My coach Nathan Fanger once said to me way back when, in his first year of coaching, “There are a thousand roads to Rome.” The original phrase, if my high school Latin is still with me, ‘Mille viae ducunt homines per saecula Romam’, which means “A thousand roads lead men forever to Rome.” He said this to me in an attempt to get me to come to grips with some my short fallings athletically, every thrower has them, and the reasons I would never have the same technique as the guys I admired at the time. As I thought about this phrase recently I believe it has taken on a dangerous new meaning. Many coaches are now using the spirit of that phrase to take shortcuts in technical progress, and shortcuts affect many throwers progress through their career. The one that comes to mind presently is the popular thought that the rotational shot put technique should end in a linear style push. While mechanically this may look efficient and may be the popular style today, physics tells us differently Newton’s 1st law to be specific.

 

    Newton’s first law says “an object either remains at rest, or continues to move at a constant velocity unless acted upon by an external force”. Velocity is the rate of change in an object. In the rotational events there are two velocities or vectors the implement to be thrown is accelerating through. A linear momentum traveling forward through the circle attached to, in an ideal throw, a fixed rotation (the spine). I believe this is where things get hazy. The linear vector of the implement has nothing to do with upper body producing force, instead the linear vector of the implement thrown is in inherent direction the legs, and center of mass have determined and is not a byproduct of the upper body's rotation. As we know a lack of leg acceleration decreases the velocity of the implement in the intended linear direction, thus the “drop and sweep” was adopted; this not only increased the linear velocity, but turbocharged the rotational velocity. Newton’s law states that an object in motion will stay in the motion unless acted on by an outside force.

 

Dr. Leo D’Acquisto of Central Washington University, as part of his syllabus for his class called anatomical kinesiology, found here http://www.cwu.edu/~acquisto/NLangular.htm, taught a lesson applying Newton’s laws to the leverage systems of the body during athletic movement. He states that

 

“If the mass is concentrated farther away from the axis of rotation, the moment of inertia will be greater, thus the system (i.e., lever) will be harder to start or stop. The greater the moment of inertia, the more difficult it is for an external torque to change the state of rest or uniform motion of a rotating body."

 

This not only states that a negative external force, meaning a force counter to the direction of motion, is unwanted in an accelerating system, but would lead one to the conclusion that shortening a lever during said motion would constitute a negative external force and lessen the acceleratory properties of the object furthest from the axis of rotation. If you consider the shot put thrower system, the axis of rotation is ever shifting but, it’s most central locus in the spine. One reason we don’t want the elbow to drop is not only loss of tension but loss of system speed, the further the shot put is away from the spine it slows the rotational system down, instead of constant acceleration of the implement. This is evidenced by the comparing the best rotational throwers and the best and most appreciated glide shot putters in the Olympic era (i.e. Ulf Timmerman, Werner Gunthor) and their placement of the shot under the chin closer to the axis of rotation. This means there is a physics explanation for the linear vs. rotational differences in style. Now the question is can elements of each style be combined for the best possible acceleration of the implement, specifically a linear push to end a rotational movement.

 

   In proper rotational shot put technique, the movement is started with a shift in body weight to the pivot leg. This essentially shifts the spine and the center of mass over the pivoting point making the turn easier for the body to execute and accelerate. Then is followed by a quick dropping of the center of mass to allow the most centrally located and dense part of the system to accelerate in a linear direction without greatly affecting the rotational path of the implement to be thrown. The same is done in the glide, the unseating motion; this is one of two traits a rotational and a glide technique should share, to maximally accelerate the implement. Whereas the center of mass should do the preliminary pulling of the implement in the glide technique, the opposing leg of the pivot leg initiates the second pull of the implement (the first being from the shift of the spine towards the pivot) by stretching the leg, trunk, and chest muscles in the rotational technique. This is important because why the attempt to resist rotation in the beginning of a linear technique? The answer is acceleration. An outside force creating rotation in an implement that has been set on a linear path slows the implement down for the final movement before the final movement is even thought about. Why would it not be the same changing a rotational path to a linear one. I believe it is. 

