Linking the Fundamentals of Putting with the Mechanics

Linking The Fundamentals with the Mechanics

Degrees of Freedom: (DOF)

“In mechanics degrees of freedom (DOF) are the set of independent displacements and/or rotations that specify completely the displaced or deformed position and orientation of the body or system. For a rigid body there are six degrees of freedom.”

In the putting stroke, we have many moving parts but we need to lock these parts together to form a rigid system.

We must consider the shoulders, arms, wrists, and hands as parts of a single rigid system to which we attach a putter. Each part of the system is able to move independently which will change the orientation and position of the putter. We can make at least six major movements of the putter using our shoulders, arms, wrists and hands as well as swaying the body left and right.

The most important movements we are able to make in the putting stroke we call the Degrees of Freedom (DOF) as listed below:

1. Moving the putter head Left and Right (in the direction required to make stroke).

2. Moving the putter head Forward and Backward (away from or toward the body).

3. Moving the putter head Up and Down ( off the ground).

4. Opening and Closing the face by rotating the wrists.

5. Swaying the axis point of the spine left and right and thus changing the Swing Radius.

6. Wrist Break, creating an additional second swing axis.

Each DOF (Degree of Freedom) has errors associated with it. For example if we break our wrists during the putting stroke -- depending on the length of the putt etc. -- we have errors associated with synchronizing this additional pivot point with the main pivot point of the system i.e. the spine between the shoulders.

The object in making a putting stroke is to move the putter head into a specific position, with a specific orientation, varying only in head speed to produce a consistent ball direction with a required ball speed.

If we are able to do this by eliminating or minimizing the various movements ( the Degrees of Freedom) we will also minimize or eliminate the associated sources of error and be able to reproduce a more consistent stroke.

FUNDAMENTALS

The Fundamentals of Putting: Because these fundamentals build on each other sequentially they should be presented to the student in the order listed. In this section we are not covering the order of the fundamentals sequentially but rather how they relate to each other regarding the degrees of freedom and the effect on the kinematics of the stroke.

1. Diagnostics

2. Putter Fitting

3. Grip

4. Ball Position

5. Set-up and Alignment

6. Lock and Rock

7. Swing Plane

8. Rhythm

9. Eye Movement (Peripheral Vision)

10. Pre-Shot Routine

11. Green Reading

12. Practice Drills

THE LINKS

It is important to know what the degrees of freedom in a putting stroke are, and how each of these has an associated error. The fundamentals of the putting stroke are designed to reduce the sources of error by minimizing the effect of certain degrees of freedom. This leads to meeting the objective of producing a consistent putting stroke with minimized sources of error.

What we are trying to achieve is to allow the body to make the putting stroke as naturally and error free as possible without unnecessary external forces interfering with a natural motion. We seek to find a path of least resistance.

Taking the fundamentals one at a time -- not necessarily in sequential order -- and using them as building blocks we will see how they synergistically contribute to meeting our objective.

We understand that a smooth, rhythmic stroke with the putter head moving along a preferred path both vertically and horizontally, and oriented correctly at impact will produce the same result. In putting, the club head speed must vary depending on the conditions, but this should not be the result of a change to one of the fundamentals but only an amplitude change of the rhythm with all else remaining the same.

First, we need to fit the student to the correct length putter. This will make it easier to find his/her unique but similar swing plane, with the “system” (shoulders, arms, wrists, hands and the putter) acting as a single unit moving in this, or parallel planes. By understanding the properties of a pendulum and this form of a stroke we can develop a consistent rhythm, the head speed can be varied by working on amplitude, not frequency of the pendulum concept.

Some details about the fundamentals, which result in the preferred kinematics of the stroke, based on the analysis of hundreds of professional golfers follows:

Putter Fitting: fundamental number TWO –

The correct length putter will eliminate many potential sources of error. It will help in maintaining consistent ball position and comfortable posture. It will position the eyes directly over the ball.

It becomes less difficult to align the putter correctly when the target line, the ball, and eyes are in a vertical plane, an extension of which will coincide with optical references such as flag sticks, lamp posts or trees etc.

A correctly fitted putter will lead to a preferred swing plane and a more rhythmic stroke because of relaxed and tension-free arms and grip.

The correct putter length and student physique and posture will dictate the correct swing plane based on the location of the pivot point of the swing the distance between this point and the eyes – vertically over the ball – and the height of the eyes above the putter head at address.

Swing Plane: fundamental number SEVEN.

As mentioned above under putter fitting the swing plane is dictated by specific measurements of the student in the normal address position with a preferred but comfortable posture. This is with the eyes directly over the ball and arms hanging relatively straight and the lower back at about 45 degrees to the vertical [i.e., the trunk is flexed about 45 deg from the vertical?]. The upper portion of the spine is tilted at about ten degrees above the horizontal or in many cases horizontal (see attached sketch).

plane

Sketch I: typical posture for a six-foot male.

This 10-degree angle of the spine is not critical but common. In this postured position, the distance between the eyes and the pivot point (between the shoulders) of the swing for a six-foot male is about 9 inches. His eyes are about 51 inches directly above the putter head.

