Science - Golf not all about wrists

The perfect golf stroke

After decades of research, the world may be closer to the perfect golf swing.

University of Surrey engineer Robin Sharp has found the key is not in using full power from the start, but by building up to it quickly.

Surprisingly, the wrists don't play a critical role in the swing's outcome, according to the new model.

The analysis also shows that while bigger golfers might hit further, it's not by much.

Any golfer will tell you that the idea of swinging harder to hit farther is not as straightforward as it might seem; the new results indicate that how - and when - the power develops is the key to distance.

Tricky balance

Prof Sharp's work is based on a little-used model in which a golfer uses three points of rotation: the shoulders relative to the spine, the arms relative to the shoulders and the wrists relative to the arms.

Conventional wisdom has proven that the timing of these rotations relative to one another is the key to a long drive. However the work, reported in the journal Proceedings of the Royal Society, is the first to optimise those timings and how the power of a swing is developed as they play out.

Prior models assumed one of two things: that the torque - the power in rotation - was applied at its maximum from the backswing, or that it ramped up throughout the swing, reaching its maximum at the point of impact.
Prof Sharp used a computer model first to fit to the swing styles of three professionals whose swings were measured with high-speed photography in 1968: Bernard Hunt, Geoffrey Hunt and Guy Wolstenholme.

The model showed that the club-head speed, and thus drive distance, of these professionals could have been improved by increasing the torque quickly to the maximum value and maintaining it throughout the rest of the swing.

It's a delicate balance, however, and Sunday duffers may find it hard to implement Prof Sharp's prescription.

"Generating too much arm speed too soon causes an early release, with the club-head reaching its maximum speed before it arrives at the ball," he says.

The key, Prof Sharp says, is timing which torques are applied when. And contrary to the old saying, it's not all in the wrists.

"In the expert swings studied, control of the arms and not the wrists appears to be the priority.

"The optimal strategy consists of hitting first with the shoulders while holding back with arms and wrists and, after some delay, hitting through with the arms. At release, the wrists should hit through."

The model also shows that height is not much of an advantage in a long-distance swing.

"A 21 per cent bigger player can be expected to have just a 10 per cent advantage in club-head speed," Prof Sharp said, which he says accounts for the fact that "good little ones are often not so far behind good big ones."

Put into practice

Another person who is familiar with the swings of professional golfers is Simon Wickes, operations manager and biomechanics consultant for the Human Performance facilities at QinetiQ.

In the facility's Biomechanics lab, visitors don a tight-fitting suit covered with reflectors that are tracked by 12 infrared-sensing cameras.

By tracking the independent motions of all the limbs and the club itself, the team can analyse in detail any number of motions, including golf swings, and the lab has been visited by professionals Nick Faldo and Justin Rose.

"We're not golf pros," Mr Wickes explained, "we just show them where we think the problems are occurring."

"What we were seeing with Justin Rose was the club-head and the arms leading the body, rather than the shoulders leading the arms," Mr Wickes said.

It turns out that this reporter too had a problem of stiffness that makes the club lead the body.

"It's something we've seen with other amateurs," Mr Wickes said after an analysis of my swing. "There's this feeling of trying to keep everything in alignment and by doing that you stiffen up because you don't want to have the variability you get if you loosen up your grip and loosen joints."

Useful though it is to know Prof Sharp's result, the perfect swing is not just a matter of the mechanics.