Anatomy, Physics and the Swing
Chapter One: Guide to the Golf Swing
The golf swing works because muscles contract. The contraction of muscles creates rotation. These are the two keys to the golf swing: muscle contraction and rotation.
Let us start with muscle contraction. Muscles and their related tendons are attached to two different bones. Most muscles function as part of a lever system in which rigid rod (a bone) moves on a fixed point called a fulcrum (a joint) when a force (a muscle contraction) is applied. With levers, a heavy load can be moved with less effort than would otherwise be necessary.
Of course, there is more involved than muscle contraction. A specific muscle will pull a body part in only one direction through its contraction. It cannot push the body part to move in the opposite direction. For that movement, another muscle is necessary. Typically, muscles operate in pairs. “Agonists” are the prime movers that provide the main force. “Antagonists” oppose the action of the “agonists”. To illustrate, to cause a straight arm to bend at the elbow, the biceps on the top of the upper arm are the “agonists” which contract. To straighten the bent arm, the triceps at the back of the upper arm contract; they are the “antagonists”.
Movement will normally involve not only the contraction of the “agonists”, but also the relaxation of the “antagonists”. Our brains manage the relaxation side of movement automatically so that we rarely notice it. This Guide will focus on muscle contraction.
In the golf swing, muscles operate to cause rotation.
Consider the wheels on a car. The engine rotates a shaft to which the wheel is attached. The surface of the wheel is in contact with the road, but is some distance from the rotating shaft. The rotating shaft at the centre of the wheel causes considerable movement at the circumference where the wheel meets the road. One way to look at the golf swing is as a number of rotating shafts, each creating club head movement at the circumference of the circle tracked out by the club head during the swing.
What are these “rotating shafts”?
The eight movements in the golf swing are:
- cocking and uncocking the wrists;
- rotating the forearms at the elbow;
- moving the lead upper arm in the shoulder socket;
- rotating the upper arms within the shoulder sockets;
- moving the shoulder sockets;
- twisting and untwisting the spine;
- rotating the hips; and
- tilting the spine.
For each movement, the Guide will describe the basic anatomy, outline how anatomy is incorporated into the movement, explain why the movement “works” to provide club head speed, and offer tips to improve performance where warranted.