In this section we’ll
look at slow motion videos of some professional golf swings.
The real golf swing is more like a triple pendulum with
the ‘beam’
between the neck and the shoulder forming the third arm of the
pendulum. While watching the
videos, remember the essence of a good golf swing is the reverse of the
ice
skater effect – the transfer of energy with unfolding. The total power
produced
by the golfer (about 2.5 kW for a professional) comes from the
biggest
muscles in the body – the upper legs and torso. The problem is how to
transfer
this power, from the muscles, through the shoulders, arms, club, and
eventually, to the ball.
The
backswing
consists of a large shoulder rotation against
the hips to pretension the muscles of the torso.
minimises the moment of inertia of the arms and
the club by folding the left arm against the shoulders and cocking the
wrists. In all
cases the down swing begins with the left arm folded almost parallel
with
the shoulders, and the club typically cocked to 90 degrees.
The downswing movement
leads with the large muscles of the legs and
torso rotating and building momentum in the hips, with
the
whole folded system -- the upper body, shoulders, arms and club --
moving almost as one.
Once the rotation is firmly established, the
arms swing out – transferring energy from the body to the arms,
then the club swings out, transferring energy
to
the club.
Tiger Woods
Tiger's swing is the
swing closest to the ‘textbook swing’ of the golfers here.
Things to note:
The long extended backswing to create a large
shoulder turn and tension in the muscles of the torso.
The system stays "folded" through the early part of
the
downswing.
Excellent retention of wrist angle well into the
downswing.
Hands slow noticeably as he approaches impact. This
is not
"deceleration" in the golf instructor's [negative] sense; it is caused
by the tension in the shaft exceeding the shoulder torque, and is
evidence of the
transfer of energy from the arms to the clubhead.
Hand, wrist,
and forearm strength are not a factor here -- except to be able to stay
relaxed with the large shaft tension trying to yank the club from
his hands. And the same comment applies to the other videos as well.
Sergio Garcia
Sergio is not as tall
as many pro golfers, so to hit the ball as far as he does he must have
a more
efficient swing. The distinguishing feature here is the large wristcock
midway
through the down swing.
Things to note:
Even more shoulder turn than Tiger.
As he starts the downswing, he actually increases his
wrist cock angle. This "early release" of the club means that he's not
using sufficient positive wrist torque to maintain even a 90º angle.
Midway through the
swing, the wrist cock is probably well under 60º, so that work done
during this
part of the swing is transferred more efficiently to the club when the
wrists
unfold.
That is where his exceptional clubhead speed comes from.
Freddy Couples
Fred has one of the
most admired swings in the game, superficially an easy swing, but he’s
actually
doing a lot of work very early.
The important thing to note here is how Fred starts his downswing. At
the top, his whole body is coiled, including his hips. His first move
is a big rotation of the hips. Everything above the hips turns, but
only because the hips are turning. Everything above the
hips -- torso, shoulders, arms, and club -- are almost frozen, and just
move
with the hips. That is what we mean by "staying folded". The rest is
pure swing -- no hands.
Of course Fred, like Tiger and Sergio, keeps his wrists cocked until
very late in the downswing.
Jamie Sadlowski
Jamie is not a household name for most
golf fans -- unless they are fans of long driving. Jamie, at only 165
pounds, has been the world champion of this sport for the past two
years (2008 and 2009) with record drives
exceeding 400 yards. How does he get the clubhead speed to
accomplish
this against much bigger, more-muscled competitors?
Jamie
is an incredible athlete with extreme
flexibility, and none of us could hope to reproduce this swing. But
because the
downswing is so long, it shows very clearly the ideal of staying
folded.
As a long driver, all of his actions exceed
those of PGA tour golfers: an incredible shoulder turn and even more
incredible
wrist cock. He also has the advantage of a long shaft on the driver
(see next
section on technology).
Many
people have
trouble believing that you do not need to use wrist torque to have an
effective golf swing. But there are some good
examples
from outside golf illustrating this point.
Perhaps the best example is the trebuchet, a medieval siege machine
used to fling rocks a long way. YouTube
has many videos of trebuchets.
Let's see what we can learn from them:
Let's start with a good overview of a working trebuchet from
DGseward.
The raised weight
represents the torque applied through the shoulders,
the long wooden
beam represents the golfers arm,
and the rope sling represents the
shaft of the golf club.
Think about it; if the club had a perfectly
flexible shaft -- like the rope sling of a trebuchet -- then there is
no way to apply wrist torque to get any action from the clubhead. Yet
the trebuchet was a very effective siege weapon. It was the best, most
powerful catapult in warfare for centuries until it was replaced by
gunpowder-powered
cannons, demonstrating that "wrist torque" isn't all that important.
Let's turn DGseward's
video upside-down to show the similarity to the golf swing. It should
look more like a real golf swing this way. The arms accelerate from the
turning "shoulders" (the counterweight), and the club (the rope sling)
lags until it is whipped outward by the tension in the rope.
Trebuchet
competitions remain
something of a sport today. Games include distance and target
competitions, with "punkin chunkin" being an American championship
throwing large pumpkins for maximum distance. Here's a pretty basic
"punkin chunkin" trebuchet.
Finally, if you want to experiment with a trebuchet yourself, here's a
science kit you could build.
Last modified - Jan 25, 2010
Copyright Dave Tutelman
2024 -- All rights reserved
