Data reveal biomechanical differences between pro, amateur golfers

Put your hips into it: Stanford medical researchers use 3D digital cameras to determine what biomechanical factors make a professional golfer's swing better.

This weekend, when you're hitting the links, consider that there are very real biomechanical differences between the fluid motion of Phil Mickelson's swing and...well, whatever your brother calls the move that just put his ball into another hazard.

When it comes to striking a golf ball with force, researchers at the Stanford University School of Medicine say they have identified several biomechanical factors that separate the professionals from the amateurs.

The researchers for the first time analyzed the rotational-biomechanic elements of a complete golf stroke, from backswing to follow-through, in an attempt to pinpoint what was most important to power generation.

Using an array of eight special digital cameras in the Motion & Gait Analysis Laboratory at Lucile Packard Children's Hospital at Stanford, the researchers recorded three-dimensional motion images of the golf swings of 10 professional and five amateur male players with a fairly even distribution of handicaps.

Researchers analyzed several biomechanical elements of participants' golf swings.

Among them:

  • S-factor, or the angle or tilt of the leading shoulder relative to the level position;
  • O-factor, or tilt of the hips;
  • X-factor, or the relative rotation of the hips to the shoulders, measured in degrees.

The X-factor is considered key for power generation.

Once the data were gathered, a research team led by professor Jessica Rose generated benchmark curves and discovered that, among professional players, swing biomechanics are highly consistent -- so much so that their movements were often almost indistinguishable from one another.

To wit:

  • Among the pros, peak X-factor was "highly consistent," varying just 7.4 percent from a mean of 56 degrees.
  • The pros' club speeds were also highly consistent, varying just 5.9 percent from a mean of 79 m.p.h.
  • Among the pros, peak S-factor occurred right after impact and was highly consistent, varying just 8.4 percent from a mean of 48 degrees.
  • Among the amateurs, peak X-factor clocked in at a lesser angle: 48, 46 and 46 degrees.
  • The amateurs' club speeds were slower, at 68, 66 and 56 m.p.h.
  • Among the amateurs, peak S-factor clocked in at 42, 42 and 33 degrees.

The study also found that professional golfers' torque was highly consistent, varying just 6.8 percent from the mean.

None of this may be a surprise to you, but the assembly of granular data on an otherwise anecdotal suspicion means that this research could help golfers hit the ball farther without risking injury. (Studies show that improper swings -- especially those channeling Ty Webb or Happy Gilmore, ahem -- are the top cause of golf-related injury.)

Simply: if you want a better golf swing, you need to understand what makes it better in the first place. For example: what starts the downswing? The rotation of the hips, according to this study.

Their findings were published today in the Journal of Applied Biomechanics.

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