The putter head should swing in a plane containing the three points – the center of the putter head, the pivot point between the shoulders and the target line (the hole on a straight putt).

The putter head and the pivot point between the shoulders are in a plane titled to the vertical at an angle, the tangent of which is determined by the distance from the eyes (which are vertically above the ball) and the pivot point between the shoulders on the spine (9 inches in the example above) and the vertical dimension from the eyes to the ball ( 51 inches in example above).

In the example above, the plane is at 10 degrees to the vertical. The physique of golfers differ but there is a reasonably good relationship between distance from the eyes to pivot point and the golfers height. Accordingly as a golfer’s height decreases so does the distance from eye-to-ball and eye-to-pivot point. For this reason the tangent (swing plane) remains reasonably constant with a small range of about +/- one degree.

The putter head and full system (i.e. shoulders, arms, wrists, hands and putter) should swing in, or parallel to, the 10 degree (+/- one degree ) plane – defined by stroke pivot point and the putter head -- throughout the putting stroke.

Swinging in this plane without rotating or breaking the wrists will lead to a consistent presentation of the club face angle and head path to the ball at impact. The wrists must remain in position relative to the putter shaft and arms throughout the stroke and not rotate relative to the plane i.e. LOCK and ROCK.

Lock and Rock: fundamental number SIX.

It is important not to break the wrists or change the angle between the shoulders and arms -- i.e. the entire system is one unit. The reason for this is that the if any joint in the system breaks down – becomes flexible -- it is difficult to synchronize this flexing with the rest of the system which leads to a potential source of error.

The concept of lock and rock of the system will also help in maintaining the rotational position of the hands relative to the arms and the rest of the system. The hands do not rotate within the plane even though relative to the horizontal plane the head is describing an arc and relative to the target line will be opening and closing.

Rhythm: fundamental number EIGHT.

A consistent rhythm with only the amplitude of the swing varying – to produce different head speeds – will eliminate the need to change the input force for different lengths of putt. The putting stroke can be thought of as a pendulum stroke, which helps in developing good rhythm, but in fact it is not a true pendulum. The reason for this is that a pendulum swings with a specific cyclical frequency.

The speed of a pendulum varies from zero at the top, or start of the swing to zero half way through each cycle back and forth. The bob of the pendulum accelerates at a decreasing rate for the first quarter of the cycle reaching the maximum speed at the bottom or low point of the path. From this point it will start decelerating until it reaches the high point and half way through its cycle, only to start all over again with a consistent frequency or rhythm.

The putting stroke, however, starts at the low end of the path, at zero speed and should accelerate with almost constant acceleration until it reaches the high point or end of the back-stroke. At this point, the inertia of the system – putter, arms, hands etc. – takes over with a preferred specific frequency due to the forces of gravity. This would be the same frequency as the pendulum with similar properties. This is the rhythm we try to maintain in our putting stroke, or one very close to it.

The difference between this natural inertial frequency and our stroke is small, with the putting stroke being a little faster. Research data shows that a good putting stroke will have the putter head accelerating at a constant rate soon after the start of the down swing allowing it to reach its maximum speed at impact. For this to happen there must be a very small forward force applied to the putter in the plane of the swing.

In trying to get the student to develop the correct rhythm, it is better not to ask him to apply any force to the putter during the down swing. This happens naturally, and in fact, and in most cases, one needs to ask the student not to apply any force on the down swing. This will generally result in a constant acceleration rate to impact.

Talking forces to a student is not wise and only adds confusion unless the student is an elite golfer and even then it is better not to ask the student to apply any force but just let this happen naturally. Most golfers believe that they have to hit the ball and thus apply too much force, which changes the rhythm and acceleration rates from constant to increasing rates. This is the most common problem, which leads to bad rhythm. The best way for all golfers to achieve good rhythm is to think about a pendulum swing in a well-defined swing plane.

With putter fitting, swing plane, rock and lock, and proper rhythm in place we have reduced the sources of potential error in the swing mechanics by minimizing the effects of the degrees of freedom. We need now to work on orientation of the body to produce the correct initial ball direction.

Alignment and Ball Position : fundamentals FOUR and FIVE.

It is preferred that the body be aligned at right angles to the swing plane. This will create the correct clubhead orientation (face angle) to the ball at address and impact. If the swing plane is well defined and this is orthogonal to the target line and the club-face is positioned behind the ball at address, then if this orientation is maintained throughout the swing the ball will travel down the target line.

If for some reason the golfer has a habit of changing something immediately after address, such as a slight rotation of hand position or a forward press resulting in a change to the face angle which may be carried through the back swing and to impact then this may be corrected by a slight change in ball position or a slight adjustment to alignment.

It is most important that the club face angle at impact is correct even though there are slight errors in alignment at address.

NOTE: Other Fundamentals; One (diagnostics), Three (grip), Nine (eye movements), Ten (pre-shot routine), Eleven (green reading), and Twelve (practice drills) are not related directly to degrees of freedom nor do they directly affect the kinematics of the stroke and therefore are not covered in this section of linking the fundamentals to the mechanics.