Stanford - Searching For Perfect Golf Swing

[GolfSpy_X]

FULL ARTICLE: http://www.mercurynews.com/health/ci_18586193?nclick_check=1

 

Stanford University cameras have captured that most elusive of things: the perfect golf swing.

 

In a high-tech analysis of golfers -- following the backswing to the follow-through -- a research team identified several key biomechanical factors that produce power, separating the elite professionals from the duffers.

 

By quantifying the ideal motion of the hips and shoulders, the study could reduce injury. And frustration.

 

"A golf swing has a lot of moving parts. This gives the scientific foundation to a motion that is very dynamic and hard to measure," said Conrad Ray, head coach of the university's Cardinal team. "It reduces the guesswork."

 

At the university's Motion and Gait Analysis Lab, 10 pros used a 5 iron to swing at ping-pong balls on a linoleum floor, wearing only shorts and dozens of tiny silver light-reflecting balls. The volunteers were all Stanford alumni and included Will Yanagisawa, a Hawaii Pearl Open winner, and former pro Notah Begay, who is now an analyst with the Golf Channel.

 

Eight cameras made a digital record of their bodies as they turned, twisted and thumped the balls with a club speed averaging almost 80 mph -- then compared the data to the bouncy "worm burning" attempts of amateurs.

 

The team found that professionals' swings are highly consistent, virtually indistinguishable from each other. And the pros, unlike the five amateurs who also volunteered in the study, always initiated their downswing by rotating their hips. On impact with the ball, the pros also shared these other characteristics:

 

A 56 degree difference, on average, in the rotational position of the shoulders and hips.

A 25 degree upward tilt of the leading shoulder.

A 12 degree upward tilt of the leading hip.But before you duffers start packing protractors next to the putter, consider this: Gait and motion analysis at Stanford has a long history, tracing its roots back to pioneering photographer Eadweard Muybridge, who proved that a horse galloping at top speed has all four feet off the ground in mid-stride.

 

Stanford students use modern cameras to study the bowing techniques of violinist Barry Shiffman of the St. Lawrence Quartet, the lightning-fast strikes of tai chi master Chen Xiang and the leaps and spins of dancers with the Merce Cunningham Dance Company.

 

The lab, part of the Lucile Packard Children's Hospital at Stanford, was created to evaluate walking in children with disabilities, such as cerebral palsy.

 

Golf research is a side project. But the team hopes to use its new findings, published in Friday's Journal of Applied Biomechanics, to conduct analyses of swing biomechanics for Bay Area recreational golfers. Offered through Stanford Hospital & Clinics Sports Medicine Clinic, this service should be available by next fall."We wondered: What contributes the most to hitting a ball hard?" said lead investigator Jessica Rose of Lucile Packard Children's Hospital, an associate professor of orthopedic surgery. "With advanced biomechanical analysis, it is now possible to nail down the important elements of the motion."

 

Compared with professionals, amateurs had a narrower average hip-to-shoulder rotation angle of 46 to 48 degrees; as a result, they hit the ball more slowly. And they tilted their hips and shoulders too much, or not enough. Some twisted the upper body too much, while failing to turn the hips enough -- a common cause of back injury.

 

But a perfect technique -- with the correct angles and rotations of hips and shoulders -- created a club head speed that sent a ball soaring.

 

Some professionals can hit a ball well over 300 yards, while amateurs may barely reach 250.

 

It's long been known that correct technique is critical to ball speed. Even at the age of 61, five-time British Open winner Tom Watson can hit a ball with more power, and farther, than fit competitors half his age.

 

"Some great players don't know how they do it. Some know exactly what they do," Ray said. "This provides science."

[GolfSpy WD]

Thanks for the post. I love seeing studies with actual data backing them up. I'm going to download the study and read it to hopefully get some tips

[Tyk]

That should be an interesting study! However, I don't think knowing exactly what shoulder angle, hip turn/shoulder turn, etc is going to make much difference to us weekend warriors. I think most of us know some of our swing flaws as it is and still fight to fix them. I bet most amateurs' problems come as much from a lack of consistency as anything else, and consistency comes from practice and to some extent from just pure talent.

 

I think most pros were first good, naturally talented golfers with a good feel for the game. This initial success led them to put the time and work in to develop their games.

 

I don't think me looking at my buddies going "hey, do you think my hips were tilted 12* on that one?" is ever gonna happen!

[GolfSpy WD]

Definitions:

X-factor (relative hip-shoulder rotation, positive means greater hip rotation, negative means greater shoulder rotation)

O-factor (pelvic obliquity)

S-factor (shoulder obliquity)

Obliquity (deviation from parallelism or perpendicularity; also : the amount of such deviation)

 

Several quotes from the paper:

Downswing was initiated by reversal of pelvic rotation, followed by reversal of upper-torso rotation.

 

The O-factor theory suggests that the angle of a golfer's hips in relation to the horizontal plane should be slightly posi- tive (leading hip elevated) at address, neutral at the top of backswing, and progress to a very positive angle at impact

 

Lindsay and Horton (2002) found that golfers with lower back pain exhibited a “supramaximal” axial rotation of the trunk.

 

The pelvis continued to lead the upper torso throughout downswing. At impact, the upper torso was relatively parallel to the intended line of flight and rotated beyond the pelvis during follow-through

 

Peak X-factor occurred just before peak free moment in all trials of the professional golfers (Figure 2, bottom panel) in late backswing or early downswing. This suggests that peak X-factor may contribute to peak free moment as indicated by the very strong within-subject correlations (Table 2)

 

However, for peak pelvic rotation, there was no significant linear increase from easy, medium, to hard swings (Table 3). This suggests that upper-torso rotation may contribute to X-factor to a greater degree than pelvic rotation

 

Low back injuries are one of the most prevalent injuries in golf (McHardy et al., 2006) and have been shown to be related to an excessive X-factor (Lindsay & Horton, 2002). One case study found that a physical training

program and coaching strategy designed to reduce the X-factor significantly improved low back pain (Grimshaw & Burden, 2000).

 

Being the nerd that I am, I have to say I really enjoyed the paper. Here are my notes:

 

• A positive hip angle is controlled by the bend of your knees. Power is generated by both the rotation of the hips as well as a positive O-factor (angle of your hips compared to a parallel line to the ground).
  
• The hips need to rotate faster than the shoulders during the backswing up to the point of impact, especially right after the start of the downswing. The charts show X factor slowly reduces after the peek at the top of the swing or start of the downswing. Immediately after the club head hits the ground X factor decreases and quickly becomes negative, meaning the shoulder rotate faster than the hips only after impact.
  
• However, excessive X factor where the hips are rotating much faster than the shoulder is a cause of lower back injury. According to the paper, excessive X factor is caused by shoulder rotation, so if you find you have lower back pain, try rotating your shoulders faster.
  

 

I'll have to pay more attention to these things in my swing next time on the range, maybe even get a buddy to record me so I can measure the obliquity angle of my hips/shoulder and eyeball rotation speeds...

[GolfSpy WD]

 

I found it interesting also in this table that the Pros had a lower Peak Upper-Torso and Peak Pelvice Rotation Rotation than 15+ Handicappers, but at impact, both O-factor (pelvic obliquity) and S-factor (shoulder obliquity) were higher, showing tempo and mechanics are much more important than swinging hard.

 

I know tempo+mechanics conclusion shouldn't be surprising, but it is nice to see the numbers.