 

In the discus we urge patience because a disruption of the elliptical path slows the implement down at the moment of release. The opposite of this is expressed as the athlete “pulling too soon”, having an overactive left side pull instead of a deceleration around which the opposing side can accelerate around, or the body “rushing” expressed as the results of a weak or inactive block leg. This motion is the only possible way to create a linear acceleration at the end of a rotational path in this event. Then why is this seen as beneficial in the shot put? My belief is that the position of the ball, being very close the axis of rotation, is seen as having no, or very little rotational momentum. This by way of anatomy and physics cannot be so. Any object outside of the exact center location of the axis of rotation, has rotational momentum, and is in a natural tendency to continue that motion. For a linear path to be established, from a rotational origin the force exerted to continue acceleration in the in linear path must be massive! The faster an object moves the more mass in inherits, accelerating an already moving object in its intended direction takes far less energy than the force required to change its intended direction, thus making the shot put technically heavier in any other path but the one it is travelling mid throw. For a linear path to be used at the end of a rotational beginning, with the least amount of force exerted, the object must first stop, lose its gained mass, and then be re-accelerated. This is very hard, and extremely taxing to do. It also defeats the main means to throw far, maximum acceleration at release, as the distance of a projectile can be measured by speed of release and angle of release.

 

In order for the shot put to leave its rotational orbit for a linear finish it would have to pass directly over the center of the axis of the throwing system, it cannot maintain rotational momentum. Acceleration of an object must be accomplished by forces in the system. The force in the system of rotation in the human body is a pull by coordinating parts of the body, pulling their muscle systems ahead of the projectile, the process of accelerating an object after the stretch reflex terminates to achieve a particular predetermined position takes a push, but a push as closely behind the center of the object being accelerated is the most efficient way, which is where bench pressing and the subsequent motion come into play at the end of a shot put throw. This is expressed by Dr. D’Acquisto here:

 

“B) 1st Law: A body continues in a state of rest or uniform rotation about its axis unless acted upon by an external torque.

 

1) Eccentric force. A force which is applied off center. In other words, the direction of the force is not in line with the object’s center of gravity. An eccentric force will result in rotation, provided the body is freely moving. External forces applied to the human body are typically eccentric. Rotatory motion of a lever usually results when muscle pulls on bone, providing the external resistance is less than the amount of muscular force acting on the bone.

2) When observing segmental motion of the human body, muscle force is considered an external force.

 

If you consider the entire body undergoing general motion, muscle forces would be considered an internal force. The eccentric force is expressed as a pulling force, a force applied off of the center of the systems axis. Our bodies are made for pulling as the dominant force, many muscles can work together, upon pushing, muscles isolate making this a slower and weaker option for the human body to apply force. This makes pulling the more effective and powerful force, and pulling around a fixed point always results in rotation. The pull in rotational shot put is created by both sides of the body. The left side naturally, and the right leg moving in front of the ball stretching the musculature of the entire right side until it too is drastically ahead of the ball, we call this separation. This acceleration of the ball on a rotational path is then finished with a push directly in line with the balls path until it leaves the system. This is the crux of the problem, while the ball terminates in a linear direction; it is not caused by a linear push that would slow down the shot put and use more energy than necessary as observed by physics. The cessation of the rotation of the implement by the pulling side’s violent deceleration, and the continued pull of the right side causes the linear acceleration and direction of the shot-put, tangentially, this tangent is where the bench press “push” comes in. The push is applied directly in line with the objects momentum tendency, which allows a last second small acceleration, which is why a properly thrown shot put feels lighter on release, than at rest. This is the feel of an effortless throw.

 

I believe this applies to other technical attributes of the throw, for example the right leg drive, or the linear drive of the “knee” to the center of the circle, both of these, and many others, create a linear tendency in a rotational movement, these two things cannot work together to provide the optimum result.

 

While there may be a thousand roads to Rome all of those roads have one thing in common, the led to Rome, which at that time was considered an everlasting constant. Though we strive to increase our athletic ability, we still have the laws of physics which are, and always will be, much stronger than us. While bio mechanists can record force vectors and speeds with great accuracy, the physics are much tougher to extrapolate. In order for us to progress I believe more study is needed in this area. In the last era we have learned how to resist gravity through strength training; we must now learn how to work with physics, the things we can’t change, to progress. We have done this with great and frightening speed in the Hammer with Dr. Anatoly Bondarchuk at the helm; we must now expand his work.