I must admit all this science of the golf swing is becoming very confusing.
We have Rod White from Dave Tutelmans website claiming the following:
Double Pendulum SwingThe only two factors included in this model that are within the golfer’s control are:
The wrist-cock angle (make smaller). That is why many of the longest hitters have a very acute lag angle well into the downswing. (We shall see this in the videos later.)
Shaft length (make longer). But shaft length is limited by the rules, and in many cases further limited by the individual golfer's ability to control a long club. Long drivers routinely use long shafts, but they too are limited by their competition rules.
In summary...
The ice skater:
First builds speed in arms,
then folds the arms close to the body,
to speed up the body
The golfer:
First builds speed in body,
then unfolds the club from the body,
to speed up the club.
The unfolding of the club from the cocked position causes rotational energy to be transferred from the arms and the body to the club, and that this unfolding can be passive requiring no effort from the golfer.
Driven Double PendulumDuring the first part of the downswing, the golfer holds the club in a cocked position and accelerates the shoulders and torso. Initially some positive wrist torque is required to stop the club from being pulled into the golfers neck (the hub). Remember the passive, steadily rotating model on the previous page? There, a string (providing negative torque) was needed to keep the club from swinging outward. Here, during the initial build up of speed, some sort of "brace" (providing positive torque) is needed prevent the club from being pulled inward. The positive torque required to brace the club falls rapidly as the club accelerates. When the positive ‘bracing’ torque falls to zero, the club can be allowed to swing out -- ending the first phase.
The second phase of the downswing occurs as the club swings out. If the golfer lets the club swing out when the bracing torque falls to zero, then this is described as a swing with a natural release. If the golfer holds the club in the cocked position for a short while longer, this is described as a late release. If the golfer releases the club early, the club will swing in towards the neck for a small moment and then swing out. We won’t look at the effect of release timing because to a good approximation release timing has no effect.
During the second phase the golfer continues to turn his body and arms, but no torque is applied via the hands – they are no more than a hinge during this phase.
The normal golf swing does not require positive or negative wrist torque during the second phase of the downswing; therefore the hands are passive, and the golf stroke can be more accurate with fewer muscles involved.
Now we’ll take a look at the factors that affect the effectiveness of the swing. The two big factors are the wrist cock angle and the wrist torque. Since greater wrist cock increases the divergence of the trajectories of the hands and the clubhead, we can expect greater wrist cock (smaller wrist-cock angle) to improve the swing.
Summary for TechniqueWork done by the golfer builds up kinetic energy in the torso, shoulders, and arms. This is then transferred via tension in the shaft as the club and arms unfold away from the golfer’s body.
The good:
the greater the fold (wrist cock) the more efficient the transfer of energy from the body to the club.
The bad: the greater the wrist torque (use of the hands) the earlier the club unfolds and the less energy is transferred to the club.
These two effects, the negative effect of wrist torque and the positive effect of wrist cock, account for most of the 70 m difference between the beginner and the scratch golfer.
Dave Tutelman You will
note that using your hands and wrists to retain the lag (as opposed to forcefully helping release the lag) will actually increase clubhead speedI subscribe to golf instruction that says that the
hands are moved by the body. But that is not the only theory of instruction out there; I have read books that say things like, "The arms do the swinging part of the golf swing... The body does not swing. It reacts to the swing." I may disagree with that, but it might be a productive intent and feel for some golfers. And that makes it valid instruction for those golfers.
But -- make no mistake about this --
physics says that hand and arm motion is caused by body rotation. That is actual, as opposed to intent and feel. So, if we are going to analyze the physics of the swing, the motion of the hands and arms is driven by the body rotation. For the first approximation, we do not have to analyze hands and arms separately, just the body rotation -- which we discussed above. (
If we were to refine the analysis, which I won't here, we would next account for the left arm's separation from the body late in the downswing. Still nowhere near "arms motivating the swing", but at least there may be some change of the result due to the rotation of the arm not being exactly the same as the rotation of the body.)
"Accelerate though the ball" is an excellent swing key, for every shot from a drive to a putt.
But it is better expressed as
"rotate your body through the ball" (or perhaps "accelerate moving your hands beyond the ball"), because it is body rotation or "turning the triangle" where acceleration through the ball is beneficial. Consciously accelerating the clubhead through the ball (especially if you do it with the hands, wrists, or forearms) will probably do more harm than good.
Sasho MackenzieIndividual golfers do multiple times more linear work, relative to angular work, during the golf swing and linear work also accounts for the vast majority of differences in clubhead speed between golfers. Methods of training that increase the average force applied in the direction of the hand path during the down swing have the greatest probability in generating increases in clubhead speed. From a more practical standpoint, results from this study suggest that for amateur golfers, increasing the length of the hand
path is more likely to increase clubhead speed than rotating the shaft through a larger angle. Future research should focus on the reasons why golfers of similar
physical abilities are able to generate different levels of force in the direction of the hand path during the downswing.
There have been studies about the relationship between
delayed wrist release and club head speed, but that correlation is closer to 0.4.Improve Club Head Speed By Increasing Vertical Force At A Specific Point In The Downswing - Sasho ran the correlation on four studies he’d performed they came back at 0.84, 0.87, 0.82, and 0.91, respectively
Also we have the SMK passive torque concept for squaring the clubface .
A faster backswing means a greater starting force magnitude in the downswing (ie. having to apply a greater force to stop the club in the backswing) so that one can apply a greater average force over the hand path distance (creating more kinetic energy in the clubhead).
His claim that it is mainly the 'in plane MOF' that applies 'torque' to increase the angular velocity of the club from just after P6 to P7 (as shown in his vimeo video below).
vimeo.com/158856998He also says on his twitter account that he has never seen the 'In Plane MOF' peak before impact for any PGA Pro Tour swings he's seen.
Also he says that COAM doesn't apply to the 'golfer /club' system (see image below).
Dr Kwon - Ground force reaction and moment arm concepts.
So this mish-mash of golf science is very frustrating and I'm hoping Dr Mann's new theories will help make some sense of it all.
DG