Linear and Rotational Hitting | Hitting Theories vs Science
Helping batters develop swing mechanics that increase their bat speed has been a major goal of both linear and rotational hitting coaches. However, these coaches have very different theories on how bat speed is increased. This article compares the linear and rotational hitting theories for bat speed generation with the laws on science and physics.
Rotational Hitting Theory for Generating Bat Speed
The rotation of the body about a stationary axis supplies the energy for the rotational swing. How that energy is converted into bat speed generation is based on a law of physics. That law states: "An object tends to stay tangent to the direction of force." At Batspeed.com, we refer to the angular acceleration of the bat induced from this law as the pendulum effect.
An analogy for how the pendulum effect generates bat speed would be like - swinging a ball around on a string. -- When the hand is rotated in a circular path, the ball will accelerate around the hand. The same is true in the baseball and softball swing. When the hands are rotated in a circular path, the bat head will accelerate around the hands. Put in more scientific terms, an angular displacement rate of the hands induces an angular displacement rate to the bat.
Linear Hitting Theory for Generating Bat Speed
Rotational theory for bat speed generation is very different from the linear theory. The linear theory is based on a Crack of the Whip analogy. The Crack of the Whip analogy, explained below, is based on the batter's forward weight shift and quick (A to B) extension of the hands. Linear coaches believe this action transfers the body's kinetic energy into bat speed.
Some linear coaches have batters "snap" a towel by quickly extending and stopping the hand. This was supposed to represent what happened to the bat head. However, a rigid bat cannot unfold like a towel. As the Batspeed.com video below explains, angular acceleration of the bat requires the hands to be rotated in a circular path. Nevertheless, most batting instruction, tips and drills are based on the linear (A to B) extension theory.
"Crack of the Whip" Theory vs Physic Laws
I can safely say that Batspeed.com was the leader in disproving the "Crack of the Whip" theory as it pertains to the baseball swing. In the early 1990's, I took "The Physics of Baseball," written by Robert K. Adair to Physics Labs in Southern California. His book basically outlines the linear theory for bat speed generation. I asked the Professors at the Labs to evaluate Batspeed.com's rotational principles governing bat speed generation to those of the whip theory as outlined in Adair's book.
At the labs, tests and discussions of physics principles that govern the angular acceleration of the bat were conducted. The lab's findings from these tests concluded that the Crack of the Whip Theory, as it pertains to the baseball swing was flawed. For the speed and path of the hands to induce angular acceleration of the bat, the direction of force of the hands must take a circular path.
Note: Many of the terms Batspeed.com use to describe batting mechanics came from terminology used in the Labs discussions. Also, tests ran at the labs greatly influenced our product selection and hitting instructions.
Below is an excerpt from Adair's book, discussed above, that covers the linear theory for bat speed generation:
As the swing begins, the batter strides forward transferring his weight from his back leg to a stiff front leg. As the hands accelerate, the force from the reaction of the bat, transmitted through the hands and arms, slows down the body's forward motion and rotation. As the body slows, the hands that had been accelerated to approximately 15 MPH, also slows to a near stop. The body's kinetic energy is then transferred to the bat as forces uncocks the wrist. During this time (as the hands slows and wrist uncock) the kinetic energy that was stored in the body is transferred to bat. This kinetic energy transfer accelerates the bat head from about 40 to 70+ MPH.
Linear hitting is based on the erroneous belief that - if the batter quickly extends or throws the hands at the ball - the bat head will snap around like the crack of a whip. Unfortunately, this fallacy has wasted countless batting hours spent on the tee and in batting cages.