ground reaction force earlier than throwers with higher velocities, but it fades quickly. The harder throwers reached their peak ground reaction force later, but sustained it for a longer period of time and closer to their release point.

When coaching ground reaction force, I like to use the cue “push down into the ground while moving forward” (notice I said down not out).

Here’s a great drill that we use to train force into the ground. The King of the Hill footplate gives the athlete an audible clicking sound (objective cuing) when adequate force is being applied.

(Skyler Pichardo / King of the Hill)

Summary

Force production is not only about how much force we can apply, it’s also about how long we can apply that force, as well as how late we can produce our final “push” with the back leg.

See ya in the gym…

 

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